aLIGO LHO Logbook

H1 ISC

corey.gray@LIGO.ORG - posted 12:16, Wednesday 19 December 2012 (4950)

EX Transmon IR QPD Sled Complete

(Corey, Keita)

Continuing the work of building QPD Sleds for upcoming installations, Keita and I recently finished up the EX Transmon IR QPD Sled (we completed the Green Sled a couple of weeks ago; the overall Transmon document is T0900385).

Lisa B. roughly laid out the Sled during her last visit. We then used an IR laser/launcher for our light source and worked on setting up our lenses in a way such that our beam profile would be optimized for the QPDs (Desired beam profiles are posted in the Guoy Phase document T1000247). To measure our beam profiles we used the Mode Master PC; Nicolas Smith's "A La Mode" Matlab scripting was used to calculate & plot our Beam profile. (The matlab script used for this sled is attached to this entry.)

The toughest part is setting up the Mode Master, but once it is set up, it's fairly straightforward laying out the lenses for the Sled. Once the lenses were positioned & we had our desired beam profile, the rest of the Sled optics were laid out. The Mode Master results and Matlab Beam Profile plots are attached to this entry.

The QPDs were aligned by connecting them (via feedthrough) to a QPD LCD Readout Box, D1102092, (which powers the QPDs & has an LCD target on it). One thing with this Readout Box--make sure to have low enough laser power such that you don't saturate the Box at Low Gain (otherwise, you won't be able to center QPDs).

Wipes were draped over optical components, entire assy wrapped in foil & bagged, and is now stored in a plastic bin. This bin will be stored in the Optics Lab under our Optics Table until we are ready for installation. Keita will submit an a document about this Sled to the DCC separately.

Below are documentation notes for this Sled.

Optical Component Distances

For measurements below, the lenses are measured on the "backface" of their Lens Holder. The Mirrors & Beam Splitters are measured from their glass "front faces". Measurements were measured with a scale & all measurements are in mm.