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Computer-generated holography (CGH) is a technique that uses computer algorithms to generate holograms.It involves generating holographic interference patterns.A computer-generated hologram can be displayed on a dynamic holographic display, or it can be printed onto a mask or film using lithography. [1]
Digital holography is the acquisition and processing of holograms with a digital sensor array, [1] [2] typically a CCD camera or a similar device. Image rendering, or reconstruction of object data is performed numerically from digitized interferograms.
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.
[1] [2] The essence of the DPH technology is embedding computer designed digital holograms inside a planar waveguide. Light propagates through the plane of the hologram instead of perpendicularly, allowing for a long interaction path. Benefits of a long interaction path have long been used by volume or thick holograms. Planar configuration of ...
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.
For holographic data storage, holographic associative memory (HAM) is an information storage and retrieval system based on the principles of holography.Holograms are made by using two beams of light, called a "reference beam" and an "object beam".
Since its introduction, vibrometry by holographic interferometry has become commonplace. Powell and Stetson have shown that the fringes of the time-averaged hologram of a vibrating object correspond to the zeros of the Bessel function (), where (,) is the modulation depth of the phase modulation of the optical field at , on the object. [1]
Holographic optical element (HOE) is an optical component (mirror, lens, directional diffuser, etc.) that produces holographic images using principles of diffraction.HOE is most commonly used in transparent displays, 3D imaging, and certain scanning technologies.