Roe J Maier

US Patent:

42849640, Aug 18, 1981

Filed:

May 4, 1979

Appl. No.:

6/036252

Inventors:

Roe J. Maier - Bosque Farms NM

Assignee:

The United States of America as represented by the Secretary of the Air
Force - Washington DC

International Classification:

H01S 310

US Classification:

331 945S

Abstract:

An apparatus utilizing a resonant laser cavity to create two modes of oscillation and lock the operation of the cavity onto the mode pair. The cavity pathlength is adjusted using a feedback loop which detects the beat frequency of the pair of modes and tracks a feedback signal which is functionally proportional to the product of the square root of the mode intensities. In one variation beat frequency pulses are accumulated for a period determined by a time reference which is more accurate than the frequency gap between adjacent pairs of modes, but is less accurate than the precision to which the individual modes are known once the specific pair is designated. The exact frequency of each mode is known a priori from its wavelength to the sharpness of the atomic line. In this manner, a time reference of nominal accuracy may be used to designate the pair of modes present in the laser cavity, and in doing so, simultaneously designates their frequency to a high degree of accuracy. If laser operation is interrupted after calibration, the apparatus can ascertain the new mode frequencies and compute a compensating correction factor.