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kirkbauer2805 · Sep 16, 2009, 07:43 AM

I am trying to use a light source to project 40 distinct dots of light on a ceiling. So far I get dots but they are blurry or have a halo around them and all run together. Do I need to send the light down a tube to accomplish this?

Perito · Sep 16, 2009, 07:49 AM

... or you could use a lens.

kirkbauer2805 · Sep 16, 2009, 07:58 AM

I am trying to do this at tables at a dinner and need to have a flashlight as a light source. Then I actually am trying to have each flashlight produce 40 distinct dots. I think the parabolic nature of the flashlights reflector is causing the halo's but have not figured out how to overcome that.

ebaines · Sep 17, 2009, 06:28 AM

How are you doing this? Did you make up some sort of cover for the flashlight with holes in it? If so, then yes - the dots of light will indeed be fuzzy, because the light shining through them is not from a point source, but rather comes from a filament (which is more like a line than a point) and the reflector behind the bulb smushes the light out into a broad source. You would probably be better off if you removed the reflector, although this will make the points of light dimmer. You can also experiment with increasing the distance between the cover and the bulb - this should help sharpen the dots a bit. But in the end Perito is correct - the only way to get true points of light is to have a lensing system that focuses the light from each hole.

kirkbauer2805 · Sep 17, 2009, 07:17 AM

Thank you. I was attempting to keep costs low, because I have 50 tables and I wanted to have each projecting 40 dots for a total of 2,000. So a lens for each is a deal breaker. I could live with the ring of light as long as I can get them far enough apart and keep the intensity up. So I am not done experimenting.