alexan.staley@LIGO.ORG - posted 18:52, Tuesday 10 December 2013 - last comment - 14:22, Friday 13 December 2013(8898)
ALS Fiber Distribution Chassis S1202528
As noted in alog6341, the gain on the Dual PD Amp board was set to 30dB (photo 1). I have reduced the gain to 10dB (photo 2). However, I still see saturation at 10V in the external PD monitor. Tomorrow I will try reducing the gain to 0dB.
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I have reset the internal PD gain to 30dB (since we were never saturating there), and set the external PD gain to 0dB.
For the external PD:
Transimpedance = 20kOhm
Responsivity = .268A/W
Power @ ext PD = 0.93mW (w/ a drift of 7% of the ref cav alignment)
Gain = 0dB
Volts = (resp) x (power) x (trans) x (gain) = 5V
...Ignore above calculation for external PD...