nutsinee.kijbunchoo@LIGO.ORG - posted 15:06, Friday 13 May 2016 - last comment - 16:03, Monday 16 May 2016(27183)
PSL power precisions measurement
Quick conclusion:
Bad news: The further away the rotation stage has to travel, the less accurate the measured requested power becomes.
Good news: The uncertainty is within 1-3%.
Slightly more details:
- The first set of measurement I ran the random walk script to let the RS rotate between -25.4 and -19 degree (roughly 0 W and 3 W) 100 times. The result yields ~1% deviation at 3W.
- The second set of measurement I ran the same code to let the RS rotate between -25.4, -19, -7, and 20 degree (which correspond roughly to 0 W, 3 W, 20 W, and 55 W) 66 times (people needs the IFO back and this RS measurement is taking forever). The result yields 2-3% deviation of the mean.
- Both measurement overlapped at 0W.
- ISS and FSS was locked during the time of measurement, IMC was left unlocked so it doesn't kick FSS. ISS integrator was off according to Jason. ISC_LOCK and LASER_PWR guardian nodes were paused.
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A little further investigation shows that the power deviation during the second set of measurements started at 58th measurement where 19 W jumped to nearly 20 W and 54 W jumped to 56 W (first attachment). This jump did not correspond to the measured angles which stayed consistant throughout the measurement (second attachment). Third attachment shows the histogram of power of the first set of measurement (going back and forth between 0W and 3W) that didn't appear to have any power jump.
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