Since the HAM1 vent, I have done a few different measurements of the ASC that provide information on how to calibrate WFS signals from counts to microradians. Here is a summary:
CHARD, INP1 and PRC2 results come from this alog
DHARD results come from this alog
SRM results come from this alog (if you are comparing values, I made a power normalization error in the linked alog)
BS results were taken but never alogged (shame on me)
All of these measurements were taken by notching all ASC loops at 8.125 Hz and injecting an 8.125 Hz line in the desired DoF. The osem wits provide the urad reference.
Unless otherwise specified, the witness channels are the bottom stage osems
| DoF |
Input Matrix |
Calibration |
Notes |
| CHARD P |
-1 * REFL A 45 I + 0.6 * REFL B 45 I |
0.0161 urad [ETMY L2] / ct [REFL A 45 I]
0.0109 urad [ETMY L2] / ct [REFL B 45 I]
|
measured as ETMY L2 wit, must transform to L3 urad, can also convert to cavity angle
coherence near 1
|
| CHARD Y |
-1 * REFL A 45 I + 0.8 * REFL B 45 I |
0.0113 urad [ETMY L2] / ct [REFL A 45 I]
0.00965 urad [ETMY L2] / ct [REFL B 45 I]
|
measured as ETMY L2 wit, must transform to L3 urad, can also convert to cavity angle
coherence near 1
|
| DHARD P |
0.5 * AS A 45 Q - 0.5 * AS B 45 Q |
0.00312 urad [ETMX L2] / ct [AS A 45 Q]
0.00312 urad [ETMX L2] / ct [AS B 45 Q]
|
measured as ETMX L2 wit, must transform to L3 urad, can also convert to cavity angle
coherence = 0.8, 10 averages
|
| DHARD Y |
0.5 * AS A 45 Q - 0.5 * AS B 45 Q |
0.00612 urad [ITMY L2] / ct [AS A 45 Q]
0.02 urad [ITMY L2] / ct [AS B 45 Q]
|
measured as ITMY L2 wit, must transform to L3 urad, can also convert to cavity angle
coherence = 0.5, 10 averages
|
| PRC2 P (PR2) |
1 * POP X RF I |
0.00033 urad / ct |
coherence 1 |
| PRC2 Y (PR2) |
1 * POP X RF I |
0.000648 urad / ct |
coherence 1 |
| INP1 P (IM4) |
1.5 * REFL A 45 I + 1 * REFL B 45 I
|
0.0104 urad / ct [REFL A 45 I]
0.00988 urad / ct [REFL B 45 I]
|
coherence 1 |
| INP1 Y (IM4) |
2 * REFL A 45 I + 1 * REFL B 45 I |
0.0141 urad/ct [REFL A 45 I]
0.00608 urad/ct [REFL B 45 I]
|
coherence 1 |
| MICH P (BS) |
1 * AS A 36 Q |
0.0161 urad [M2]/ct |
measured as BS M2 WIT/AS A 36 Q, must transform into M3 urad, coherence near 1 |
| MICH Y (BS) |
1 * AS A 36 Q |
|
data not taken |
| SRC1 P (SRM) |
1 * AS A 72 Q |
16.9 urad/ct |
coherence near 1 |
| SRC1 Y (SRM) |
1 * AS A 72 Q |
10.6 urad/ct |
coherence near 1 |
