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As a probable correction to my earlier post, "crawling" watercolor/gouache paint (during a holographic exposure) seems more likely due to glycerin or glucose. Glycerin is known by many of us to be hygroscopic (glucose is said to be, also). One author stated that artist's watercolor paint can contain...

For those of us who have a Sapphire 488 (which has become a fairly common and inexpensive surplus blue laser), I've found a blue pigment which reflects an excellent blue color (similar to the appearance of a clear blue sky) when illuminated with 488nm: Cobalt Blue. I tried a number of other blues un...

I always had trouble sourcing AR-coated glass in larger sizes (and at reasonable cost), but found the following company today. I plan to use it for homemade diffusers: https://www.framedestination.com/prod/sh/anti-reflective-water-white-artglass-ar70.html?gclid=CjwKCAjwwL6aBhBlEiwADycBILhaLY3cwRGl58...

Thanks to all the forum members who contributed to this post. I've learned quite a bit. Having run some tests to reduce speckle in my holograms, I've found that a moving piece of clear acrylic (or glass) placed after the spread beam, and before the diffusion screen, will reduce speckle to a large ex...

Many of us are probably customers of Surplus Shed Optics: https://www.surplusshed.com/ John Pecora suggested them a long time ago. At the time, I didn't know about the company. Very helpful, especially for lenses. You can enter the search parameters: lens type, diameter, and focal length (expressed ...

Thanks Din, that helps a lot. From what you wrote, I get the impression that the thickness variation (during a holographic exposure) of any optical component in the beam path is the key factor for speckle reduction (i.e., speckle averaging in the final holographic image). I tried jiggling a single p...

Today I noticed something, and was wondering if anyone can explain it. I put a spatially filtered laser beam (spread with 40X objective) on a white screen. Speckle is very strong. A diffusion screen was placed before the white screen, and while my hand was holding the diffusion screen (and it was in...

Thanks. Yes, I already had an output duct with two duct-fans in tandem, which removed air from the lab, directly to the outside. In a colder area such as mine, this involved a lot of heat loss, which was expensive due to my electric baseboard heaters. I think a simple opening to the outside would wo...

Probably you've seen this already:

https://www.degruyter.com/document/doi/ ... ml?lang=en

I had a problem recently where I needed to change the beam diameter of a laser at a point about 12 feet away, using lenses to modify beam divergence and make the beam smaller at that point (and also make the spot size adjustable). I had always wanted to try my hand at a ray-tracing program, but thou...