Reports until 15:48, Tuesday 31 July 2012
H2 ISC
eleanor.king@LIGO.ORG - posted 15:48, Tuesday 31 July 2012 (3668)
Doubler crystal temperature of the green laser

Jax, Bram, Elli.  We repeated the measurement we made last week on 26 July of measuring how the 532nm laser power output changes as you vary the doubler crystal temperature.  Measurements were taken over a greater range than last time.  The attached graph shows today's measurements (blue) and well as those taken last week (red).

The laser diode current was set to 1.725A and the 1064 crystal temperature was 42.14 degrees C.  As the graph shows, the maximum power output occurs at about 34.36 degrees C, althought the actual power output at this temperature varies between 40-45mW.

We also took a couple of measurements about the REFL_PWR_MON, GREEN_PWR_MON and IR_PWR_MON photodiodes.  First we measured the signal in counts of the output of these channels.  Then we covered each diode so no laser light hit it and measured the output signal again.  Then we measured the power incident on each diode in mW using the power detector.  The readings are as follows:

     Normal operation, beam incident on PD (# counts) No light incident on PD (# counts) Power (mW)
REFL_PWR_MON ~400 14276 1.2
GREEN_PWR_MON 8520 20 0.68
IR_PWR_MON 13350 170 0.73
Images attached to this report