DaisukeTatsumi - 13:36, Monday 04 April 2016 (238)
Checking of optical chopper SR540
Because Manuel claimed that the optical chopper has some problems,
I checked the chopper before sending it back.
[ CONCLUSION ]
The chopper has no problems and works well.
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I tightly fixed the chopper to the optical table;
I monitored the frequency value for about 1.5 hours;
I didn't change any parameter or move anything;
Just took some snapshot of the spectrum analyzer every few minutes.
The attached file shows each snapshot and a summary plot
The result is:
- For a short time (few minutes), the frequency fluctuations are within the specifications (2%), in agreement with previous Tatsumi-san's measurements.
- For a long period, the frequency fluctuations can be larger than 2%
I couldn't upload the file because it's a bit more than 10MB, so here is the link https://www.dropbox.com/s/ajzduvo0ingj5an/chopper%20long%20time%20stability.pdf?dl=0
I wrote a python script to record the frequency value from the lockin amplifier through the serial port.
Sample rate: 1Hz
Acquisition time: 8h
I attach a plot of the entire acquisition (0 - 480min)
and a plot of the first 1000 seconds