I measured the power incident on the cryo chamber viewport and the reference PD reading to calibrate the incident power. Data is attached. Power meter head = S148C.
LD,REFPD,POWER -0.4,0.207,0.314 -0.3,0.263,0.452 -0.2,0.32,0.589 -0.1,0.373,0.719 0,0.432,0.865 0.1,0.486,0.99 0.2,0.534,1.106 0.3,0.585,1.238 0.4,0.64,1.363