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Entry  Wed Jun 2 11:20:02 2010, Alastair, Laser, GYRO, Mirror transmission 
    Reply  Wed Jun 2 14:05:59 2010, Alastair, Laser, GYRO, Mirror transmission 
    Reply  Wed Jun 2 17:11:58 2010, Zach, Laser, GYRO, Mirror transmission 
Message ID: 792     Entry time: Wed Jun 2 14:05:59 2010     In reply to: 791
Author: Alastair 
Type: Laser 
Category: GYRO 
Subject: Mirror transmission 

I tried some more mirrors:

Mirror 7 : CVI PR1-1064-99.5-1037 for 0degrees, 1".  Transmission 1.28% for 45S.  Taken from the PSL lab.  Mirror is dirty.

Mirror 8 : CVI PR1-1064-98-1037 for 0degrees, 1".  Transmission 69% for 45S.  Taken from PSL lab.  Mirror is dirty.

Mirror 9 : VLOC FM-25.4-6.35-1FS-1010-1064-2, 1".  Transmission 101ppm.  Taken from 40m.

One possible configuration would be to use Mirror 7 as the input and Mirror 1 as the output.  That gives us a finesse of around 330 and a contrast defect of 0.13.


Quote:

I re-measured the mirror transmissions for 45S for all the candidate mirrors for the cavity.  The Y1 45P mirrors that were borrowed from the 40m have very low transmission for 45S.  I think that when they were measured before, the polarization had been rotated at the wave plate just after the faraday, and this is what gave the higher transmission values for the 45P mirrors.  I rotated it back to S using one of the good polarizers and power meter.  I have labelled each mirror with a number and the measured transmission.

 

Mirror 1:  BS1 - 99 - 45S, 2".  Old input mirror from the gyro.  Power in 115.4mW.  Power transmitted 0.657mW.  Transmission 0.57%

Mirror 2: Y1 - 45S, 2".  Old output mirror from the gyro.  Power in 115.3mW.  Power transmitted 19uW.  Transmission 165ppm.

Mirror 3: Y1 - 45P, 2".  From the 40m.  Power in 115.1mW.  Power transmitted 13uW.  Transmission 113ppm.

MIrror 4 Y1 - 45P, 2".  From the 40m.  Power in 115.3mW.  Power transmitted 20.2uW.  Transmission 175ppm.

Mirror 5: Y1 - 45S - 6.00m, 1".  Old curved mirror from gyro.  Power in 114.9mW.  Power transmitted 15.3uW.  Transmission 133ppm.

Mirror 6: Y1 - 45S - 6.00m, 1".  Old curved mirror from gyro.  Power in 115mW.  Power transmitted 20.5uW.  Transmission 178ppm.

 

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