Tonight , tonight, wont be just any night

These are all of the old posts from the first two years of the forum. They are locked.
Updated: 2005-03-28 by HoloM (the god)
JohnFP

Tonight , tonight, wont be just any night

Post by JohnFP »

Yes sir!

And I had to get up early and get one of my sons off to school. Then I put in the vegitable garden, did some brick work around one of our gardens, planted some flowers and worked on the pool. I am going to sleep goooood tonight!

Hey I offered before but I would be willing to make some extra DCG's if you or anyone is interested. I could ship them next day and you could have them in 12 - 18 hours. I would sell them cheap as they are not factory made. I could advise you on processing also.
Dinesh

Tonight , tonight, wont be just any night

Post by Dinesh »

"Do you or Joy have a notion as to why this is?"
Because the light does not have to come through the glass. In a single-beam pseudoscopic (assuming you shot it with the emulsion toward the object) the light hits the emulsion and expands outwards while when viewing the orthoscopic, the reconstruction beam goes through the glass, hits the emulsion, reconstructs object light which then has to go through the glass again to get to you.
Tom B.

Tonight , tonight, wont be just any night

Post by Tom B. »

My notion (probably also wrong ) is that the pseudoscopic image is brighter, at least when viewed from near the plate, because it concentrates and focuses the light (the real image that you capture in an H2) to form an object image which doesn't spread out so much before hitting the eye as the virtual image coming from behind the plate.

When checking H1 focus by substituting a white card for the H2, I notice that the bright spots look pretty bright (on good days), and I imagine that if I placed my eye at the focus, the view would be dazzling indeed.
Dinesh

Tonight , tonight, wont be just any night

Post by Dinesh »

"My notion (probably also wrong ) is that the pseudoscopic image is brighter, at least when viewed from near the plate, because it concentrates and focuses the light"
You have a point, but I think this would be true if the object, as opposed to your eye, were further away from the image plane. Given an equal reconstruction beam, the power of the light from both images of the hologram is dependant on the efficency of the hologram. Assuming no absorption of the material itself, the virtual image, call it orthoscopic because we're assuming single-beam Denisyuk, emanates spherically from some point beyond the medium. The percieved brightness is the total power entering the iris and hitting the retina. This is a small fraction of the area of the expanding sphere of light from the hologram. If the distance of the object behind the plate were d and you were observing at a distance e from the plate, then the total area of the wavefront is A_ortho=4*pi*(e+d)^2. The total power carried in the reconstructed beam would therefore be spread over this area. If your iris had a radius i, then the area of the iris is A_iris = pi*i^2. Thus the brightness, would be the fraction B_ortho = k*(A_iris/A_ortho) where k is some constant of proportionality. Now if you look at the pseudo, the image is now d in front of the plate and the area of the expanding reconstructed beam is now A_pseudo = 4*pi*(e-d)^2 and the brightness is proportional to B_pseudo = k*(A_iris/A_pseudo). Since A_pseudo is less than A_ortho, we can conclude that B_Pseudo is larger than B_ortho. However, the ratio B_ortho/B_pseudo = A_pseudo/A_ortho = (e-d)^2/(e+d)^2 (assuming same viewing conditions so your eye radius doesn't change). This dependance on the ratio of the square of the distance difference would be small if the distance difference were small, ie the image were close to the image plane. In fact, if e were much larger than d, this ratio would just be 1.
I think we're both right. There's a balance between the distance of the image and the absorption of the plate. If the image is near, I think absorption dominates, if far, then light loss dominates.
danny bruza

Tonight , tonight, wont be just any night

Post by danny bruza »

danny bruza
1236 w. monte vista
visalia CA 93277
Anonymous

Tonight , tonight, wont be just any night

Post by Anonymous »


Anonymous

Tonight , tonight, wont be just any night

Post by Anonymous »

back in the 80s/90s ,we would reprocess the bad DCG holograms ,and some times save a few. a light baking in between processing can also help.The baking process can also help greatly when trying to make a color shift,ie... a blue re-play master(H1)
JohnFP

Tonight , tonight, wont be just any night

Post by JohnFP »

So far I have never gotten a reprocessed DCG to come out better then the first processing. I have color shifted it with reprocessing but never brighter or to get rid of streaks. So, after the first processing, you bake the hologram then reprocess? At what temp and how long for baking? And by reprocessing, at what step do you start, at the water swelling then through the alcohols again?

Thanks,
John
JohnFP

Tonight , tonight, wont be just any night

Post by JohnFP »

Danny, e-mail me. I want to be able to coordinate with you when you want them. I will make them and send them fresh to you. Thursdays night I can make some. Send them to you Thursday night (I have to let you know how much overnight shipping is). You will get the plates Friday morning or afternoon. I will do some exposures on the same batch Thursday night and post results Friday. That way you will have a head start on processing.
JohnFP

Tonight , tonight, wont be just any night

Post by JohnFP »

If you look at the Vodka bottle hologram you see that the bottom, which is a white card, goes from red in the foreground to blue in the background. Then you see that the reflection of those colors in the mirror reflect the opposite colors, that is, in the far corner where the bottom white card is blue, its reflection in the mirror is red. Distance from the plate is the nearly the same at that corner. Remember, the light does not hit the mirror directly anywhere. This is puzzling to me. I have to give this some thought as to why it is happening and how it can be used to my benefit for multi color holograms. The more I look at that hologram the more I like it.
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