Holography

Journal entries imported from the previous iteration of wisrd.org

HOLOGRAPHY

Conor G.

Uses of Holography

Holographic data storage records information throughout the volume of the recording medium, as well as recording multiple images in the same area. By using the same light at a different angle. Holographic storage also is capable of recording millions of bit of data parallel to each other, allowing for faster data transfer. This is far more efficient than magnetic or traditional optical storage, which can only record individual pieces of information at a time. Similar to a recorded hologram, holographic data storage records data by creating an optical interference pattern on a photosensitive material. Light from a Laser is split into two separate beams, one making light pixels while the other makes dark pixels. Changing the angle, wavelength, or position of the reference beam can make it possible to record many holograms in a single volume. To read the stored information, a reference beam identical to that of the reference beam used to record the information must be focused onto the photosensitive material. This will illuminate the interference pattern which can then be projected onto a detector. The detector will read as much data as possible, resulting in a fast rate of data transfer.

Holography is an imperative concept in interferometry. Holographic interferometry is a type of interferometry that allows for both static and dynamic displacement of objects with rough surfaces to be measured to optical interferometric precision. These can be applied to vibration analysis as well as non-destructive optical testing. Holographic interferometry is a key concept in interferometric microscopy.

Holography is widely used in security. It is very difficult to recreate a hologram exactly. Therefore an object or objects with a recorded hologram on it is expensive and difficult recreate.

Science of Holography

Interference and diffraction are key concepts in understanding holography. Interference occur when one or more wavefronts clash. Diffraction occurs when wavefronts clash with an object. When the reference beam and the object beam intersect the interfer with each other. This interference pattern is what is recorded on the recording media. The pattern that is record seems random, this is because the recording shows how the object beam interfered with the reference beam. Therefor for the hologram to be visible it requires the reference beam to be shone upon it. The reference beam diffracts off the holograms surface pattern. This produces a light field the same as that of the original object that had been recorded.