LightMon

LightMon monitors the light in the interferometer arms by way of the normalized light leaking through the end test masses to quadrant photodiodes (QPDX, QPDY). The raw sum of the currents from the four quadrants is called QPDX_DC, e.g., H1:ASC-QPDX_DC. Separate channels, LA_PTRX_NORM and LA_PTRY_NORM, e.g., H1:LSC-LA_PTRX_NORM are rescaled versions of these channels, where a value of 1 indicates the light leakage measured during lock acquisition, when neither the arm nor the recycling cavity is resonant. When the interferometer fully resonates at high power the normalized value is O(1000-2000).

LightMon's main purpose is to create the following data quality flags based on the arm light:


Author: Keith Riles - U. Michigan
This monitor is based strongly on the LockLoss monitor written by David Chin.