Eleonora, Raffaele, Yaochin and Yuhang

Yesterday night we came to TAMA and improved especially the matching and alignment from OPOtra to filter cavity. We moved the lens position and also tried to align a bit the steering mirror. After this work, the matching level is estimated as following

TEM00: 460

TEM10: 108

LG10: 108

offset: 100

So the mis-matching level is about 5%

This matching level is better than the measurement of locking accuracy of last time. And we think the matching level will also influence the locking accuracy. So we characterize the locking accuracy again. This time we used the same setting as last time. The AOM was scanned with a modulated sine wave. The modulation is 2000Hz/s. We measured the PDH signal and use it for calibration. The measured PDH signal pk-pk is 234mV with a seperation of 118ms.

So the calibration is 2000/(2*234/118) Hz/V

We measured the demodulated BAB reflection spectrum, the locking accuracy is integrated as 5Hz. But now we have some new peaks.