Search found 794 matches
- Sun Jul 30, 2023 8:17 am
- Forum: General Holography
- Topic: collimated reference beams
- Replies: 5
- Views: 8030
collimated reference beams
I was wondering if other holographers have a preferred way to collimate a reference beam. Some of my holograms lately showed "hotspots" in the middle, which were thought to be from the Gaussian reference beam profile (in DCG maybe a better word would be "hard" spots since the mid...
- Sat Jul 22, 2023 10:15 am
- Forum: DCG
- Topic: energy distribution across DCG plate
- Replies: 2
- Views: 5659
Re: energy distribution across DCG plate
An even more important reason to have an even beam is beam ratio. The beam ratio is proportional to the modulation, and modulation is the most important parameter for efficiency. However, the modulation is a non-linear function of the beam ratio*, so a small loss in beam ratio creates a larger loss...
- Fri Jul 21, 2023 5:02 pm
- Forum: DCG
- Topic: energy distribution across DCG plate
- Replies: 2
- Views: 5659
energy distribution across DCG plate
I was wondering if other DCG holographers have a rule of thumb for measuring energy distribution across the plate, to get reasonably uniform results in the hologram. It seems that an even energy distribution in DCG is more important than in silver, since the hardening issues are so critical. Today's...
- Tue Jun 27, 2023 1:38 pm
- Forum: DCG
- Topic: question about PFG-04
- Replies: 11
- Views: 11593
Re: question about PFG-04
I can't seem to get the same sharpness/depth as I did back in 2007 with traditional DCG (gelatin + ammonium dichromate):
- Tue Jun 27, 2023 1:34 pm
- Forum: DCG
- Topic: question about PFG-04
- Replies: 11
- Views: 11593
Re: question about PFG-04
Thank you, Din, those points are much appreciated, especially the following practical note: We generally coated on Friday, and left the plates to dark react at least till Monday, usually till Wednesday. In about two weeks, we got optimal performance, but after that images tended to get weaker (this ...
- Tue Jun 27, 2023 8:59 am
- Forum: DCG
- Topic: question about PFG-04
- Replies: 11
- Views: 11593
Re: question about PFG-04
Thank you, Martin, I appreciate the information. I'm not sure if I've seen that particular paper by Stojanoff, but I've read others. Regarding the pH of DCG, thanks for the discussion. I'm doing some guesswork about practical DCG which is RGB sensitive (488/532/633). Jeff's alkaline (pH 9-9.5) TMG s...
- Mon Jun 26, 2023 2:40 pm
- Forum: DCG
- Topic: Diazo (Speedball) gelatin hologram
- Replies: 33
- Views: 209021
Re: Diazo (Speedball) gelatin hologram
Martin, you've almost certainly seen this old 1978 report, but in case you haven't, it includes some info on diazo sensitization:
https://erdc-library.erdc.dren.mil/jspu ... L-0128.pdf
Also some mention of casein, and among other things, corn zein
https://erdc-library.erdc.dren.mil/jspu ... L-0128.pdf
Also some mention of casein, and among other things, corn zein
- Mon Jun 26, 2023 1:01 pm
- Forum: DCG
- Topic: question about PFG-04
- Replies: 11
- Views: 11593
Re: question about PFG-04
Thank you Din!
- Mon Jun 26, 2023 8:00 am
- Forum: DCG
- Topic: question about PFG-04
- Replies: 11
- Views: 11593
Re: question about PFG-04
By the way, Martin, since you are the best-read person in holography that I know of, do you recall any studies concerning the hardening/dark reaction of gelatin/dichromate at high (~9) pH? I'm drawing a blank. Thanks.
- Mon Jun 26, 2023 6:06 am
- Forum: DCG
- Topic: "bad" batch of dichromate chemical?
- Replies: 6
- Views: 6818
Re: "bad" batch of dichromate chemical?
My thermostat for the water bath was malfunctioning, and I was cooking the gelatin without knowing it. (No problem with the potassium dichromate.)