Patent Number: 6,801,324

Title: Interferometer control and laser frequency locking

Abstract: This invention provides a method and an optical system for sensing and controlling the frequency for a laser with respect to an optical cavity and for sensing and controlling the length difference of interferometer paths in a two beam interferometer. A misalignment is introduced in the incident laser radiation to produce a fundamental mode (TEM00) in the cavity or interferometer and the reflection of a least one higher order mode (TEM01). A split photodetector (10) allows the interference between these two modes to be measured separately by detecting two spatially distinct portions of the single reflected beam. An error signal indicative of the difference between the fundamental mode frequency and the cavity resonant frequency is obtained by substracting the outputs from the two parts of the photodetector.

Inventors: Gray; Malcolm Bruce (Scullin, AU), Shaddock; Daniel Anthony (Kaleen, AU)

Assignee: The Australian National University

International Classification: G01J 9/00 (20060101); G01S 7/48 (20060101); G01S 7/491 (20060101); G01B 9/02 (20060101); G01J 9/02 (20060101); G01B 009/02 (); H01S 003/13 (); H01S 003/083 ()

Expiration Date: 10/05/2021