New Photopolymer Material

[Tom B.]

"Effect of film thickness on the performance of photopolymers as holograhic recording materials" - Boyd, Trentler et al
http://nanonet.rice.edu/papers/appopt.pdf

For the materials they used (NVC and NVP), diffraction efficiency for plane-wave holograms increased linearly with film thickness up to 300 um (NVP) or 500 um (NVC). So maybe going for very thin films for reflection holos is not a good idea. I wonder what the base material for Polygrama might be?

They also mention preexposure - "Before recording, this viscous fluid must be exposed to a flood illumination to create a solid and stable matrix". Maybe UV illumination might achieve this without bleaching the dye?

[Tom B.]

Unfortunately, the polymer is not compatible with gelatin.

Hmm. Maybe epoxy?
"Epoxy Resin-Photopolymer Composites for Volume
Holography" Timothy J. Trentler, Joel E. Boyd, and Vicki L. Colvin:

http://nanonet.rice.edu/papers/cm9908062.pdf

[Sergio]

One important point is, as with any photopolymer, a minimum energetic power of ~0.2 mJ/cm² is desirable for recording

0.2mJ? I thought the minimum was 20mJ.

the halogen (or a clear tungsten lamp) post exposure must be adequate too, 75W lamp at ~10~15cm.

Have you studied the effect of heat on the polymer? At 10-15cm from a 75W bulb the plates get very hot. I've noticed that the polymer doesn't respond well to high heat (tends to become runny again).

Are you cooling the plate at the same time?

Are you doing the post process with the plate horizontal or vertical?

Power density corrected to 0.2mW/cm².

Yes, the heat enhace the post exposure process, the heat could be dissipated with an aluminum foil, excessive heat may affect the polymer.

Post process is made horizontal.



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[MichaelH]

Green samples are available now
Their site states sensitivity from 500-532nm and requires 20-60mj exposure.

http://polygrama.co.nr/

[Sergio]

"Effect of film thickness on the performance of photopolymers as holograhic recording materials" - Boyd, Trentler et al
http://nanonet.rice.edu/papers/appopt.pdf

For the materials they used (NVC and NVP), diffraction efficiency for plane-wave holograms increased linearly with film thickness up to 300 um (NVP) or 500 um (NVC). So maybe going for very thin films for reflection holos is not a good idea. I wonder what the base material for Polygrama might be?

They also mention preexposure - "Before recording, this viscous fluid must be exposed to a flood illumination to create a solid and stable matrix". Maybe UV illumination might achieve this without bleaching the dye?

Tom, in our case we found that with our increased index modulation attained material is able to record thin (~10um) reflection holograms that are still bright. The transmission diffraction efficiency increases linearly until a level of overmodulation, so you need to pay attention on thickness or exposure.

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[MichaelH]

Anyone have any experiments they'd like me to try with the polymer? I may try one more pre-halogen exposure and one epoxy mix test but I'm getting polyer'd out and need to finish upgrading my table.

I've got about 1.5ml left. Sergio, can the polymer be refrigerated for longer shelf life?

[Tom B.]

Anyone have any experiments they'd like me to try with the polymer?

If you have a UV source (or black light fixture) I'd be interested in whether it thickens the polymer, the exposure needed, and whether the blue dye gets bleached out. Or maybe try a green laser? The idea being to see if it's possible to partially pre-thicken the stuff without losing red sensitivity.

I think I'll use microscope slides as plates for initial experiments - less material waste and they're easy to handle and cheap.

[MichaelH]

If you have a UV source (or black light fixture) I'd be interested in whether it thickens the polymer, the exposure needed, and whether the blue dye gets bleached out. Or maybe try a green laser? The idea being to see if it's possible to partially pre-thicken the stuff without losing red sensitivity.

Done. I don't have a good UV source but do have a 75W blacklight spot. Placing it 6" above the sandwich for 5 minutes resulted in hardening of the polymer. I tested the sandwich periodically by trying to slide the plates against each other and was able to do so until the last 30 seconds.

As it turns out though, that has bleached out the polymer. I'm going to attempt a hologram with it anyway since the alternative is to just wash it down the drain.

I think I'll use microscope slides as plates for initial experiments - less material waste and they're easy to handle and cheap.

I happened to have lots of window glass available that wasn't good for master plates

[MichaelH]

So, did I get a hologram? Yes. Is it any better than the last dozen? A little, but it still requires a lot of light to see the image. So far, the polymer isn't worth the effort compared to silver. It's promising to see a new polymer becoming available but it's still at such an early stage in its development that it's more of a science project at this point than a product. I may continue to experiment next week but for the moment I'm going back to silver. I've had some specific holograms on my mind and it's time to make them. If anyone else is working or going to work with the Polygrama polymer I'd be very interested in hearing how your experiments come out.

[MichaelH]

dos that mean theirs no samples for green? and is the behavior similar to its counter part made for the Red?

Yes there are green samples as I linked to before. Here's the link again.
http://polygrama.co.nr/
I'm not trying green because my green laser is only 5mW.

1 are you just using pre exposer to get it to the edge..so its solid ?

Or at least a little more solid.

2 wide band like dcg... is that done by over exposing?

As I understand it, the bandwidth is selectable by varying the thickness of the polymer layer.

3 it sounds like its way too contrasty an would be good in a h2 setup is this true

Perhaps. The reflection hologram, while dim, were also of very high contrast.