video

iPod/TV Video Laser Projector – Proof of Concept

Dichroic Laser Beam Combining
Dichroic Laser Beam Combining

The idea came to me when I saw that microvision was coming out with some pico laser projectors that had some neat properties. First it was tiny and portable, second there were no lenses needed since it was a laser display and laser light doesn’t diffuse out as much as… well… diffuse light. Lastly and most importantly the aspect ratio could be changed indefinitely with the wall to be projected on. This means you could place the projector basically at 90o to the wall you want to project on! COOL! So I decieded I’d have to make one, the simplest way I could think of was to use RGB combined lasers and shine them through an LCD screen. Here are my first attempts:

That video shows the dismantling of the LCD screen and the first test of unfocused laser light as a transmitting light source. It seems to work.

I’m also using some Dichroic Mirrors / Beamsplitters from Thor labs to mix my red, green, and blue lasers to make white laser light. This will enable me to output full color laser video. The way the dichroic filter works is by selective reflection, this will allow laser mixing in the following manner:

Dichroic Laser Beam Combining
Dichroic Laser Beam Combining

I bought multiple mirrors, each one selectively reflects a narrow band of light. So when I want to combine red and blue I would use a cyan subtractive filter aim the red through it, but have the blue bounce off at the same angle the red went through. This will have the effect of spectral laser combining and the resulting laser light will not be coherent. For more methods of laser combination and an explanation check out The Encyclopedia of Laser Physics.

Here’s the album of photos that i have of this project… So far: