Frequency stabilization of an internal mirror He–Ne laser by digital control

A simple digital control system has been developed for the frequency stabilization of an internal mirror He–Ne laser. The system is based on a microcontroller with embedded BASIC interpreter and various functions such as analog and digital input/output. The new control system is very compact and totally digital. The output frequencies of two lasers have been stabilized using two-mode power-balance and beat frequency offset locking techniques in a transverse magnetic field. Their frequency stabilities for 1 s average are 7.2×10−11 and 4.0×10−10, respectively.