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Denisyuk setup, three wavelengths (640, 532, 457), 3mins exposure or so.
Proper lamination on glass is difficult. Tips welcome

https://youtu.be/SzVLz2yhPO4
https://youtu.be/pP2MUUNUlaE

Super nice ! What thickness glass are you using to carry the PP, I found thicker works better, like 1/4”...

Thanks.
I have used 2 and 3mm 4x5" plates (recycled from Agfa and Ultimate Agx).
1/4" sounds very thick, I wonder what makes it work better with thicker plates

It’s what they recommend on PP?

holomaker wrote: ↑Mon Oct 05, 2020 11:29 am It’s what they recommend on PP?

No idea.
Here they laminate on 1mm glass: http://geola.com/product/photopolymer/

Kodak used 4 x 5 in plates at 1mm THK.
Agfa used more, 2mm, perhaps

Agfa was 1.5mm for 4x5", 3mm for larger. 1mm is fine for photopolymer, even 0.7mm. Thicker works better for DCG because DCG is formed via crosslinking, which can bend substrates that are too thin during exposure causing motion fringes.

BobH wrote: ↑Tue Oct 13, 2020 10:16 pm Agfa was 1.5mm for 4x5", 3mm for larger. 1mm is fine for photopolymer, even 0.7mm. Thicker works better for DCG because DCG is formed via crosslinking, which can bend substrates that are too thin during exposure causing motion fringes.

You can use very thin glass for dcg holograms. Don Broadbent coated on glass less than 1mm thick, and so have we. The problem occurs in coating. We use Meyer bars to coat, which means pressure on the glass as you coat, which can crack the glass. You have to coat very delicately. You can coat thin films by some sort of 'flow' method, but it's difficult to accurately determine emulsion thickness and uniformity. Emulsion thickness and uniformity is not so important for display holography because in display holography, brightness is more important than efficiency and the variability in photopic response is broad. However, in technical holography, the thickness has to be known quite precisely. We measured our emulsion thickness to 10%.

BobH wrote: ↑Tue Oct 13, 2020 10:16 pm Agfa was 1.5mm for 4x5", 3mm for larger. 1mm is fine for photopolymer, even 0.7mm. Thicker works better for DCG because DCG is formed via crosslinking, which can bend substrates that are too thin during exposure causing motion fringes.

Bob, based on your great experience, what is the best procedure to temporarily mount the photopolymer on the glass support without trapping air bubbles which, due to the micro-movements induced during exposure, will inevitably result in black spots on the final hologram ? Thank you

First, I do it in a dedicaterd area that's kept clean. I use an anti-static airgun (pictured below) to blow the dust off the glass plate first. That keeps dust from being attracted to the surface. Then I use a small laminator I got and modified 20+ years ago to put the film down. Finally, I trim with a razor blade to prevent the edges from lifting while handling the plate. No bubbles.

https://www.terrauniversal.com/blog/ion ... t-quality/