by whoiswei » Sat Sep 12, 2026 10:31 pm
Joe Farina wrote: ↑Thu Sep 10, 2026 5:14 pm
I have used 12ml of 5% potassium dichromate with 6 grams gelatin (exposed at 488nm), and have not seen silver/white holograms. I doubt that the silver/white (a very broadband result?) was caused by the film formula. Rather, I think it's likely due to the processing or other factors. I was not able to view the photo, since my anti-virus software (Norton) blocked it for some reason. Your earlier photos of the coins did come through, however. There was some discussion a very long time ago by John Pecora about white DCG holograms. I will look for that thread. If I can find it, I will provide a link.
Update: I couldn't find the thread in which John described how he got a white DCG hologram, but the example he used was the angel hologram shown on the holowiki:
https://holowiki.org/wiki/Main_Page As I recall, John used some kind of soaking step involving water (it must have been different from the usual water soak?) Maybe another forum member can find the post, or maybe other DCG people here can describe how it's done. I never got a really white (super-broadband) DCG hologram.
It appears that this processing protocol is remarkably reproducible. He remade the batch strictly following the exact same formula, and the newly processed plates yielded identical, stunning silver-white results.
What is most fascinating is that when tilting or rocking the plate, there is virtually zero spatial chromatic dispersion or rainbow color breakup. Instead, the entire hologram undergoes a uniform, monolithic spectral shift. This synchronized optical response across the whole field suggests an unexpectedly complex, super-broadband Bragg interference mechanism operating within the swollen gelatin structure.
In terms of optical performance, this behavior almost mirrors supercontinuum generation in nonlinear fiber optics—where an intense pulsed laser beam propagating through a silica fiber broadens into a white-light coherent spectrum via complex nonlinear dynamics. Here, we seem to be witnessing an analogous spatial-domain phenomenon: a ultra-broadband reflection response that somehow maintains immaculate phase locking, spatial coherence, and image sharpness.
[quote="Joe Farina" post_id=73918 time=1789078455 user_id=2184]
I have used 12ml of 5% potassium dichromate with 6 grams gelatin (exposed at 488nm), and have not seen silver/white holograms. I doubt that the silver/white (a very broadband result?) was caused by the film formula. Rather, I think it's likely due to the processing or other factors. I was not able to view the photo, since my anti-virus software (Norton) blocked it for some reason. Your earlier photos of the coins did come through, however. There was some discussion a very long time ago by John Pecora about white DCG holograms. I will look for that thread. If I can find it, I will provide a link.
Update: I couldn't find the thread in which John described how he got a white DCG hologram, but the example he used was the angel hologram shown on the holowiki: https://holowiki.org/wiki/Main_Page As I recall, John used some kind of soaking step involving water (it must have been different from the usual water soak?) Maybe another forum member can find the post, or maybe other DCG people here can describe how it's done. I never got a really white (super-broadband) DCG hologram.
[/quote]
It appears that this processing protocol is remarkably reproducible. He remade the batch strictly following the exact same formula, and the newly processed plates yielded identical, stunning silver-white results.
What is most fascinating is that when tilting or rocking the plate, there is virtually zero spatial chromatic dispersion or rainbow color breakup. Instead, the entire hologram undergoes a uniform, monolithic spectral shift. This synchronized optical response across the whole field suggests an unexpectedly complex, super-broadband Bragg interference mechanism operating within the swollen gelatin structure.
In terms of optical performance, this behavior almost mirrors supercontinuum generation in nonlinear fiber optics—where an intense pulsed laser beam propagating through a silica fiber broadens into a white-light coherent spectrum via complex nonlinear dynamics. Here, we seem to be witnessing an analogous spatial-domain phenomenon: a ultra-broadband reflection response that somehow maintains immaculate phase locking, spatial coherence, and image sharpness.
[img]https://i.meee.com.tw/YVSCJsM.jpg[/img]
[img]https://i.meee.com.tw/syKT0Dg.jpg[/img]