TF measurement of RFQPD

• At the HIGH signal, it is off-peak at the HIGH frequency. The LOW signal came between the peaks. It is the depth at the opposite target frequency at the HIGH and LOW signals. These are as designed. 
  However, the AM laser measurement did not reveal the depth at the LOW frequency of the HIGH signal. This may be buried by noise.
• Measurements with the AM laser resulted in Seg 1 and 3 being doubled relative to Seg 2 and 4 because the beams were elliptical. DC power per segment at QPD 3 and 4 in AM laser measurements(Fig1, Fig2). This is true for the LOW signal in measurements with the AM laser. But in the HIGH signal, the gain was almost the same in all segments. The reason for this is not known. 
• Also, the AM laser often turned off the OUTPUT signal output this time, as if the main unit was not in good condition.
• Destination of files with measurement results:  Dropbox/Measurements/IFO/ASC/REFL/RFQPD/characterization/TF

Did phasing for each segment

• For the HIGH and LOW signals, the following target frequencies were modulated into the AM laser at 1 Vp-p.
  • LOW signal: 11.248830066MHz(5.624365033MHz(Seed freq)× 2+100Hz)
    As a result, a demodulated signal was seen at 90 Hz.
  • High signal: 89.990010528MHz (5.624365033MHz × 16+100Hz+70Hz)
    Originally the demodulated signal was planned to be 100 Hz, but adjusted the frequency 70 Hz. 86 Hz signal was seen.
• In MEDM screen we installed 0 for R and 90 for D. In this state, we measured the phase difference of the I error signal of Seg 2-4 with respect to Seg 1. We dubstituted the difference in R. After phasing, The difference of each segment with respect to Seg1 is almost reduced to less than 0.2 deg.
• D has not been adjusted. The method for adjusting D is probably described in klog8359.