Low noise, high bandwidth, high sensitivity laser seismometer

US10247850B1 · kind B1 · utility

Assignee

• Triad National Security, LLC · US

Inventors

• Stephen Judd · Los Alamos, US
• Gerald J. Seitz · El Rancho, US
• Michael Shinas · Los Alamos, US
• Matthew Briggs · Los Alamos, US

Key dates

• Filing date: Sep 20, 2017
• Grant date: Apr 2, 2019
• Expiry date: Sep 20, 2037

Classification

• Technology area (CPC G): Physics
• CPC primary: G01H9/004
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A laser seismometer may measure the change in a phase modulated optical signal. Unlike traditional interferometers, the laser phase is first modulated by a radio frequency (RF) source, which is then demodulated following detection to provide the signal of interest. The net result is a direct measurement of displacement with the effects of amplitude noise eliminated via limiting and the effects of 1/f phase noise (frequency drift, etc.) eliminated by self-interfering the signal. Because the signal-to-noise ratio (SNR) of the optical signal is strong, the technique provides a strong measure of the displacement and avoids the extremely low voltages and associated problems of traditional sensors.