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Though I won't be in San Francisco this weekend, I received a note from Vitali Kosenko of Laserand Inc. regarding the high-power 640nm lasers. (I had inquired about the pricing of these lasers.): "And regarding the SPIE PW 2025. You can suggest your colleagues visiting us at the booth #5017 You...

They're based in Montreal, Canada. I don't want to check the price because I can't afford it . Thanks for the tip about air-spaced waveplates and the link to Union Optics. I did find another Chinese company which gives prices:

https://crysmit.com/Achromatic-Waveplate

Up to two watts of single-frequency red at 640nm: https://laserand.com/en/lasers/single-frequency-cw-dpss-lasers/640-nx-single-frequency-cw-c-dpss-640-nm-vis-laser/ They have some interesting optics also. At least the achromatic half waveplates are in my price range :) https://laserand.com/en/achrom...

I couldn't see the rings in the photo. (edit: oops, I didn't scroll down to see the second photo showing the rings.) Probably, this effect is due to water vapor that has managed to penetrate the edge seal and contact the gelatin. The rings seem to be in a non-image area, so it's a bit difficult to b...

Thanks, I plan to try it.

Thanks for the clarification. Regarding the use of fixer, I didn't fully appreciate the importance of the tug-of-war taking place between the post-exposure hardness level, and the hardening effect of the fixer bath. It seems that the holographer (with the fixing bath) is at one end of the rope. The ...

Joe Farina wrote: ↑Mon Jan 13, 2025 9:14 am I probably underestimated the importance of post-exposure hardening/reducing by the use of fixer. Din wrote: It's quite important. As I mentioned earlier, it hardens the surface so that it limits the differential swelling. It's a bit of a balancing act (a...

Thanks for the helpful comments, I'm making progress.

The use of fixer is helping, thanks for suggesting it. In the recent tests, I probably underestimated the importance of post-exposure hardening/reducing by the use of fixer. The thiosulphate of rapid fixer is its major component. Since I believe this is superfluous (and the stuff doesn't agree with ...

I would say, almost certainly, laser instability. I would wager that you're not seeing this effect with a helium-neon laser. Anyone who has made holograms with laser diodes probably knows this situation well. I have seen it frequently with laser diodes, and also occasionally with OPSL's like Sapphir...