NAOJ GW Elog Logbook 3.2
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YuhangZhao - 09:09, Tuesday 13 March 2018 (693)
Charaterization of Filter Cavity
Participant: Yuefan, Yuhang, Eleonora
Yesterday, we did some characterization of our filter cavity.
1. Open Loop Transfer Function: The unity gain frequency is 10kHz and the phase margin is 39 degree. Actually this is not the practical case, we changed the gain of our loop. And we suspected this is because of the increase of circulating power.(Fig 1)
2. Calibration: We measured the calibration of green and infrared again. The calibration factor is similar with before.(Fig 2)
3. Error signal noise spectrum: We plot out the direct measurement and calibrated one together.(Fig 3 and 4)
You can use the data attached. They are not calibrated.
ger25k6 is green error signal with highest frequency 25600Hz(calibration factor is 2.6e-3V/Hz).
ier25k6 is infrared error signal with highest frequency 25600Hz(calibration factor is 6.3e-3V/Hz).
ol51k2 is open loop transfer function with highest frequency 51200Hz.
Yesterday, we did some characterization of our filter cavity.
1. Open Loop Transfer Function: The unity gain frequency is 10kHz and the phase margin is 39 degree. Actually this is not the practical case, we changed the gain of our loop. And we suspected this is because of the increase of circulating power.(Fig 1)
2. Calibration: We measured the calibration of green and infrared again. The calibration factor is similar with before.(Fig 2)
3. Error signal noise spectrum: We plot out the direct measurement and calibrated one together.(Fig 3 and 4)
You can use the data attached. They are not calibrated.
ger25k6 is green error signal with highest frequency 25600Hz(calibration factor is 2.6e-3V/Hz).
ier25k6 is infrared error signal with highest frequency 25600Hz(calibration factor is 6.3e-3V/Hz).
ol51k2 is open loop transfer function with highest frequency 51200Hz.
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Comments related to this report
I've compared the error signals measured in the entry 690 with the new ones. There is something strange: now the error signal for the IR is 10 times smaller than before.