I am just starting out in holography and I am using several years old red sensitive idford holography film (400 feet!) that I got for a good price. The film isn't fogged and it darkens up quite well when exposed to laser light. So I belive the film is good. I have been able to create holograms on the film but they are quite dim. On The last test strip I did, one image was not bad, but I would like to get brighter images. I use a 2mw nehe, single beam, film between two plates, coin subject fixed to the plate. For developing I use metol, asorbic acid (MAA) developer and edta bleach as recomended by the saxby book. So if any can help me out that would be great.
Jonathan - Mon, Jun 04, 01 10:43:14 AM
John, it's great that you have been able to get images from film that is several years old. No one likes to see holographic film wasted, especially that much of it. You mentioned that you are using a 2 mw HeNe, single beam, and mounting the film between two plates, and are interested in brighter holograms. Given your success so far it's quite possible the film is still good.
But these conditions can all place restrictions on brightness. The low power means longer exposure times and therefore more opportunity for vibration and air currents to cause loss of fringe contrast, which directly affects brightness. Try a more powerful laser pointer - they are very inexpensive.
The single beam technique has an inherent restriction on brightness in that it prevents you from adjusting the ratio between the object and reference beams. The beam ratio needs to be in the proper range for optimum brightness, but there are techniques for making single beam holograms that are quite bright. This web site has many links that can help, including Frank's discussions on the subject.
Mounting the film between two plates is going to cause all sorts of "noise" in the hologram which reduces brightness. Again there are ways around it that are simple and inexpensive. Mounting the film with index matching fluid is quite effective and I find lamp oil works well. It takes a while to work out a useable technique. I use a roller followed by squeegeeing. Make sure the squeegee is made of a good rubber. Some will simply smear and make a mess. Try a high quality windshield wiper mounted on a stiff handle.
The chemistry you mentioned is excellent for bright holograms, and is especially good for transmission holograms since emulsion shrinkage is kept low. It's also very good for reflection holograms, and if you can work out satisfactory techniques for pre-swelling with TEA then you can also produce excellent reflection holograms in a range of colours. Good luck.
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John K - Tue, Jun 05, 01 10:09:17 PM
Thanks for the reply, It's good to know that I'm on the right track using the maa developer. I have tried using two different cheapo diode laser pointers, but couldn't get an image with them. I will have to buy another one. I do think the ilford film is good, the company rep. said the red sensitizing dye may break down over time, but I have no trouble getting the film dark with an exposure from the laser. The images I've done look detailed, but dim. I am going to look at all the varibles and try to control for them. The interesting thing about this film is ilford has a chemical in the film that will shift the color from red, to green gold if you use a nonstaining developer, which is why I used MAA instead of a pyrogallic acid type developer. The person that I got the film from does sell it on e-bay once in a while, He must have quite a few tin of it. He is selling a tin now on e-bay under "holographic film". 63.228.61.24
Colin - Wed, Jun 06, 01 12:03:11 AM
John, Try the diode from Integraf. I have had very good results with it. I think it was about $30. I found it for a few bucks cheaper but thought I would support a holographer. members.aol.com/integraf/catalog.html Also when trying to fix a dim image don't forget object stability. :-) 64.170.192.178