Search found 802 matches

by Joe Farina
Fri May 10, 2024 7:51 am
Forum: General Holography
Topic: noise due to a large (extended) object
Replies: 10
Views: 1513

Re: noise due to a large (extended) object

According to the paper by Gabor, if you illuminate the diffusion screens with multiple beams, you may get rid of speckle, but, at the cost of increased complexity in the geometry. That's an interesting suggestion, thanks. I want to try a transmission diffraction grating to break up the object beam ...
by Joe Farina
Wed May 08, 2024 5:10 pm
Forum: General Holography
Topic: noise due to a large (extended) object
Replies: 10
Views: 1513

Re: noise due to a large (extended) object

Did you want me to try a simplified explanation without Gabor's "gobbledygook" ? To make Gabor's paper comprehensible to me, it might take a superhuman effort. I think you once said on this forum that conversations must, at some point (probably sooner than later!), get technical/scientifi...
by Joe Farina
Tue May 07, 2024 8:40 am
Forum: General Holography
Topic: noise due to a large (extended) object
Replies: 10
Views: 1513

Re: noise due to a large (extended) object

The 1970 paper on speckle by Dennis Gabor has been posted in the pdf collection.
by Joe Farina
Tue May 07, 2024 8:18 am
Forum: holoforum administration
Topic: problem with attachments
Replies: 2
Views: 1622

Re: problem with attachments

Thank you!
by Joe Farina
Wed May 01, 2024 7:50 am
Forum: General Holography
Topic: noise due to a large (extended) object
Replies: 10
Views: 1513

Re: noise due to a large (extended) object

Thank you for the clear and superbly written explanation!
by Joe Farina
Tue Apr 30, 2024 6:56 am
Forum: General Holography
Topic: noise due to a large (extended) object
Replies: 10
Views: 1513

Re: noise due to a large (extended) object

Thanks for the very helpful clarifications. The hologram does not "record" a grainy-looking hologram. Subjective speckle is an illusion of the eye, objective speckle is the speckle pattern on the object that the reflected laser light reflects onto; if a laser beam is reflected off some obj...
by Joe Farina
Tue Apr 30, 2024 6:25 am
Forum: holoforum administration
Topic: problem with attachments
Replies: 2
Views: 1622

problem with attachments

Hi John,

I've recently been getting error messages when trying to add attachments, the message says: "Sorry, the board attachment quota has been reached."

Just wanted to check if there's an easy fix for this.

Thanks for all your efforts in maintaining the forum.

Joe
by Joe Farina
Sun Apr 28, 2024 4:42 pm
Forum: General Holography
Topic: noise due to a large (extended) object
Replies: 10
Views: 1513

noise due to a large (extended) object

Since the forum has been slow lately, I would like to pose the following question (which I've been wondering about). Say we make two holograms that measure 10cm X 10cm. These would be single-beam Denisyuk DCG reflection holograms (with a wide dynamic range associated with DCG, if that makes a differ...
by Joe Farina
Sat Mar 30, 2024 6:00 am
Forum: Beginning Holography
Topic: Hello! Good books for interested peeps?
Replies: 3
Views: 2238

Re: Hello! Good books for interested peeps?

Welcome to the forum. Practical Holography by Saxby, G., I saw someone mention 4th edition is best, but is it really worth an extra $140 over a 3rd edition In my opinion, probably not. My favorite is the 2nd edition. As for getting started in holography, I would recommend a green (532nm) laser of at...
by Joe Farina
Tue Mar 19, 2024 1:30 pm
Forum: General Holography
Topic: beam ratios: silver vs. polymer vs. DCG
Replies: 8
Views: 2509

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

Wow, thank you Din and Joy! Joy's comments seem to confirm my impressions about Bayfol HX200 photopolymer. When I did the first two, they were just simple Denisyuk with no extra object light. I didn't measure the reference/object ratio, but the reference must have been much, much stronger. White obj...