Jason O, Matt H

So we decided to see if we could find a simple smoking gun to why the SR3 pitch appears to be so far out.

Using a clean scale and scale stand I measured the height of the HeNe beam behind the SR3 optic. With the BS optic pitch and yaw offsets on (we didnt change the values just used what was already in the fields), we measured the HeNe beam to be  at ~205mm on the scale. The scale stand holder is ~18mm high so the beam is ~223mm high. Jason looked it up and should be 229mm, but I was measuring ~8-10 inches behind the optic (in front of the baffle), and the beam from the BS to SR3 is angled up, so to fist order we are close to the center of the optic. Even so as the SR3 optic is curved, being low should help direct it up.

Also I locked the face stops of the three stages so I could push on the mechanical sliders to see if perhaps one was loose and had moved. They all appear tight, so doesn't appear to be that.

I cant really get a good look at the suspension due to not being able to lock the ISI (and thus not being able to get onto the table to get at the angles I need to look at), so I think I will try to just use the EQ stops to move the optic to direct the beam from SR3 onto SR2, until a more complete investigation can be made. Also will be interesting to see how the beam comes off SR2 and towards SRM.

The pondering as to what is going on continues