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Message ID: 2377     Entry time: Thu Jul 25 20:43:12 2019
Author: ScottA and anchal 
Type: DailyProgress 
Category: RFAM 
Subject: Setting up pick-off for RFAM measurement 

The plan is to put a half-wave plate before the mirrors which steer the beam into the faraday isolator before the South cavity. The mirror which will act as a pickoff is only reflective to S polarization at 45 degrees, so with the HW plate, we can get enough light in transmission to measure RFAM with a photodetector.

  • First we found a working new focus 1811 photodetector.
  • Then I used two irises to mark the beam alignment with as much precision as possible.
  • We had to rotate the pick-off mirror's mount by 90 degrees to make clearance for the transmitted beam.
  • We re-steered the beam to pass back through both irises, regaining as close to the original alignment as possible.
  • We then used a power meter to maximize the power at the output of the faraday, first using the rotated mirrors dials, then fine-tuning with the other two steering mirrors.
  • After fine-tuning, there was 13.5 mW going into the isolator, and 11.88 mW at the output.
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