Heterodyne frequency offset locking of a miniature TEA laser

A novel heterodyne frequency offset locking technique is described which is applicable to a broad range of pulsed or CW lasers. The technique is based on the use of a 'cosine discriminator'. Offset locking of a pulsed TEA CO2 laser to a CW CO2 laser is demonstrated with an accuracy of <+or-500 kHz for long periods. Lock frequency is independent of signal level over a wide range. Extensive RF measurements of the discriminator characteristics are presente