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David Notebook: Difference between revisions
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==Daily Log==
'''9/24/14'''
I've continued to have 1555 diode problems. Threshold tests were showing many small peaks of similar power. These individual peaks were generally single mode, but as I increased the current it went multi-mode well before reaching operating power. Deniz thought this was indicative of a failing diode, although Josh says this is consistent with the normal behavior he's observed (but that maybe it has never been working correctly). I tried re-collimating the laser and also moving the diode in the housing and re-tuning the grating and collimation. Neither of these procedures helped.
I decided today to change the diode before spending more time with a possibly bad diode. I was using the soldering iron at only 500 degrees to avoid possibly damaging the diode from heat, but this made it very difficult to solder a good joint. Eventually I changed to 550 and the process was easy and didn't seem to heat up the diode too much. The new diode works, although I haven't looked at its behavior closely yet. It might be worth trying to change the polarization since this can affect how much feedback goes to the diode and maybe would improve performance.
'''9/16/14'''
After looking at the power meters, the visible one definitely does not read 1064 nm accurately. The short story is that its values should be multiplied by 0.62. Graphs are [https://wiki.physics.wisc.edu/yavuz/images/6/64/Adjusted_Power_Meter_Response.png here] and [https://wiki.physics.wisc.edu/yavuz/images/3/3d/Power_Meter_Response.png here], full data is [https://wiki.physics.wisc.edu/yavuz/images/6/6c/Power_Meter_Comparison_at_1064_nm_modified.xlsx here]. This makes the theory agree better with the experimental data, although the experiment is still low.
I've been continuing to work on the 1555 laser. The power has been dropping low enough that it sometimes turns the amplifier off, so I finally just re-
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