Laser light length control assembly for ring laser gyro

A device for translationally shifting a mirror surface of a mirror of a ring laser gyro for controlling its path length, comprising:

• a diaphragm assembly carrying the mirror surface and having a centrally disposed solid portion, an outer wall substantially surrounding said solid portion and coaxial therewith, and a chamber between said solid portion and said outer wall, said solid portion extending axially from said mirror surface and having a transverse surface coextensive therewith, said diaphragm assembly also including, on opposite sides, a pair of thin diaphragm sections connecting said solid portion to said outer wall and, in an unactuated state of said diaphragm assembly, lying in respective transverse planes parallel to said mirror surface;
• and
• actuator means engaging said diaphragm assembly at an end thereof opposite said mirror surface and in an area of contact substantially centered with respect to said solid portion for transmitting a translational force thereto shift said mirror surface, wherein
• said diaphragm assembly comprises of pair of diaphragm members substantially identical structurally, each of said diaphragm members including one of said diaphragm sections, a solid case and a peripheral wall substantially surrounding said core and coaxial therewith, said diaphragm members being attached to one another at a joint disposed substantially midway between said diaphragm sections to minimize bending stress on said joint, and wherein
• said joint lies in a plane extending parallel to said mirror surface, and wherein
• said solid portion is cylindrical and said diaphragm sections are annular, and wherein
• said actuator means includes a support structure attached to said outer wall, said support structure having a carrier member disposed in a plane parallel to said mirror surface, said actuator means further including a pair of piezoelectric discs attached to said carrier member on opposite sides thereof, and wherein
• said carrier member is in the form of a disc with perforations therein and has, for deflection in a direction perpendicular to said mirror surface, a spring constant with a magnitude predetermined by said perforations.