To both of you beginners, you seem to be having conniptions over stability. Us older holographers from the 70's and 80's didn't have a lot of resources such as forums and EBay, so we made do with whatever we could lay our hands on. A lot of us turned dumpster driving into an art form! So, yes, I agree with Jason (Dr Laser), use a piece of gum, or plasticine or glue or hot glue (Once described to me as "The holographer's friend").
Perhaps a bit of background. When you record a hologram, there are places (actually twisty, bendy lines) that have a lot of light, and parts that have no light, and parts between 1 and 0. These "iso-lines" all twist, bend and form circles. Now, when you make a hologram, you're taking a picture, a photograph, of those twisty and bendy lines. Just like taking any photograph, if your subject moves during the exposure, the picture will blur. But, in this case, the efficiency of the hologram, the brightness (they're not the same thing, but that's for another day), is dependant on the sharpness of theses twisty lines. If these lines blur, the hologram will lose brightness, quite fast actually; a 5% drop in sharpness could reduce the brightness by 50% or more. So, you need to keep those lines - and hence, the whole recording system - from moving. But,
only during the time of the exposure.
However, clearly, the more complicated the system, the more likely that different parts of the system will move relative to each other. So, the more complicated the system, the more you need to be careful of stability over the entire system. Also, for a given system, the longer the exposure time,the more stable it needs to be.
However, in the case of a single beam Denisyuk, the "system" has only two components: the plate and the object. Well, there's the mirror, if you're diverting the beam from the laser, and the expanding lens, but those are all before the laser beam "splits" (at the plate). So, all you have to do is to ensure that there is no
relative motion between plate and object. The two can dance the fandango on your table, so long as they do it together! One way to ensure this is to create a "plateholder" with a leg on it, like an "L". The vertical, long arm of the "L" can be three pieces of metal, shaped like a "U", grooved to accept the plate, and the short horizontal base can be screwed/glued or attached any way, so long as there's no
relative motion. The object is then glued or bubble-gummed, onto the short horizontal piece. Bob brought this up also. Another way is to hie down to your local metal shop and get a sheet of metal, roughly 4 ft x 4 ft and about an inch thick. These are pretty inexpensive, especially if they're scrap. Then place said metal "table" on old carpeting, maybe two, three layers thick.
Using this same "table", you can make a simple mirror holder by getting a strip of metal, maybe two, three inches wide and about 3 inches tall. and also shaped like an "L". Glue the mirror on top of the strip, and glue the base of the "L" onto the metal "table". If you want a lens holder, maybe the metal shop owner can drill a hole in the upper arm of the "L", about the size of the lens.
For what it's worth, here's our plateholder. It's sideways, relative to my above description;that is, "U" is sideways.
- plateholder.jpg (34.11 KiB) Viewed 4606 times
