Aidan. Greg.

Good news first:

Using the periscope, we got the green ALS beam aligned to the on-table irises that were pre-aligned to the HWS probe beam. This, nominally, mated the in-vacuum and in-air axes. To test this, we turned on the probe beam and recorded a frame with the HWS camera to see if there was a return beam. And ...

There was a return beam from ITMX. It looks clean (as clean as possible with the Hartmann plate on). The next steps are to remove the plate and

1. Tweak the position of the probe beam on the ITM using the shadow of the baffles as a guide.

2. Move the HWS along the optical axis until it is imaging the ITMX HR surface.

Bad news second:

The in-vacuum lens for the Y-arm Hartmann sensor is not correct (I'm 99% sure of this). It appears to be a concave lens when it should, in fact be a convex lens (PLCX-50.8-360.6-UV). There are two things that indicate this.

1. The green ALS leakge field is quite large (vs the X arm green beam which is quite small). The beams are designed to be small coming out of the viewports and should be, roughly, the same size.

2. The lens is close to the viewport and you can see objects through it. For instance, the SR2 triple, about 3 or 4 feet away) can be seen through the lens off-axis. It appears smaller when viewed through the lens. We I take a spare PLCX-50.8-360.6 (what should be in there) and look through it, objects that are 3 or 4 feet away look bigger.

So I'm pretty convinced the in-vacuum lens is concave when it should be convex. We'll continue investigating how occured (it looks like some typos in a design change have propagated through a few documents). The more important thing is what to do about it. We won't get it working this week, but it may be possible to correct this using additional in-air optics in, what Eric G has dubbed, a Hubble Space Telescope optical fix.

FYI: Livingston has the correct lenses installed in the vacuum system.