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Joe, Just listened to a webinar on "Materials and Methods for Creating 3D GRIN Diffractive Optics in Photopolymers." In the course of the webinar, the speaker brought up scattering and noise in a holographic volume recording and recommended this paper: https://opg.optica.org/ao/abstract.cfm?uri=ao-5...

Joe, Just saw your comment about turbitity in the gel while stirring. This may be due to the stirrer whirling at too high a speed. The stirrer should create a circular laminar flow. however, if the stirrer is too rapid, you may start to get turbulence. This could be the cause of the bubbles. Also, t...

One property not mentioned is that the helical structure of gelatin makes it slightly birefringent. This sometimes manifests itself in what appear to be odd holographic effects.

Another thing I noticed was that you were illuminating your samples with a narrow, raw laser beam. This means the volume illuminated inside the gelatin sample may be a small ratio of the beam's volume*. In other words, if the scattering centres are widely dispersed, a narrow laser beam illuminating ...

If you want to quantify your results, you'll need a beamsplitter, a mirror and two meters (see below). The reading on the two meters will be RI (where I is the intensity of the laser and R is the reflectivity of the beamsplitter) and RS(1 - RI), where S is the scattering intensity. The power of the ...

Joe Farina wrote: ↑

Thu May 04, 2023 12:11 pm

Also, can a DCG hologram be made narrowband enough to produce a very sharp image with say three inches of depth, comparable to what silver halide can do?

Thanks.

Yes, this one is about 4 inches deep.

Joe, The first thing that occurred to me was the size of the reproduction source. But, you say you can get sharp holograms with silver, so this does not appear to be the problem. Joy asked if you used the same source, at the same distance, for the sharp hologram as the blurred ones. Assuming it to b...

Isn't it strange that after all these years it's still unclear what we're really looking for in order to get a highly efficient gelatin. What makes it particularly well suited for DCG, FEG etc.? We know certain brands and types are working well while others don't. But we don't know why. Actually, M...

https://opg.optica.org/ViewMedia.cfm?r=1&uri=NP-2014-NTu2A.1&seq=0 I thought this was interesting. Non-linear CGH can alter the phase and amplitude of a Gaussian beam. From the paper: "Specifically, nonlinear CGH were recently used to convert a fundamental Gaussian beam into high order Hermite-Gauss...

It's possible that your cube beamsplitters may have some kind of structure within them, ie cracks, bubbles etc. This would cause scattering and cause your freckles. I used a variable neutral density filter ( https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=1393 ) simply because the studio I...