Frequency shifter and optical displacement measuring apparatus using the same

摘要

A frequency shifter is capable of controlling the adverse influences of electric noise caused by the voltage applied to electrooptical elements of a frequency shifter. The frequency shifter modulates the phase of the luminous flux entering the electrooptical elements by applying a voltage to the electrooptical elements; the shifter is provided with a shield for electrically shielding the circuit for generating the voltage to be applied to the electrooptical elements and the electrooptical elements from an external circuit.