Right exposure

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)
Peter

Right exposure

Post by Peter »

Hello,

I've just begun with holography. I begun witch Standard kit from Integraph, but I changed PFG-03M with PFG-01.
My first hologram was reflection, 5 mw laser without lens, distance betwen laser and plate 37 cm, exposure time 25s. I think the result is good. The hologram is very sharp when illuminated with red laser diode and good viewable with white light. But the image is not as bright as I see on hologaphers webs. So I made another 2 holograms with the same setup, first with 6s exposure and second with 40 second exposure. But I didn't see very high difference between them, even the exposure was very different. Both of them were lighter than first hologram witch 25s exposure. I was expecting, that I will see, how the exposure time will effect the holograms.
So, how can I find out the right exposure. And how can I know from completed hologram if the exposure was right and make corrections for next holograms.

Thanks,

Peter
Tony

Right exposure

Post by Tony »

Peter-

Welcome to the ranks of holographers! As for exposure, I've done many test exposures and found that for Denisyuk holograms, there's a pretty wide range of exposures that will work, but that you can't get really bright Denisyuk holograms unless you can get additional light on the object. You can get some effect by increasing exposure and decreasing development. You should be aiming for a density of ~2 before bleaching the hologram. This appears 'pretty dark' by eye - and technically, it means that 99% of the light passing through the hologram is blocked. You can measure this with a photocell, or there are various ways of estimating density (search this forum).

Like me, you may be expecting more brightness from a Denisyuk hologram than can be easily achieved without extra lighting on the subject. I haven't personally tried the BB640 plates from Colourholographics - they may be brighter than the Slavich materials.
Michael Harrison

Right exposure

Post by Michael Harrison »

Are you keeping the development times constant as you vary the exposure? If not, make sure that you do. You only want to change one variable at a time.

When you say that the hologram is not as bright, are you:
1) Comparing it to other equivalent single-beam setups?
2) Comparing you laser-lit or white light lit hologram?


Both of them were lighter than first hologram witch 25s exposure.

Do you mean "dimmer" where you've written "lighter"?


So, how can I find out the right exposure. And how can I know from completed hologram if the exposure was right and make corrections for next holograms.

You're on the right track. There's a fair amount of experimentation involved when doing your first hologram since there are so many variables involved. Just remember to change one variable at a time.







---------------------------
If someone says it can't be done but they haven't tried it, don't believe them.
http://www.dragonseye.com/Holography

Are you going to the next PCG Gathering?
http://www.dragonseye.com/Holography/PCGGI.html
Bob

Right exposure

Post by Bob »

When I use that material with CWC2 developer and PBQ (or I suppose PBU) bleach, I expect that the time it takes for the hologram to tlear in the bleach is about the same as the developer time (both 2 minutes). The developer is full strength. If the clearing time is too long (say, twich as long), I'm overexposed. Maybe someone on this forum can tell you what clearing time to expect when using your chosen chemistry.
HoloM

Right exposure

Post by HoloM »

I fully agree Tony, I also tried making bright Denisjuks on PFG-01.
With a normal denisjuk setup you will not get as bright holograms as they
are commonly known from exhibitions. I tried this a long long time with no
good result. I tried all variables like developer, develop time, bleach, bleach time, exposure time, warmth of baths.... The results were good, but not bright enough. I then thought it would be a problem of the pfg-01 and bright white light holograms are not possible with it at all. But this is definetively not so! I then started to make masters and H2 copies. Here I got bright results. Very bright results! This is a problem of the ratio between reference and object beam. With the denisjuk setup the ratio is every time bad. with H2 copies you can adjust the ratio to get really bright results with pfg-01

Anonymous

Right exposure

Post by Anonymous »

I my next experiments I was bleaching less time, until hologram was clear (about 20 s).
Peter

Right exposure

Post by Peter »

I also want to make H2 holograms. I want to make holograms, where the virtual image is in front of the plate and viewable by white light. Is H2 the right way? Is H2 the same as a rainbow hologram? Can you show me some of your H2 holograms? I made first H2 hologram from transmission hologram, but it is very dim. I'll make some photos a I'll show my setup. Can I make H2 hologram from reflection hologram?

Michael Harrison

Right exposure

Post by Michael Harrison »

While my results are similar to your with regard to single-beam holograms, using an assisted single-beam setup you can greatly improve your results by making use of the otherwise wasted light.

Tom's holograms are very bright and I believe he's using a straight single-beam setup.
http://www.network54.com/Forum/message? ... 1086578709





---------------------------
If someone says it can't be done but they haven't tried it, don't believe them.
http://www.dragonseye.com/Holography

Are you going to the next PCG Gathering?
http://www.dragonseye.com/Holography/PCGGI.html
Michael Harrison

Right exposure

Post by Michael Harrison »

I also want to make H2 holograms. I want to make holograms, where the virtual image is in front of the plate and viewable by white light. Is H2 the right way? Is H2 the same as a rainbow hologram?

"H2" is really just a way to indicate that you've made a hologram using another hologram as the subject or "master". H2's can be made from both transmission (the most common way) or reflection masters.

Can you show me some of your H2 holograms?

If you're interested, all of the reflection holograms I've made since August 2003 (except for the ones in Belize) were H2's made using a transmission master.

http://www.dragonseye.com/holography/present.html


I made first H2 hologram from transmission hologram, but it is very dim.

You probably just didn't balance the light ratios between the reference and object beams.

I'll make some photos a I'll show my setup.

Please do. There are a lot of us who like to see how other people are doing things.

---------------------------
If someone says it can't be done but they haven't tried it, don't believe them.
http://www.dragonseye.com/Holography

Are you going to the next PCG Gathering?
http://www.dragonseye.com/Holography/PCGGI.html
Peter

Right exposure

Post by Peter »

I made first H2 hologram from transmission hologram, but it is very dim.

You probably just didn't balance the light ratios between the reference and object beams.

Yes, you are right. I have only modest setup (laser + one mirror). I was doing H2 from transmission master. I had H2 emulsion side away from H1. Is it right? Are PFG-03M better for copies, than PFG-01? I've read, that thay are better for reflections holograms.
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