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Top1. Introduction
The 3D market blew away all other technologies in such a way that 3D got the major popularity at its time. After the introduction of 3D 4D 5D 6D 7D etc techniques in the market there was still something missing. The missing part was the reality in all the dimensional techniques, a huge illusion can be created but the reality was missing. Then the digital market introduced HOLOGRAPHY (Paschotta, R., 2008). Holography is the science of making holograms; it is based on the principle of interference. Holograms captured the beam (interference pattern) between two or more beams of coherent light. Let’s understand this from an example, say you went to a tourist place and you took a picture of the scene you saw and captured some information in your camera, now if you will see this by optics than it is found that storing of time-averaged the amplitude of light coming from sensors such as in separate RGB channels. As a result, a very huge amount of rest of the specifications is leftover or you may say that thrown away. For collecting such small information or specification or capturing the tiny percentage of the scene present a hologram was developed which was first invented by Dennis Gabor in 1947 (in Greek “Holograms” =” whole drawing”). It is the recording of the light rays’ construction when viewed by an observer in such a way that one cannot differentiate and tell the difference between the real and holographic image. It basically provides all the original information about the image(J. Eichler, H., Orlic, S., 2001).
Holography was better than 3D because holography provided virtual reality to the 3D objects. It did not require any additional glass for the viewer to see the image. It is the art of recording light waves and viewing it as the real image that appeared to the eye
1.1. Physics of Hologram and Image Reconstruction
For A physical structure that diffracts light into an image can be seen by looking into an illuminated holographic print or by shinning a laser through hologram and projecting the image onto a screen(H. Jeong, T., 2010)
There are 4 elements of holography.
1.2. Constructive and Destructive Interference
It is the case in which two light waves moving with a coherent light source are superposed upon each other in this case both the waves come upon one another forming a big wave twice the height of two superposed wave. Here the two waves crest starts from the same point so this is called constructive interference. Whereas when two same waves again are superposed but this time the crest of one is trough of the other, it lowers the amplitude thus providing a straight line cancelling the wave (Paschotta, R., 2008)(Rossing, Thomas, D., J. Chiaverina, C., 1999).
Figure 1. (a) Constructive interference (b)Destructive Interference
1.3. Coherent (Laser) Light
It basically depends on 3 properties.
So basically, in this part what happens is a coherent laser light is reflected on a beam splitter which splits the beam into two identical beams. One of them is the object beam which reflects through the object plate and the other beam is the reference beam. The object beam after reflecting from the object comes to the plate and the reference beam directly goes to the pate where the interference of the laser light is recorded to form a hologram (Yang, X., Y. Xu, F., Zhang, Ha., Zhang, H., Huang, K., Li, Y., Wang, Q., 2020).