The frequency shifter and the optical type displacement measuring device which uses that

摘要

A frequency shifter for modulating the frequency of an incident light beam is disclosed. This frequency shifter includes an electro-optic crystal portion to be arranged at an incident position, an electrode arranged on the electro-optic crystal portion, a voltage application unit for applying a voltage to the electro-optic crystal portion via the electrode, and a unit which is arranged at least at a portion of the electro-optic crystal portion to uniformize the temperature of the electro-optic crystal portion.