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