Search found 867 matches

by Joe Farina
Tue Jan 28, 2025 7:23 am
Forum: General Holography
Topic: Photonics West 2025
Replies: 21
Views: 1147

Re: Photonics West 2025

However... When assessing color, one has to differentiate between "unrelated color", i.e., a color partch without any surroundings, and "related color", i.e., a color in image. Color perception changes a lot when looking at images -- although colorimetrically there may be no roy...
by Joe Farina
Mon Jan 27, 2025 11:58 am
Forum: General Holography
Topic: Photonics West 2025
Replies: 21
Views: 1147

Re: Photonics West 2025

Thanks, Petr, the analysis is much appreciated. I noticed variations in the reproduction of the CIE diagram before, but didn't realize how much they varied until you pointed out how inaccurate that one was. The simulation you posted (the second diagram) looks like what I've experienced so far with 4...
by Joe Farina
Mon Jan 27, 2025 10:13 am
Forum: General Holography
Topic: Photonics West 2025
Replies: 21
Views: 1147

Re: Photonics West 2025

Assuming you're recording DCG, it could depend on how you process. Display DCG always shifted to a lower wavelength due to differential swelling, so the 488 might have shifted down to a lower band; sky blue seems to be about 480. Yes. That's true, I've seen a lot of variation in the final hologram ...
by Joe Farina
Mon Jan 27, 2025 8:43 am
Forum: General Holography
Topic: Photonics West 2025
Replies: 21
Views: 1147

Re: Photonics West 2025

One very practical difference is luminous efficacy of those wavelengths, i.e., how bright they look like. If we set luminous efficacy of 555 nm as 100%, then luminous efficacies of 610, 640 and 660 nm are 50%, 17% and 6%. In short, a bright red object would appear much dimmer with 660 nm than with ...
by Joe Farina
Sun Jan 26, 2025 8:11 am
Forum: General Holography
Topic: Photonics West 2025
Replies: 21
Views: 1147

Re: Photonics West 2025

Haven't used it, but at least they say it's good for holography: https://www.cnilaser.com/PDF/MDL-C-660.pdf 120mW is quite good. I wonder what the practical difference is between 640 and 660nm for color holography. According to Kaveh's paper (which is the one that makes most sense to me), the ideal ...
by Joe Farina
Sat Jan 25, 2025 2:12 pm
Forum: General Holography
Topic: Photonics West 2025
Replies: 21
Views: 1147

Re: Photonics West 2025

Thanks Din and Joy. That's interesting. The nearest equivalent at 640nm, as far as I know, is the 300mW Cobolt Bolero, which is over $20,000. The problem with these expensive lasers is that, after the warranty expires (maybe 2 years at most), any customer support would be an open question. I'm not w...
by Joe Farina
Fri Jan 24, 2025 11:29 am
Forum: General Holography
Topic: Photonics West 2025
Replies: 21
Views: 1147

Re: Photonics West 2025

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...
by Joe Farina
Thu Jan 23, 2025 3:55 pm
Forum: General Holography
Topic: Two watts of 640nm
Replies: 3
Views: 279

Re: Two watts of 640nm

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
by Joe Farina
Thu Jan 23, 2025 3:25 pm
Forum: General Holography
Topic: Two watts of 640nm
Replies: 3
Views: 279

Two watts of 640nm

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...
by Joe Farina
Thu Jan 23, 2025 11:01 am
Forum: General Holography
Topic: Richard Rallison Hologram Repair
Replies: 1
Views: 179

Re: Richard Rallison Hologram Repair

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...