Creating a circular laser beam projection [closed]

Question

I’m looking to create a small device (<5 in.) that will project a circular beam around it, a certain distance away from the object. The goal is to have a laser/projector module/something at the top of this device, that will project a circle downward onto the table, roughly 5-10” away. (360 degrees around object)

Not sure what the best approach to take here is, as I want this device to be as small and cheap as possible, while displaying a fairly quality circular around the object.

Any suggestions would be greatly appreciated

Answer 1

The circle can be generated using a diffraction plate (like in the decorative winter snowflake projectors, etc). All you need is a laser pointing up, a diffraction plate for a circle shape, and a mirror to get the conical beam reversed to go down.

Or, without a mirror, just put the laser and the diffraction plate somewhat higher.

Without a diffraction plate, the mirror could be mounted at an angle on a small rotating stage, with a hole in the center. Laser points up, shines through the center of the rotating stage, reflects off the rotating mirror, projecting a cone of light that looks like a circle when it hits a flat surface.