Gautam and Steve,
Quote: |
Corrected oplev laser RIN plot at day 3
RXA:
- to measure RIN, the lever arm should be really short, not long.
- the beam should be 3x smaller than the active area of the diode
- the specular beam should be dumped on a razor dump.
- we need to make a summary page for HeNe laser testing so that we can see 24 hour specgrams of these things for ~3-4 lasers at the same time.
- We should add specgram stuff for the existing HeNe SUM channels on the active OLs.
GV: The channel the PD Steve is using is hooked up to C1:ALS-FC_X_F_IN. As I found out today, there can be considerable RF pickup between the C1:ALS-FC_X_F_IN and C1:ALS-FC_Y_F_IN channels, which share a common 4-pin LEMO cable - this is because the rise time of the square wave output of the Wenzel dividers is <1us, so suitability of this particular channel for the RIN measurement set up has to be reconsidered. Perhaps we can use one of the six spare PEM channels over at 1X6.
|
We did the following:
1, switched data channel from C1:ALS-FC_X_F_IN to C1:PEM-MIC_1_OUT_DQ Actual connection at 1X7 rack, input C17
Tested channel with 1Hz, 100 mV sine wave through DV
2, placed BS into the beam path so the reflected value on the PDA100A 0.1mW, beam od ~1mm, beam path lenght 11 cm, gain 20dB 3.7Vdc
The full output of this 1103P 2.8 mW was saturating the PDA100A
Summery :finding it to be too good to be this good |