Search found 405 matches

by Din
Mon Oct 23, 2023 5:59 pm
Forum: Gallery
Topic: recent DCG hologram
Replies: 4
Views: 22000

Re: recent DCG hologram

Nice. Wonder what difference it would have made if just 532 or 488nm. Jody, The sensitivity of dcg at 532 is close to 1/5th of the sensitivity at 488. So, assuming no dyes were used, just exposing with 488 would have made little difference. The image may be just a little more narrow band, but the e...
by Din
Tue Oct 17, 2023 8:43 am
Forum: DCG
Topic: Purple transmitted light in DCG
Replies: 3
Views: 8135

Re: Purple transmitted light in DCG

Your hologram seems to reflect mostly in the green. Therefore, what's left in the transmission, ie what's taken away from the reflected light, is red and blue, which makes purple. The brighter the hologram, the more green is reflected, and the more purple is the transmitted.
by Din
Thu Oct 12, 2023 8:53 am
Forum: DCG
Topic: Angular Bandwidth in DCG
Replies: 10
Views: 14826

Re: Angular Bandwidth in DCG

Remember also, if there's water in the film, you have to fix for longer to draw out the water. Don Broadbent and his student Augie Muth both had humidifiers in the coating room to control the water content that seeped into the film during the drying phase. If you don't draw out the excess humidity,...
by Din
Mon Oct 09, 2023 12:24 pm
Forum: DCG
Topic: Angular Bandwidth in DCG
Replies: 10
Views: 14826

Re: Angular Bandwidth in DCG

Dave, yes, all of the things you mention will affect spectral response. Thickness: The thicker the emulsion, the more the differential swelling, because, as I said before, the top layers of the emulsion continue swelling as the water penetrates deeper into the emulsion. This means that for a thick e...
by Din
Tue Oct 03, 2023 12:54 pm
Forum: General Holography
Topic: Open aperture holograms w/lens
Replies: 2
Views: 15817

Re: Open aperture holograms w/lens

One of the problems that plagues display holography is the plethora of names for specific types of holograms. This is the case here, where "open aperture holograms" in Saxby is not "open aperture holograms" in the Handbook. The phrase "open aperture hologram" or "a...
by Din
Fri Sep 29, 2023 2:08 pm
Forum: General Holography
Topic: Moving the object to reduce speckle?
Replies: 9
Views: 8864

Re: Moving the object to reduce speckle?

I did try placing my finger on the isolation table while making an exposure. (I may be completely mistaken, but you or someone else mentioned something like this -- sorry if I have you confused with another holographer.) The motion I introduced was probably huge -- maybe a few millimeters. (Another...
by Din
Fri Sep 29, 2023 10:41 am
Forum: General Holography
Topic: Moving the object to reduce speckle?
Replies: 9
Views: 8864

Re: Moving the object to reduce speckle?

Yes, no and possibly irrelevant. Speckle is caused by the rms of a surface, a figure giving the non-uniformity of an apparently flat surface. So, if you have two nearby points on a surface where the variation in height is > λ/2 (~ 300nm), then you get interference due to the extreme coherence of the...
by Din
Thu Sep 28, 2023 1:38 pm
Forum: Off Topic
Topic: Mixed Reality
Replies: 2
Views: 7082

Re: Mixed Reality

Hi Jody It's from today's (9/28) New York Times Business/Technology Section. It's too large for me to scan all of it, but here ( https://www.nytimes.com/2023/09/27/technology/personaltech/meta-quest-3-vr-headset.html ) the full article. You'll need a Times subscription to read all of it. Basically, ...
by Din
Thu Sep 28, 2023 11:50 am
Forum: Off Topic
Topic: Mixed Reality
Replies: 2
Views: 7082

Mixed Reality

From the article: "Imagine reading a holographic recipe in the corner of your eye, while cooking." Also: "After a two hour session playing with Quest 3, I removed the goggles and asked Meta employees the $10 billion question (that's the amount the company invests annually in VR techno...
by Din
Thu Sep 28, 2023 8:38 am
Forum: holoforum administration
Topic: Status of email service
Replies: 3
Views: 21611

Re: Status of email service

Still, I get some gems that arrive in my inbox. Here is one from today I felt compelled to share. I particularly like the "I think you have a 7+ figure business" part. I had no idea we were so valuable. The heck with 7 figures! We're over 9 figures! Somewhere between 3 and 10 billion - ht...