The last week I've started setting up the HeNe laser on the PSL table and doing some basic measurements (Beam waist, etc) with the beam scan, shown on the graph. Today I moved a few steering mirrors that steve showed me from at table on the NW corner to the PSL table. The goal setup is shown below, based on the UCSD setup. Also, I found something that confused me in the EUCLID setup, a pair of quarter wave plates in the arm of their interferometer, so I've been working out how they organized that to get the results that they did. I also finished calculating the shot noise levels in the basic and UCSD models, and those are also shown below (at 633nm, 4mw) where the two phase-shifted elements (green/red) are the UCSD outputs, in quadrature (the legend is difficult to read).
0. Probably, you are working on the SP table, not on the PSL table.
1. The profile measurement looks very nice.
2. You can simplify the optical layout if you consider the following issues
A. The matching lenses just after the laser:
You can make a collimated beam only with a single lens, instead of two.
Just put a lens of f0 with distance of f0 from the waist. (Just like Geometrical Optics to make a parallel-going beam.)
Or even you don't need any lens. In this case, whole optical setup should be smaller so that your beam
can be accomodated by the aperture of your optics. But that's adequately possible.
B. The steering mirrors after the laser:
If you have a well elevated beam from the table (3~4 inches), you can omit two steering mirrors.
If you have a laser beam whose tilte can not be corrected by the laser mount, you can add a mirror to fix it.
C. The steering mirrors in the arms:
You don't need the steering mirrors in the arms as all d.o.f. of the Michelson alignment can be adjusted
by the beamsplitter and the mirror at the reflected arm. Also The arm can be much shorter (5~6 inches?)
D. The lenses and the mirrors after the PBS:
You can put one of the lenses before the PBS, instead of two after the lens.
You can omit the mirror at the reflection side of the PBS as the PBS mount should have alignment adjustment.
The simpler, the faster and the easier to work with!