This may be of interest to those who have money to burn building a multi-wavelength pointer to coaxially combine laser diode outputs from UV through red wavelengths:
https://www.newport.com/f/dichroic-laser-beam-combiners
Be prepared for a shock, these are expensive, too much. I need to find low price alternatives to combine seven wavelengths together from 375 nm UV through near 650 nm.
My thought is all of the diodes would be single mode of 100 mw or more, combining several beams together would produce 250 mw or more for RGB, more if adding additional wavelengths together.
For the cost of the project, it would be a shame to use multimode laser diodes with their higher divergences and poor beam quality compared to single modes. Also, less heat and lower power source requirements.
These are the dichroics I came across yesterday and a while back. Too expensive for sure.
Wise to use single modes. Also a lot of power balancing would be needed to get them all even and have the right overall RGB balance for the white output.
6 diodes are easily done by using PBS.
Just combine two times 3 wavelengths with common dichroics and mix these two beams by using polarizing beam splitters.
I did exactly this to combine
405
450
488
520
571
660
I mixed 405 / 488 / 571 with common dichroics (cheap) and did the same for 450/520/660.
I combined both beams with a polarizing beam splitter.
I was investigating this route yesterday evening, great minds think alike. Was trying to find surplus PBS to combne 375 and 405-412 nm. I went to the Thorlabs web site to find one too, or a plate PBS. If just two wavelengths I want to have 375 nm and a visible wavelength coaxially combined, but more wavelengths would be great whether coaxial or not.
I started to think about just combining two wavelengths due to the difficulty of finding a dichro which could reflect 375 nm and pass 412, that lead me to look for a PBS to combine 375 and 412. If I could find a dichro which can reflect 375 and pass 412-638 that would be perfect and then no need for a PBS which I have not been able to find for both 375 and 412.
I was also thinking to just knife edge four to eight wavelengths, but even four makes a pointer big. That would produce something like a rainbow output which is fine, I am really not needing coaxial, just want switchable wavelengths. However, if just two wavelengths then I would prefer coaxial.
