Bots, Bureaucrats, Interface administrators, Suppressors, Administrators, Upload Wizard campaign editors
573
edits
David Notebook: Difference between revisions
Jump to navigation
Jump to search
→Daily Log
No edit summary |
|||
|
==Daily Log==
'''7/18/14'''
The value that the lock-in displays is actually slightly different from what it outputs. When viewing the signal on an oscilloscope, the mean voltage better matches what I would have expected yesterday (about 8.6 V for a 2 V peak to peak square wave--closer to the 9.0 V it should be than what the screen shows). Looking at the output of the function generator on another oscilloscope revealed that the output is slightly noisy--this might account for the difference in the expected and measured values. I'm going to just assume that the lock-in is operating on square waves according to the formula from yesterday. It's certainly close.
'''7/17/14'''
I'm trying to calibrate the chopper/lock-in system to get better measurements of the 633 power and make sure our conversion efficiency numbers are accurate. I cut the power of the HeNe beam with irises to 20 nW as measured on the power meter (filters might have been better so that the intensity is reduced too, but I couldn't find a good combination to get the power I wanted. It probably won't matter since there is a lens in front of the photodiode anyway). However using the lock-in and my previous procedure to convert photodiode signals to power, I calculated only 1.25 nW.
| |||