User name X. Zheng
Log entry time 07:00:35 on June11,2001
Entry number 62868
keyword=Target - EPR - photodiode5:48 am, EPR, 1 laser, oven 170, polarization 39.1 %.
At 2:00 am, check old PIN photodiode performance. D2 lineshape measured by FMSweep doesn't look bad. I used more "# of samples" to average out the noise, but still the noise is lower than what I expected.
Tried another PIN 10D photodiode, DC signal is about 220 uV @ 3 lasers, but lineshape doesn't look too much different.
Then tried the new PIN 10DI (without BNC connector). Run FM sweep. With 1 or 2 or 3 laser(s), got 25 uV D2 signal (1st plot) superimposed on big background (2nd plot). Adjusted lenses/diode position, cannot get rid of it.
Did one AFP measurment, after tens of FMsweeps, polarization now is 39.1 % with stat. err 0.9%. Did not have enough time (and don't know how to) deal with the background.
Can only make a new procedure for "how to adjust lock-in phase", will optimize electronics later today:
-With any phase, do one FMSweep, try to find lineshape by eyes. (if no zero crossing);
-Set RF frequency @ approx. resonance, use "auto phase", now the signal is completely junk background;
-Increase/decrease lockin phase by 90 degrees;
-Go to higher (or lower) maximum, check signal amplitude in X channel, should be > 20 uV;
- Continue to AFP measurement.
FIGURE 1
FIGURE 2
