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.
2nd Test Hologram 1/6/99
(NOTE: Holograms are not 3-dimensional on your computer monitor).
Above is my second test shot at controlling color using a laser pointer ($7.99 US). I was working to create a gold image using the red diode. I used a 10% pre-swelling of the holographic emulsion with TEA (triethanolomine). If I were using a 633nm HeNe laser this concentration (10%) would have been more into the yellow, but since the diode is at 650nm it takes a higher concentration to get where you're going. The digital camera in the hologram is the same camera used to take the picture of the hologram after it was finished. It is an early Kodak DC20 and is certainly limited in its quality. However, I think it captured the holographic image OK. Exposure time was 6 seconds, using a 5mW, 650nm laser pointer. Processing was the PyroChrome process (pyrogallol developer and Dichromate bleach). Development was at 2 minutes. Hologram size is 4 x 5-inches (AGFA8E75HD glass plate). If you're a holographer, you'll probably notice the bands of interference on the body of the camera. I found this interesting. I used the camera to take the pictures below just before making the hologram. I believe (although I'm not sure) that you're seeing micro changes in the body of the camera due to the thermal cool-down of the circuits over the 6-second exposure time. Amazing.
All-in-all, quite an improvement over the first test hologram. Given the right conditions, I still think this pointer will create an 8x10 single beam. I've only got a few 8x10 plates left, so I want to have everything perfect before doing one. I'm only going to give it one shot. An 8x10, multi-color reflection hologram created using a $7.99 laser pointer would be a hoot! I'm having a great time. It's like discovering holography all over again -- there's a long road ahead and I'm looking forward to each and every step.
The above photo is a close up of the configuration of the diode and spatial filter on my holography table. The diode (laser pointer) is held in place using slight pressure from the small vise attached to the side of the table. The piece of equipment on the left hand side of the photo is the spatial filter, which expands and cleans up the beam. I originally had the beam bounce off a mirror at 45-degrees before going into the spatial filter, but since each piece of optics (mirrors and lenses) take their toll (however small) on the final energy reaching the plate or film, I thought I would reposition the vise so that the pointer fired directly into the objective lens of the spatial filter. With this type of holography, you need every bit of optical energy delivered to the plate. "Keep it simple" was never more appropriate than now.
The little standard batteries (watch-type batteries) that are included with the laser pointer (and slide into the barrel) have a continuous operating life of 2.5 hours. I believe it costs around $9-10 dollars to replace them. I was running the pointer off of a standard 4.5 volt Rectocon power supply, but this time I wanted to try something different so I went over to Radio Shack and purchased three holders for 1.5volt, AA batteries (RS part number 270-401A). I put these in series with one another to supply the necessary 4.5 volts and then connected it to the pointer. I will report back with how long these batteries last. --- (Using DuraCell ULTRA's the laser pointer has run for 72 hours straight, with very little change to power output)--- The above hologram of the Kodak digital camera was made while using these batteries. Since power supplies can burn out a laser diode in just nanoseconds, it is much safer to run the pointer off of batteries -- so I wanted an inexpensive alternative to the expensive watch-type batteries supplied with it. Of course, you can burn-out your diode by using batteries as well (for instance putting 4.5 volts into a diode that only needs 2), so make sure your voltage/current matches up. It looks like these AA batteries are just what the doctor ordered -- much cheaper (especially in quantity) than the watch-type batteries and easy to find at any 24-hour "7-11" store or gas station when you find yourself in the mood to shoot a hologram at 4:00 in the morning.
Please move on to Page Three for the first test shot of a multiple-color hologram.
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Frank DeFreitas Holography