Author Options:

1 bit x-y scanning laser projector? Answered

A lot of the laser projectors I have seen have problems with seek times and stability. This guy seems to have done pretty well. Would it be possible to create a scanning laser projector with a single bit input?

Replace the x and y galvo(or any other type) scanners with motor powered wheels rotating at a constant speed. This would create a filled in square of laser light. Then all you would need to do is send an off-on signal to the laser to create an image. It is the same principle as a black and white CRT TV.

What do you think?

Edit: I think one motor should be stepper and the other permanent magnet. If both were pm's it would only create a diagonal line. The pm motor would scan from side to side while the stepper would tick along at the refresh rate. I guess you are kind of running into the same problems as you would with traditional galvo scanners.

Edit (again): With a high speed motor from a dremel (max 35,000 rpm) you could only get about 130x100 pixels with 24fps... hardly the best projector. Not to mention the extreme vibration you would have to deal with if you didn't balance it correctly. I guess I kinda answered my own question.


The way it IS done doesn't wobble mirrors around, but uses polygonal metal mirrors spinning at very high speed - you can see them in bar code scanners in supermarkets. They have no vibration to worry about. The N side polygon scans N times faster than the RPM.


That's brilliant! It is amazing how often we reinvent the wheel. Or rather my idea would be like a square wheel in comparison.
So how about a 3 sided mirror for the refresh rate(x axis) and an 8 sided mirror for the y axis. Set the refresh rate to 48 fps and a 800x600 pixel screen. This means that the refresh rate motor spins at 960 rpm and the other one at 3571 rpm. You would need at least a 23 MHz clock rate on your on-off signal. Even cheap laser diodes can handle several Gbps.

Or you could try what this guy did. You would need several hundred mirror faces to get any sort of good resolution though.

You'd need an AWFULLY bright laser though !
And some method of synchronising the drums.

This might amuse you.


one answer is to try it and see what happens.

Your range won't be great

As an example you can glue a mirror to a loud speaker and shine the laser on it the resulting image shows the audio waveform

You can scan this with your rotating mirror.