We update the hardware part of the pr2 oplev.
1. Turned off the oplev control
Before this work, I turned off the oplev control of IM and TM stage.
But I changed the 10 usec in pitch and 6 usec in yaw before removing the DC control... I am sorry.
2. Changed the fiber collimator
As we discussed in klog21279, we changed the LPC type fiber collimator to LPF type fiber collimator.
After changing the fiber collimator, we tweaked the alignment by centering the tilt QPD
3. Length sensing QPD tuning
As Ushiba-san pointed out in klog21351, the large angle component were there in length sensing oplev.
So I re-set the position of length sensing QPD by oscillating 0.89 Hz (30 count in TM pitch), as shown in Fig.1.
The length information is
d_vb = 115 mm
d_bt = 80 mm
d_bl = 65 mm
d_lm1 = 100 mm
d_m1m2 = 220 mm
d_m2l = 80 mm
4. Characterization of power budget
Power budget is
IN : XXX mW
TILT : XXX mW
LEN : XXX mW
(I could not find the result now...)
5. Characterization of the beam profile
In front of tilt QPD
Width major = 1.360 mm
Width minor = 1.292 mm
In front of len QPD
Width major = 0.7884 mm
Width minor = 0.722 mm
6. Calibration factor measurement
The result were shown (But, we measured the calibration factor with pitch oscillation for the length sensing QPD...)
TILT VER = 2.27 [count/mm] (Fig.2.)
TILT HOR = -2.36 [count/mm] (Fig.3.)
LEN HOR = -3.53 [count/mm] (Fig.4.)
So,
VER=340.851335 [urad/cnt]
HORI=-215.090768 [urad/cnt]
LONG=-455.121319 [um/cnt]
LENS=283.211679 [1/mm]
I implemented new calibration factor into MEDM.
After that, I requested ALIGNED state to guardian but faild due to some oscillation of OpLev controls.
So, I measured the TFs of PR2 and made susmpension models.
Figure 1 to 3 shows the measured TFs.
I haven't checked TML to TML but gains of TFs from TMP to TMP and TMY to TMY increase more than 10 dB.
So, I ajusted the gain of filters and now PR2 can reach LOCK_ACQUISITION state from the guardian now.
Note:
I'm not sure why TF gains to calibrated signals changes so much (of course, it is likely that old calibration is just wrong because PR2 TF gains are 10dB or more smaller than the other Type-B suspensions).
So, further investigation is necessary.
Yokozawa-san, I forgot to share the result. Sorry.
4. Characterization of power budget
Power budget is
IN : 0.918 mW
TILT : 0.130 mW
LEN : 0.204 mW
