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Entry  Wed Dec 11 15:53:48 2019, Aidan, Chris, Raymond, Howto, Cryo vacuum chamber, Procedure to record photodiode output vs temperature 
    Reply  Wed Dec 11 19:50:25 2019, rana, Howto, Cryo vacuum chamber, Procedure to record photodiode output vs temperature 
Message ID: 2476     Entry time: Wed Dec 11 15:53:48 2019     Reply to this: 2477
Author: Aidan, Chris, Raymond 
Type: Howto 
Category: Cryo vacuum chamber 
Subject: Procedure to record photodiode output vs temperature 

[Aidan, Chris, Ray]

  1. Add LN2 to cryo-chamber
  2. Turn on heater to 25W
  3. Wait for LN2 to boil off
  4. Turn on the REFPD bias switch, and enable a 200 mV bias on the JPL PD (set C4:TST-FM13_OFFSET to 200)
  5. Switch the readout to the transimpedance amplifier (relay control output from C4:TST-FM15 at 30k ct)
  6. Turn on the laser
    1. Power up the LDC201C and set it for half-power output (50 mA), with the modulation output from C4:TST-FM12 at zero
    2. Set C4:TST-FM12_OFFSET to 1 to go up to full power
  7. Monitor the PD output on oscilloscope and adjust horizontal and vertical alignment of laser beam so that the output of the PD is maximized (also adjust TIA gain if needed so the output is not saturated)
  8. Switch the readout to the Keithley (relay control output from C4:TST-FM15 at zero)
  9. Record bright PD response
    1. Turn on laser (set C4:TST-FM12_OFFSET to 1)
    2. Scan bias voltage and record the PD response using the source meter (scripts are located in $HOME/JPL_PD/scripts on qil-ws1)
      1. ./runsweep.py triggers the Keithley to sweep the bias (range of sweep is defined in the script)
      2. ./getdata.py FILENAME downloads data from the Keithley and writes it to FILENAME
    3. Record REF PD reading
    4. Record RTD resistance
  10. Record dark PD response
    1. Turn off laser (set C4:TST-FM12_OFFSET to -1)
    2. Repeat steps 9-2 through 9-4
  11. Switch the readout to the transimpedance amplifier (relay control output from C4:TST-FM15 at 30k ct)
  12. Measure dark noise vs bias (using either the SR785 or the cymac, TBD)
  13. Wait two minutes and repeat steps 6 through 12 (there is a script ./autorun.sh which continuously repeats steps 9 and 10)
  14. Continue until RTD reaches room temperature (approximately 60-90 minutes).
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