How important/significant are spacial filters regarding the techniques and corresponding results with laser pointer and laser diode holography of the Denisyuk format?... does collimating render spacial filters any less needed? If spacial filters do significantly improve the end results, does anyone know of a source "a-round" where one can get a decent s.f. setup without spending an arm and five hundred legs?
Ray - Tue, Nov 23, 99 09:44:39 PM
You do not need a spacial filter to make Deniysuk holograms. Collimating simply stops the beam from expanding. A spacial filter "cleans" up the beam and expands it. Spacial filters do make a difference, when doing split-beam holography, but for simple holograms you don't need one. 192.248.248.34
Steve Michael - Wed, Nov 24, 99 09:05:29 PM
As Ray mentions, you don't need a spatial filter to make Deniysuk holograms with a laser pointer or any other laser for that matter. Just a simple double concave lens. Just make sure the lens is kept clean of dust and should be covered when not in use. If you're doing split beam H1 and H2 holograms, then spatial filters do become important as Ray mentions because most likely you'll be doing an image-plane for H2 and any extraneous interference patterns caused by dust or internal laser cavity noise will degrade the image quality. Actually, you can make a pinhole using aluminum fold and a straight pin. But then you would have to mount the fold on a substrate and make an x-y-z positioner, which is totally do able. By the way, collimating in a split beam setup for H1 is used so the real image you project for H2 is the same size (and is not magnified) as the original object. 216.164.130.83
Ronny Andreassen - Thu, Nov 25, 99 03:11:47 PM
Thomas, if you are interested there is some good drawings how to build spat.filters in the Holography Handbook. I'v made me some of these and they are easy to use. You can buy pinholes from Edmund & Schentific. 130.67.15.246
F. Aaron - Thu, Oct 11, 01 11:47:05 PM
Does anyone know the name of a component that aligns lasers modes which are not spacialy coherent. 64.12.102.41