Search found 399 matches

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: 1676

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: 908

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: 908

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: 1676

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: 1676

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: 1259

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: 2585

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: 4498

some mathematical gobbledygook

Untitled.jpg
Untitled.jpg (5.94 KiB) Viewed 4498 times
by Din
Mon Nov 27, 2023 12:49 pm
Forum: DCG
Topic: OBIS LS/LX Can OBIS LS/LX lasers be used to create holograms?
Replies: 10
Views: 10996

Re: OBIS LS/LX Can OBIS LS/LX lasers be used to create holograms?

With your gelatin and dichromate, you should be dissolving in about 35 mls of water. However, most dcg holographers us ammonium dichromate, not potassium. Potassium dichromate is less sensitive than ammonium dichromate and you need a longer exposure than you'd normally use. As a rough estimate, I'd ...
by Din
Sun Nov 26, 2023 1:36 pm
Forum: DCG
Topic: OBIS LS/LX Can OBIS LS/LX lasers be used to create holograms?
Replies: 10
Views: 10996

Re: OBIS LS/LX Can OBIS LS/LX lasers be used to create holograms?

I'm sorry I can't make out the image you uploaded. As I understand, you placed a lighter underneath the plate, and a coin next to it. If the lighter was about 5 mm thick, the coin was 5 mm below the lighter? If this is all correct, the coherence of your laser is very probably more than 5 mm, and the...