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David Notebook: Difference between revisions
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==Daily Log==
'''8/11/14'''
Using the regression equation from the data for the PDA36A, and accounting for the 16% higher power 633 nm light should have from the sensitivity differences, P=1.77V with power in nW and the lock-in set at 5 mV and the photodiode at 60 dB gain. I was getting chopped powers of about 1 nW today which is lower than what I calculated using the previous photodiodes. The 633 light seems noticeable brighter to me though. I'm not sure which is the best measurement--all the methods seem somewhat inconsistent.
'''8/10/14'''
Running more tests with the PDA36A. I checked it from 5 to 100 nW as measured on the power meter (again though, I'm not very confident in it's measurements at the nW level--lots of fluctuations and hard to get 0 offset) and found the response to be logarithmic when the gain was set to 0 dB as I was using it on 8/8/14. I don't think this will work unless I can more accurately measure nW level beams with the power meter and then make a good regression equation for a logarithmic response. I then repeated these measurements with the gain at 60 dB and found the response to be much more linear. Data is [https://wiki.physics.wisc.edu/yavuz/images/2/29/Thorlabs_pda36a_response.xlsx here]. Maybe I can find the best gain setting that gives the most linear response at these powers and get a good linear fit at slightly higher beam powers and extrapolate to the single nW level even though I can't measure those powers well with the power meter.
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