School of Holography
LASER POINTER / SEMICONDUCTOR LASER HOLOGRAPHY
by Frank DeFreitas Holography Studio
Creative Holography Using
My magical journey of making
Inexpensive Laser Pointers
holograms with a $7.99 laser pointer
and inexpensive laser diodes.
4th Test Hologram (non-AGFA) 1/12/99
(NOTE: Holograms are not 3-dimensional on your computer monitor).
Above is my first test shot using plates other than AGFA. It was shot on BB-Plates (640 series) from Germany (included URL on the link page) and is the clearest, brightest single-beam reflection hologram that I have ever created in my 16 years of holography. The digital photos do not do it justice. Once again, it was shot with a 5mW, 650nm off-the-shelf laser pointer. I have a good 35mm camera with a Zeiss lens that I will have to use and then scan the photos at a later time. There's nothing quite like nailing a good shot. The feeling of nailing it with a $7.99 laser pointer is hard to put into words.
Getting By Without AGFA
As many of you already know, AGFA has discontinued manufacturing red-sensitive holographic recording materials. Other manufacturers have stepped in, but many of the materials require longer exposure times. This can be troublesome for lower power situations. The above hologram was exposed at 3 times the exposure for AGFA and I used a 5% pre-swelling of Triethanolomine -- not so much to alter the color of the hologram but to hyper-sensitize the emulsion. Exposure time was 18 seconds (the previous camera hologram on page 2 was 6 seconds on AGFA plates). Now we know that the laser pointer will handle the alternate materials, at least at this size (4 x 5-inches) and at this power (5mW) with single-beam techniques.
(response curve of BB-640 holographic plates).
The BB-Plates 640 series emulsion has two nice areas of the response curve -- one at 633nm for HeNe lasers and the other at 647nm for Krypton lasers. This increased response for 647nm is great for the laser pointers/diodes operating at either 640nm or 650nm. Actually, it appears that the 647nm wavelength is the peak. Exposure times for a split-beam with this material will have to be determined and experimented with.
Is Split-Beam Holography Even Necessary?
Just as with a single-beam reflection hologram, "direct" split-beam reflection holograms do not exhibit any of the image projected out toward the viewer either (with the exception, of course, of the full-aperture focused-image technique). It is bascially used for increasing the brightness of the hologram through adjustment of the reference and object beam ratios. These plates exhibit excellent brightness with single beam work. The overall "feel" of the image is very reminecent of the famous Russian single-beam work. Very low noise/scatter as well. I'm questioning whether split-beam would even be necessary, other than for H1 to H2 image-plane transfers.
How Much Depth Will Pointers Record?
The above digital photo shows another perspective of the same hologram, this time looking down from the top. You can see the camera going back into the plate. Once again, please take the photo into consideration, as the camera is non-focus, non-zoom and I had to get close to the hologram for the shot, causing some of the blurring. The holographic image is razor-sharp going all the way back.
I took this shot to show that the laser pointer is capable of recording depth beyond the general area of the plane of the emulsion. The stand that the camera was sitting on receeds into the hologram several inches, although you cannot see it from either photo. One of the biggest questions has been exactly how much depth can you expect using a diode or pointer. This area still needs to be explored, but all indications are that we're looking at several inches, at the very least. This coherence length will come in handy with split-beam holograms -- which I still have to begin experimenting with (Steve Michael is working on this at present as well.)
So, that's my report for this entry. I took a little side-trip trying out these new plates, but I'm glad I did. I was worried that this process would only work with AGFA, and that it would be all over before it began. No need to worry anymore.
GoodBye to the Helium-Neon Gas Laser?
My Helium-Neon laser has been turned off for weeks. I do not think I will replace it. If I order one of the Hitachi 35mW diodes ($41), I may never have to use it again. For me at least, this latest hologram above signals the beginning of a new era -- and the end of gas-laser holography. I am completely satisfied with the quality and brightness and would match it up against just about any AGFA silver-halide hologram of it's size, regardless of the power of the laser used to create it.
If you would like to learn more about laser pointer holography and are in the Allentown, PA area -- I have workshops where you can come in and make your own from start to finish, while you learn how to do it. And you won't have to go home and buy an $800 laser to do it on your own either. $10 should just about do it!
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Frank DeFreitas Holography