I'm still using my old inner tubes, however the piece of stone has been replaced with cinder blocks. The one on the left has a slow leak, which I haven't been able to find yet.
The cinder blocks are not cemented or glued together. Then I would never be able to move it... They are instead held together with two 2x4's, and threaded rod. The threaded rod is under significant tension, the final assembly is quite rigid. Standing on it is extremely strange, its solid yet wobbly from the inner tubes.
I then put a couple of pieces of plywood on top of the cinder blocks, my shiny new optical breadboard, and all the optics from previous versions.
So, I have a new base for the big lens (I increased my nominal beam height from 5 1/4 inches to 9 and 1/8 inches), a new stand for the laser, new rods for holding optics (they are 1/2 inch threaded rod JB-welded to floor flanges, which are then bolted to the breadboard) and a spatial filter.
The assembly on the breadboard in the picture is an interferometer, with a bunch of extra stuff (like the big lens) which didn't have anywhere better to go. The first theory was to try to hang steering mirrors off the edges of the breadboard, similar to how the small lens on the far left is on an "out rigger", and save active breadboard area for more interesting stuff. Unfortunately that was nowhere near stable enough. I tried a couple of different designs. An aluminum angle out-rigger can be seen sitting on the edge of the plywood on the far left. None were rigid enough, and I finally went with the mirror mount seen in the next image.
This is the first hologram with the new setup. To put things in perspective, this image was taken on July 24, 2005. My previous hologram was in early January.
The final arrangement uses about 1/4 of one end of the breadboard for the beam splitter, spatial filter, a mirror, and the big lens, to make a reference beam going down the left edge and object beam going down the right edge. The rest of the breadboard is then rearranged for different holograms. I don't generally have to move and re-adjust the spatial filter (Yay!).