US 10,473,787 B2Granted

Target rotation determination by speckle motion characterization

AssigneeRaytheon Company

InventorMaurice J. Halmos

Life of this patent

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Abstract

Systems and corresponding methods for use in measuring rotation characteristics (e.g., rotation magnitude and direction) of remote targets are provided. A laser light of a known frequency is incident upon the target and reflected. A portion of the reflected laser light is directed to detector field of view, where it is measured and analyzed. The detector field of view is divided into multiple segments, each capable of independently measuring the intensity of laser light incident thereon as a function of time. The linear rotation of the target may be determined from cross-correlation of the light intensity-time response measured at orthogonal pairs of detector halves arranged from combinations of the detector segments. The angular rotation of the target is further determined from this linear rotation.

Claims18

Dependent claims

A method of remotely measuring rotation of a target, comprising:

transmitting a coherent light beam;
measuring, at a receiver including a detector having a field of view divided into at least four spatially distinct light sensing segments, coherent light of the coherent light beam reflected from a target incident upon the detector field of view, the incident coherent light including a speckle pattern that moves over time with respect to the detector field of view;
outputting, by the detector, a plurality of signals to one or more processors, each signal representing an intensity of the reflected light received at a respective detector segment as a function of time;
and
determining, by the one or more processors:
a first intensity as a function of time for reflected light received at a first half of the detector;
a second intensity as a function of time for reflected light received at a second half of the detector corresponding to the second half, the first and second halves of the detector separated along a first detector axis of division;
a third intensity as a function of time for reflected light received at a third half of the detector;
a fourth intensity as a function of time for reflected light received at a fourth half of the detector corresponding to the third half, the third and fourth halves of the detector separated along a second detector axis of division oriented orthogonal to the first detector axis of division;
measuring, by the one or more processors, a first time delay representing a time for the speckle pattern to move between the first and second detector halves;
measuring, by the one or more processors, a second time delay representing a time for the speckle pattern to move between the third and fourth detector halves;
calculating, by the one or more processors, a linear velocity of the target, V, as the sum of:
a first vector aligned perpendicular to the first detector axis of division and having a magnitude given by the measured first time delay;
and
a second vector aligned perpendicular to the second detector axis of division and having a magnitude given by the measured second time delay.

12 more elements

A detection system for measuring rotation of a target, comprising:

a light source for transmitting a coherent light beam;
a detector including a field of view divided into at least four spatially distinct light sensing elements, the detector adapted to:
measure coherent light of the coherent light beam reflected from a target incident upon the detector field of view, wherein the incident coherent light includes a speckle pattern that moves over time with respect to the detector field of view;
and
output a plurality of signals, each signal representing an intensity of the reflected light received at a respective detector segment as a function of time;
one or more processors in communication with the detector, the one or more processors adapted to:
receive the plurality of signals;
determine a first intensity as a function of time for reflected light received at a first half of the detector;
determine a second intensity as a function of time for reflected light received at a second half of the detector corresponding to the second half, the first and second halves of the detector separated along a first detector axis of division;
determine a third intensity as a function of time for reflected light received at a third half of the detector;
determine a fourth intensity as a function of time for reflected light received at a fourth half of the detector corresponding to the third half, the third and fourth halves of the detector separated along a second detector axis of division oriented orthogonal to the first detector axis of division;
measure a first time delay representing a time for the speckle pattern to move between the first and second detector halves;
measure a second time delay representing a time for the speckle pattern to move between the third and fourth detector halves;
calculate a linear velocity of the target, V, as, as the sum of:
a first vector aligned perpendicular to the first detector axis of division and having a magnitude given by the measured first time delay;
and
a second vector aligned perpendicular to the second detector axis of division and having a magnitude given by the measured second time delay.

14 more elements

A non-transitory computer-readable medium having computer-readable program codes embedded thereon including instructions that, when executed by the one or more processors, cause the one or more processors to:

receive a plurality of signals output from respective segments of a detector including at least four spatially distinct light sensing segments, each signal representing an intensity of coherent light transmitted from a light source and reflected from a target and received at the respective detector segment as a function of time, wherein the received light includes a speckle pattern that moves over time with respect to the detector field of view;
determine a first intensity as a function of time for reflected light received at a first half of the detector;
determine a second intensity as a function of time for reflected light received at a second half of the detector corresponding to the second half, the first and second halves of the detector separated along a first detector axis of division;
determine a third intensity as a function of time for reflected light received at a third half of the detector;
determine a fourth intensity as a function of time for reflected light received at a fourth half of the detector corresponding to the third half, the third and fourth halves of the detector separated along a second detector axis of division oriented orthogonal to the first detector axis of division;
measure a first time delay representing a time for the speckle pattern to move between the first and second detector halves;
measure a second time delay representing a time for the speckle pattern to move between the third and fourth detector halves;
calculate a linear velocity of the target, V, as, as the sum of:
a first vector aligned perpendicular to the first detector axis of division and having a magnitude given by the measured first time delay;
and
a second vector aligned perpendicular to the second detector axis of division and having a magnitude given by the measured second time delay.

8 more elements

Dependencies are inferred from the claim text.

Facts

Application: 14/451,038Filed 4 Aug 2014 · continuation
Published: US 2016/0033645 A14 Feb 2016
Granted: 12 Nov 2019
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

G01S 17/58
Systems of measurement based on relative movement of target: velocity or trajectory determination systems; Sense-of-movement determination systems
G01S 7/4802
Of systems according to group G01S17/00: using analysis of echo signal for target characterisation; Target signature; Target cross-section
G01S 7/4808
Of systems according to group G01S17/00: evaluating distance, position or velocity data
G01S 17/50
Systems using the reflection of electromagnetic waves other than radio waves: systems of measurement based on relative movement of target

Family

Application14/450,888Parent of this continuation · filed 4 Aug 2014
US 2016/0033646 A1Pre-grant publication · published 4 Feb 2016
US 9,726,761 B2Parent of this continuation
US 2016/0033645 A1Published application
US 10,473,787 B2This patent

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