Active phase locking of radiations from argon ion lasers

An active automatic electronic control system, based on a beat signal, was used in phase locking of two Ar⁺ lasers with an error not exceeding 0.1 rad. An intracavity electro-optical modulator and a phase detector with a dynamic range ±2π rad ensured reliable operation of the laser system in the beat signal frequency range 1–15 MHz.