DCG Hologram - Raspberry Pi

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pluto
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DCG Hologram - Raspberry Pi

Post by pluto » Tue Mar 15, 2016 8:11 am

The last hologram of a bad run. I was seeing lots of striping with the previous ones. I think I was tuned into an unstable zone in the power output or was seeing the effects of vibrations for the first time.

I like how this one turned out though! Nothing extraordinary, but probably one of my bigger, brighter holograms to date.

video: https://www.youtube.com/watch?v=ebE5tTKI4D0
Image

Looks better IRL, of course :)

holomaker
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Re: DCG Hologram - Raspberry Pi

Post by holomaker » Tue Mar 15, 2016 9:25 am

Looks great for coating a tiny plate ! did you set the laser power while viewing the Fizeau interferometer? long exposures, the more AMDI you get into the emulsion the more sensitive the film be ....what recipe/formula are u using ?

pluto
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Re: DCG Hologram - Raspberry Pi

Post by pluto » Tue Mar 15, 2016 10:20 am

I eventually did bust out the Fizeau interferometer, that seemed to help with stability! I'm actually using KDi, with ratio 100:12:3. I was previously using 100:12:2, and this seems to work out better.

The long exposure is likely partially due to the angle of incidence. I'm not using Brewster's angle or anything, it's hitting the plate almost straight on. This is mostly a limitation of my setup.

Bit of a non-sequitur, but I was wondering what the best way to store unsealed plates is. I've actually left holograms just laying around and didn't notice any noticeable change, but that seems a little precarious. Sometimes if you take a hologram out of the house, the thermal shock causes condensation or something and the image vanishes. Could you store holograms under alcohol to preserve the image?

holomaker
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Re: DCG Hologram - Raspberry Pi

Post by holomaker » Tue Mar 15, 2016 10:24 am

I think you get more dichromate in the film maybe up to 5 g /100 ml, should speed it up 2fold?

pluto
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Re: DCG Hologram - Raspberry Pi

Post by pluto » Tue Mar 15, 2016 2:30 pm

holomaker wrote:I think you get more dichromate in the film maybe up to 5 g /100 ml, should speed it up 2fold?
Oh wow, is this a common DCG recipe? Or just to accommodate less powerful lasers? I did notice that my plates weren't very yellow, so I didn't see much difference after fixing.

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admin_jsfisher
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Re: DCG Hologram - Raspberry Pi

Post by admin_jsfisher » Tue Mar 15, 2016 3:12 pm

Richard Ralliston had a lot to say about DCG formulations. Rallison claimed that water content influenced both thickness and bandwidth and dichromate content had an effect on not only sensitivity but also color shift. There is an unlinked page on the holo-wiki that summaries Rallison's findings: http://holowiki.org/wiki/DCG . (The page is unlinked because "Exposure Sensitivity" section at the end isn't validated and should be ignored.)

holomaker
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Re: DCG Hologram - Raspberry Pi

Post by holomaker » Tue Mar 15, 2016 5:54 pm

I think most of Richards recipes pertain to him using the blue green (argon)and blue laser lights not green only...

holomaker
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Re: DCG Hologram - Raspberry Pi

Post by holomaker » Wed Mar 16, 2016 8:11 am

Here's a snapshot of how much dichromate you can get into the film, compare the color of this film to yours ....
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Green DCG film
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pluto
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Re: DCG Hologram - Raspberry Pi

Post by pluto » Wed Mar 16, 2016 7:02 pm

holomaker wrote:Here's a snapshot of how much dichromate you can get into the film, compare the color of this film to yours ....
Holy hell, is that what DCG plates are supposed to like? Actually, come to think of it, I've never seen a coated plate in normal lighting. Actually I have, it was a plate that I had dropped and missed a piece, but I assumed the yellow colour was from light exposure. Huh... I'll have to check when I get home.

Dave, which DCG recipe do you personally use?

I'm also curious how using more dichromate affects the final transparency of the unexposed portions. I've seen holograms where the object is "floating", i.e., the unexposed parts are perfectly transparent whereas the object is very bright. I imagine these are taken using a black backdrop.

holomaker
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Re: DCG Hologram - Raspberry Pi

Post by holomaker » Wed Mar 16, 2016 8:10 pm

Here's a white DCG I shot using 532 nm for master and proximity copy. 100-14-5. http://youtu.be/XDYuwT-vwzI
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White Venus
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