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by **jrburns47** » Mon Oct 19, 2020 9:57 am

I’m no expert although i’ve done a fair amount of research on the topic. Here’s a photo of a page of info from a Covestro flyer. Use at your own risk

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by **SarahC** » Mon Oct 19, 2020 9:42 am

I see, thanks!

I've just had a look at my blue LED darkroom light with a little spectrometer, and it peaks at ~465nm.

The spectral absorption on https://geola.com/product/photopolymer/ shows 465nm blue is just a teeny bit higher than using a 660nm yellow safe light.
Save the pennies, and the holograms look after themselves. =D

Aren't indoor hobbies great for the lockdown? =D
I wonder if anyone's done a Covid scene with the virus particles floating around in a green tinted magical space.... I imagine the spikey critters would look rather good in a hologram - an excuse to have a lot of depth too.
If I may - something like this.... https://codepen.io/SarahC/pen/xxGbGEr

by **jrburns47** » Mon Oct 19, 2020 9:16 am

As you know, the HX200 is panchromatic. The work necessary for using photopolymer is pre-exposure (laminating without bubbles and dust to a clean substrate under dim safelight, not to mention good substrate prep) as opposed to post-exposure like silver halide. This is covered on the Covestro/Bayer website in support docs and videos. Completely different skill set but important to master if one intends to show publicly. Additionally, the aspect of archival protection and longevity for public display hasn’t been investigated yet as far as I’m aware.

by **jrburns47** » Mon Oct 19, 2020 9:06 am

Westinghouse Lighting 03465 Nanolux 1-Watt G19 LED Bulb, Amber https://www.amazon.com/dp/B000UQ0HO8/re ... JFb3YBQR81

Kind of pricey but good- don’t know if available in UK. Go on Covestro (Bayer) website for more specifics if you can’t get this one. Maybe others here can give better info.

by **SarahC** » Mon Oct 19, 2020 8:56 am

I'm just in the process of talking to Tatjana to get an 18 sheet pack of 10 x 15cm Bayfol HX200... currently at ~£100.

Oh no........ I've got a rainbow of colours for safe lights, from super deep cherry red luxor, through to near UV-A, but not yellow. =(

Any torches on Amazon UK have the right frequency yellow would anyone recommend?

My dark room is the kitchen at 3am - I'm THAT dedicated I get up early rather than change the bulb in the shed.

by **jrburns47** » Mon Oct 19, 2020 8:44 am

Interesting point re photopolymer. I’ve only made a few tests with it and hadn’t considered the edge diffraction issue with it yet. I’ve been mostly using silver halide glass plates for which the 235 tape is useful. i’ve been gearing up for more extensive HX200 work and worked out a homebrew laminar flow hood and gotten the 1watt yellow safelights and even had a 4x8ftx3/16” glass sheet of Starfire glass cut up for use as substrates but haven’t bitten the bullet to spend the $ necessary to get a roll of material.

by **BobH** » Mon Oct 19, 2020 8:20 am

My favorite tape too, and a "must have" for any hololab. You're right about edge "ringing" from cards used to mask edges, but if they are only a few inches away, the issue is minimized. Also, I'd worry about tape touching photopolymer that's only very lightly attached to the glass. If one uses ink on the top edge, the line across the scene in a Denisyuk setup is minimized. An edge mask for the bottom edge seems like the easiest to do. All will work. Best is what's available and easiest for the holographer.

by **jrburns47** » Mon Oct 19, 2020 7:34 am

Set up a card to block laser light so that some of the laser light falls onto a white card downstream. Sometimes i’ve noticed a series of black lines on the white card matching the edge of the blocking black card, i.e., edge diffraction. BobH is an excellent holographer and card blocking obviously works well for him. I use black blocking cards extensively but always keep an eye out for unwanted edge diffraction. The 3M 235 black tape i previously described comes in different widths and is generally useful to have around a holo lab/studio in my opinion, in addition to the plate/film edge blocking I mentioned. I don’t own stock in 3M

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by **SarahC** » Mon Oct 19, 2020 4:14 am

"..........no risk of diffraction interference from blocking card edges."

Ooo, what's that? I thought blocking the edges stops interference.

by **jrburns47** » Sun Oct 18, 2020 2:59 pm

Personal preference, I prefer 3M 235 black Photographer’s Tape, 1/4” width for blocking edges from laser light scatter. Removes easily without residue and is opaque to laser light. Nothing to wipe off and no risk of diffraction interference from blocking card edges.
https://www.hisco.com/Product/00021200028373-31196

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