Holography

How to acquire 3D photographic images by holography Since these images can be obtained without lenses, this method is also called lensless photography. These records are called holograms derived from Greek horror, meaning "whole", and gram means "message". The theoretical principle of holography was developed by British physicist Dennis Gabor in 1947. The first actual manufacture of the hologram was done in the early 1960s when the laser was available. By the latter half of the 1980s, it became possible to produce true color holograms as well as holograms from microwave to spectral X-ray region.

In 2006, a huge excess of holographic mass green laser (Coherent C 315) was released, and dichromate gelatin (DCG) holography was introduced in the hands of amateur holographic photographers. The holographic community is surprised by the amazing sensitivity of DCG to green light. People have always thought that this sensitivity is useless or not at all. Jeff Blyth has adopted the G307 DCG method to increase the speed and sensitivity of these new lasers. Kodak and Agfa, formerly holographic quality silver halide plates and major film suppliers, are no longer on the market. Other manufacturers have helped to compensate for this gap, but many amateurs are now making their own materials. Preferred formulations are dichromate gelatin, methylene blue sensitized dichromate gelatin and diffusion method silver halide formulations. Jeff Blyth announced a very accurate way to make these methods in small laboratories and garages.

Electron holography is a holographic technique applied to electron waves rather than light waves. Dennis Gabor invented electronic holography to raise the resolution of the transmission electron microscope and avoid aberrations. Today, magnetic fields and electric fields can change the phase of the interference wave that passes through the sample, so it is commonly used for the study of electric and magnetic fields in thin films. The principle of electronic holography can also be applied to interference lithography.

Acoustical holography is a method for estimating a sound field near a sound source by measuring an acoustic parameter away from the sound source by a pressure and / or particle velocity sensor array. Measurement techniques included in acoustic holography are increasingly prevalent in various fields, especially traffic, automotive and aircraft design, and NVH. The general idea of ​​acoustic holography has resulted in different versions such as near-field acoustic holography (NAH) and statistically optimal near-field acoustic holography (SONAH). Wavefront synthesis is the most appropriate process for audio playback.