frustrated beginner

On: Fri, Jan 11, 02 10:15:45 PM

john wagner wrote:

Hi everyone,I have just begun shooting my first reflection holograms and they are all turning out very dark. I'm using BB-640 plates with infiniter 200 laser and kodak D19 developer ( JD-2 bleach ) I have tried adjusting exposure times and development times etc and still the same result. I have built a sand table and although have not constructed an interferometer I do not think I am getting any movement. The images I am getting are actually quite sharp, just very dark. I am hoping that the problem is due to the age of my plates. I got a bit over enthusiastic and purchased the plates long before I was ready to use them, the plates were about 16-18 months old before I opened the box and stared using them, they were stored at room temp over that time. Do these plates have a use by date? Do they degrade over time? I hope so because then the problem is not in my technique :-) If the age of my plates are not an issue, i would appreciate any advice on what the problem could be. John
RESPONSES

Colin Kaminski - Sat, Jan 12, 02 12:14:30 AM

D-19 is really not the best developer for reflection holograms. You could try CW-C2: Catechol 10g L-Ascorbic Acid 5g Sodium Sulfite (anhydrous) 5g Urea 50g Sodium Carbonate (anhydrous) 30g Distilled Water 1 L Develop for 2 min at 20 Deg. C Add the sodium carbonate just before use. Or make two stock solutions one with the sodium carbonate. This should work well with JD-2 bleach. D-19 with no bleach should make good transmision holograms. 64.170.193.212

Tom B. - Sat, Jan 12, 02 03:54:58 AM

A few suggestions and guesses - - I agree with Colin that CW-C2 will likely work better than D19. Photographer's Formulary http://www.photoformulary.com sells an affordable chemical kit (they call it their JD-2 holography kit) for about $12.95. - As I understand it, when plates expire, it's because the chemical inhibitors wear out leading to spontaneous fogging. If an unexposed plate turns black in the developer, it has likely expired, though if the black stuff clears quickly in the bleach (faster than exposed areas) the plate might still be somewhat useable. - Are you turning on the laser to let it warm up for a while before exposing? At least 5 minutes is recommended. Also, using external batteries (I use D cells) is highly recommended. - Air currents can be a problem - you couold try covering the setup with something to keep the wind off. Also sound vibrations. A quiet basement with a concrete floor is ideal. - Checked your safelight? If the green filter is leaking red light, it will cause fogging. I use 4 layers of green cel (don't recall the type). Expose part of the plate to safelight up close for 2 minutes - if exposed areas turn dark in developer you need a better safelight. - Using distilled water for mixing developer? Rinsing (for 2 minutes) before and after bleaching? - Constructing an interferometer is well worth the effort - If you can get good stable fringes then you will know that the laser and table is OK and can focus on debugging the chemistry and setup. - Expecting too much brightness from a simple reflection hologram? Is the object bright and shiny? Even so, it is a real challenge with a single-beam setup to get anything like the brightness of a well-made commercial hologram with optimized object-reference ratios and reduced vertical parallax. But we love challenges. Hope some of this helps. 24.67.253.203

john W - Sat, Jan 12, 02 07:03:12 AM

Thanks guys, I guess I'll just have to go through everything step by step. I'll try and shoot a transmission first and see what happens, that may be a good way to eliminate problems with my optics. Meanwhile I've ordered a box of the Slavich plates. I'll use the last couple of bb- 640s to check the safelight and to see if they have expired by developing an unexposed plate. I've just put together a power supply using D-cells so that should eliminate one of the potential problems. Getting hold of all the gear ( chemicals and plates ) is difficult sometimes, I live in New Zealand so it's all overseas orders, and as far as know I'm the only holography hobbist in this part of the world! Thanks again for your suggestions. John 203.96.111.200

Tom B. - Sat, Jan 12, 02 02:51:19 PM

Re checking safelight - if you have some diffraction grating, you can look at the safelight spectrum. I found that with eyes dark adapted, even small amounts of red leakage showed up pretty well. With two layers of green gel, a tiny amount of red was still visible, with four, none, and the safelight was safe - no fogging after 5 minutes close exposure. 24.67.253.203

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