| 摘要 |
PURPOSE:To eliminate the need for phase compensation by giving a sin (GAMMAt) signal a saw-tooth phase shift, detecting GAMMAt which is a component of its interference light with a sin GAMMAt ana a cos (GAMMAt) signal synchronously, and summing their squares and extracting the square root. CONSTITUTION:The sin GAMMAt generated by an oscillator 13 is shifted in phase in a sine-wave shape by a saw-tooth wave generating circuit 12 so as to increase in phase continuously from 0 to 2mpi while its period is 2pi/(mGAMMA). A phase modulator 11 increases the phase at a rate GAMMAt and resets the phase to 0 when t=2pi/(mGAMMA). Them interference light contains a component GAMMAt. This is detected synchronously by synchronization detecting circuits 15 and 16 with the sin GAMMAand cos GAMMAt signals. Those synchronously detected signals are squared by squaring circuits 17 and 18 and added by an adding circuit 19 and a square root arithmetic circuit 20 extracts the square root.
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