Mechanically Raster Scanned RGB Laser Projector

Final Project for 6.115 Microcomputer Project Lab

Laser light show

This class is a chance to remember why you came to MIT: to learn and to build. In the humble and unbiased opinion of the lecturer and TA’s, 6.115 is one of the most exciting classes you can take at MIT to further your professional growth as an engineer. – 6.115 course description

The course description was so taintalizing I had to take it. Having taken the class, I think I’m qualified to say the description is completely accurate.

6.115 is possibly the hardest class you can take at MIT, but also the most rewarding.

If the class you will spend all your time in lab. But you will learn how to build real things; there is really no substitute for the 6.115 way of just doing it.

The class has 5 labs, and exam, and a free choice final project. When you finish the labs and exam, the professor takes out the class for a fancy dinner and drinks.

For the final project I wanted to make a 24-bit color mechanically raster scanned laser projector. The basic idea is that you have an R, G, and B laser diode put into a combinator (using half silvered mirrors) which can each be pwm’ed with an 8 bit counter. The light engine is directed at a mirror clad disk which rotates at 24HZ+ to scan the laser across each pixel row. I chose 8 rows for the design. The raster scanner gets a sync pulse from an IR LED/Phototransistor pair pointed at a reflective dot on the disk. Graphics are then double buffered on the chip and the pwm’s are updated to match the sync pulse for position.

Unfortunately, I didn’t get my project working 100% – diodes in my light engine burned out and I didn’t have enough time in the semester to debug all the components, but I was really close and I learned a ton!

You can check out my lab code here .

© 2017 Jeremy Rubin. All rights reserved.