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How Holograms Work

Posted on March 9th, 2013 under Learner's Corner

In the past months we had learnt of various facts from the world of math, economics and even nanotechnology. This time it’s time to dive into physics. In this edition of Learner’s Corner, we’ll learn how holograms work!!

Holography is a technique that produces images called holograms, in which information can be stored, retrieved, and processed optically. It is termed as lens-less photography, where the interference pattern of light plays a vital role. Hologram is defined as a three-dimensional image formed by the interference of light beams from a laser or other coherent light source. One can see holograms on driving license card, ID cards, credit cards etc. Dennis Gabor, in 1947, came up with the idea of holograms, and it was Emmett Leith and Juris Upatnieks of Michigan, USA, and Yuri Denisyuk of Soviet Union, who produced the first holograms in the year 1963.

Photo Courtesy: Eric Leiser

Photo Courtesy: Eric Leiser

Elements that produce holograms are called holographic optical elements (HOE), and these elements perform the functions of mirrors, lenses, gratings, or combination of them. To elaborate, when a point source light with a fixed wavelength encounters a light of same wavelength from an object, they produce interference patterns on a two dimensional or three dimensional medium called hologram. Holograms are broadly classified into two types

  1. Reflection holograms
  2. Transmission holograms

A reflection hologram is produced when an object is beginning to illuminate by a spot of white light at a specific angle and distance on the viewer?s side. A simple example of reflection hologram can be seen in a diamond. When diamond is illuminated with light, it sparkles; this sparkle is the holographic image of diamond. A transmission hologram is produced with a laser light, which is directed from behind the hologram and the image is transmitted to the observer?s side.

Between the reflection and transmission types of holograms, many variations are made in the hologram for their use in different fields. To name a few:

  1. Embossed holograms – For security application such as the eagle on VISA cards
  2. Holographic interferometry – For engineering applications in the field of holometry
  3. Multichannel holograms ? Used in large computer memories
  4. Computer-generated holograms – Used in making holographic optical elements (HOE) for scanning, splitting, focusing, and controlling laser light in optical devices such as CD player

Holography is beginning to be used in areas like commerce, scientific research, medical science, and industry. They are predominantly used for authentication in credit cards and debit cards for added security and to minimize counterfeiting.

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Astounding are the marvels of  physics!! If you are having trouble in understanding any such physics marvels or even your physics assignments, reach out to Classof1′s Physics homework help

If you’re interested to learn more from other fields do check out “Learner’s Corner” in our blog. The previous posts in Learner’s Corner includes:

1. Life of “i” : The Story of Complex Numbers

2. How is Exchange Rate Determined!

3. Mysteries of Nano-medicine and Nano-bots

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