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Message ID: 1020     Entry time: Thu Oct 2 16:44:28 2008
Author: steve 
Type: Summary 
Category: oplevs 
Subject: optical levers 
The idea is to push the UGF to 10 Hz of the TM oplev servos with quiet HeNe laser.
We measured good intensity noise of JDS 1103P in May 2007 and converted most of the TM oplevs to it.
The ITMs still have the noisy 670nm , 1 mW, diode lasers to begin with.
In order to get 1 mW power returning to the qpds I measured the power going to TMs
and returning on qpds ...so we can select the appropriate laser power for the conversion.

40m optical lever lasers:

HeNe laser JDS 1103P, 633nm, linear polarization 500:1,

ETMX: qpd 0.12 mw (4%) reflected of 3 mW,
ETMY: qpd 0.1o (3.8%) " 2.6
BS: qpd 0.02 ( 2.5%) " 0.8
PRM: qpd 0.01 (1.3%) " 0.75
SRM: qpd 0.08 (10%) " 0.8

Coherent 670 nm Diode Lasers VLM-tm, 0.95 mW, linear polarization 100:1,

ITMX: qpd 0.1 mW (11%) reflected back from TM of 0.9 mW
ITMY: qpd 0.04 (7%) " " 0.6

It seems that JDS HeNe laser 633 nm, linear polarization 500:1, 10 mW will do the job
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