Search found 401 matches

by Din
Tue Feb 07, 2023 1:07 pm
Forum: General Holography
Topic: Holographic testing of CMB radiation telescopes
Replies: 0
Views: 20993

Holographic testing of CMB radiation telescopes

CMB (Cosmic Microwave Background) radiation is radiation in the ~1.9mm region, ie in the microwave region, that pervades space.It's the result of the Big Bang origin of the universe, and detecting it is important to validate and improve the Big Bang Theory. But, the extreme cold of space means that ...
by Din
Mon Jan 23, 2023 12:10 pm
Forum: General Holography
Topic: A blue pigment for Sapphire 488
Replies: 2
Views: 6718

Re: A blue pigment for Sapphire 488

Here is a hologram made by painting on the model. We shot this about 2015. Joy's procedure for testing appropriate paints was to illuminate each colour paint by all three lasers. Using a red paint as an example for red information from the model: 1. Choose a set of red paints and paint a white card ...
by Din
Sat Jan 07, 2023 9:50 am
Forum: General Holography
Topic: Purchasing Lasers
Replies: 5
Views: 7494

Re: Purchasing Lasers

Ont thing I forgot to mention is that you need a lens before the screen to expand the combined beam so as to enlarge the interference pattern. The unexpanded beam is too small to see any structure.
by Din
Fri Jan 06, 2023 10:07 am
Forum: General Holography
Topic: Purchasing Lasers
Replies: 5
Views: 7494

Re: Purchasing Lasers

That leads to another related question: Is there an easy way to measure coherence length of a laser? Thanks again. Yes. You set up a Michelson interferometer, and vary the path difference. I've drawn up a diagram. The beams splitter sends the beam along both path a and path b (black lines). On refl...
by Din
Wed Jan 04, 2023 3:04 pm
Forum: General Holography
Topic: Purchasing Lasers
Replies: 5
Views: 7494

Re: Purchasing Lasers

You may be interested in a white paper I wrote for Melles Griot
Melles_WhitePaper.pdf
(413.06 KiB) Downloaded 540 times
by Din
Fri Dec 16, 2022 11:48 am
Forum: AgX
Topic: Printout revisited
Replies: 3
Views: 25539

Re: Printout revisited

The solubility of potassium iodide in ethyl alcohol decreases as the concentration of ethyl alcohol increases*. Since the way the iodide reduces printout is by replacement of the bromide ion in emulsions with the iodide ion, the large number of bromide ions still in the emulsion (depending, of cours...
by Din
Tue Dec 13, 2022 4:27 pm
Forum: Off Topic
Topic: 3D Zero Order Imaging
Replies: 0
Views: 21351

3D Zero Order Imaging

new hologram20221213_13243499.jpg
new hologram20221213_13243499.jpg (502.7 KiB) Viewed 21351 times
by Din
Mon Oct 17, 2022 9:10 am
Forum: General Holography
Topic: Question about speckle reduction
Replies: 2
Views: 6554

Re: Question about speckle reduction

Do inhomogeneities in the glass or acrylic cause this? Basically, yes. Speckle is caused by phase differences due to index and thickness differences of components along the optical path, and the rms (root mean square) height of the surface. Because of the extreme coherence of laser light, if the rm...
by Din
Fri Sep 23, 2022 8:53 am
Forum: Optics
Topic: Color proximity copies ?
Replies: 2
Views: 10425

Re: Color proximity copies ?

Yes. This is a full colour H2 from a full colour, single H1 (not 3 separate H1's) we shot about 7 years ago. The subject matter is the holographic joke referring to the Utah Teapot. The first test of a computer graphic, 3D algorithm used a teapot as a test. The Utah teapot is considered the "He...