Holograms

by: Hera

Holograms

by: Hera

What is a hologram?

A hologram is a 3D image formed by the interference of light beams from a laser or other light sources. There have been a variety of different holograms that have been made over the past couple year. Some examples include transmission holograms, and rainbow holograms (used on credit cards,ID cards, licenses etc). Holograms are usually used in ID cards for security purposes as it is difficult to forge holograms.

How do holograms work?

In a hologram a laser beam is shined upon an object and the recording medium. It is necessary that a laser is used rather than any other source of light because in a laser the light waves are coherent which allows more control over the hologram being made. Then, using mirrors, the laser is split into two equal beams and redirected. One beam is directed towards the object and the other, towards the recording medium. The two beams intersect with each other and create a unique pattern which is then burned on to the recording medium to recreate the image.

History of Holograms

Holograms were invented in the UK by a Hungarian physicist named Dennis Gabor (1900-1979) while he was trying to figure out how to improve the resolutin of an electron microscope. He studied optical physics, but had his revolutionary idea of holograms in the early 1950's. 'He had invented holograms ahead of him time as lasers had not been invented then.

In 1960, Russian scientists N. Bassov and A. Prokhorov , and american-born Charles Towns invented the laser which were ideal for making holograms.

Later in the same year, the pulse-rugby laser (laser that emits shrp bursts of light for a couple nanoseconds) was invented by Dr. T.H. Maimam. The first hologram was made in 1967.