Search found 20 matches
- Sun Jun 21, 2015 11:35 am
- Forum: General Holography
- Topic: Spatial Filter
- Replies: 9
- Views: 6728
Re: Spatial Filter
.......The distance between the two plates (for the microscope objective and for the mounted pinhole) is adjustable. I should write: The MIN and MAX distance between the two plates (for the microscope objective and for the mounted pinhole) is adjustable, so that also longer or shorter than normal m...
- Fri Jun 19, 2015 10:15 am
- Forum: General Holography
- Topic: Spatial Filter
- Replies: 9
- Views: 6728
Re: Spatial Filter
I am very satisfied with the spatial filter from HOLMARK (an Indian producer). Model number SFA-S http://holmarc.com/spatial_filter_mounts.php Good quality, with micrometer movement and NOT expensive. About five years ago, I paid ca. USD140 each new. Additionally, it is very versatile: The distance ...
- Fri Feb 07, 2014 11:29 am
- Forum: Optics
- Topic: question about beamsplitter cube & waveplates
- Replies: 10
- Views: 14493
question about beamsplitter cube & waveplates
I'm having some difficulty with a broadband beamplitter.......... Joe, your cube's characteristics seems to be OK ( http://search.newport.com/?x2=sku&q2=5811 ). In my opinion, the problem is caused by the wave plate. I may have a mounted Double Fresnel Rhomb Assembly (achromatic) available, if ...
- Fri Jan 18, 2013 2:53 am
- Forum: For Sale / Want to Buy / Trade
- Topic: Long Red Lasers
- Replies: 64
- Views: 24847
Long Red Lasers
Paulos, I don't believe the coherence length of a laser with an etalon in it is limited to twice the cavity length. Bob, The equations are from Hariharan's "Optical Holography, Principles, Techniques and Applications". Those I've used had much, much greater coherence length than that. Are...
- Thu Jan 17, 2013 2:00 pm
- Forum: For Sale / Want to Buy / Trade
- Topic: Long Red Lasers
- Replies: 64
- Views: 24847
Long Red Lasers
1) The coherence length of a HeNe laser WITH AN ETALON is proportional to the mirror separation 2) The Coherence Length of a HeNe WITHOUT AN ETALON = c/Bandwidth . Bandwidth is typically 1.7GHz for a HeNe laser and 3.5GHz for an Ar+ laser, hence the coherence length is ca. 17cm for HeNe and ca. 8cm ...
- Thu Jul 05, 2012 8:29 am
- Forum: DCG
- Topic: Film Thickness
- Replies: 37
- Views: 18000
Film Thickness
..... The orginal question was thick film results in narrow band while thinner was BB. Your results indicate the opposite. I found the same thing, I thicken up my film I observed more BB deeper yellow. Adding more water (making the film thinner) I got a greener result that also was easier to reproc...
- Fri Jun 29, 2012 2:58 am
- Forum: DCG
- Topic: Flat Object
- Replies: 5
- Views: 3886
Flat Object
Last night I was testing some film and used a very flat plaster of paris slab. Every result looked as though it had moved. The were fairly large rings. The image was only visible a odd angles (not the angle I shot). ....... It looks like your object expanded or contracted during exposure. How long ...
- Thu Jan 19, 2012 3:38 pm
- Forum: General Holography
- Topic: Vertical Dark Bands on H2
- Replies: 47
- Views: 15102
Vertical Dark Bands on H2
John, Your film is strong birefringent, and the orientation of its optic axis varies quasi randomly. Without a a lambda/4 plate, I am afraid that almost all your holograms will show these lines. To overcome this problem, you should use a circular-polarized beam to illuminate H1, whereas the emulsion...
- Sun Nov 13, 2011 2:32 pm
- Forum: DCG
- Topic: Ye Old Red Sensitive DCG
- Replies: 14
- Views: 9697
Ye Old Red Sensitive DCG
.................. If you can get your hands on some Rhodamine 6G (not an easy task) then you can combine this with MB and the rest of Jeff Blyth's system for full RGB sensitvity via the "Chinese" method of Zhu et al . .................. Zhu's paper: "True-color reflection holograms ...
- Fri Jul 08, 2011 4:27 am
- Forum: Beginning Holography
- Topic: The price of happiness
- Replies: 9
- Views: 4237
The price of happiness
There is an easy way to first check if your safelight is really safe: In your darkroom, turn on your safelight and look at it through the emulsion. If it looks glass clear, light is fully safe. If you see it more or less gray, emulsion absorbs light and may get fogged. I am using red LEDs for green ...