Laser translator of standard frequency to submillimeter range

A description is given of a system for automatic phase control (APC) of the HCN laser frequency relative to a reference signal. This system reproduces signals whose nominal frequencies are 890 760.0, 74 232.5, and 8 247.5 MHz. The frequency instability of the system does not exceed 10^–12 in a period of 10 sec. The APC circuit is described and its choice is justified.