Product info here User manual here Interface manual here Software here Brain dump: - Most of the bias control parameters can be found in the additional info above.
- The MBC provides the bias needed to operate the EOM at the zero-point such that any applied voltage from the AWG translates to intensity-modulated output.
- In order to detect where the appropriate operating point should be, the MBC applies a dither to the voltage output and monitors the drifts in the necessary voltage set-point. This is a MASSIVE problem because the dither clock is NOT locked to the house clock. This means that when the actual pulses are triggered, the EOM is likely NOT operating at the necessary voltage set-point because it is being constantly driven AWAY from that setpoint by the dither. The dither frequency and voltage can be controlled directly by the manufacturer's software, but it has its problems (the available settings range for voltage and frequency is limited, and we had issues with the software being able to run at all unless the OS's default numbering protocol was set to European style with a comma representing a decimal rather than a point), and these settings aren't accessible from the IOC.
- As a result, shaping performance is very unstable and unpredictable UNLESS the bias dither is turned OFF for any high-consequence activities such as recipe creation/shaping and on-target (user) shots. For the short term, disabling the bias dither should not cause any degradation in performance – the drift being monitored by the dither generally takes place on the time scales of tens of minutes or hours. The dither can be turned off by switching from AUTO to MAN(ual) voltage control in the IOC.
- HOWEVER, re-engaging the dither causes the voltage output to be scanned across the full output range of -10V to +10V. If CW light is seeded into the amplifiers, then high-energy microsecond pulses can be output that can damage the serrated aperture at the output of the YFE or other optics. As such, the currents of the YFE heads need to be turned down before the MBC is switched back from MAN to AUTO. The shaping code should do this automatically if controlling the MBC from there; if controlling it from the IOC directly, exercise caution!
- Upgrade ideas:
- Solve the dither problem – either get it locked to the house clock or get rid of it completely!!
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