Methods and systems for flash detection

Patent metadata

Field	Value
Publication number	US-2016178433-A1
Application number	US-201514976215-A
Country	US
Kind code	A1
Filing date	Dec 21, 2015
Priority date	Dec 21, 2014
Publication date	Jun 23, 2016
Grant date	—

Abstract

The present disclosure provides an optical system suitable for detecting muzzle flashes in a scene, the optical system comprising: a first optical module customized for detecting flashes at short range of the optical system by analyzing irradiance received on a first infrared sensor; a second optical module customized for detecting flashes at long range of the optical system by analyzing irradiance received on a second infrared sensor; wherein: the first and second optical modules are configured to share a common field of view and to operate independently of each other.

First claim

1 - 30 . (canceled)

31 . An optical system suitable for detecting muzzle flashes in a scene, the optical system comprising:
a first optical module customized for detecting flashes at short range of the optical system by analyzing irradiance received on a first infrared sensor; a second optical module customized for detecting flashes at long range of the optical system by analyzing irradiance received on a second infrared sensor;
wherein:
the first and second optical modules are configured to share a common field of view.

32 . The optical system according to claim 31 , wherein the first and second optical modules are configured so that a first maximum detection distance at which a predetermined flash is sensed by the first infrared sensor with a predetermined marginal signal to noise ratio is significantly inferior to a second maximum detection distance at which the predetermined flash is sensed by the second infrared sensor with the predetermined marginal signal to noise ratio.

33 . The optical system according to claim 31 , wherein the first and second optical modules are configured so that the first maximum detection distance is superior to a minimum detection distance of the second optical module at which the predetermined flash saturates the second infrared sensor.

34 . The optical system according to claim 31 , wherein an instantaneous field of view of the first optical sensor is significantly superior to an instantaneous field of view of the second optical sensor.

35 . The optical system according to claim 31 , wherein a sampling rate of the first infrared sensor is significantly superior to a sampling rate of the second infrared sensor.

36 . The optical system according to claim 31 , wherein the first and second optical modules are configured so that the first and second optical modules exclusively operate concurrently.

37 . The optical system according to claim 31 , wherein the first and second optical modules both output detection results to an output module.

38 . The optical system according to claim 37 , wherein the output module is configured to:
discard the detection results of the second module for flash detection when the second infrared sensor is saturated by a flash occurring at short range of the optical system; discard the detection results of the first module for flash detection when the signal to noise ratio of a signal produced by the first infrared sensor in response to a flash occurring at long range of the optical system is below a predetermined threshold; and combine the detection results of the first and second modules for flash detection when a flash occurs at an overlapping range of detection of the first and second module so that a signal to noise ratio of the first module is above the predetermined threshold and the second infrared sensor is not saturated.

39 . The optical system according to claim 31 , wherein the first and/or second optical modules are configured for detecting flashes using one or more power threshold detection algorithms.

40 . The optical system according to claim 39 , wherein the one or more power threshold detection algorithms comprises either an absolute threshold detection or a adaptive average threshold detection.

41 . The optical system according to claim 31 , wherein the first optical module is configured for detecting flashes using one or more temporal pattern matching algorithm.

42 . The optical system according to claim 41 , wherein the one or more temporal pattern matching algorithms comprise correlating pre-stored target patterns to a signal produced by the first infrared sensor in response to infrared illumination.

43 . The optical system according to claim 41 , wherein the one or more temporal pattern matching algorithms comprise detecting a pulse shape in a signal produced by the first infrared sensor in response to infrared illumination and comparing a length of the detected pulse shape with a predetermined pulse length range.

44 . The optical system according to claim 31 , the first optical module and/or the second optical module are further configured to provide multi-spectral sensing of the common field of view and wherein said first and/or second optical modules are configured for detecting flashes using one or more spectral ratio algorithms.

45 . The optical system according to claim 44 , wherein the one or more spectral ratio algorithms comprise comparing an irradiance distribution received from one or more portions of the common field of view in several wavebands with pre-stored target irradiance distributions.

46 . The optical system according to claim 31 , the first infrared sensor and/or the second infrared sensor comprising a focal plane array and wherein said first and/or second optical modules are configured for discarding flashes based on a spatial extent of a flash on the focal plane array.

47 . The optical system according to claim 46 , wherein the second optical module is configured to discard flashes spanning over more than a predetermined number of adjacent pixels of the focal plane array.

48 . The optical system according to claim 31 , wherein the first infrared sensor is a first focal plane array and the first optical module further comprises first imaging optics to form an image on the first focal plane array of the common field of view.

49 . The optical system according to claim 31 , wherein the second infrared sensor is a second focal plane array and the second optical module further comprises second imaging optics to form an image on the second focal plane array of the common field of view.

50 . The optical system according to claim 31 , wherein the second infrared sensor comprises a two dimensional array of isolated sensors arranged in an insect eye configuration wherein each said sensor is associated with a collecting non imaging optics.

Assignees

• Elta Systems Ltd

Inventors

• Aphek Ori

Classifications

• G01J1/44

  Electric circuits {(for command of an exposure part G03B7/02)} · CPC title

• G01J1/4228 Primary

  arrangements with two or more detectors, e.g. for sensitivity compensation · CPC title

• G01J1/1626 Primary

  Arrangements with two photodetectors, the signals of which are compared · CPC title

• G01S3/784

  using a mosaic of detectors · CPC title

• G01J2003/2826

  Multispectral imaging, e.g. filter imaging · CPC title