With the DARM offset moving to 40mA total DCPD photocurrent (69358), this should correspond to an IFO readout angle of about -12 degrees, given the 1.7mA contrast defect (69361).
Using Craig's calculation of the homodyne / readout angle (65000), as a function of DCPD power level for a 1.7 mW of junk light (68859, 69361),
total_dcpd_light = 20 #mA # total dcpd mA level
contrast_defect = 1.7 #mA # this is a recently measured value
darm_offset_power = total_dcpd_light - contrast_defect
homodyne_angle = np.arctan2(np.sqrt(contrast_defect), np.sqrt(darm_offset_power)) #radians
homodyne_angle*180/np.pi #degrees
Here's the resulting homodyne angle for various DCPD powers:
| total dcpd light (mA) | homodyne angle (degrees), upper limit |
| 20 | -17.0 |
| 30 | -13.8 |
| 40 | -11.9 |
Attached here are some gifs of gwinc-calculated quantum noise for DARM with NO squeezing, rotating through some homodyne angles. The following NO-SQZ GPS times were used:
