US 2017/0285063 A1Published application

Method for simultaneous observation of three degrees of vibrational freedom using single heterodyne beam

AssigneeThe United States of America as represented by the Secretary of the Army

InventorsBradley W. Libbey, James D. Perea

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Abstract

A laboratory system has demonstrated the measurement of three degrees of vibrational freedom simultaneously using a single beam through heterodyne speckle imaging. The random interference pattern generated by the illumination of a rough surface with coherent light can be exploited to extract information about the surface motion. The optical speckle pattern is heterodyne mixed with a coherent reference. The recorded optical data is then processed to extract three dimensions of surface motion. Axial velocity is measured by demodulating the received time-varying intensity of high amplitude pixels. Tilt, a gradient of surface velocity, is calculated by measuring speckle translation following reconstruction of the speckle pattern from the mixed signal.

Claims10

Dependent claims

A signal processing method for computing on a computer three-degrees of vibrational freedom using a heterodyne beam, the signal processing method comprising the steps of:

accessing a complete measurement of temporal spatial irradiance data obtained using a heterodyne beam as stored as pixel frames of image data on the computer;
high-pass filtering each pixel independently to isolate heterodyne signal from the complete measurement to output heterodyne information at a local oscillator frequency ωLO;
applying a computation process for sequential estimates of a detected probe speckle pattern amplitude to compute two dimensions of tilt based on time sequences;
applying a parallel demodulation process based on an arctangent demodulation for Doppler shifted heterodyne signals applied to each pixel to calculate z-axis velocity;
and
displaying a representation of the computed tilt based on time sequences and the calculated z-axis velocity on a data display device.

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Dependencies are inferred from the claim text.

Facts

Application: 15/485,261Filed 12 Apr 2017
Priority: 1 Apr 2016
Published: 5 Oct 2017
Term ends: Not estimatedThe source records don’t support an estimate.

Classification11 codes

G01P 3/36
Measuring linear or angular speed; Measuring differences of linear or angular speeds: devices characterised by the use of optical means, e.g.…
G01H 9/00
Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive
G01H 9/002
Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means: for representing…
G01N 21/1702
Systems in which incident light is modified in accordance with the properties of the material investigated: with opto-acoustic detection, e.g. for…

Family

Application15/088,201Division · filed 1 Apr 2016
Application15/485,261Division
US 9,651,477 B1Related patent
US 9,995,761 B2Related patent
US 2017/0285063 A1This patent

From the US filing history. Foreign family members aren’t listed.

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