Jonathan D Berger

US Patent:

7224463, May 29, 2007

Filed:

Jan 5, 2005

Appl. No.:

11/030596

Inventors:

Mark A. Zumberge - San Diego CA, US
Jonathan Berger - San Diego CA, US
Robert L. Parker - San Diego CA, US
Matthew Dzieciuch - La Jolla CA, US

Assignee:

The Regents of the University of California - Oakland CA

International Classification:

G01B 9/02

US Classification:

356450

Abstract:

Techniques and devices for digitally resolving quadrature fringe signals from interferometers such as optical interferometers and interferometer-based sensing devices. In one implementation, two quadrature fringe signals from an interferometer which causes two signals in two signal paths to interfere with each other are sampled to obtain digital data samples from the two quadrature fringe signals. The digital data samples are used to perform a linear least square fitting to establish coefficients for an ellipse traced by the two quadrature fringe signals as a phase difference between the two signal paths changes. A pair of digital data samples are respectively obtained from the two quadrature signals at a given moment and are used to compute a corresponding phase difference between the two signal paths of the interferometer from established coefficients of the ellipse. The coefficient for the ellipse can be updated over time. This digital processing allows for real time processing.

US Patent:

8023116, Sep 20, 2011

Filed:

May 29, 2007

Appl. No.:

11/754963

Inventors:

Mark A. Zumberge - San Diego CA, US
Jonathan Berger - San Diego CA, US
Robert L. Parker - San Diego CA, US
Matthew Dzieciuch - La Jolla CA, US

Assignee:

The Regents of the University of California - Oakland CA

International Classification:

G01B 9/02

US Classification:

356450

Abstract:

Techniques and devices for digitally resolving quadrature fringe signals from interferometers such as optical interferometers and interferometer-based sensing devices. In one implementation, two quadrature fringe signals from an interferometer which causes two signals in two signal paths to interfere with each other are sampled to obtain digital data samples from the two quadrature fringe signals. The digital data samples are used to perform a linear least square fitting to establish coefficients for an ellipse traced by the two quadrature fringe signals as a phase difference between the two signal paths changes. A pair of digital data samples are respectively obtained from the two quadrature signals at a given moment and are used to compute a corresponding phase difference between the two signal paths of the interferometer from established coefficients of the ellipse. The coefficient for the ellipse can be updated over time. This digital processing allows for real time processing.

US Patent:

20120247213, Oct 4, 2012

Filed:

Apr 2, 2012

Appl. No.:

13/437901

Inventors:

Mark A. Zumberge - San Diego CA, US
Jonathan Berger - San Diego CA, US
Erhard Wielandt - Kirchheim, DE

International Classification:

G01V 1/52
G01H 9/00

US Classification:

73653, 73652

Abstract:

Methods, structures, devices and systems are disclosed for implementing optical seismometers that detect seismic information based on optical interferometry. In one aspect, a device includes a first retroreflector attached to a mass of a seismometer, a second retroreflector attached to a member of a frame of the seismometer, the frame structured to suspend the mass, and optical components attached to the member of the frame and configured with the first and second retroreflectors to form an interferometer, in which a change in position of the mass is identified by detecting by a change in an optical path of a light beam generated by a light energy source transmitted to the interferometer.

US Patent:

6788417, Sep 7, 2004

Filed:

Apr 30, 1999

Appl. No.:

09/303331

Inventors:

Mark Zumberge - San Diego CA
Jonathan Berger - San Diego CA

Assignee:

The Regents of the University of California - Oakland CA

International Classification:

G01B 902

US Classification:

356477, 385 12, 385 13

Abstract:

Infrasound signals in the band 0. 02 to 4 Hz are sensed in the presence of ambient noise generated chiefly by wind as integrated pressure variations, which induce detectable changes in the optical path length, along optic fibers, typically extending 100 m. to 1000 m. and more, arrayed at arbitrary geometries. Two fibers connected as a Michelson, Mach-Zehnder or equivalent interferometer where (i) one fiber is coupled to atmosphere while (ii) the other is not for being hermetically sealed in a tube, permit common mode rejection of noise from (i) temperature changes and (ii) strain, including ground vibration. Because the optic fiber infrasound sensors are longer than the distance over which wind-induced pressure changes are coherent, the effects of wind noise on the sensing of infrasound is reduced, and signal-to-noise ratio is increased over a wide bandwidth.