Photonics Dictionary

A computer-generated hologram (CGH) is a holographic image produced using computational methods and algorithms, rather than traditional optical techniques. CGHs are generated entirely in digital form...

A hologram formed when the light of the illuminating beam is absorbed in correspondence with the recording exposure. In application, absorption holograms are intended for use in satellite...

The recorded interference pattern formed by the interference of two sound beams.

The optical reconstruction of image information contained in a sound field. First the diffraction pattern, formed by an object irradiated by ultrasonic rays, interferes with a mutually coherent...

A hologram in which diffraction is produced by the silver image, resulting in a dimmer image than in a phase hologram, where diffraction takes place at the gelatin relief image left once the silver...

The recording of three or more separate holograms having a different color on a medium, so that illumination with a tricolor beam yields three separate wavefronts, each representing one of the...

Also known as real holographic image. The indistinct, highly distorted image produced on the side of the hologram closest to the observer, in addition to the primary image. When the location of the...

Optical elements that use diffraction to control wavefronts. Diffractive optical elements include diffraction gratings, surface-relief diffractive lenses, holographic optical elements and...

Digital holographic microscopy (DHM) is an advanced imaging technique that combines holography and digital image processing to capture and reconstruct three-dimensional images of objects. This method...

The formation of an interferogram by means of two holograms on the same recording medium, often used for determining small changes in an object. One hologram produces a primary image that constitutes...

A hologram having an object wave that has been transmitted through the transparent object media to a mirror, reflected again and recorded on a medium.

The superimposition of a pilot object on each hologram. The fixed relative position of the scanning and pilot beam during the recording process ensures that sensing and fixing the pilot beam position...

A technology that uses electrically activated holograms stored within specially developed crystals to route information in the form of lightwave signals from one optical fiber to another within and...

A hologram imprinted on plastic or another medium; e.g., those commonly found on credit cards.

A hologram produced by a pair of radiation beams, each carrying information.

A hologram formed by the recording of a plane object situated in the focal plane of a lens so that each object gives rise to a parallel beam of light incident on the plate. A collimated reference...

A far-field pattern holographically reproduced image that is categorically considered with three-dimensional lensless photographs.

A hologram formed with an object located close to the recording medium.

The holographic recording of sequences of high-speed phenomena. With a multiple beam laser, multiple holograms that depict rapid events can be formed on a single medium.

A camera system used to form a high-precision hologram of the subject on a photographic plate. It contains a high-power pulsed laser as the illuminating source.

An interference pattern that is recorded on a high-resolution plate, the two interfering beams formed by a coherent beam from a laser and light scattered by an object. If after processing, the plate...

A holographic camera, also known as a holographic imaging system or holographic recorder, is a specialized device used to capture 3D holographic images of objects or scenes. Unlike conventional...

The interferometric analysis of a complex object by utilizing the three-dimensional hologram. By causing a laser beam to diverge into two directions, one of which directly strikes a holographic...

A specific type of hologram that will transmit a pure plane wave when the hologram is illuminated by the type of wave it is matched to.

The storage of data as bits in memory by holographic processes. The laser beam is divided into reference and object beams, and bit information is stored as a hologram.

A method of measuring flow velocity by seeding the flow with neutrally buoyant particles and using a pulsed laser to holographically record particle displacement during a short time period. An...

Holographic tomography is an advanced imaging technique that combines holography and tomography to provide three-dimensional reconstructions of transparent or weakly scattering objects with high...

A series of permanent holograms in dichromated gelatin formed by opening total page-composer apertures and setting a point source of light in each storage location. It performs much like a...

A hologram in which the image of an object, or the object itself, is located near the hologram recording plane, for optimum image reconstruction. Because the images are close to the hologram plane,...

The formation of a hologram by single reference-beam interferences with waves that are diffracted or scattered from a small object.

The production of holograms initially from either conventional photographs or incoherent optical equipment.

A reflection hologram using multiple color lasers that integrates various graphical techniques to allow the display of three-dimensional images of live objects in motion, as well as outdoor scenes,...

A hologram formed without lenses and with the object and reference points sharing the same plane. In the initial recording, each object point produces fringes having one spatial frequency across the...

Lensless microscopy, also known as computational or holographic microscopy, is an imaging technique that captures and reconstructs microscopic images without the use of traditional lenses. Instead of...

The acoustical holographic process in which the hologram consists of slight elevations in a liquid surface, in the areas of the antinodes of the interference pattern. Light diffracted from this...

A hologram having an image scale that is orders of magnitude smaller than microfiche images.

A computer-generated, phase-and-amplitude, off-axis hologram made by a multi-exposure technique that uses three computer generated transmission masks. Each mask controls one fixed-phase component of...

Method for reducing laser speckle in which the object field comes from a real diffuse object or the reconstructed object field from a hologram. During recording of the image, an aperture is moved in...

A hologram formed by reconstruction of multicolor wavefronts. The system used to produce the hologram is designed to combine the different colored wavefronts of the separate illuminating sources, and...

In holography, the wave of light that illuminates the object to be recorded, which diffracts it to the recording medium, where it interferes with the reference beam, generating the hologram.

A hologram facet illumination technique in which the illuminating beam is twice the size of the hologram facet so that full hologram resolution capability can be realized and scanning dead time is...

A hologram that is formed on a recording medium by changing the phase of the illuminating wave in correspondence with the recording exposure. It may be formed by contact printing onto a resist...

In optics and photolithography, a phase mask refers to a device that modifies the phase of light waves passing through it. The phase mask is used to control the spatial distribution of the light's...

A holographic plate coated by photopolymeric mixtures that are composed of one or more monomers and a photoredox catalyst sensitized to visible light. The material becomes a plastic solid when...

A process in which a mixture of one or more monomers, plus a catalyst, polymerize under exposure to light radiation. Photopolymerization permits a hologram to be exposed, fixed and reconstructed in...

A two-dimensional hologram.