I am trying to track down Greg Cherry. I have a very old hologram of his on glass. It was the image of the telescope and planets and by "was" i mean that the image no long exists. All that you can see is a sort of prismatic effect of rainbows but no identifiable images. What happened? It was kept in a dark hallway where the sun did not shine.
Thanks
greg cherry hologram circa 1987
Re: greg cherry hologram circa 1987
Oh, that's a pitty!
As holograms consist of gelatins, no only sunlight can destroy a hologram.
Also temperature and especially humidity can cause problems.
If it is stored in a humid surrounding, the gelatin can grow and the image vanishes, as the Bragg planes are growing, too.
Therefore the hologram would replay in a longer wavelength, in infrared light for example.
If I get's dryer, you may have luck to see the image again, as the Bragg planes shrink. But it would be essential to dry slow and equal. On the other hand humidity and temperature can cause the growth of bacteria in the gelatine. This may result in a damaged hologram, which can not be repaired, in think.
I am curious, if someone can explain more or other dangers for holograms, and what would be the best storage conditions?
Which temperature and humidity would you suggest?
As holograms consist of gelatins, no only sunlight can destroy a hologram.
Also temperature and especially humidity can cause problems.
If it is stored in a humid surrounding, the gelatin can grow and the image vanishes, as the Bragg planes are growing, too.
Therefore the hologram would replay in a longer wavelength, in infrared light for example.
If I get's dryer, you may have luck to see the image again, as the Bragg planes shrink. But it would be essential to dry slow and equal. On the other hand humidity and temperature can cause the growth of bacteria in the gelatine. This may result in a damaged hologram, which can not be repaired, in think.
I am curious, if someone can explain more or other dangers for holograms, and what would be the best storage conditions?
Which temperature and humidity would you suggest?
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sharlevine
Re: greg cherry hologram circa 1987
Thanks so much for your reply. If anyone knows Greg Cherry, please ask him to contact me as I would love to speak to him about the picture. our whole family loved it for so many years.
Re: greg cherry hologram circa 1987
The prismatic effect is probably surface scattering.
Any number of effects could have made the hologram disappear:
High humidity in and of itself, and high heat in and of itself is unlikely to cause any damage. But, high humidity and high temperatures could have caused the emulsion to swell. Here in San Diego, the lab goes upwards of 90 deg in the summer with no loss of holograms. But, one time we had a humidity of over 60% and a temperature in the 80's, and we lost a lot of holograms.If the swelling is uniform, a gentle heating ,might bring it back. However, this is unlikely, so the planes may have got corrupted by non-uniform swelling.
If it was blacked, and it probably was since a lot of those early reflections were, then the emulsion and paint could have separated from the base and the emulsion is "stuck"to the paint.
Chemicals, ie cleaning solvents etc, may have suffused into the emulsion over time.
Any number of effects could have made the hologram disappear:
High humidity in and of itself, and high heat in and of itself is unlikely to cause any damage. But, high humidity and high temperatures could have caused the emulsion to swell. Here in San Diego, the lab goes upwards of 90 deg in the summer with no loss of holograms. But, one time we had a humidity of over 60% and a temperature in the 80's, and we lost a lot of holograms.If the swelling is uniform, a gentle heating ,might bring it back. However, this is unlikely, so the planes may have got corrupted by non-uniform swelling.
If it was blacked, and it probably was since a lot of those early reflections were, then the emulsion and paint could have separated from the base and the emulsion is "stuck"to the paint.
Chemicals, ie cleaning solvents etc, may have suffused into the emulsion over time.