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Apr 29

A few questions about projectors

So I searched on YouTube and Google and couldn't find any "how it's made" on projectors. I found only 1 thread on here where someone claimed that they're coated with or made of some aluminum, on the reflective part at least. Is that true? In your opinion, if you 3D printed a normal projector bowl and coated the inside with chrome somehow, how would it compare to the real bowl (given the same lens, cutoff, etc.)?
Also, I see some people on here post pictures of a light source and a lens I think. It has some lines and demonstrates how the lens performs. I took honors and AP physics in high school but I forgot exactly how to do the lens problems. What mainly interests me is the lens and the reflector bowl. I saw one person say something like "the lens is the most important part, the bowl just directs the light", is that true? Are all lenses around the same though? I ask because I see people talk about switching from fresnel lenses to clear lenses like it's really easy and you don't need to worry about anything besides the diameter. Do they all have the same focal length or something?
Also, I know the bowl is an ellipsoid, but how does it focus so much light on the horizontal plane? If you could look at the light entering the lens (ignore the cutoff), how would the intensity look on an xy plane with a circle being the perimeter of the lens? Last, can someone explain in great detail how the bowls are designed (geometrically) or can someone point me in the right direction to find out how the shape is designed to make a specific light distribution?

Thanks! I'll post any more questions I come up with or I might have forgotten.