http://www.lunchboxcollections.com/wars-holographic/
Why do hologram only work with lasers?
Luke Skywalker stumbles upon a droid robot that plays a distress hologram for Princess Leia over and over. This scene is from the first-ever Star Wars film. And the viewing of the holographic messages was the first step in one of the greatest science-fiction sagas of all time. These days, we see and use lasers and holographic technology on a daily basis and think nothing of it. That Disney cartoon that banners its three-dimensional animated characters, that shiny, embossed image on your credit card or banknote, uncannily realistic and multifaceted museum displays-- these are all made possible because of holography, and the key element here is the laser beam, why only lasers?
The key to making a hologram is to record the interference patterns of light reflecting off an object compared to light not reflecting off the object. This recording is made on light-sensitive film similar to what's in a camera.
Normal light is such a random mixture of wavelengths and phases (its peaks are "out of step") that any interference patterns will not remain constant.
A laser consists of light that is all the same length and "in phase" or coherent which means its peaks are all synchronized. The analogy here is usually a band marching in step - they all take the same size steps at the same rate.
As a result, interference patterns from lasers will be stable and can be recorded. A lot of care has to be taken in the process though. If the table where the hologram is being made vibrates even a few wavelengths of light, the hologram will be ruined.
 |
 FUNKO STAR WARS HOLOGRAPHIC YODA 2008 COMIC CON $15.99 Time Remaining: 1d 8h 51m Buy It Now for only: $15.99 |