Anoiher signal with 90 degree delay is obtained by phase shift circuit. The accurate and stable circle counting is done by a reversible counter.

The low-voltage driving circuit is adopted to drive a piezoelectric ceramic phase shifter to shift the phase of the reference beam, so as to make the instrument lighter, smaller and cheaper.

This article introduces the characteristics of stabilized arc circuit, sync shift-phase circuit, trigger circuit and control circuit, also illuminates each unit circuit.