Holography

Holography is a three dimensional recording of an image using interference pattern and not regular image focused on film also called lensless photography.The term ‘hologram’ can refer to both the encoded material and the resulting image. Holography was invented by Dennis Gabor in 1948 later awarded Nobel prize.

The light used to make a hologram must be coherent, i.e. of a single wavelength or frequency and with all the waves in phase.  Before reaching the object, the beam is split into two parts, one the reference beam is recorded directly on the photographic plate and the other is reflected from the object to be photographed and is then recorded. Since the two parts of the beam arriving at the photographic plate have traveled by different paths they combine to create an interference pattern of the object. 

A hologram exhibits a property called parallax, the image will change its appearance if you look at it from a different angle, just as if you were looking at a real 3D object.

The image can be reconstructed even from a damaged or partially available film because every point of the hologram contains the image of the object.

The images are scalable. They can be made with one wavelength and viewed with another, with the possibility of magnification.

Applications

Bubble chamber holography has been performed at the Enrico Fermi National Laboratory.Three-dimensional tracks in a 15-foot deep bubble chamber were recorded. The creation and annihilation of matter and antimatter can be seen through these holograms.

Biomedical applications of holography is actively pursued in the U.S. and Europe. Holograms are made inside live organs through optical fibers, providing more details than any previous alternate techniques.

Instantaneous growth rate of a live plant can be directly observed through a hologram. Using optical fibers, the rigid body movements can be isolated from the net growth information.

Bi-focal contact lenses are being manufactured. Compact discs players use holograms to handle light. Grocery store scanners use spinning holograms. High resolution spectrometers use holographic gratings. Anti-counterfeiting in credit card is now a common practice.