Patent ID: 6801324
Filing Date: 2004-10-05
Classification: G01J,G01S

Abstract:
A method for sensing and controlling the frequency of a laser with respect to an optical cavity including the steps of:directing at least part of the laser beam to the optical cavity, introducing a misalignment in incident laser radiation associated with the laser beam to produce substantially only a resonant TEM00 mode and a non-resonant TEM01 mode, producing a single control beam resulting from modal interference of the TEM00 and TEM01 modes and detecting at least two spatially distinct portions of the control beam to produce at least two signals, each of the at least two signals indicative of the respective interference of the two correspondingly spatially distinct portions of the TEM00 mode with two correspondingly spatially distinct portions of the TEM01 mode, and producing an error signal indicative of the difference between the TEM00 mode frequency and the cavity resonance frequency from the two signals.