I'd like to build an installation which projects a star sky on the ceiling. The picture will explain the concept and the problem I've encountered:

enter image description here

As you can see, there is plenty factors that I would need to take into account which I don't know. I'm looking for suggestions on how to approach this problem and would be grateful for some buzzwords on what to google for similar projects (light projecting and similar didn't yield results).


When you say "LED lamp" do you mean some random thing sold in stores as a replacement for incandescent bulbs? Those are terrible "point light sources", because they go to extremes to diffuse the light like the old frosted-bulb incandescent. Precisely because one of the things people hate about LEDs is their intense single-point light.

The technology is not a problem, rather it's finding it in a screw-in off-the-shelf consumer product. You might want to look at bulbs intended for track lighting, flashlight or automotive replacement - specifically ones that have a single multi-watt LED emitter. Explore SuperBrightLEDs.com ... you'll know it when you see it.

It is likely to be 12 volts, which means getting a 12 volt DC power supply also (those are readily available, and if you kept the old power bricks off old Internet routers, you may even own a few.)


Focusing the light requires some tinkering. The size of the hole is a factor. The distance between the light source and the apeture is another factor. Also, if you are using multiple LEDs then there will be multiple stars per hole; each LED will make a star.

Some words to google might be diffraction, interferance, and apeture. Also you could perhaps pick up some info from making an eclipse viewer.


This is also known as a GOBO light. That might be able to help you find more resources online, like this: http://www.instructables.com/id/Gobo-Light-Projector


To get sharp shadow projection you need either something close to a single-point light source, or lenses

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