Search found 280 matches

by lobaz
Tue Apr 19, 2022 2:03 pm
Forum: General Holography
Topic: Alternative photopolymer film
Replies: 6
Views: 1076

Re: Alternative photopolymer film

I want over 98% transparency. I get 92% right now. How do you measure transparency, Tekosh? If it is just power after the photopolymer / power in front of, I doubt you can get over about 92% due to Fresnel reflections -- you lose about 4% at both air-photopolymer boundaries. I don't think you can g...
by lobaz
Sun Mar 20, 2022 12:48 pm
Forum: AgX
Topic: Using a 660nm laser to expose legacy AgX Agfa, Ilford, HRT (BB) plates
Replies: 11
Views: 2152

Re: Using a 660nm laser to expose legacy AgX Agfa, Ilford, HRT (BB) plates

Hi Jody, a few years ago I had exactly the opposite problem: red Agfas (more than 20 years old) worked perfectly, while the green ones were completely dead. You could be correct about trying a blue laser, assuming one has an appropriate blue laser with which to test. You don't need a SLM one for tes...
by lobaz
Sun Jan 23, 2022 6:26 am
Forum: AgX
Topic: Reuse of Pyrogallol developer
Replies: 46
Views: 16118

Re: Reuse of Pyrogallol developer

The size of the 818-ST detector should be 1x1 cm2. That is, if light completely fills the sensor area (unlike measuring a thin collimated beam) and you read 25 mW, it means the irradiance is 25 mW/cm2. As 1 W = 1 J/s, it follows it equals to 25 mJ/s/cm2. For the exposure time 1 s, the plate gets 25 ...
by lobaz
Tue Dec 07, 2021 5:07 pm
Forum: holoforum administration
Topic: Insults and character assassination
Replies: 16
Views: 2622

Re: Insults and character assassination

Come on, guys. Both of you are very valuable members of the forum.
If I got a dollar each time I see something I consider silly, I'd be a millionaire.
by lobaz
Sat Nov 13, 2021 10:22 am
Forum: Российский Форум
Topic: Восстановление просроченных фотопластинок ВРП
Replies: 8
Views: 5618

Re: Восстановление просроченных фотопластинок ВРП

Hi guys, sorry, I forgot to write Russian (although I understand a bit), so I'll answer in English. Alexey, since you are in St Petersburg, it would be the best to contact people from ITMO or the Vavilov Institute. I am sure Nikolay Petrov from ITMO can recommend you someone experienced with VRP emu...
by lobaz
Sat Nov 13, 2021 9:32 am
Forum: Beginning Holography
Topic: RGB white laser for holography?
Replies: 5
Views: 5127

Re: RGB white laser for holography?

Hi, a few notes. The term "grain size" applies just to silver halide material, as there are grains of silver halide (often abbreviated AgX) dispersed in the gelatin layer. Materials such as photopolymer do not have any grains of anything like that. This results to an important fact: grainy materials...
by lobaz
Fri Nov 05, 2021 10:59 am
Forum: Beginning Holography
Topic: RGB white laser for holography?
Replies: 5
Views: 5127

Re: RGB white laser for holography?

Hi, I'm 99.9% positive these lasers are not suitable for holography, at least without considerable effort. Lasers for holography must be strictly single wavelength (so called single longitudinal mode, SLM), while most lasers are far from that. The result of using non-holographic lasers is extremely ...
by lobaz
Sun Jun 20, 2021 12:51 pm
Forum: Optics
Topic: Dammit!
Replies: 6
Views: 3924

Re: Dammit!

I guess most researchers are on the same boat :)
Anyway, after reading the article, do you think that WKB approximation is a useful tool here? Not every published method is useful in the end...
by lobaz
Tue Jan 19, 2021 5:27 am
Forum: AgX
Topic: A pdf of all known bleaches
Replies: 10
Views: 6839

Re: A pdf of all known bleaches

Thanks, Dinesh. I mostly use Fe-EDTA or Ultimate. I mostly do reflection display holograms. I don't like PBUs due to their short shelf life.
by lobaz
Mon Jan 18, 2021 5:20 am
Forum: AgX
Topic: A pdf of all known bleaches
Replies: 10
Views: 6839

Re: A pdf of all known bleaches

Thank you for the comment, Dinesh.
Are you aware of any rules of thumb when matching a developer and a bleach?