I just returned from a long day at Palomar. Here's what I got done on the BtO: (I will also post this on the TWiki site BtO page...)

1. Checked stability and alignment of BtO Coude breadboard

The new breadboard has been mounted to the spectrograph frame using a single wide steel L-bracket along the lower edge. While alignment is good, I'm somewhat concerned about vibrations. A diagonal brace behind might be necessary to stiffen the mount, but this is not an immediate priority. The breadboard surface is parallel to the polar axis to better than 0.10 deg., and parallel to the vertical plane to ~0.2 degrees (the top leans very slightly East). The surface is 3.50" from the polar axis, making this the beam height on the breadboard. No shimming was necessary.

2. Define polar axis

I mounted an iris on the new breadboard, centered on the polar axis as defined by the 635nm diode laser installed last week. This laser allowed us to transfer the knowledge of the location of the polar axis from the old breadboard to the new one. I expect this iris is within ~3mm of the true polar axis. The other point defining the axis is the center of the Coude output window (well, not exactly the center - actually a point 2/3 of the way up, along the central axis).

3. Simulate CSFL beam

I set up an unpolarized HeNe laser to reflect off a mirror placed in front of the CSFL shutter, to replicate the geometry of the yellow laser for alignment and testing.

3. Populate BtO Coude breadboard.

I installed all optics, stages, and the 660nm polarized diode laser on the new breadboard. These were aligned to the simulated CSFL beam and polar axis. The simulated CSFL and 660nm beams are now co-aligned, and reflect off the FSM onto the polar axis. I took some photos of the setup, but my camera apparently doesn't feel like showing them off right now.

NOTE: I may have installed the 1/2-wave plate rotary stage backwards from its previous orientation due to mounting constraints. If this is the case, a sign will have to be changed in the software controlling this motor.

Tasks left for next week:

I ordered a few small parts which will simplify some of the optomechanics - these should arrive at Palomar tomorrow (6/2). After installing these, we should be ready to test the Q1 and Q2 signal levels with the 660nm laser. This will be a repeat of the testing Chris and John did 2 weeks ago, with new optics on the Coude breadboard, the enhanced-Al mirror on the trolley, and RG610 filters in front of quad cells - all are in hand. Other than this, I don't think there is really much more to do until we have yellow light to work with. I will discuss with Viswa when we might be able to do this.

Sincerely,

Antonin

-- AntoninBouchez - 02 Jun 2006