Cigar Box Laser Light Show

It was spring break last week so I had some spare time to kill. I wanted to do a project that would be done fairly quickly and still have some time to study for classes resuming. I do have several other projects going that I could have worked on but, I figured a laser light show would be appropriate for the occasion, being spring break and all. Actually, I have no idea if spring break party goers are the least bit interested in seeing laser light shows but, I am interested in getting some motors spinning programmatically. And to seal the deal there is a new cat in the mix over here so I have buckets full of laser pointers.

A cigar box made a really nice case for this project due to the nature of mounting the motors. Initially I was going to use a Fossil watch tin but it proved too small for everything to fit nicely. Cigar shops sell empty boxes for a few dollars each.

Here is an overview of the theory of operation. When a mirror is mounted on a motor shaft so that the mirrors' face is less than perpendicular and less than parallel to the motors axis of rotation and a laser is reflected off of this rotating mirror, the reflected laser light will trace a circle on a projection surface and dependent on the speed of the motor being high enough, the laser path traced will appear to be a solid circle on the projection surface (a wall in my case) due to the persistence of vision. You can think about it like a laser cone being reflected off of the mirror. If you stopped there, with one motor and mirror, you would have a laser light show that can draw circles. If instead, you aim this reflected "laser cone" onto another one or more motor/mirror pairs, very interesting shapes begin to appear and change too, depending on the relative speed of all the motors.

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