Wanted!

holorefugee · Post by **holorefugee** » Sun Sep 11, 2011 11:53 pm

100mw 470ish nm laser SLM for less than $1000. What are my options?

Joe Farina · Post by **Joe Farina** » Mon Sep 12, 2011 8:13 am

About the only option would be to find someone who is willing to sell it to you for far less than what he could get from someone else.

Joe Farina · Post by **Joe Farina** » Mon Sep 12, 2011 9:01 am

Colin, I guess 445nm too short for silver halide (color) work because of too much scatter? If you're working with DCG, the 445nm wavelength would be excellent, if you can get the diode to behave, and can live with much less than 100mW. I haven't had time to work with my 445 diode yet. But it seems if these diodes are cooled passively with a good heatsink (TE cooling does not appear necessary) and the beam has some kind of corrective optics (probably the hardest part, I admit) then it might be possible to get them to work. Others have reported good results when using a microscope slide for feedback (Thieu, on the old form) and Paulos devised an excellent way to monitor the stability by reflecting the end "wings" of the diode output beam back towards the laser with two glass plates or microscope slides (of two different thicknesses) to project some fringes for visual monitoring. There was a post on the old forum by Paulos on this subject. I could be wrong, but with careful work with the 445nm diode, you might be able to get a stable 50mW.

142laser · Post by **142laser** » Mon Sep 12, 2011 10:12 am

It would be awesome if there was a solution to this problem on the $1K budget; I just don't see one. SLM blue lasers are still expensive. W just figured out how to defeat the power settings and raise the current limit for Coherent Sapphires so maybe one can get 30-50 mW from a healthy 20 mW head but most of these are 488 nm and the 460 nm LP heads are 10 mW spec. In addition not all run SLM and some hop back and forth between MLM and SLM. Sorry dude, save more money. Phil

holomaker · Post by **holomaker** » Mon Sep 12, 2011 11:20 am

Joe Farina wrote: Others have reported good results when using a microscope slide for feedback (Thieu, on the old form) and Paulos devised an excellent way to monitor the stability by reflecting the end "wings" of the diode output beam back towards the laser with two glass plates or microscope slides (of two different thicknesses) to project some fringes for visual monitoring.

There is really no need to retro reflect these casio diodes, Joe you are correct about them not needing any TEC, as a matter of fact i built/sold many of these units all running stable (see holograms below), ill let you in on a secret i used to make them run stable, mount these diodes on a good thermal mass and locate the driver near by it and bolted to the same thermal mass, now the diode is WARMED slightly keeping it stable, now insulate it well and as long as you are happy with crappy MTF output all is good !

Joe Farina · Post by **Joe Farina** » Mon Sep 12, 2011 11:30 am

Thanks for the good tips and photos Dave. As for the feedback not being needed, thanks, I will keep that in mind. That's interesting about warming the diode slightly. There was an old paper in the Review of Scientific Instruments which stated exactly the same thing: if the diode is held slightly above ambient, it can be made stable.

holorefugee · Post by **holorefugee** » Thu Sep 15, 2011 7:34 pm

142laser wrote:It would be awesome if there was a solution to this problem on the $1K budget; I just don't see one. SLM blue lasers are still expensive. W just figured out how to defeat the power settings and raise the current limit for Coherent Sapphires so maybe one can get 30-50 mW from a healthy 20 mW head but most of these are 488 nm and the 460 nm LP heads are 10 mW spec. In addition not all run SLM and some hop back and forth between MLM and SLM. Sorry dude, save more money. Phil

Still saving and aksing...