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 Parameter Description Default Value Lock-in Amplifier Visa Lock-in Amplifier GPIB address GPIB0::8::INSTR Sensitivity Lock-in Amplifier Sensitivity 100 uV / -67 dBm Time Constant Lock-in Amplifier Time Constant 10 ms No. Averaging Points Number of points used to find the peak value 5 Variation Limit Maximum variation from the nominal value 1.00 dBm PC Voltage Maximum voltage applied to the polarization controllers during the optimization process. 3.0 V Voltage Steps Voltage steps applied to the polarization controllers during the optimization process 0.01 V Wait Time Interval delay time 1000 ms Table 3.1: Default values for the main parameters used in the optimization process. <p> â If the optical signal is low, check to make sure:
⢠The probe and the crystal on its tip is fine.
⢠The operating frequency is correct.
⢠CPW is functioning properly.
⢠Lower the probe down close to the surface of CPW and make sure the probe positions right above the CPW slot and move it around the slot.
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==== Probe Optimization ====
3.3 Probe Optimization
The [[NeoScan]] software monitors and controls the polarization of the optical beam in the system. The optimization status for each probe at each channel needs be maintained for an extended period of time. Not only an initial optimization process for each probe at each channel is needed, but also additional optimization processes are needed if the status is not maintained. In general, you have to perform optimization whenever you detach the fiber connectors from the fiber ports of the [[NeoScan]] system or when the fluctuation in the total return optical power and the polarization power are varied more than 20%. After the optimization procedure, the system is ready for real-time measurement or scan.