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July 12, 2004

I've been watching Frank's work with LCD panels over the last several months and even bought a couple with plans to do my own experiments.  Because of work I've had little time to pursue those plans but that changed somewhat this morning.

I never found any information on removing the polarizer on an LCD panel so I decided to experiment on my own.

It turns out to be pretty easy with the particular Sharp color panel I'm working with.

I just picked at one corner of the "something" that was on one surface of the panel (given that another panel actually had multiple flexible overlays for each color, I couldn't be 100% sure that I was picking at a polarizer on this one) and carefully lifted up the corner until I could tell if a semi-clear sheet was coming off or if a color overlay was being lifted up.

Turns out it was the former and I kept lifting very carefully. The sheet was stuck down with an adhesive that wasn't much different from rubber cement and was still flexible. Still, I had to go slow as it took a fair amount of force to lift the sheet off and I didn't want to break the glass. To ease some of the pressure I started cutting the sheet so I could pull off thin strips until I had all of the polarizer off.

I was a little worried at first because I couldn't see any image at all after doing this but found that if I put one of the pieces of polarizer back on the glass (it was quite sticky on one side) that the image from my second "monitor" showed up just fine.

Next I turned on one of my many spare lasers and shone some light through the panel. Hmmm. Not so good. The image shows a bizarre diffraction pattern. How about if I put a diffuser behind the panel. Worse, the image disappears. How about if I put the diffuser in front of the panel (between me and the panel). Hey! That gives me a nice bright image!

I'll post some photos when I get the chance but since this is the first time I've had time away from work to make some holograms I'm going to put another piece of film on the table and work on the PCGGI videos while that settles.



July 20, 2004

I started working on what I'm calling a "light box" for my large laser today.  This is a simple wooden box with a hinged door and fans added that will house the laser and allow me to mount it on the wall and shield the table from the incredible amount of light it emits.  Up to this point I've had the laser sitting on the table, elevated using some marble tiles and covered with cardboard to keep the light away from the rest of the table.

The box is a simple 48" x 7" x 7" affair with an open back and hinged front.  I left the back open since it will be up against the wall

I've cut holes for the fans, one will pull air into the box and the other will pull it out so that the laser doesn't overheat and drilled an exit hole just below the mirror shown above.  The metal bar is the same bar I've used for many of my other mounts and holds a mirror which is attached to a strong rectangular magnet.

Later this evening I'll mount the box on the wall, put the laser inside and give it a good holographic testing.


July 21, 2004

I finished up the box last night and after putting a back on it (I decided not to take the chance that light would leak out the back) I hauled it upstairs and mounted it on the wall.

Shots of the box closed (the tape is temporary until I can purchase some magnetic cabinet catches) and open.  I'll also be purchasing some tubing so air can be brought in from outside the canopy, vented through the box and back outside the canopy.

Here's the shutter and beam steering mirror.  Having the shutter inside the box is nice because with it closed the entire box acts as a beam dump and I don't have to card off the shutter anymore.


July 25, 2004

Along with some good old relaxation time, I spent a bit of time today trying to get a hologram with the new Polygrama photopolymer.

After setting up my table for a two-beam transmission image of R2D2 and making a successful test shot on PFG-01 I gathered together the following materials:

  • Two 4x5" pieces of glass (old holographic plates).
  • Five small binder clips.
  • Three pieces of tape (taken from an old backup data tape).
  • SM633T Red-sensitive photopolymer.
  • 1ml syringe.

I then:

  • Cleaned the glass with household bleach followed by a thorough rinsing and hand-drying with a paper towel by rubbing hard until all the water was gone.
  • Placed the three pieces of tape onto one sheet of glass so that the glass was divided into three sections. Only one section was used but the third. piece was necessary so that the glass wouldn't warp when the binder clips were attached.
  • Using the syringe I put a approximately 1ul of polymer onto the glass.
  • Carefully hinged down the second piece of glass so that bubbles would not be trapped in the polymer.
  • Pressed down firmly to cause the polymer to spread.
  • Clamped the two pieces of glass together, applying the clamps over the tapes to prevent the glass from warping.
  • Placed the plate into the plate holder.
  • Let the table settle for 20 minutes.
  • Exposed to laser light for 16 seconds (approximately 184uj exposure).
  • Exposed the plate with a 75w halogen lamp for 10 minutes.

For the first exposure I left the plate in the holder and shone the 75W light on it while still in the holder.  Here you can see the sandwich in the plate holder after the polymer has been bleached out.

After taking the sandwich out of the plate holder.  The polymer occupies about half of the section on the left but has been completely bleached out.

Unfortunately that first attempt yielded no image at all.  Not even a flash of light from any angle.

I double-checked the exposure times and realized that even though the sensitivity given for the polymer is approximately half of PFG-01 I was exposing somewhat short.  So I increased my exposure time to 20 seconds to get closer to the bottom range of 200uj.  In this case, I was giving the polymer a total exposure of 230uj.

That was a dud as well.  Still no flashes of light or sign of an image.  I also noticed that prior to the halogen post-exposure treatment that that polymer was still a blue of approximately this color:


After corresponding with Polygrama one possibility was that the polymer layer was too thin.  With that in mind I switched to the only other spacing material I had handy.  Scotch tape.

Following the same general procedures I created my polymer sandwich and exposed for 20 seconds.  Nothing.  Not even a flash of light.

According to the information on the polymer, "The emulsion will bleach as receive the laser power, autobleaching feature will indicate end of exposure." Since it appeared that the auto-bleaching wasn't happening, I doubled the exposure time.

Same general procedures for sandwich making and exposed for 40 seconds.  Still nothing.

This is a color-simulated image of what the polymer looked like before post-exposure to the halogen light.  After post-exposure the polymer was completely clear.

Oddly enough, two hours later the polymer had begun to turn light blue.

It still looks like I'm not exposing long enough although according to the given sensitivity my last exposure should have been at the upper end of the range for the polymer.

[Editors note, Jul26:  I hate it when a conversion error bites me.  In this case I was converting from uj to mj by simply dividing by 10.  Stupid.  I should have been dividing by 1000.  Rather than a 20 second exposure I should have been exposing for 30 minutes.]

July 26, 2004

More testing of the polymer.  For this round I'm using the scotch tape again but I've changed two variables:

  1. The object is now a mirror so that I'm effectively creating a HOE.  This allows me to increase the energy applied to the polymer and shorten the exposure time.
  2. I set up the polymer sandwich and let it settle in a light-tight box for an hour before exposure.

I'm measuring 26uW at the plate so according to the data given with the polymer I should expose for 12 minutes minimum and 32 maximum.  The longest exposure I've done to date has been about two minutes, 12 should be interesting to say the least.

8:30am: First attempt was using manual control of the shutter.  Unfortunately the sleep time on the RCX was set to 10 minutes and the shutter closed early meaning that this attempt was another dud.  After this I set about re-programming the shutter control to allow exposures of up to 45 minutes.

9:00am: Second attempt today involved changing the table setup for a single-beam Denisyuk of a british coin.  This is a particularly good subject because it is composed of a central circle of nickel surrounded by a copper donut with a variety of designs that are easy to see.  Why a single-beam setup?  Power.  I needed to get the exposure times down as far as possible.  I decided on a 6 minute exposure after attempting to measure the beam strength with my home-made meter.  Unfortunately my 30mW laser easily overpowers my meter and I had to guess at the exposure based on the distance from the plate where the meter could measure the power (good ole inverse square law).  The coin was taped to the back of the glass.

At the end of the exposure I noticed that the polymer was a much lighter blue than with the previous attempts.  Not clear but definitely much lighter.

So, did it work?  Yes, this time I ended up with a very dim red hologram of a coin.  It's brighter in laser light but still not the brightness that I was hoping for.

9:30am: Tried another single-beam attempt with a 10 minute exposure.  After settling for 20 minutes the bot ran the shutter for 10.  The polymer was much lighter this time, almost clear.  After the post treatment I was rewarded with a slightly brighter red coin hologram.  Unfortunately both are dim enough that there's no way I could get a decent photo although I may try later.

Well, that's it for this morning.  Time to get some chores done (although the settling and exposure times this morning have allowed for a lot of that already).

6:45pm: Moved the plate holder closer so that the only light hitting the plate is right around the coin.  There's almost no wasted light.  Using an OD 1 filter and my light meter I calculated the intensity at 654uW at the plate.  I'm going to give it a 45 second exposure which should apply 30mJ of energy to the polymer.
I modified the sandwich this time and used backup tape as spacers which should give me a thinner layer and more narrow band replay.

After exposure I could clearly see a difference between the area that had been exposed and the area that hadn't.  The former was almost completely clear and the latter still had a noticeable blue tinge.

Unfortunately this one was largely a dud.  While I can get a partial image in laser light, the polymer was still spreading out through the glass as the exposure was made and so most of the coin is invisible.  I know the polymer was still spreading because the "spot" was quite a bit larger when I took the plate out of the holder vs when I put it in.

July 27, 2004

My last day at Paradigm Entertainment.  On August 9th I start with Multigen-Paradigm, a CA company.  Woot!

It's going to be another polymer morning.  I've cut an old plate into small 2"x2" squares and I'm attempting a transmission as I've been told that this polymer is optimized for transmissions.

For the first plate I've moved the setup even closer to the spatial filter (note to self, take some more pictures) and calculated the exposure at approximately 30 seconds.  Total dud.  The polymer began to move after the plate had been clamped into the plate holder.

The second plate I've zapped with a white light for two seconds from 1 foot away prior to exposure. Partial dud.  The polymer still moved some when placed into the plate holder.  There's a fairly bright flash of a sliver of subject though.

Third, horizontal arrangement 90s exposure, partial image but the polymer was still moving perhaps because I ran into the room while the exposure was still going.

Switched to a horizontal reflection layout at this point and changed the object to a flat off-white Celtic magnet.

Fourth, horizontal, prelatens 3s 1 foot 50W, 90s exp. Bright in an odd way under laser light.

Fifth, horizontal, no prelatens, 120s exp. Bright under laser light but shows clear movement of the polymer.


Summary of the latest results:

Pre-latensification: I tried both two second and three second exposures with a 50W halogen bulb 1 foot from the plate. I was concerned about going much longer because the polymer bleaches out fairly rapidly. Unfortunately there's still enough movement of the polymer that I couldn't tell a difference between latensified plates and normal. They all showed film movement.

Horizontal setup: This definitely made a difference as the polymer continues to settle long after being placed on the table. This is especially true when the plate is vertical but even when placed horizontally I could see clear signs of "film" movement even after allowing the setup to settle for 30 minutes before exposure.

My last exposure of the morning was the best although it's obvious that the polymer was in motion during the exposure. I'm unsure if this is because the liquid was flowing or if there was some movement as it polymerized. The polymer was almost completely clear (just a bare hint of blue) when I took it off the table, indicating sufficient exposure.

This last hologram is fairly bright under laser light but has an odd quality in that it looks almost binary due to the high contrast. I used an off-white subject that has some black areas. The black areas are totally black and the non-black areas look like mirrors. The image looks kind of metallic.

For all of these tests I used 2mil glass, scotch tape as the plate separator and small binder clips to hold the plates together.


8:30pm: Prepared a new plate using backup tape as the separator and three binder clips to form a tripod.  Prepared the plate and put it in a light-tight box to settle.  I've modified the table layout for a horizontal single-beam transmission setup using the same Celtic magnet as the subject.  Two minute exposure and the polymer was completely clear.  Image isn't very bright but is visible and very mirror like where the image shows through.


July 28, 2004

I only had time for one polymer test today and that consisted of a transmission test using 2" glass and backup tape.  Ended up with a transflection hologram and is dim but you can see the object in transmission mode and the base the plate was sitting on as reflection.  Pictures are going to be near impossible to get but I'll try soon.


July 29, 2004

Asked by TomB on the Holography Forum

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.

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 came out.



2003: Feb | Mar | Apr | Jun | Jul | Aug | Sep | Oct | Nov | Dec
2004: Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec
2005: Blog
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