How I Make My Holograms
Ok, I thought I might describe the steps involved in making one of my hologram. Enjoy!!!
Overview
I recently started working with a new type of film, which I make myself, called Dichromated Gelatin (DCG). Originally when I started with this new film I made holograms of simple subjects just to get a feel for the film. Since then I have been doing research with the DCG and this has taken me away from artistic, display holography. Some of my research involves controlling the color of the hologram as well as introducing multiple colors in one hologram. The following procedures will put aside research and outline how I make a display hologram.
Subject
The first thing I do is find an object that I want to make a hologram of. Then I set up a scene which I feel will describe the subject of the object. With the skateboarder hologram I made a ¼ pipe out of a cut piece of PVC pipe and used some soldering wire for the coping. I then glued the skateboarder onto the ¼ pipe. I thought this had more action then a skateboarder simply setting on the ground. Then I take the entire object and glue it in place on my holographic table just behind the place where the holographic plate will rest when I perform the exposure.
Setting up the Holographic Table
I turn on the laser and tweak it in to the wavelength I want to shoot in. I then set up mirrors to reflect the beam to the place where the holographic plate will rest and additionally toward the object. I may use additional mirrors to get more lighting to the object until it is lit up satisfactorily to my liking. This also included putting in an expanding lens (Microscope Objective) and a beam cleaner (Spatial Filter/Pinhole). This provides the plate and the object with a nice uniform expanded laser beam.
Making the Plates
I take a beaker and put an amount of distilled water into it. I then place the beaker on a hot plate/stirrer with a stirring magnet in the water. Setting the hotplate to the correct temperature and correct speed, it heats the water and keeps it moving. I also have a thermometer in the liquid to monitor the temperature more precisely. Once the water get to about 80 degree F. I put an amount of Gelatin in it and allow it to come up to the desired cooking temperature. I keep monitoring the stirring speed and the temperature for 45 minutes minimum up to an hour or more insuring the temperature does not exceed my upper limit temperature. While the gelatin/water solution is mixing I take glass precut to size which has been soaking overnight in a 20% household bleach solution and scrub it with a plastic wool and place it in a rinse tray. I rinse the glass and set them leaning against the back wall of my Laminar Flow bench. This is a bench I built which provides positive, heppa filtered air over the work area which keeps dust off the glass. Then I take a paper towel and wipe both sides of the glass until there is no dust, dirt or smears on the glass. After 45 minutes minimum I put an amount of Ammonium Dichromate in the Water/Gelatin mixture an allow this to mix for a minimum of 15 minutes. At this time and from now on only a safe light can be used. Once the solution is mixed I filter the solution. I then coat the plates usiing the veil method. I place the coated plate in a rack on a spinner which spins the plate. This is all done in the Laminar Flow bench. I let the plates spin for about 5 minutes. I then stop the spinning and place the rack off the spinner but still in the laminar flow bench for another 2 hours. After this time I place the entire rack in a light tight container. The plates can be used between 4 hours and 36 hours after being coated.
Making the Hologram
I take one of the plates I made and place it in the plate holder The laser is running but there is a shutter blocking the beam from the Holographic table. I program the computer to allow the plate to settle unexposed for 15 minutes then open the shutter for the desired time and then close the shutter again. The plate now has the latent holographic image.
Processing the Hologram
I take the plate out of the plateholder and place it back in another light tight box. I let it set for 5 minutes. I then place the plate in a fixer solution for 20 seconds to 2 minutes depending on a variety of factors. I then take the plate and place it in running water at a specific temperature for 5 minutes. The plate is then placed in 4 separate isopropyl alcohol baths with specific temperatures and specific concentrations of alcohol to water for a desired time in each bath. After the final bath I take the hologram out and dry it with forced hot air.
Sealing the Hologram
If the hologram comes out to my liking I take a razor blade and scrape off the emulsion around the edge leaving a clear, uncoated, ¼ inch border. I then mix some two part epoxy and put a bead of epoxy around the edge on the cleared border. I then place another piece of glass of the same size on top of the hologram. This provides an o-ring type seal for the hologram. After the epoxy is hard, I can take the hologram out of the lab and hang it on my wall.
John F. Pecora
Dec. 2005