What Is Holography?

Holography, also known as holography, refers to the technique of recording the amplitude and phase distribution of light waves on a photographic film or a dry plate and reproducing a three-dimensional image of an object. Also known as holography, holography. Holography can be used not only in the light wave band, but also in electronic waves, acoustic waves, X-rays, and microwaves. Ordinary photography can only record the amplitude (intensity) of the reflected or transmitted light of an object, so a two-dimensional image of the object is recorded. Holography can record not only the amplitude but also the phase of light, so it can record the depth information of objects. "Hologram" comes from the Greek word "holos", which means complete information-including not only the amplitude information of the light, but also the phase information. ^[1]

Hungarian-born British physicist D.

The reflected light waves of the illuminated object carry the shape of the object

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Application of particle field holography theory and particles

Holography

Advanced noise measurement system based on acoustic holography

It has obtained a certain degree of application in the fields of science and technology, culture, industry, agriculture, medicine, art, and commerce. The application of holography has the following aspects. ^{[1] [2]}

Holographic display

The biggest feature of holography is that it can reproduce three-dimensional images that are very realistic with objects. Using three wavelengths of red, green, and blue lasers to sequentially record the three primary color reflection holograms of an object on a recording dry plate, white light can be used to reproduce a three-dimensional image of a true color object. ^[1]

Holographic Microscopy

Ordinary microscopes cannot observe some deeper fine structures due to the small focal depth and small working distance. Holographic three-dimensional volume imaging can achieve hyperfocal depth microscopy. As long as the coherent laser can irradiate the deep structure, holograms can be taken. It then reproduces its image in space, and then observes it face-to-face with an ordinary microscope. The pulsed laser records the field of moving microorganisms or moving particles, which can be stored for a long time, and can be observed and analyzed layer by layer under static conditions. ^[1]

Holographic storage

The use of Fourier transform holograms can realize large-capacity and high-density information storage of information such as text and images. Since it is stored and displayed in pages, it can be recorded and read in parallel at a very high rate. The volume hologram is very sensitive to the angle and wavelength of the incident light when reproducing. It can record light with different angles or different wavelengths to record multiple holograms at the same volume of the medium. Read separately under conditions. ^[1]

Holographic interferometry

The wavefront of object light contains the complete information of the object. Holography can record and reproduce wavefronts, and can compare two wavefronts generated before and after deformation of an object to achieve interferometric measurement. Normal interference can only measure polished transparent objects or reflective surfaces, and holographic interference can measure transparent or opaque objects, even three-dimensional diffuse reflection surfaces. Non-destructive testing of materials can also be achieved. ^[1]