Optical Mode Tuning; Figure 8-5. Warmup Mode Timing Diagram; Figure 8-6. Feedback Loop During Optical Mode - HP 5501B Operating And Service Manual

8-34. Optical Mode Tuning

8-35. In optical mode, the state machine switches the subtracting sample and hold inputs from
warmup feedback to optical feedback as shown in Figure 8-6. The optical mode feedback
controls the laser cavity length by measuring and comparing the power of the two laser
frequency components. Cavity length is controlled such that the difference in power is zero.
When the difference is maintained at zero, the desired characteristics of the laser beam are
established and a measurement can be performed.

Figure 8-5. Warmup Mode Timing Diagram

Figure 8-6. Feedback Loop During Optical Mode

HP5501B
Service
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