Search found 401 matches

by Din
Tue Mar 19, 2024 12:03 pm
Forum: General Holography
Topic: beam ratios: silver vs. polymer vs. DCG
Replies: 5
Views: 198

Re: beam ratios: silver vs. polymer vs. DCG

Having done my first few photopolymer holograms (Bayfol HX200), it seems that polymer is more dependent on beam ratio equality (ideally ~1:1 for a reflection hologram) compared to DCG. It reminds me of silver halide, but perhaps not as extreme. Maybe this is due to the dyes present in polymer and s...
by Din
Sun Mar 10, 2024 9:51 am
Forum: General Holography
Topic: One-step real-image reflection hologram?
Replies: 4
Views: 260

Re: One-step real-image reflection hologram?

Yes, a 2f-2f geometry will create the real image on the other side. But, you have to consider aberrations, particularly coma and astigmatism. Coma will distort the image and astigmatism will cause a variation of the focus through the depth of the image. To avoid this, the lens has to be much larger ...
by Din
Mon Feb 19, 2024 2:18 pm
Forum: For Sale / Want to Buy / Trade
Topic: Donate and Help Conservation Research?
Replies: 14
Views: 2234

Re: Donate and Help Conservation Research?

Given your extensive experience in creating and testing -- 1. Would you agree that UV light exposure is the biggest risk to black-backed SHG holograms? P.S. We found that UV filtering plexiglass did not impair our image reconstruction. 2. Do you agree with the Wise article's statement about heat ex...
by Din
Fri Jan 26, 2024 9:41 am
Forum: For Sale / Want to Buy / Trade
Topic: Manual for the Coherent Sapphire 532-300
Replies: 7
Views: 1064

Re: Manual for the Coherent Sapphire 532-300

There's no such thing as a zero divergence beam. Any plane wavefront would have to be infinite in extent to have zero divergence. Diffraction causes any finite plane wavefront to diverge: "Diffraction causes light waves to spread transversely as they propagate, and it is therefore impossible to...
by Din
Thu Jan 25, 2024 9:36 am
Forum: For Sale / Want to Buy / Trade
Topic: Manual for the Coherent Sapphire 532-300
Replies: 7
Views: 1064

Re: Manual for the Coherent Sapphire 532-300

... it is reasonably collimated. (But divergence looked rather substantial.) Joe Joe a laser cannot be collimated and have a divergence. The beam exiting the laser is always diverging because it's in the nature of the Gaussian profile (I can give you the mathematics of it if interested). There is a...
by Din
Tue Jan 23, 2024 1:37 pm
Forum: For Sale / Want to Buy / Trade
Topic: Donate and Help Conservation Research?
Replies: 14
Views: 2234

Re: Donate and Help Conservation Research?

Thanks, Din, this paper is new to me, and I appreciate it. The paper is disappointing, because it's more of a "survey" of art, rather than a technical study. It did have an interesting list of potential problems with silver halide materials. I think this might be useful for the original p...
by Din
Tue Jan 23, 2024 9:32 am
Forum: For Sale / Want to Buy / Trade
Topic: Donate and Help Conservation Research?
Replies: 14
Views: 2234

Re: Donate and Help Conservation Research?

Joe Farina wrote: Mon Jan 22, 2024 9:47 am Hi,

I think this would be a very interesting area of research. As far as I know, there has never been an independent and unbiased evaluation of the permanence or longevity of holograms.
http://resources.culturalheritage.org/p ... 5_Wise.pdf
by Din
Wed Jan 17, 2024 2:09 pm
Forum: The Dump
Topic: PFG-3m vs PFG-1
Replies: 1
Views: 1476

Re: PFG-3m vs PFG-1

Hi everyone, I am new to this forum and new to holography. I am planning to start with Denisyuk reflection holograms using a 5mw 650nm laser diode. Q1: should I opt for PFG-3m or the older PFG-1 plates to start with? Start with 01 Q2: is the recording / developing of PFG-3m more difficult than PFG-...
by Din
Sat Jan 06, 2024 2:56 pm
Forum: General Holography
Topic: SPIE West Holography Program
Replies: 0
Views: 2725

SPIE West Holography Program

This is the program for the holographic part of SPIE West later this month in San Francisco. I'm particularly interested in the IR sensitive Bayfol to be given by the Covestro people. I was once asked to develop an IR sensitive holographic medium for eye tracking because of the interest in eye track...
by Din
Sat Dec 23, 2023 9:28 am
Forum: Off Topic
Topic: some mathematical gobbledygook
Replies: 0
Views: 4961

some mathematical gobbledygook

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