At Rana's request, I've made an in-situ measurement of the RIN of all of our OpLevs. PSL shutter closed, 10mHz BW. The OpLevs are not neccesarily centered, but the counts on darkest quadrant on each QPD is not more than a factor of a few lower than the brightest quadrant; i.e. I'm confident that the beam is not falling off.
I have not attached that raw data, as it is ~90MB. Instead, the DTT template can be found in /users/Templates/OL/ALL-SUM_141125.xml
Here are the mean and std of the channels as reported by z avg 30 -s, (in parenthesis, I've added the std/mean to estimate the RMS RIN)
SUS-BS_OLSUM_IN1 1957.02440999 1.09957708641 (5.62e-4)
SUS-ETMX_OLSUM_IN1 16226.5940104 2.25084766713 (1.39e-4)
SUS-ETMY_OLSUM_IN1 6755.87203776 8.07100449176 (1.19e-3)
SUS-ITMX_OLSUM_IN1 6920.07502441 1.4903816992 (2.15e-4)
SUS-ITMY_OLSUM_IN1 13680.9810547 4.71903560692 (3.45e-4)
SUS-PRM_OLSUM_IN1 2333.40523682 1.28749988092 (5.52e-4)
SUS-SRM_OLSUM_IN1 26436.5919596 4.26549117459 (1.61e-4)
Dividing each spectrum from DTT by these mean values gives me this plot:

ETMY is the worst offender here... |