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FMCG/Data Acquisition with LabVIEW Software: Difference between revisions
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FMCG/Data Acquisition with LabVIEW Software (view source)
Revision as of 20:49, 26 August 2016
, 26 August 2016→Z-mode
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The setup and data acquisition for Z-mode is a little more involved, though not terribly so. Generally I do all of my field nulling and optimization in DC-SERF mode. Only small adjustments are then required to get Z-mode up and running. The process is aided by a "test" LabVIEW VI which allows one to play with the Z-mode parameters to optimize. All of the following will assume the magnetometer(s) are properly nulled and the laser powers and detunings are optimized.
# Since Z-mode will involve applying a 1 kHz modulation to the atoms, and then using the LabVIEW code to demodulate that signal, it's necessary that there not be any low pass filters below 1 kHz between the photodiodes and the input to the ADC on the FPGA. It's likely that a ~300 Hz low pass filter was applied to data being taken. Make sure to either move this filter up in frequency (10 kHz recommended for a 1 kHz modulation frequency) or disable it completely.
# Because the Z-mode modulation is quite large, it is necessary to reduce the output resistors on the shell coils. Using the 500 Ω resistors is sufficient for 1 kHz modulation, 2 kHz and above will likely require using the 100 Ω resistors. Remember that to maintain the correct field coupling, all channels should be adjusted to use the same Z output resistors.
# In order to allow the modulation to be sent to the current supplies, the '''Z-mode''' switch on the front of the main control box must be switched to '''ON'''.
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