what is a three dimensional image produced by laser light

In its pure form, holography requires the use of laser light for illuminating the subject and for viewing the finished hologram. In a side-by-side comparison under optimal conditions, a holographic image is visually indistinguishable from the actual subject. A microscopic level of detail throughout the recorded volume of space can be reproduced. In common practice, however, major image quality compromises are made to eliminate the need for laser illumination when viewing the hologram, and sometimes, to the extent possible, also when making it. Holographic portraiture often resorts to a non-holographic intermediate imaging procedure, to avoid the hazardous high-powered pulsed lasers otherwise needed to optically "freeze" living subjects as perfectly as the extremely motion-intolerant holographic recording process requires. Holograms can now also be entirely computer-generated to show objects or scenes that never existed.

Holography

Holography is the science and practice of making holograms. Typically, a hologram is a photographic recording of a light field, rather than of an image formed by a lens, and it is used to display a fully three-dimensional image of the holographed subject, which is seen without the aid of special glasses or other intermediate optics. The hologram itself is not an image and it is usually unintelligible when viewed under diffuse ambient light. It is an encoding of the light field as an interference pattern of seemingly random variations in the opacity, density, or surface profile of the photographic medium. When suitably lit, the interference pattern diffracts the light into a reproduction of the original light field and the objects that were in it appear to still be there, exhibiting visual depth cues such as parallax and perspective that change realistically with any change in the relative position of the observer.

Holography is distinct from lenticular and other earlier autostereoscopic 3D display technologies, which can produce superficially similar results but are based on conventional lens imaging. Stage illusions such as Pepper's Ghost and other unusual, baffling, or seemingly magical images are also often incorrectly called holograms.

The Hungarian-British physicist Dennis Gabor (in Hungarian: Gábor Dénes)[1][2] was awarded the Nobel Prize in Physics in 1971 "for his invention and development of the holographic method".[3] His work, done in the late 1940s, was built on pioneering work in the field of X-ray microscopy by other scientists including Mieczysław Wolfke in 1920 and William Lawrence Bragg in 1939.[4] The discovery was an unexpected result of research into improving electron microscopes at the British Thomson-Houston (BTH) Company in Rugby, England, and the company filed a patent in December 1947 (patent GB685286). The technique as originally invented is still used in electron microscopy, where it is known as electron holography, but optical holography did not really advance until the development of the laser in 1960. The word holography comes from the Greek words ὅλος (holos; "whole") and γραφή (graphē; "writing" or "drawing").

The development of the laser enabled the first practical optical holograms that recorded 3D objects to be made in 1962 by Yuri Denisyuk in the Soviet Union[5] and by Emmett Leith and Juris Upatnieks at the University of Michigan, USA.[6] Early holograms used silver halide photographic emulsions as the recording medium. They were not very efficient as the produced grating absorbed much of the incident light. Various methods of converting the variation in transmission to a variation in refractive index (known as "bleaching") were developed which enabled much more efficient holograms to be produced.[7][8][9]

Several types of holograms can be made. Transmission holograms, such as those produced by Leith and Upatnieks, are viewed by shining laser light through them and looking at the reconstructed image from the side of the hologram opposite the source.[10] A later refinement, the "rainbow transmission" hologram, allows more convenient illumination by white light rather than by lasers.[11] Rainbow holograms are commonly used for security and authentication, for example, on credit cards and product packaging.[12]

Another kind of common hologram, the reflection or Denisyuk hologram, can also be viewed using a white-light illumination source on the same side of the hologram as the viewer and is the type of hologram normally seen in holographic displays. They are also capable of multicolour-image reproduction.[13]

Specular holography is a related technique for making three-dimensional images by controlling the motion of specularities on a two-dimensional surface.[14] It works by reflectively or refractively manipulating bundles of light rays, whereas Gabor-style holography works by diffractively reconstructing wavefronts.

Most holograms produced are of static objects but systems for displaying changing scenes on a holographic volumetric display are now being developed.[15][16][17]

Holograms can also be used to store, retrieve, and process information optically.[18]

In its early days, holography required high-power expensive lasers, but nowadays, mass-produced low-cost semi-conductor or diode lasers, such as those found in millions of DVD recorders and used in other common applications, can be used to make holograms and have made holography much more accessible to low-budget researchers, artists and dedicated hobbyists.

It was thought that it would be possible to use X-rays to make holograms of very small objects and view them using visible light.[citation needed] Today, holograms with x-rays are generated by using synchrotrons or x-ray free-electron lasers as radiation sources and pixelated detectors such as CCDs as recording medium.[19] The reconstruction is then retrieved via computation. Due to the shorter wavelength of x-rays compared to visible light, this approach allows imaging objects with higher spatial resolution.[20] As free-electron lasers can provide ultrashort and x-ray pulses in the range of femtoseconds which are intense and coherent, x-ray holography has been used to capture ultrafast dynamic processes.[21][22][23]

Holography is a technique that enables a light field, which is generally the product of a light source scattered off objects, to be recorded and later reconstructed when the original light field is no longer present, due to the absence of the original objects.[24] Holography can be thought of as somewhat similar to sound recording, whereby a sound field created by vibrating matter like musical instruments or vocal cords, is encoded in such a way that it can be reproduced later, without the presence of the original vibrating matter.

In laser holography, the hologram is recorded using a source of laser light, which is very pure in its color and orderly in its composition. Various setups may be used, and several types of holograms can be made, but all involve the interaction of light coming from different directions and producing a microscopic interference pattern which a plate, film, or other medium photographically records.

In one common arrangement, the laser beam is split into two, one known as the object beam and the other as the reference beam. The object beam is expanded by passing it through a lens and used to illuminate the subject. The recording medium is located where this light, after being reflected or scattered by the subject, will strike it. The edges of the medium will ultimately serve as a window through which the subject is seen, so its location is chosen with that in mind. The reference beam is expanded and made to shine directly on the medium, where it interacts with the light coming from the subject to create the desired interference pattern.

Like conventional photography, holography requires an appropriate exposure time to correctly affect the recording medium. Unlike conventional photography, during the exposure the light source, the optical elements, the recording medium, and the subject must all remain perfectly motionless relative to each other, to within about a quarter of the wavelength of the light, or the interference pattern will be blurred and the hologram spoiled. With living subjects and some unstable materials, that is only possible if a very intense and extremely brief pulse of laser light is used, a hazardous procedure which is rare and rarely done outside of scientific and industrial laboratory settings. Exposures lasting several seconds to several minutes, using a much lower-powered continuously operating laser, are typical.

A hologram can be made by shining part of the light beam directly into the recording medium, and the other part onto the object in such a way that some of the scattered light falls onto the recording medium. A more flexible arrangement for recording a hologram requires the laser beam to be aimed through a series of elements that change it in different ways. The first element is a beam splitter that divides the beam into two identical beams, each aimed in different directions:

Several different materials can be used as the recording medium. One of the most common is a film very similar to photographic film (silver halide photographic emulsion), but with a much higher concentration of light-reactive grains, making it capable of the much higher resolution that holograms require. A layer of this recording medium (e.g., silver halide) is attached to a transparent substrate, which is commonly glass, but may also be plastic.

When the two laser beams reach the recording medium, their light waves intersect and interfere with each other. It is this interference pattern that is imprinted on the recording medium. The pattern itself is seemingly random, as it represents the way in which the scene's light interfered with the original light source — but not the original light source itself. The interference pattern can be considered an encoded version of the scene, requiring a particular key — the original light source — in order to view its contents.

This missing key is provided later by shining a laser, identical to the one used to record the hologram, onto the developed film. When this beam illuminates the hologram, it is diffracted by the hologram's surface pattern. This produces a light field identical to the one originally produced by the scene and scattered onto the hologram.

Holography may be better understood via an examination of its differences from ordinary photography:

For a better understanding of the process, it is necessary to understand interference and diffraction. Interference occurs when one or more wavefronts are superimposed. Diffraction occurs when a wavefront encounters an object. The process of producing a holographic reconstruction is explained below purely in terms of interference and diffraction. It is somewhat simplified, but is accurate enough to give an understanding of how the holographic process works.

For those unfamiliar with these concepts, it is worth while to read those articles before reading further in this article.

A diffraction grating is a structure with a repeating pattern. A simple example is a metal plate with slits cut at regular intervals. A light wave that is incident on a grating is split into several waves; the direction of these diffracted waves is determined by the grating spacing and the wavelength of the light.

A simple hologram can be made by superimposing two plane waves from the same light source on a holographic recording medium. The two waves interfere, giving a straight-line fringe pattern whose intensity varies sinusoidally across the medium. The spacing of the fringe pattern is determined by the angle between the two waves, and by the wavelength of the light.

The recorded light pattern is a diffraction grating. When it is illuminated by only one of the waves used to create it, it can be shown that one of the diffracted waves emerges at the same angle as that at which the second wave was originally incident, so that the second wave has been'reconstructed'. Thus, the recorded light pattern is a holographic recording as defined above.

If the recording medium is illuminated with a point source and a normally incident plane wave, the resulting pattern is a sinusoidal zone plate, which acts as a negative Fresnel lens whose focal length is equal to the separation of the point source and the recording plane.

When a plane wave-front illuminates a negative lens, it is expanded into a wave that appears to diverge from the focal point of the lens. Thus, when the recorded pattern is illuminated with the original plane wave, some of the light is diffracted into a diverging beam equivalent to the original spherical wave; a holographic recording of the point source has been created.

When the plane wave is incident at a non-normal angle at the time of recording, the pattern formed is more complex, but still acts as a negative lens if it is illuminated at the original angle.

To record a hologram of a complex object, a laser beam is first split into two beams of light. One beam illuminates the object, which then scatters light onto the recording medium. According to diffraction theory, each point in the object acts as a point source of light so the recording medium can be considered to be illuminated by a set of point sources located at varying distances from the medium.

The second (reference) beam illuminates the recording medium directly. Each point source wave interferes with the reference beam, giving rise to its own sinusoidal zone plate in the recording medium. The resulting pattern is the sum of all these 'zone plates', which combine to produce a random (speckle) pattern as in the photograph above.

When the hologram is illuminated by the original reference beam, each of the individual zone plates reconstructs the object wave that produced it, and these individual wavefronts are combined to reconstruct the whole of the object beam. The viewer perceives a wavefront that is identical witg the wavefront scattered from the object onto the recording medium, so that it appears that the object is still in place even if it has been removed.

A single-frequency light wave can be modeled by a complex number, U, which represents the electric or magnetic field of the light wave. The amplitude and phase of the light are represented by the absolute value and angle of the complex number. The object and reference waves at any point in the holographic system are given by UO and UR. The combined beam is given by UO + UR. The energy of the combined beams is proportional to the square of magnitude of the combined waves as

If a photographic plate is exposed to the two beams and then developed, its transmittance, T, is proportional to the light energy that was incident on the plate and is given by

where k is a constant.

When the developed plate is illuminated by the reference beam, the light transmitted through the plate, UH, is equal to the transmittance, T, multiplied by the reference beam amplitude, UR, giving

It can be seen that UH has four terms, each representing a light beam emerging from the hologram. The first of these is proportional to UO. This is the reconstructed object beam, which enables a viewer to'see' the original object even when it is no longer present in the field of view.

The second and third beams are modified versions of the reference beam. The fourth term is the "conjugate object beam". It has the reverse curvature to the object beam itself and forms a real image of the object in the space beyond the holographic plate.

When the reference and object beams are incident on the holographic recording medium at significantly different angles, the virtual, real, and reference wavefronts all emerge at different angles, enabling the reconstructed object to be seen clearly.

To make a hologram, the following are required:

These requirements are inter-related, and it is essential to understand the nature of optical interference to see this. Interference is the variation in intensity which can occur when two light waves are superimposed. The intensity of the maxima exceeds the sum of the individual intensities of the two beams, and the intensity at the minima is less than this and may be zero. The interference pattern maps the relative phase between the two waves, and any change in the relative phases causes the interference pattern to move across the field of view. If the relative phase of the two waves changes by one cycle, then the pattern drifts by one whole fringe. One phase cycle corresponds to a change in the relative distances travelled by the two beams of one wavelength. Since the wavelength of light is of the order of 0.5 μm, it can be seen that very small changes in the optical paths travelled by either of the beams in the holographic recording system lead to movement of the interference pattern which is the holographic recording. Such changes can be caused by relative movements of any of the optical components or the object itself, and also by local changes in air-temperature. It is essential that any such changes are significantly less than the wavelength of light if a clear well-defined recording of the interference is to be created.

The exposure time required to record the hologram depends on the laser power available, on the particular medium used and on the size and nature of the object(s) to be recorded, just as in conventional photography. This determines the stability requirements. Exposure times of several minutes are typical when using quite powerful gas lasers and silver halide emulsions. All the elements within the optical system have to be stable to fractions of a μm over that period. It is possible to make holograms of much less stable objects by using a pulsed laser which produces a large amount of energy in a very short time (μs or less).[26] These systems have been used to produce holograms of live people. A holographic portrait of Dennis Gabor was produced in 1971 using a pulsed ruby laser.[27][28]

Thus, the laser power, recording medium sensitivity, recording time and mechanical and thermal stability requirements are all interlinked. Generally, the smaller the object, the more compact the optical layout, so that the stability requirements are significantly less than when making holograms of large objects.

Another very important laser parameter is its coherence.[29] This can be envisaged by considering a laser producing a sine wave whose frequency drifts over time; the coherence length can then be considered to be the distance over which it maintains a single frequency. This is important because two waves of different frequencies do not produce a stable interference pattern. The coherence length of the laser determines the depth of field which can be recorded in the scene. A good holography laser will typically have a coherence length of several meters, ample for a deep hologram.

The objects that form the scene must, in general, have optically rough surfaces so that they scatter light over a wide range of angles. A specularly reflecting (or shiny) surface reflects the light in only one direction at each point on its surface, so in general, most of the light will not be incident on the recording medium. A hologram of a shiny object can be made by locating it very close to the recording plate.[30]

There are three important properties of a hologram which are defined in this section. A given hologram will have one or other of each of these three properties, e.g. an amplitude modulated thin transmission hologram, or a phase modulated, volume reflection hologram.

An amplitude modulation hologram is one where the amplitude of light diffracted by the hologram is proportional to the intensity of the recorded light. A straightforward example of this is photographic emulsion on a transparent substrate. The emulsion is exposed to the interference pattern, and is subsequently developed giving a transmittance which varies with the intensity of the pattern â€“ the more light that fell on the plate at a given point, the darker the developed plate at that point.

A phase hologram is made by changing either the thickness or the refractive index of the material in proportion to the intensity of the holographic interference pattern. This is a phase grating and it can be shown that when such a plate is illuminated by the original reference beam, it reconstructs the original object wavefront. The efficiency (i.e., the fraction of the illuminated object beam which is converted into the reconstructed object beam) is greater for phase than for amplitude modulated holograms.

A thin hologram is one where the thickness of the recording medium is much less than the spacing of the interference fringes which make up the holographic recording. The thickness of a thin hologram can be down to 60Â nm by using a topological insulator material Sb2Te3 thin film.[31] Ultrathin holograms hold the potential to be integrated with everyday consuming electronics like smartphones.

A thick or volume hologram is one where the thickness of the recording medium is greater than the spacing of the interference pattern. The recorded hologram is now a three dimensional structure, and it can be shown that incident light is diffracted by the grating only at a particular angle, known as the Bragg angle.[32] If the hologram is illuminated with a light source incident at the original reference beam angle but a broad spectrum of wavelengths; reconstruction occurs only at the wavelength of the original laser used. If the angle of illumination is changed, reconstruction will occur at a different wavelength and the colour of the re-constructed scene changes. A volume hologram effectively acts as a colour filter.

A transmission hologram is one where the object and reference beams are incident on the recording medium from the same side. In practice, several more mirrors may be used to direct the beams in the required directions.

Normally, transmission holograms can only be reconstructed using a laser or a quasi-monochromatic source, but a particular type of transmission hologram, known as a rainbow hologram, can be viewed with white light.

In a reflection hologram, the object and reference beams are incident on the plate from opposite sides of the plate. The reconstructed object is then viewed from the same side of the plate as that at which the re-constructing beam is incident.

Only volume holograms can be used to make reflection holograms, as only a very low intensity diffracted beam would be reflected by a thin hologram.

The recording medium has to convert the original interference pattern into an optical element that modifies either the amplitude or the phase of an incident light beam in proportion to the intensity of the original light field.

The recording medium should be able to resolve fully all the fringes arising from interference between object and reference beam. These fringe spacings can range from tens of micrometers to less than one micrometer, i.e. spatial frequencies ranging from a few hundred to several thousand cycles/mm, and ideally, the recording medium should have a response which is flat over this range. photographic film has a very low or even zero response at the frequencies involved and cannot be used to make a hologram – see, for example, Kodak's professional black and white film[33] whose resolution starts falling off at 20 lines/mm — it is unlikely that any reconstructed beam could be obtained using this film.

If the response is not flat over the range of spatial frequencies in the interference pattern, then the resolution of the reconstructed image may also be degraded.[34][35]

The table below shows the principal materials used for holographic recording. Note that these do not include the materials used in the mass replication of an existing hologram, which are discussed in the next section. The resolution limit given in the table indicates the maximal number of interference lines/mm of the gratings. The required exposure, expressed as millijoules (mJ) of photon energy impacting the surface area, is for a long exposure time. Short exposure times (less than 1⁄1000 of a second, such as with a pulsed laser) require much higher exposure energies, due to reciprocity failure.

An existing hologram can be copied by embossing[37] or optically.[38]

Most holographic recordings (e.g. bleached silver halide, photoresist, and photopolymers) have surface relief patterns which conform with the original illumination intensity. Embossing, which is similar to the method used to stamp out plastic discs from a master in audio recording, involves copying this surface relief pattern by impressing it onto another material.

The first step in the embossing process is to make a stamper by electrodeposition of nickel on the relief image recorded on the photoresist or photothermoplastic. When the nickel layer is thick enough, it is separated from the master hologram and mounted on a metal backing plate. The material used to make embossed copies consists of a polyester base film, a resin separation layer and a thermoplastic film constituting the holographic layer.

The embossing process can be carried out with a simple heated press. The bottom layer of the duplicating film (the thermoplastic layer) is heated above its softening point and pressed against the stamper, so that it takes up its shape. This shape is retained when the film is cooled and removed from the press. In order to permit the viewing of embossed holograms in reflection, an additional reflecting layer of aluminum is usually added on the hologram recording layer. This method is particularly suited to mass production.

The first book to feature a hologram on the front cover was The Skook (Warner Books, 1984) by JP Miller, featuring an illustration by Miller. The first record album cover to have a hologram was UB40 - "UB44" this album cover was produced in 1982 for the British group UB40 by Advanced Holographics in Loughborough. This featured a 5.75" square embossed hologram showing a 3D image of the letters UB carved out of polystyrene to look like stone and the numbers 44 hovering in space on the picture plane. On the inner sleeve was an explanation of the holographic process and instructions on how to light the hologram and National Geographic published the first magazine with a hologram cover in March 1984.[39] Embossed holograms are used widely on credit cards, banknotes, and high value products for authentication purposes.[40]

It is possible to print holograms directly into steel using a sheet explosive charge to create the required surface relief.[41] The Royal Canadian Mint produces holographic gold and silver coinage through a complex stamping process.[42]

A hologram can be copied optically by illuminating it with a laser beam, and locating a second hologram plate so that it is illuminated both by the reconstructed object beam, and the illuminating beam. Stability and coherence requirements are significantly reduced if the two plates are located very close together.[43] An index matching fluid is often used between the plates to minimize spurious interference between the plates. Uniform illumination can be obtained by scanning point-by-point or with a beam shaped into a thin line.

When the hologram plate is illuminated by a laser beam identical to the reference beam which was used to record the hologram, an exact reconstruction of the original object wavefront is obtained. An imaging system (an eye or a camera) located in the reconstructed beam'sees' exactly the same scene as it would have done when viewing the original. When the lens is moved, the image changes in the same way as it would have done when the object was in place. If several objects were present when the hologram was recorded, the reconstructed objects move relative to one another, i.e. exhibit parallax, in the same way as the original objects would have done. It was very common in the early days of holography to use a chess board as the object and then take photographs at several different angles using the reconstructed light to show how the relative positions of the chess pieces appeared to change.

A holographic image can also be obtained using a different laser beam configuration to the original recording object beam, but the reconstructed image will not match the original exactly.[44] When a laser is used to reconstruct the hologram, the image is speckled just as the original image will have been. This can be a major drawback in viewing a hologram.

White light consists of light of a wide range of wavelengths. Normally, if a hologram is illuminated by a white light source, each wavelength can be considered to generate its own holographic reconstruction, and these will vary in size, angle, and distance. These will be superimposed, and the summed image will wipe out any information about the original scene, as if superimposing a set of photographs of the same object of different sizes and orientations. However, a holographic image can be obtained using white light in specific circumstances, e.g. with volume holograms and rainbow holograms. The white light source used to view these holograms should always approximate to a point source, i.e. a spot light or the sun. An extended source (e.g. a fluorescent lamp) will not reconstruct a hologram since its light is incident at each point at a wide range of angles, giving multiple reconstructions which will "wipe" one another out.

White light reconstructions do not contain speckles.

A reflection-type volume hologram can give an acceptably clear reconstructed image using a white light source, as the hologram structure itself effectively filters out light of wavelengths outside a relatively narrow range. In theory, the result should be an image of approximately the same colour as the laser light used to make the hologram. In practice, with recording media that require chemical processing, there is typically a compaction of the structure due to the processing and a consequent colour shift to a shorter wavelength. Such a hologram recorded in a silver halide gelatin emulsion by red laser light will usually display a green image. Deliberate temporary alteration of the emulsion thickness before exposure, or permanent alteration after processing, has been used by artists to produce unusual colours and multicoloured effects.

In this method, parallax in the vertical plane is sacrificed to allow a bright, well-defined, gradiently colored reconstructed image to be obtained using white light. The rainbow holography recording process usually begins with a standard transmission hologram and copies it using a horizontal slit to eliminate vertical parallax in the output image. The viewer is therefore effectively viewing the holographic image through a narrow horizontal slit, but the slit has been expanded into a window by the same dispersion that would otherwise smear the entire image. Horizontal parallax information is preserved but movement in the vertical direction results in a color shift rather than altered vertical perspective.[45] Because perspective effects are reproduced along one axis only, the subject will appear variously stretched or squashed when the hologram is not viewed at an optimum distance; this distortion may go unnoticed when there is not much depth, but can be severe when the distance of the subject from the plane of the hologram is very substantial. Stereopsis and horizontal motion parallax, two relatively powerful cues to depth, are preserved.

The holograms found on credit cards are examples of rainbow holograms. These are technically transmission holograms mounted onto a reflective surface like a metalized polyethylene terephthalate substrate commonly known as PET.

To replicate the original object beam exactly, the reconstructing reference beam must be identical to the original reference beam and the recording medium must be able to fully resolve the interference pattern formed between the object and reference beams.[46] Exact reconstruction is required in holographic interferometry, where the holographically reconstructed wavefront interferes with the wavefront coming from the actual object, giving a null fringe if there has been no movement of the object and mapping out the displacement if the object has moved. This requires very precise relocation of the developed holographic plate.

Any change in the shape, orientation or wavelength of the reference beam gives rise to aberrations in the reconstructed image. For instance, the reconstructed image is magnified if the laser used to reconstruct the hologram has a shorter wavelength than the original laser. Nonetheless, good reconstruction is obtained using a laser of a different wavelength, quasi-monochromatic light or white light, in the right circumstances.

Since each point in the object illuminates all of the hologram, the whole object can be reconstructed from a small part of the hologram. Thus, a hologram can be broken up into small pieces and each one will enable the whole of the original object to be imaged. One does, however, lose information and the spatial resolution gets worse as the size of the hologram is decreased â€” the image becomes "fuzzier". The field of view is also reduced, and the viewer will have to change position to see different parts of the scene.

Early on, artists saw the potential of holography as a medium and gained access to science laboratories to create their work. Holographic art is often the result of collaborations between scientists and artists, although some holographers would regard themselves as both an artist and a scientist.

Salvador Dalí claimed to have been the first to employ holography artistically. He was certainly the first and best-known surrealist to do so, but the 1972 New York exhibit of Dalí holograms had been preceded by the holographic art exhibition that was held at the Cranbrook Academy of Art in Michigan in 1968 and by the one at the Finch College gallery in New York in 1970, which attracted national media attention.[47] In Great Britain, Margaret Benyon began using holography as an artistic medium in the late 1960s and had a solo exhibition at the University of Nottingham art gallery in 1969.[48] This was followed in 1970 by a solo show at the Lisson Gallery in London, which was billed as the "first London expo of holograms and stereoscopic paintings".[49]

During the 1970s, a number of art studios and schools were established, each with their particular approach to holography. Notably, there was the San Francisco School of Holography established by Lloyd Cross, The Museum of Holography in New York founded by Rosemary (Posy) H. Jackson, the Royal College of Art in London and the Lake Forest College Symposiums organised by Tung Jeong.[50] None of these studios still exist; however, there is the Center for the Holographic Arts in New York[51] and the HOLOcenter in Seoul, which offers artists a place to create and exhibit work.

During the 1980s, many artists who worked with holography helped the diffusion of this so-called "new medium" in the art world, such as Harriet Casdin-Silver of the United States, Dieter Jung of Germany, and Moysés Baumstein of Brazil, each one searching for a proper "language" to use with the three-dimensional work, avoiding the simple holographic reproduction of a sculpture or object. For instance, in Brazil, many concrete poets (Augusto de Campos, Décio Pignatari, Julio Plaza and José Wagner Garcia, associated with Moysés Baumstein) found in holography a way to express themselves and to renew Concrete Poetry.

A small but active group of artists still integrate holographic elements into their work.[52] Some are associated with novel holographic techniques; for example, artist Matt Brand[53] employed computational mirror design to eliminate image distortion from specular holography.

The MIT Museum[54] and Jonathan Ross[55] both have extensive collections of holography and on-line catalogues of art holograms.

Holography can be put to a variety of uses other than recording images. Holographic data storage is a technique that can store information at high density inside crystals or photopolymers. The ability to store large amounts of information in some kind of medium is of great importance, as many electronic products incorporate storage devices. As current storage techniques such as Blu-ray Disc reach the limit of possible data density (due to the diffraction-limited size of the writing beams), holographic storage has the potential to become the next generation of popular storage media. The advantage of this type of data storage is that the volume of the recording media is used instead of just the surface. Currently available SLMs can produce about 1000 different images a second at 1024Ã—1024-bit resolution. With the right type of medium (probably polymers rather than something like LiNbO3), this would result in about one-gigabit-per-second writing speed. Read speeds can surpass this, and experts believe one-terabit-per-second readout is possible.

In 2005, companies such as Optware and Maxell produced a 120 mm disc that uses a holographic layer to store data to a potential 3.9 TB, a format called Holographic Versatile Disc. As of September 2014, no commercial product has been released.

Another company, InPhase Technologies, was developing a competing format, but went bankrupt in 2011 and all its assets were sold to Akonia Holographics, LLC.

While many holographic data storage models have used "page-based" storage, where each recorded hologram holds a large amount of data, more recent research into using submicrometre-sized "microholograms" has resulted in several potential 3D optical data storage solutions. While this approach to data storage can not attain the high data rates of page-based storage, the tolerances, technological hurdles, and cost of producing a commercial product are significantly lower.

In static holography, recording, developing and reconstructing occur sequentially, and a permanent hologram is produced.

There also exist holographic materials that do not need the developing process and can record a hologram in a very short time. This allows one to use holography to perform some simple operations in an all-optical way. Examples of applications of such real-time holograms include phase-conjugate mirrors ("time-reversal" of light), optical cache memories, image processing (pattern recognition of time-varying images), and optical computing.

The amount of processed information can be very high (terabits/s), since the operation is performed in parallel on a whole image. This compensates for the fact that the recording time, which is in the order of a microsecond, is still very long compared to the processing time of an electronic computer. The optical processing performed by a dynamic hologram is also much less flexible than electronic processing. On one side, one has to perform the operation always on the whole image, and on the other side, the operation a hologram can perform is basically either a multiplication or a phase conjugation. In optics, addition and Fourier transform are already easily performed in linear materials, the latter simply by a lens. This enables some applications, such as a device that compares images in an optical way.[56]

The search for novel nonlinear optical materials for dynamic holography is an active area of research. The most common materials are photorefractive crystals, but in semiconductors or semiconductor heterostructures (such as quantum wells), atomic vapors and gases, plasmas and even liquids, it was possible to generate holograms.

A particularly promising application is optical phase conjugation. It allows the removal of the wavefront distortions a light beam receives when passing through an aberrating medium, by sending it back through the same aberrating medium with a conjugated phase. This is useful, for example, in free-space optical communications to compensate for atmospheric turbulence (the phenomenon that gives rise to the twinkling of starlight).

Since the beginning of holography, amateur experimenters have explored its uses.

In 1971, Lloyd Cross opened the San Francisco School of Holography and taught amateurs how to make holograms using only a small (typically 5Â mW) helium-neon laser and inexpensive home-made equipment. Holography had been supposed to require a very expensive metal optical table set-up to lock all the involved elements down in place and damp any vibrations that could blur the interference fringes and ruin the hologram. Cross's home-brew alternative was a sandbox made of a cinder block retaining wall on a plywood base, supported on stacks of old tires to isolate it from ground vibrations, and filled with sand that had been washed to remove dust. The laser was securely mounted atop the cinder block wall. The mirrors and simple lenses needed for directing, splitting and expanding the laser beam were affixed to short lengths of PVC pipe, which were stuck into the sand at the desired locations. The subject and the photographic plate holder were similarly supported within the sandbox. The holographer turned off the room light, blocked the laser beam near its source using a small relay-controlled shutter, loaded a plate into the holder in the dark, left the room, waited a few minutes to let everything settle, then made the exposure by remotely operating the laser shutter.

Many of these holographers would go on to produce art holograms. In 1983, Fred Unterseher, a co-founder of the San Francisco School of Holography and a well-known holographic artist, published the Holography Handbook, an easy-to-read guide to making holograms at home. This brought in a new wave of holographers and provided simple methods for using the then-available AGFA silver halide recording materials.

In 2000, Frank DeFreitas published the Shoebox Holography Book and introduced the use of inexpensive laser pointers to countless hobbyists. For many years, it had been assumed that certain characteristics of semiconductor laser diodes made them virtually useless for creating holograms, but when they were eventually put to the test of practical experiment, it was found that not only was this untrue, but that some actually provided a coherence length much greater than that of traditional helium-neon gas lasers. This was a very important development for amateurs, as the price of red laser diodes had dropped from hundreds of dollars in the early 1980s to about $5 after they entered the mass market as a component of DVD players in the late 1990s. Now, there are thousands of amateur holographers worldwide.

By late 2000, holography kits with inexpensive laser pointer diodes entered the mainstream consumer market. These kits enabled students, teachers, and hobbyists to make several kinds of holograms without specialized equipment, and became popular gift items by 2005.[57] The introduction of holography kits with self-developing plates in 2003 made it possible for hobbyists to create holograms without the bother of wet chemical processing.[58]

In 2006, a large number of surplus holography-quality green lasers (Coherent C315) became available and put dichromated gelatin (DCG) holography within the reach of the amateur holographer. The holography community was surprised at the amazing sensitivity of DCG to green light. It had been assumed that this sensitivity would be uselessly slight or non-existent. Jeff Blyth responded with the G307 formulation of DCG to increase the speed and sensitivity to these new lasers.[59]

Kodak and Agfa, the former major suppliers of holography-quality silver halide plates and films, are no longer in the market. While other manufacturers have helped fill the void, many amateurs are now making their own materials. The favorite formulations are dichromated gelatin, Methylene-Blue-sensitised dichromated gelatin, and diffusion method silver halide preparations. Jeff Blyth has published very accurate methods for making these in a small lab or garage.[60]

A small group of amateurs are even constructing their own pulsed lasers to make holograms of living subjects and other unsteady or moving objects.[61]

Holographic interferometry (HI) is a technique that enables static and dynamic displacements of objects with optically rough surfaces to be measured to optical interferometric precision (i.e. to fractions of a wavelength of light).[62][63] It can also be used to detect optical-path-length variations in transparent media, which enables, for example, fluid flow to be visualized and analyzed. It can also be used to generate contours representing the form of the surface or the isodose regions in radiation dosimetry.[64]

It has been widely used to measure stress, strain, and vibration in engineering structures.

The hologram keeps the information on the amplitude and phase of the field. Several holograms may keep information about the same distribution of light, emitted to various directions. The numerical analysis of such holograms allows one to emulate large numerical aperture, which, in turn, enables enhancement of the resolution of optical microscopy. The corresponding technique is called interferometric microscopy. Recent achievements of interferometric microscopy allow one to approach the quarter-wavelength limit of resolution.[65]

The hologram is made with a modified material that interacts with certain molecules generating a change in the fringe periodicity or refractive index, therefore, the color of the holographic reflection.[66][67]

Security holograms are very difficult to forge, because they are replicated from a master hologram that requires expensive, specialized and technologically advanced equipment. They are used widely in many currencies, such as the Brazilian 20, 50, and 100-reais notes; British 5, 10, and 20-pound notes; South Korean 5000, 10,000, and 50,000-won notes; Japanese 5000 and 10,000 yen notes, Indian 50,100,500, and 2000 rupee notes; and all the currently-circulating banknotes of the Canadian dollar, Danish krone, and Euro. They can also be found in credit and bank cards as well as passports, ID cards, books, DVDs, and sports equipment.

Covertly storing information within a full colour image hologram was achieved in Canada, in 2008, at the UHR lab. The method used a fourth wavelength, aside from the RGB components of the object and reference beams, to record additional data, which could be retrieved only with the correct key combination of wavelength and angle. This technique remained in the prototype stage and was never developed for commercial applications.[citation needed]

Holographic scanners are in use in post offices, larger shipping firms, and automated conveyor systems to determine the three-dimensional size of a package. They are often used in tandem with checkweighers to allow automated pre-packing of given volumes, such as a truck or pallet for bulk shipment of goods. Holograms produced in elastomers can be used as stress-strain reporters due to its elasticity and compressibility, the pressure and force applied are correlated to the reflected wavelength, therefore its color.[68]

These are the hologram adhesive strips that provide protection against counterfeiting and duplication of products. These protective strips can be used on FMCG products like cards, medicines, food, audio-visual products etc. Hologram protection strips can be directly laminated on the product covering.

Hologram tags have an excellent ability to inspect an identical product. These kind of tags are more often used for protecting duplication of electrical and electronic products. These tags are available in a variety colors, sizes and shapes.

Some vehicle number plates on bikes or cars have registered hologram stickers which indicate authenticity. For the purpose of identification they have unique ID numbers.

These are holograms with high security features like micro texts, nano texts, complex images, logos and a multitude of other features. Holograms once affixed on Debit cards/passports cannot be removed easily. They offer an individual identity to a brand along with its protection.

In principle, it is possible to make a hologram for any wave.

Electron holography is the application of holography techniques to electron waves rather than light waves. Electron holography was invented by Dennis Gabor to improve the resolution and avoid the aberrations of the transmission electron microscope. Today it is commonly used to study electric and magnetic fields in thin films, as magnetic and electric fields can shift the phase of the interfering wave passing through the sample.[69] The principle of electron holography can also be applied to interference lithography.[70]

Acoustic holography is a method used to estimate the sound field near a source by measuring acoustic parameters away from the source via an array of pressure and/or particle velocity transducers. Measuring techniques included within acoustic holography are becoming increasingly popular in various fields, most notably those of transportation, vehicle and aircraft design, and NVH. The general idea of acoustic holography has led to different versions such as near-field acoustic holography (NAH) and statistically optimal near-field acoustic holography (SONAH). For audio rendition, the wave field synthesis is the most related procedure.

Atomic holography has evolved out of the development of the basic elements of atom optics. With the Fresnel diffraction lens and atomic mirrors atomic holography follows a natural step in the development of the physics (and applications) of atomic beams. Recent developments including atomic mirrors and especially ridged mirrors have provided the tools necessary for the creation of atomic holograms,[71] although such holograms have not yet been commercialized.

Neutron beam holography has been used to see the inside of solid objects.[72]

Effects produced by lenticular printing, the Pepper's ghost illusion (or modern variants such as the Musion Eyeliner), tomography and volumetric displays are often confused with holograms.[73][74] Such illusions have been called "fauxlography".[75]

The Pepper's ghost technique, being the easiest to implement of these methods, is most prevalent in 3D displays that claim to be (or are referred to as) "holographic". While the original illusion, used in theater, involved actual physical objects and persons, located offstage, modern variants replace the source object with a digital screen, which displays imagery generated with 3D computer graphics to provide the necessary depth cues. The reflection, which seems to float mid-air, is still flat, however, thus less realistic than if an actual 3D object was being reflected.

Examples of this digital version of Pepper's ghost illusion include the Gorillaz performances in the 2005 MTV Europe Music Awards and the 48th Grammy Awards; and Tupac Shakur's virtual performance at Coachella Valley Music and Arts Festival in 2012, rapping alongside Snoop Dogg during his set with Dr. Dre.[76]

An even simpler illusion can be created by rear-projecting realistic images into semi-transparent screens. The rear projection is necessary because otherwise the semi-transparency of the screen would allow the background to be illuminated by the projection, which would break the illusion.

Crypton Future Media, a music software company that produced Hatsune Miku,[77] one of many Vocaloid singing synthesizer applications, has produced concerts that have Miku, along with other Crypton Vocaloids, performing on stage as "holographic" characters. These concerts use rear projection onto a semi-transparent DILAD screen[78][79] to achieve its "holographic" effect.[80][81][82]

In 2011, in Beijing, apparel company Burberry produced the "Burberry Prorsum Autumn/Winter 2011 Hologram Runway Show", which included life size 2-D projections of models. The company's own video[83] shows several centered and off-center shots of the main 2-dimensional projection screen, the latter revealing the flatness of the virtual models. The claim that holography was used was reported as fact in the trade media.[84]

In Madrid, on 10 April 2015, a public visual presentation called "Hologramas por la Libertad" (Holograms for Liberty), featuring a ghostly virtual crowd of demonstrators, was used to protest a new Spanish law that prohibits citizens from demonstrating in public places. Although widely called a "hologram protest" in news reports,[85] no actual holography was involved â€” it was yet another technologically updated variant of the Pepper's Ghost illusion.

Holography has been widely referred to in movies, novels, and TV, usually in science fiction, starting in the late 1970s.[86] Science fiction writers absorbed the urban legends surrounding holography that had been spread by overly-enthusiastic scientists and entrepreneurs trying to market the idea.[86] This had the effect of giving the public overly high expectations of the capability of holography, due to the unrealistic depictions of it in most fiction, where they are fully three-dimensional computer projections that are sometimes tactile through the use of force fields.[86] Examples of this type of depiction include the hologram of Princess Leia in Star Wars, Arnold Rimmer from Red Dwarf, who was later converted to "hard light" to make him solid, and the Holodeck and Emergency Medical Hologram from Star Trek.[86]

Video games have used fictional holographic technology that reflected real life misrepresentations of potential military use of holograms, such as the "mirage tanks" in Command & Conquer: Red Alert 2 that can disguise themselves as trees.[87] Holographic decoys are used in games such as Halo Reach and Crysis 2.[87]

Fictional depictions of holograms have, however, inspired technological advances in other fields, such as augmented reality, that promise to fulfill the fictional depictions of holograms by other means.[88]


what type of car was in back to the future

The DeLorean DMC-12 (commonly referred to simply as "the DeLorean", as it was the only model ever produced by the company) is a sports car originally manufactured by John DeLorean's DeLorean Motor Company for the American market from 1981 to 1983. The car features gull-wing doors and an innovative fiberglass body structure with a steel backbone chassis, along with external brushed stainless-steel body panels. It became widely known and iconic for its appearance, and because a modified DMC-12 was immortalized as the DeLorean time machine in the Back to the Future media franchise.

DeLorean DMC-12

The first prototype appeared in October 1976. Production officially began in 1981 in Dunmurry, a suburb of southwest Belfast, Northern Ireland, where the first DMC-12 rolled off the production line on January 21. Over the course of production, several features of the car were changed, such as the hood style, wheels, and interior. About 9,000 DMC-12s were made before production halted in early 1983.[3]

The DMC-12 was the only model produced by the company, which was later liquidated as the US car market went through its largest slump since the 1930s. In 2007, about 6,500 DeLorean Motor cars were thought to still exist.[4]

In 1995, Stephen Wynne, a British entrepreneur from Liverpool, created a separate company based in Texas using the "DeLorean Motor Company" name. Wynne acquired the trademark on the stylized "DMC" logo shortly thereafter, along with the remaining parts inventory of the original DeLorean Motor Company. The company builds new cars at its suburban Humble, Texas location from new old stock (NOS) parts, original equipment manufacturer (OEM), and reproduction parts on a "made to order" basis using existing vehicle identification number (VIN) plates.[5]

On January 27, 2016, DMC in Texas announced that it planned to build about 300â€“325 replica 1982 DMC-12 cars, each projected to cost just under US$100,000.[6]

In October 1976, the first prototype DeLorean DMC-12 was completed by American automotive chief engineer William T. Collins, formerly chief engineer at Pontiac. Originally, the car was intended to have a centrally-mounted Wankel rotary engine. The engine selection was reconsidered when Comotor production ended, and the favored engine became Ford's "Cologne V6". Eventually the French/Swedish PRV (Peugeot-Renault-Volvo) fuel-injected V6 was selected. Also the engine location moved from the mid-engined location in the prototype to a rear-engined installation in the production car. The chassis was initially planned to be produced from a new and untested manufacturing technology known as elastic reservoir moulding (ERM), which would lighten the car while presumably lowering its production costs. This new technology, for which DeLorean had purchased patent rights, was eventually found to be unsuitable.[citation needed]

These and other changes to the original concept led to considerable schedule pressures. The entire car was deemed to require almost complete re-engineering, which was turned over to engineer Colin Chapman, founder and owner of Lotus Cars. Chapman replaced most of the unproven material and manufacturing techniques with those then employed by Lotus, like the steel backbone chassis.[citation needed]

In an interview with James Espey of the new incarnation of the DeLorean Motor Company of Texas, a drawing surfaced showing that the car originally had the potential to be named "Z Tavio". John DeLorean's middle name and his son's first name were both Zachary, while Tavio was his father's name and his son's middle name. Due to only sporadic documentation, there is little more that is currently known about the Z Tavio name and why it was ultimately rejected in favor of the DMC-12.[7]

DeLorean required US$175Â million to develop and build the motor company.[8] Convincing Hollywood celebrities such as Johnny Carson and Sammy Davis, Jr. to invest in the firm,[9][10] DeLorean eventually built the DMC-12 in a factory in Dunmurry, Northern Ireland, a neighborhood a few miles from Belfast city center.[citation needed]

The company had originally intended to build the factory in Puerto Rico,[11][12] but changed its plans when the Northern Ireland Development Agency offered £100 million towards it,[13] despite an assessment by consultants hired by the NIDA that the business had only a 1-in-10 chance of success.[12]

Construction on the factory began in October 1978, and although production of the DMC-12 was scheduled to start in 1979, engineering problems and budget overruns delayed production until early 1981.[citation needed]

By the time production actually began in 1981, the unemployment rate was high in Northern Ireland, and local residents lined up to apply for jobs at the factory. The workers were largely inexperienced, but were paid premium wages and supplied with the best equipment available. Most quality issues were solved by 1982, and the cars were sold from dealers with a one-year, 12,000-mile (19,000 km) warranty and an available five-year, 50,000-mile (80,000 km) service contract.[citation needed]

The DeLorean Motor Company went bankrupt in late 1982 following John DeLorean's arrest in October of that year on drug-trafficking charges. He was later found not guilty, but it was too late for the DMC-12 to remain in production. Approximately 100 partially assembled DMCs on the production line were completed by Consolidated International (now known as Big Lots). The remaining parts from the factory stock, the parts from the US Warranty Parts Center, as well as parts from the original suppliers that had not yet been delivered to the factory were all shipped to Columbus, Ohio in 1983â€“1984. A company called KAPAC sold these parts to retail and wholesale customers by mail order. In 1997, DeLorean Motor Company of Texas acquired this inventory.[14] There had also been a long-standing rumor that the body stamping dies were dumped into the ocean to prevent later manufacture. Evidence later emerged that the dies were used as anchors for nets at a fish farm in Ards Bay, Connemara, Ireland.[15]

About 9,200 DMC-12s were produced between January 1981 and December 1982.[16] Almost a fifth of these were produced in October 1981. About a thousand 1982 models were produced between February and May 1982, and all of these cars had the VINs changed after purchase by Consolidated to make them appear as 1983 models. There are the 15XXX, 16XXX, and 17XXX VINs, which were originally 10XXX, 11XXX, and 12XXX VINs. Only a dozen 12XXXX VIN cars still exist. These are the Wooler-Hodec right-hand-drive cars (see below).[citation needed]

The DMC-12 features a number of unusual construction details, including gull-wing doors, unpainted stainless-steel body panels, and a rear-mounted engine.

The body design of the DMC-12 was a product of Giorgetto Giugiaro of Ital Design and is panelled in brushed SS304 stainless steel. Except for three cars plated in 24-karat gold, all DMC-12s left the factory uncovered by paint or clearcoat.[17] Painted DeLoreans do exist, although these were all painted after the cars were purchased from the factory. Several hundred DMCs were produced without stainless panels, for training workers, and are referred to as "black cars" or "mules", in reference to their black fiberglass panels instead of stainless, although these were never marketed. Small scratches in the stainless-steel body panels can be removed with a non-metallic scouring pad (since metal pads can leave iron particles embedded in the stainless steel, which can give the appearance of the stainless "rusting"), or even sandpaper.[18] The stainless-steel panels are fixed to a fiberglass underbody. The underbody is affixed to a steel double-Y frame chassis, derived from the Lotus Esprit platform.[citation needed]

The unpainted stainless body creates challenges during restoration of the cars. In traditional automotive body repair, the panel is repaired to be as original ("straight") as possible, and imperfections are sculpted back to form with polyester body filler like Bondo or lead (body solder). This poses no problem (aside from originality) with most cars, as the filler will be hidden by the car's paint (for example, most new cars have filler hiding the seam where the roof meets the quarter panel). With an unpainted stainless body, the stainless steel must be reworked to exactly the original shape, contour, and grain, which is a tremendously difficult job on regular steel (a dented or bent panel is stretched, and a shrinking hammer or other techniques must be used to unstretch the metal) and even more difficult with stainless due to its tendency to work-harden. Furthermore, it is exceedingly difficult to paint stainless steel due to difficulties with paint adhesion. DeLorean envisioned that damaged panels would simply be replaced rather than repaired; each DeLorean service center today has at least one experienced body-repair person on staff, and there are decades worth of new stainless panels still available in most instances.[citation needed]

Another distinctive feature of the DMC-12 is its gull-wing doors. The common problem of supporting the weight of gull-wing doors was solved by other manufacturers with lightweight doors in the Mercedes-Benz 300SL and a hydraulic pump in the Bricklin SV-1, although these designs had structural or convenience disadvantages. The DMC-12 features heavy doors supported by cryogenically preset torsion bars and gas-charged struts.[19] These torsion bars were developed by Grumman Aerospace (and built by Unbrako in the UK, a division of SPS Technologies of Jenkintown, PA) to withstand the stresses of supporting the doors.[20] A popular misconception of the DMC-12's gull-wing doors is that they require far more side clearance to open relative to ordinary side-hinge doors, such as when parked in a parking lot. In fact, the opposite is true: the DMC-12 requires far less clearance than side-hinge doors, and this can be physically demonstrated. This misconception of side clearance may stem from a misunderstood location of the hinge point of the doors by persons unfamiliar with DMC-12s. These doors, when opening, only require 11 inches (28Â cm) clearance outside the line of the car, making opening and closing the doors in crowded spaces relatively easy. Much like the doors fitted to the Lamborghini Countach, the DMC-12 doors featured small cutout windows, because full-sized windows would not be fully retractable within the short door panels. Additionally, the doors featured red and amber "safety" lights around the perimeter. These lights illuminated when the door was open and could be seen from the front, rear or side of the vehicle at night or in low-light situations.[21][22]

The engine is a Peugeot-Renault-Volvo (PRV) 2.85 L (2,849 cc) V6, rated at 130 hp (132 PS; 97 kW) @ 5500 rpm and 207 N⋅m (153 lb⋅ft) @ 2750 rpm of torque,[23][24] that was designed and built under special contract with the DeLorean Motor Company. These PRVs were a development of the 2.7-litre V6 in the Renault 30 and were built in the PRV Factory in Douvrin, Northern France. The 5-speed manual transmission, also designed by PRV, was built at the Renault facility near Caen in Normandy. The engines and gearboxes were shipped weekly by sea from the PRV factories to the DMC factory.

The suspension of the DMC-12 is a four-wheel independent suspension, coil springs, and telescopic shock absorbers. The front suspension uses double wishbones, while the rear is a multi-link setup. In its original development stages, the car is said to have handled quite well. Design drawings clearly show that the design met NHTSA minimum bumper and headlight heights of the time.[25][26] Many owners have subsequently replaced or modified the front springs to return the front height to the original design specification.[27]

Steering is rack and pinion, with an overall steering ratio of 14.9:1, giving 2.65 turns lock-to-lock and a 35-foot (11 m) turning circle. DMC-12s are fitted with cast alloy wheels, measuring 14 inches (360 mm) in diameter by 6 inches (150 mm) wide on the front and 15 inches (380 mm) in diameter by 8 inches (200 mm) wide on the rear. These were fitted with Goodyear NCT steel-belted radial tires. The DeLorean is a rear-engine vehicle with a 35%–65% front–rear weight distribution.[28]

The DMC-12 features power-assisted disc brakes on all wheels, with 10-inch (250 mm) rotors front and 10.5-inch (270 mm) rear. [29]

DeLorean's comparison literature noted that the DMC-12 could achieve 0–60 miles per hour (0–97 km/h) in 8.8 seconds, when equipped with a manual transmission. When equipped with an automatic transmission, the DeLorean would accelerate from 0 to 60 miles per hour (0 to 97 km/h) in 10.5 seconds as tested by Road & Track magazine. The car's top speed is 110 miles per hour (177 km/h).[30]

The car was named the DMC-12 because of its intended price of US$12,000. Upon release in 1981, a DMC-12 had a suggested retail price of US$25,000 ($650 more when equipped with an automatic transmission); this is equivalent to approximately US$67,295 in 2017.[31].  MSRP would increase in 1982 to $29,825[32] and again in 1983 to $34,000[33].  At the outset, there were extensive waiting lists of people willing to pay up to $10,000 above the list price; however, after the collapse of the DeLorean Motor Company, unsold cars could be purchased for less than the retail price.[34]

The DMC-12 was only available with two factory options; a no-cost manual transmission or automatic transmission and the choice of a grey or black interior. Several dealer options were available, including a car cover; floor mats; black textured accent stripes; grey scotch-cal accent stripes; a luggage rack and a ski-rack adapter. The standard feature list included stainless-steel body panels; gull-wing doors with cryogenically treated torsion bars; leather seats; air conditioning; an AM/FM cassette stereo system; power windows, locks and mirrors; a tilt and telescopic steering wheel; tinted glass; body side moldings; intermittent/constant windshield wipers; and an electric rear-window defogger.[35][36]

Although there were no typical "yearly" updates to the DeLorean, several changes were made to the DeLorean during production.[2] John DeLorean believed that model years were primarily a gimmick used by automobile companies to sell more cars. Instead of making massive changes at the end of the model year, he implemented changes mid-production, which has become more common in car manufacturing.[citation needed]) This resulted in no clear distinction between the 1981, 1982, and 1983 model years, but with subtle changes taking place almost continuously throughout the life of the DeLorean. The most visible of these changes related to the hood style.[citation needed]

The original hood of the DeLorean had grooves running down both sides. It included a tank flap to simplify fuel filling. The flap was built so that the trunk could be added to the total cargo area of the DeLorean. These cars typically had a locking cap to prevent fuel theft by siphoning. In August 1981, the hood flap was removed from the hood of the cars (although the hood creases stayed). This style was retained well into 1982.[37] Based on production numbers for all three years, this hood style is probably the most common. After the supply of locking caps was exhausted, the company switched to a non-locking version (resulting in at least 500 cars with no flap, but with locking caps). The final styling for the hood included the addition of a DeLorean name badge and the removal of the grooves, resulting in a completely flat hood. According to senior personnel who worked at the Dunmurry factory, initial elimination of flapped  hoods has a simple if unglamorous explanation; Chuck Benington, managing director, did not like the design.[38]

John DeLorean was 6 ft 4 in (1.93 m) tall, and he designed the car to comfortably fit someone of his stature.[39] For shorter people, the addition of a pull strap made closing the doors much easier from the inside. Pull straps were manufactured as an add-on for earlier vehicles in November 1981. These attach to the existing door handle. Late-model 1981 cars, and all cars from 1982 and 1983, have doors with integrated pull straps.[40]

The side bolstering in the DeLorean was originally separate from the main interior pieces. In cars with this construction, is a tendency to place pressure on this piece when entering and exiting the vehicle, which eventually causes the bolstering to separate from the trim panel. To solve this problem, cars built in and after late 1981 have one solid trim piece with the bolster permanently attached.[citation needed]

As an addition to later cars, a foot rest, or "dead" pedal, (in the form of an unusable pedal) was added to the cars to help prevent fatigue while driving. This is one of the few changes that is directly tied to a model year. These were built into only a few of the late-1981 vehicles and were added to all cars starting with 1982 production.[40]

Although the styling of the DeLorean's wheels remained unchanged, the wheels of early-model 1981 vehicles were painted grey. These wheels sported matching grey centre caps with an embossed DMC logo. Early into the 1981 production run, these were changed to a polished silver look, with a contrasting black center cap. The embossed logo on the center caps was painted silver to add contrast.[citation needed]

In 1981, the DeLorean came stocked with a Craig radio; this was a standard 1980s tape radio with dual knob controls. Since the Craig did not have a built-in clock, one was installed in front of the gear shift. DeLorean switched to an ASI stereo in the middle of the 1982 production run. Since the ASI radio featured an on-board clock, the standard DeLorean clock was removed at the same time.[citation needed]

The first 2,200 cars produced used a windshield-embedded antenna. This type of antenna proved to be unsuitable with poor radio reception. Oftentimes the radio would continually "seek", attempting to find a signal. A standard whip antenna was added to the outside of the front right fender. While improving radio reception, this resulted in a hole in the stainless steel, and an unsightly antenna. As a result, the antenna was again moved, this time to the rear of the car. Automatic antennas were installed under the grills behind the rear driver's-side window. While giving the reception quality of a whip antenna, these completely disappear from view when not in use.[citation needed]

The small sun visors on the DeLorean have vinyl on one side and headliner fabric on the other side. Originally these were installed such that the headliner side would be on the bottom when not in use. Later on in 1981, they were reversed so that the vinyl side would be on the bottom.[41][42]

The original Ducellier alternator supplied with the early-production DMC-12s could not provide enough current to supply the car when all lights and electrical options were on; as a result, the battery would gradually discharge, leaving the driver stranded on the road. Additional battery drainage problems were caused by faulty or improperly adjusted door jamb switches. This switch activated the "safety" lights located around the door perimeter when it was open. When the door was closed, the door seals prevented the light from being seen. Due to the faulty switches the lights remained on, further draining the battery. This happened to DeLorean owner Johnny Carson shortly after he was presented with the vehicle. Later cars were fitted from the factory with a higher-output Motorola alternator, which solved this problem. This also is believed[by whom?] to be the reason behind the improvement in the sound quality of the horn. Earlier models emitted a weak sound, not loud or strong enough to be effective in normal traffic.[citation needed]

DMC-12s were primarily intended for the American market. All production models were therefore left-hand-drive. Evidence survives from as early as April 1981, however, that the DeLorean Motor Company was aware of the need to produce a right-hand-drive version to supply to world markets such as the United Kingdom, Ireland, India, Thailand, Australia, New Zealand, and Japan.[citation needed]

The company faced the choice of building right-hand-drive models from scratch or performing a post-production conversion exercise. Given the cost of new body molds, tooling, and a host of specific parts that a factory-built right-hand-drive configuration would require, the company opted to investigate the idea of a post-production conversion using a company based in Hampshire called Wooler-Hodec Ltd.[citation needed]

Only 16 right-hand-drive factory-authorised DeLoreans were ever produced.[43] These cars can be divided into two distinct groups:

A common misconception surrounding the factory-authorized right-hand-drive DeLoreans is that they were all fitted with different, so-called "Euro-spec", tail lights[44] as part of the right-hand-drive conversion program. This is not the case. Due to the nature of these cars as prototypes, they were not officially type-approved for use in the UK. Owners who bought these cars at auction in the early 1980s encountered difficulty in registering them as new vehicles in the UK. At this point a former DeLorean Motor Cars executive offered to modify and register the cars so that they could be used in the UK. These modifications included:

Over half of the 16 right-hand-drive cars had these modifications carried out. In recent years several owners of these cars have replaced the Rubbolite lights with original federal-style tail lights in an effort to return the cars to their original specification. Some owners have also fitted federal-style license-plate bezels on their cars.[citation needed]

There were a number of official alterations made to the right-hand-drive cars' lights. The extent of these modifications varies between the first batch of "Wooler-Hodec" cars and the later "AXI" cars:

All of the 13 Wooler-Hodec cars were modified to the OEM front turn-signal lens fixing method in order to make them fit flush with the front fascia.[49] The cars' headlights were also changed for right-hand-drive spec lights that incorporate a UK sidelight feature. The rest of the lights appear to have been left untouched by Wooler-Hodec during the conversion process.

By contrast, the 3 "AXI" cars had further modifications to the amber front door lights, which were exchanged for clear lenses of the same style.[50] Perhaps the most significant alteration on the "AXI" cars is the deletion of the front and rear side markers. These are replaced by a single small round European-style indicator side repeater, situated on the front wing (fender). The body rubstrips are also of a different configuration in order to cover the areas that would otherwise have had federal side marker lenses fitted.[51]

Several special-edition DMC-12 cars have been produced over the years, and the car is most notably featured as the time machine in the Back to the Future film trilogy. Six DeLorean chassis were used during the production, along with one manufactured out of fiberglass for scenes where a full-size DeLorean was needed to "fly" on-screen; only three of the cars still exist, with one that was destroyed at the end of Back to the Future Part III, two additional were abandoned, and the fiberglass replica was scrapped. Universal Studios owns two of the remaining cars, occasionally putting them on display or using them for other productions, and the last resides in a private collection after having been extensively restored.[52] The official Back to the Future DeLorean can be viewed at the Petersen Automotive Museum.[53]

A number of production DeLoreans have been modified by the aftermarket into Back to the Future time machine replicas, whose bodies and interiors are modified to mirror the appearance and functions of the film cars.[54]

Only one of two DeLorean prototypes still exists.[55] Proto 1 received a complete restoration and is now on display at the DeLorean Motor Company of Florida (DMCFL). Proto 2 was sent to Lotus Cars for development and evaluation in 1978. It was reported to have been destroyed in the 1990s.[56]

There were several mules that were fiberglass-bodied cars used by Lotus during development and engineering.  None are known to exist today.

An estimated 28 pilot cars were built by DMC.  The pilot cars are best identified by the subtly different interiors and sliding side windows. These cars, used for evaluation and regulatory testing of the DeLorean, were previously thought to have been destroyed.  Subsequently, several of the  pilot cars were found to have survived.[57][58]   The test car featured on the front cover of Autocar in 1981 announcing the DeLorean to the world was found in 2003 in a barn in Northern Ireland.[citation needed]

With the 1980 NADA meeting approaching, DMC planned to show a final “production” version of the DeLorean DMC 12, however there were no production cars ready at the time or even any production stainless steel panels.

In 1979, the revised Giugiaro styling mock-up was shipped to Visioneering, a Detroit based company, to create data needed to make the stamping dies for the stainless panels.  This project would expand to create dies used to create a “production” car for the NADA show.

Using a prototype chassis supplied by Lotus, Visioneering completed the assembly of this car at a cost of $750,000.  The car was presented at the 1980 NADA show and was later used for engineering development and technical training as well as press photos.  The Visioneering car would eventually be sold at the bankruptcy auction in late 1984.  Today, the car is in a private collection.[59]

It was determined that the DeLorean needed additional power when automotive magazine road tests showed 0–60 mph (0–97 km/h) times for the DMC-12 between 9.5 and 10.5 seconds, while its rivals were in the 7.5–8.5 second range. There had been interest in turbocharging the DeLorean early on, but the DMC engineering staff was busy with other projects, so DeLorean decided to go outside to develop a turbocharged version of the DeLorean.[60]

Having had previous success with turbocharging Fiat Spiders, DeLorean entered into a contract with Legend Industries, based in Hauppauge, New York. DMC wanted to increase power without sacrificing fuel efficiency. DMC wanted a wide power band and did not want a surge of power similar to the Porsche 930 Turbo. Legend used twin IHI RHB52 turbos along with twin intercoolers. The results were an engine capable of accelerating smoothly in fifth gear from 1,500 rpm to full turbo boost at 2,500 rpm, reaching 150 mph (240 km/h) at 6,500 rpm.[60]

In addition, Legend Industries developed a single turbocharged setup that was never finished.
The company converted a total of four DeLoreans and two Renault Alpines, which were the first development cars.[61] VIN 530 was written in numerous press articles as the fastest production car of its era.[citation needed]

In a test run of VIN 530 at Bridgehampton Raceway in 1981, the twin-turbo DeLorean was quicker than a Ferrari 308 and a Porsche 928. It has been a misconception for many years that VIN 502 was at Bridgehampton and used in testing; however, evidence from pictures, along with information from a Legend employee published by PJ Grady,[citation needed] indicates that 530 was used with the aspirated VIN 558. By the time of Bridgehampton, Legend had perfected modular boosting, which the earlier prototypes did not have installed apart from one of the Alpine mules and VIN 530. This has also been proven by a Legend Engineer who actually worked on the cars.[citation needed]

VIN 530 tested 0–60 mph in 5.8 seconds and the 1⁄4 mile (402 m) in 14.7 seconds. DeLorean was so impressed with the engine, he committed to ordering 5,000 engines from Legend Industries. DeLorean planned to offer a turbocharged engine as a $7,500 option in 1984 (presumably to compete with the newly redesigned 1984 Corvette). Before any of the 5,000 cars could be put into production, DMC had declared bankruptcy, which drove Legend Industries, as well as other suppliers, into bankruptcy.[62]

For Christmas 1980, a DeLorean/American Express promotion planned to sell 100 24K-gold-plated DMC-12s for US$85,000 each to its gold-card members, but only two were sold.[64] One of these was purchased by Roger Mize, president of Snyder National Bank in Snyder, Texas. VIN #4301 sat in the bank lobby for over 20 years before being loaned to the Petersen Automotive Museum of Los Angeles. It has a black interior and an automatic transmission.[65]

The second gold-plated American Express DMC-12 was purchased by Sherwood Marshall, an entrepreneur and former Royal Canadian Naval Officer. Marshall donated his DeLorean to the William F. Harrah Foundation/National Automobile Museum in Reno, Nevada. This car, VIN #4300, is the only one of the three existing gold-plated cars to be equipped with a manual transmission. It has a saddle-brown interior and, like its golden siblings, is a low-mileage vehicle with only 1,442 miles (2,321Â km) on the odometer.[66]

A third gold-plated car exists with 636 miles (1,024Â km) on the odometer; it carries the VIN plate for the last DeLorean, #20105, although final assembly was actually completed in Columbus, Ohio in 1983.[67] This car was assembled with spare parts that were required by American Express in case one of the other two that were built were damaged and all necessary gold-plated parts were on hand, with the exception of one door. Thus the car was assembled after another door was gold-plated, though the added door does not precisely match the rest of the car in color and grain. The car was first acquired by the winner of a Big Lots store raffle. Consolidated International, which owned the department store, had purchased 1374 DMC-12s during the DeLorean Company's financial troubles, acquiring the remaining stock after the company went into receivership. Now held by a private owner in La Vale, Maryland, this third and last gold-plated DeLorean was for sale online at a price of US$250,000, but remains unsold.[67] After being offered for sale for over a decade, it is unclear whether it has sold.[68] This car and the example in Reno have saddle-brown leather interiors, a color scheme which was intended to become an option on later-production cars, however, these two cars were the only DeLoreans to ever be equipped with these factory parts.[citation needed]

A gold-plated DeLorean was reproduced privately by an enthusiast.[69]

DMC Texas (based in Humble, Texas) announced on July 30, 2007 that the car would be returning into very limited production (about 20 cars a year) in 2008.[70] They were subsequently sued by John DeLorean's widow for illegally licensing the family name. DMC Texas settled this lawsuit in September 2015 by paying his widow an undisclosed sum and in turn received rights to use the name, images, and trademark in the future.[71]

The cars were announced to have a new stainless-steel frame; with optional extras such as GPS, an enhanced "Stage 2" engine, and possibly a new modern interior. Given that the cars were made with 80% old parts,[72] the term "return to production" is something of a misnomer; the cars are constructed on DeLorean underbodies built by the original company in the 1980s and retaining their VINs. The cars' titles show the year of the underbody's manufacture. They are, therefore, not new DeLoreans, but complete rebuilds of the car from the underbody with enhancements. In 2009, the price of a refurbished DeLorean from DMC Texas started at US$57,500, and the project was featured in an episode of Modern Marvels.[73]

On October 18, 2011, it was announced that an all-electric model would be available for sale by 2013. It was said to have a 200-horsepower (150 kW) motor, accelerate from 0 to 60 miles per hour (0 to 97 km/h) in 8 seconds, and sell for US$90,000.[74][75][76] Initial test drives revealed that the prototype had a range of 70 miles (110 km), approaching the 100 miles (160 km) that was announced.[77] However, 2014 saw criticism from fans who tried to buy the electric DeLorean only to learn that it was still unavailable.[78]

Due to the passage of the Low Volume Vehicle Manufacturing Act, DMC Texas announced that they would be producing replica DeLoreans with an expected release date in 2017. DMC anticipates to build approximately 50 vehicles per year over the next 6 years with an estimated retail price of US$100,000.[79][80]  In October 2016, DMC announced that they are expecting to build 12 units in the first production year with as many as 50 in the second year of production.[81]  In February 2018, it was reported that production should start in January 2019.[82]


who did dan win dancing on ice with

Daniel J Whiston[1] (born 21 November 1976 in Blackpool) is an English ice skater. He appeared in Strictly Ice Dancing on BBC One and all series of ITV show Dancing on Ice. He won the first series of Dancing on Ice while partnering actress Gaynor Faye, the fifth series with former Emmerdale actress Hayley Tamaddon and the eighth series with Olympic artistic gymnast, Beth Tweddle.

Daniel Whiston

Whiston was born on 21 November 1976 in Blackpool and is the son of Marj and William Whiston,[2] he still lives in Blackpool. He started ice skating at the age of seven at the Blackpool Pleasure Beach's Ice Arena. He worked in the Arena and took part in his first show there when he was 18 years old. He also appeared in a tour of Grease on Ice in North America,[3] and appeared in the Hot Ice Show at the Arena until 2006.[4] He appears in the DVDs of the Hot Ice shows Quixotic, Xylatomia, H2O, Amarin and Chill.[citation needed]

Whiston appeared in the one-off Strictly Ice Dancing broadcast on BBC One on 26 December 2004.

Whiston performed at the 2010 Royal Variety Show, performing a combination of roller-blading and acrobatic.[5]

Whiston has appeared in every series of Dancing on Ice since ITV started broadcasting it in January 2006, he is the first and only professional skater to win the show three times. He is famous for his cheeky wink at the start of each performance. On 21 May 2013, ITV confirmed that Dancing on Ice would end in 2014 after its ninth series meaning that with three wins as a professional Whiston will become the most successful professional partner in the show's history. Whiston will return to Dancing on Ice for its tenth series in January 2018. He is partnered with Cheryl Baker.

Whiston won the first series of Dancing on Ice on 3 March 2006 with partner, actress Gaynor Faye, [6] He was also a presenter at the British Soap Awards on 24 May 2006.[7]

In the second series in 2007 Whiston reached the semi-finals, finishing fourth, with actress Emily Symons, before being eliminated in a skate-off against singer Duncan James and his partner, Maria Filippov. With Symons also appearing in the soap opera, Emmerdale set in and filmed in West Yorkshire, they initially trained at Bradford Ice Arena in Bradford each week before travelling down to London for dress rehearsals.

In the third series in 2008, Whiston was partnered with another Emmerdale actress, Linda Lusardi and again they initially trained in Bradford. Following Lusardi's departure from the soap, and subsequent return to her family home in the south of England, it was revealed that Whiston had temporarily moved in with her family, to enable them to practise without the need for excessive travelling.[8] Initial training was problematic as Lusardi broke her foot. They were voted out in week seven, finishing sixth, in a skate-off with actress Zaraah Abrahams and her partner Fred Palascak. Both Whiston and Lusardi appeared in the Dancing on Ice Tour 2008.[8]

In the fourth series in 2009, Whiston was partnered with Roxanne Pallett another former Emmerdale actress. In week 8 Daniel and Roxanne were in the skate off against Zöe Salmon and Matt Evers and were eliminated 5-0.

Whiston won the fifth series of Dancing on Ice on 28 March 2010 with yet another former Emmerdale actress and childhood friend Hayley Tamaddon.[9]

In the sixth series in 2011, Whiston was partnered with former Reality TV Star Kerry Katona. They were eliminated in week 5, in a skate off against Jeff Brazier & partner Isabelle Gauthier.

In the seventh series in 2012 Whiston's Partner was Brookside actress Jennifer Ellison. They were eliminated in the semi-final against Jorgie Porter and her partner Matt Evers.

Whiston won the eighth series of Dancing on Ice on 10 March 2013 and became a three-time champion with Olympic gymnast Beth Tweddle.

Whiston returned for his ninth series of Dancing on Ice for its "All-Star" series in 2014 with Hayley Tamaddon whom he won the show with in 2010. They made it to the final on 9 March 2014 and finished as runners-up.

When Dancing On Ice return in 2018 for its 10th series, Whiston competed with singer Cheryl Baker from Bucks Fizz. They were eliminated in week 5, in a skate off against Donna Air and her partner Mark Hanretty.

Whiston trained as a fitness and Zumba instructor in 2014 and runs a number of classes across the Fylde Coast. In 2015 he released his first fitness DVD "Dance Fit." [10]

Following Dancing on Ice, in December 2015 Whiston starred in the panto Snow White as Prince Charming at the Grand Theatre, Blackpool. The theatre reported the panto as its best-selling show ever.

In October 2016 Whiston starred in Intimissimi on Ice with international opera great Andrea Bocelli in Verona, Italy.[11]

With business partner and fellow ice skater Karen Barber, Whiston owns a number of Subway restaurants across Lancashire. In 2017 Whiston, Karen Barber and their business partners opened Clip n' Climb Blackpool - an indoor climbing and activity attraction.

Whiston lives close to his family in Blackpool. While maintaining his businesses and skating, he is also a Patron of Fylde children's hospice Brian House He regularly supports events for Brian House and in 2014 organised a charity Zumbathon to raise money.[12]


what is the meaning of khalid in arabic

Khaled and its variant Khalid (in Arabic خالد) is a popular Arabic male given name meaning "eternal", and it also appears as a surname.[1]

Khalid

Film, television, theatre


what is the term for a legislature with two bodies

Each state in the United States has a legislature as part of its form of civil government. Most of the fundamental details of the legislature are specified in the state constitution. 49 state legislatures are bicameral bodies, composed of a lower house (Assembly, General Assembly, State Assembly, House of Delegates, or House of Representatives) and an upper house (Senate). The United States also has five non-state territories and one federal district with local legislative branches, which are also listed below. Among the states, the Nebraska Legislature is the lone unicameral body, although three other areas (the District of Columbia, Guam and the U.S. Virgin Islands) also have unicameral bodies.

List of United States state legislatures

The exact names, dates, term lengths, term limits, electoral systems, electoral districts, and other details are determined by the individual states' laws.

The party composition of the legislatures (and party summary of the individual legislative chambers), as of January 2017, is:

“Split” means that either the two chambers have different majority parties (e.g., Democratic Senate and Republican House), that one chamber is evenly split between parties, or that a coalition or "hung" chamber has occurred. The Nebraska legislature, though officially nonpartisan, is de facto Republican-controlled, and listed as such.

In several states, the political party that controls the legislature is not the one that usually wins the state in Presidential elections. Also note that, due to the workings of politics, a party with a numerical majority in a chamber may be forced to share power with other parties due to informal coalitions or may cede power outright because of divisions.

The table below shows total state government control in 32 states, which means that the Governor and the legislative-chamber majorities are all of the same political party.

â€  Includes legislators who are unaffiliated, unenrolled, etc.