by Joe Farina » Fri May 05, 2023 2:57 pm
Thanks very much Din. Please thank Joy also.
After a 6 year hiatus from DCG, I'm having to re-learn many things. I will be carefully re-reading your posts, and also searching the forum for old posts. There is truly a wealth of information here, if one is willing to search. Regarding scattering in the emulsion, I've made numerous sins lately, including not filtering the emulsion. Another potential error was only heating the emulsion to about 40C (just above the melting temp). If I go higher, say to 50C as you mentioned, I have a feeling the emulsion will be more homogenous. The many potential sources of scattering need to be considered, I think, as you outlined so well in this thread. I also found an old post of yours at:
https://holographyforum.org/forum/viewt ... 3B+gelatin
Today, I bought some silicone molds which I think can be used to make small cubes of gelatin/dichromate. Then I can send a laser beam through the cube, and observe scattering on the sides. This may help considerably with the choice of gelatin, etc. My current DCG formula has a lot in it: gelatin, potassium chromate, TMG, acetic acid, methylene blue, rhodamine 6G, and chrome alum (the latter I've found helpful for bias hardening). All this stuff could contribute to scattering. The cube test may help with this also.
My current plan is to go back to basics for a while, and temporarily forget about color. I just want to do regular DCG (gelatin/dichromate/488nm) and then start to think about color. The most important thing to me is the strength of the image, its clarity, the clarity being maintained over a reasonable depth, say 2.5 inches, and being narrowband overall. Brightness needs to be at a certain level, but it's not the overriding factor to me.
Thanks for the photo, I appreciate it. I've taken a photo of a very poor hologram I made this week (of some painted marbles). There was no attempt at balancing the power of the lasers, the 488nm was turned all the way up to 200mW (much higher than 532nm and 633nm), so the image is quite blue overall. I've gotten so out of practice that I still can't identify the reason for the miserable horizontal splash marks.
- P1010054.JPG (76.31 KiB) Viewed 89398 times
Thanks very much Din. Please thank Joy also.
After a 6 year hiatus from DCG, I'm having to re-learn many things. I will be carefully re-reading your posts, and also searching the forum for old posts. There is truly a wealth of information here, if one is willing to search. Regarding scattering in the emulsion, I've made numerous sins lately, including not filtering the emulsion. Another potential error was only heating the emulsion to about 40C (just above the melting temp). If I go higher, say to 50C as you mentioned, I have a feeling the emulsion will be more homogenous. The many potential sources of scattering need to be considered, I think, as you outlined so well in this thread. I also found an old post of yours at:
https://holographyforum.org/forum/viewtopic.php?f=7&t=847&hilit=%26amp%3Bamp%3Bamp%3Bamp%3Bamp%3Bquot%3Btype+A%26amp%3Bamp%3Bamp%3Bamp%3Bamp%3Bquot%3B+gelatin
Today, I bought some silicone molds which I think can be used to make small cubes of gelatin/dichromate. Then I can send a laser beam through the cube, and observe scattering on the sides. This may help considerably with the choice of gelatin, etc. My current DCG formula has a lot in it: gelatin, potassium chromate, TMG, acetic acid, methylene blue, rhodamine 6G, and chrome alum (the latter I've found helpful for bias hardening). All this stuff could contribute to scattering. The cube test may help with this also.
My current plan is to go back to basics for a while, and temporarily forget about color. I just want to do regular DCG (gelatin/dichromate/488nm) and then start to think about color. The most important thing to me is the strength of the image, its clarity, the clarity being maintained over a reasonable depth, say 2.5 inches, and being narrowband overall. Brightness needs to be at a certain level, but it's not the overriding factor to me.
Thanks for the photo, I appreciate it. I've taken a photo of a very poor hologram I made this week (of some painted marbles). There was no attempt at balancing the power of the lasers, the 488nm was turned all the way up to 200mW (much higher than 532nm and 633nm), so the image is quite blue overall. I've gotten so out of practice that I still can't identify the reason for the miserable horizontal splash marks.[attachment=0]P1010054.JPG[/attachment]