Laser Projector Optical Path Drawing?

[Harold Hallikainen]

I'm giving a presentation on theater technology to a non-cinema group. As part of that, I'd like to include drawings of the optical path used in laser primary and laser phosphor projectors. I'm sure they are out there, but have found everything except what I'm looking for.

Ideas?

[Harold Hallikainen]

Following up on my own question, I did a little research and found that the light path is apparently very similar to a xenon projector (from the integrator rod on out). I had thought that maybe with laser primaries, the lasers would not be combined and then separated again, but apparently it works better this way. So, I'm learning a bit!

[Marcel Birgelen]

Yes, practically all modern laser projector designs combine the laser light first and then push the light through the integrator rod. I guess they do this to save on components. The single prism block for both splitting and combining the image is already pretty efficient. Also, this still allows you to retrofit laser light sources onto xenon-based projectors. Redesigning the optical path of a projector, is probably the most expensive part and the extra efficiency by designing three separate light paths for the R/G/B paths up to the DMD is probably not worth it.

[Marco Giustini]

I think there was a Kodak laser projector which used primaries directly on DMDs. Isn't that something IMAX purchased and use in their current laser projectors?

https://www.imax.com/en/gb/pr/imax-l...neration-laser

https://moviemom.com/interview-brian-bonnick-explains-the-stunning-new-technology-of-imax-laser-projection/

So we decided to throw this prism away. So here is the part core to the design for 25 years and we have thrown it away. So it is a big risk from the development standpoint and part of our way to deal with that was through the acquisition of 120 patents from Kodak in this area.

[Dave Macaulay]

Marco: Yes. That light path was confusing. I only saw inside one very briefly, they were not showing it around. The black was really good on projectors that used this, RGB lasers in the base with flexible light pipes up to the light processing upper chassis... but I don't think current production uses this system.