I think it's a good idea. I was wondering if re-focusing the beam back into the object would create a hot spot in the object and so increase the dynamic range. Perhaps John's idea of using a plane mirror to uniformly increase the light from the back, or perhaps a slow mirror. One other possibility may be to focus the light beyond the object, ie between object and plate. That way you concentrate the beam inside the object without focusing it there and so don't increase dynamic range too much.
Look forward to results!
In search of a Brighter Denisyuk...
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JohnFP
In search of a Brighter Denisyuk...
This forum is awsome!
How about putting a little lamp with a little bulb with a little lamp shade on a little end table in your hologram with the bulb being a frosted glass ball. Then focus the additional light to the glass ball center with the effect that objects on the end table will appear bighter and my even cast shadows from the lamp which will act as a light source. Toooo coool!
How about putting a little lamp with a little bulb with a little lamp shade on a little end table in your hologram with the bulb being a frosted glass ball. Then focus the additional light to the glass ball center with the effect that objects on the end table will appear bighter and my even cast shadows from the lamp which will act as a light source. Toooo coool!
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JohnFP
In search of a Brighter Denisyuk...
That is definitely on my list now.
Let's see, vodka bottle, two frosted box test, cecadas, train, rocket and now end table. At a session a week... looks like I am 6 weeks backed up! HEHE.
Let's see, vodka bottle, two frosted box test, cecadas, train, rocket and now end table. At a session a week... looks like I am 6 weeks backed up! HEHE.
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Dinesh
In search of a Brighter Denisyuk...
I like this idea. I think you need to bring the light to the bulb from below. If possible, may be with a fiber and a sphere with a small hole in it, light the 'bulb' from the inside. That way, the bulb will seem to glow from inside out.
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Tom B.
In search of a Brighter Denisyuk...
"How about putting a little lamp with a little bulb ..." - I did, in fact, have something like this in mind as a possibility, darn it. Now the surprise is spoiled! Ah well, my chances of finding a suitable teeny lamp at the local junk stores were pretty slim, anyway.
Re short-focus concave mirrors, in desperation I bought a convex automotive mirror (Automan model C060 4 x 5 1/2" (actually 3.5 x 5") in hopes of popping it free of its plastic mount, stripping off the backing paint and using it as a concave front-surface mirror. The good news is that paint stripper does eventually remove the baked-on paint, and does not attack the aluminum. The bad news is that it took me OVER 2 HOURS tonight of applying stripper (Poly Super Stripper), swishing it around with a small brush, waiting, wiping off the exhausted goop before it dried, reapplying stripper and so on. I got a bit impatient toward the end, but fortunately the aluminum coating was fairly tough and came out not too badly messed up. Focal length of the mirror is about 3.5" with some pretty severe aberrations, but in my setup it can indeed focus the collimated beam to a fairly small spot, perhaps 1/8" or less. I tried focusing on the back of a frosted glass sphere and looking at it from the front and indeed the sphere looked VERY bright (compared to objects lit front side only) and the mirror was hardly visible. Also, the aberrated focused beam itself looked very interesting at various points along the axis - thinking of this as a pseudoscopic real image from an H1 I wondered what the virtual image would look like if I dimmed it to match the reference and made an H2 ...
Re short-focus concave mirrors, in desperation I bought a convex automotive mirror (Automan model C060 4 x 5 1/2" (actually 3.5 x 5") in hopes of popping it free of its plastic mount, stripping off the backing paint and using it as a concave front-surface mirror. The good news is that paint stripper does eventually remove the baked-on paint, and does not attack the aluminum. The bad news is that it took me OVER 2 HOURS tonight of applying stripper (Poly Super Stripper), swishing it around with a small brush, waiting, wiping off the exhausted goop before it dried, reapplying stripper and so on. I got a bit impatient toward the end, but fortunately the aluminum coating was fairly tough and came out not too badly messed up. Focal length of the mirror is about 3.5" with some pretty severe aberrations, but in my setup it can indeed focus the collimated beam to a fairly small spot, perhaps 1/8" or less. I tried focusing on the back of a frosted glass sphere and looking at it from the front and indeed the sphere looked VERY bright (compared to objects lit front side only) and the mirror was hardly visible. Also, the aberrated focused beam itself looked very interesting at various points along the axis - thinking of this as a pseudoscopic real image from an H1 I wondered what the virtual image would look like if I dimmed it to match the reference and made an H2 ...
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Tom B.
In search of a Brighter Denisyuk...
Here's a pic of the setup (overhead view, collimated beam comes down from above, hits objects and concave mirror at right which focuses spillover light onto back of artfully teased out cotton batten "flame" :
and the results of a test shot on BB-640 (3% TEA, lit with amber LED):
and the results of a test shot on BB-640 (3% TEA, lit with amber LED):
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JohnFP
In search of a Brighter Denisyuk...
Tom, that is great, simply great!!!
What was your exposure time?
What was your exposure time?
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Tom B.
In search of a Brighter Denisyuk...
About 12 seconds, with about 80 uJ/cm^2 on the plate. Being able to have internally glowing objects in scenes opens a whole new realm...