Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
  • G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
  • G01S17/04—Systems determining the presence of a target
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
  • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
  • G01S7/483—Details of pulse systems
  • G01S7/486—Receivers
  • G01S7/487—Extracting wanted echo signals, e.g. pulse detection

Definitions

• the present invention relates to a method and a device for the detection of magnifying optical systems.
• magnifying optical systems such as riflescopes and eyes
• retroreflective objects such as retro-reflectors of motor vehicles, indicating signs, etc.
• the light spots shown by the images do not necessarily correspond to magnifying optical systems and therefore there is ambiguity as to the detection of the latter.
• the present invention aims to overcome this disadvantage.
• the method for distinguishing at least one magnifying optical system among other objects, capable of retroreflecting the light, being in a scene the method according to which: said scene is illuminated by at least one first laser pulse emitted by a first laser emitter and taking a first image of said scene illuminated by said first pulse by means of a detector observing said scene, said detector and said first laser emitter being at least approximately adjacent transversely to the direction of said scene; said scene is illuminated by at least a second laser pulse emitted by a second laser emitter spaced from said detector transversely to the direction of said scene, said detector being responsive to said second pulse; and - by means of said detector, taking at least a second image of said scene illuminated by said second pulse, is remarkable in that, after comparison of said first and second images, we consider:
• said objects whose images are in the first image of said scene, but are absent from said second image of the latter, are magnifying optical systems.
• the applicant has observed that the retroreflective cone of a magnifying optical system is very narrow (of the order of 0.1 mrad), whereas that of the usual reflex reflectors is much wider (at least equal to 50 mrad). ).
• said second emitter from the detector, it can receive the light emitted by the second emitter and retroreflected by the usual retro-reflectors, but will not see this light retroreflected by a magnifying optical system.
• the transverse difference between the second laser emitter and said detector to benefit from the invention depends on the distance separating the detector and said magnifying optical system, as well as the angle of the retroreflective cone thereof.
• a fixed transversal difference of at least 200 mm, preferably of the order of 400 mm makes it possible to discriminate an optical system from a conventional retro-reflector for distances of between a few meters and several meters. kilometers.
• Said first and second pulses may have the same emission wavelength; they are then shifted temporally from one another. In this case, the time offset between said first and second laser pulses is chosen small enough so that the scene is at least approximately identical in said first and second images.
• said first and second laser pulses are simultaneous and have different emission wavelengths and said detector (comprising, for example, two CCD matrices or two parts of a CCD matrix dedicated respectively to said first and second laser pulses. ) is chosen to deliver two different images respectively corresponding to these two wavelengths.
• these wavelengths are sufficiently close to each other that the backscattering of sunlight by said scene is at least approximately similar in said first and second simultaneous images. It is then advantageous to illuminate said scene by means of a sequence of pairs of laser pulses each comprising a first and a second simultaneous laser pulse, to take successive pairs of images corresponding to said pairs of laser pulses and to successively compare the first image and the second image of each pair of images.
• the present invention further relates to a device for detecting a magnifying optical system in a scene with other objects capable of retroreflecting light, said device comprising a first laser transmitter for illuminating said scene and a detector capable of detecting the light retroreflected by said objects illuminated by said first emitter, said detector and said first laser emitter being at least approximately adjacent transversely to the direction of said scene, and a second laser emitter spaced from said detector transversely to the direction of said scene, said detector being responsive to the emission wavelength of said second emitter.
• Figure 1 schematically illustrates the present invention in the case of a magnifying optical system.
• Figure 2 schematically illustrates the present invention in the case of a conventional retro-reflector.
• a device comprising a first and a second impulse laser emitters E1 and E2 and a detector D, for example of the matrix type (s) CCD.
• the first laser emitter E1 and the detector D are very close to each other and can even form a single physical unit. They are oriented in a direction towards a scene which is distant from the distance L and in which there is an object OP or OR able to retroreflect the light.
• the second laser emitter E2 is located, transversely to the direction d, of a distance x with respect to the detector D.
• the angles of the emission cones of the laser emitters E1 and E2 have been designated by e1 and e2, respectively.
• the retroreflective object OP shown in FIG. 1, is a magnifying optical system, such as an eye, a telescope, etc. Consequently, its retroreflection cone is narrow, with an angle r, for example order of 0.1 mrad.
• the light emitted by the emitter E1 adjacent to the detector D and retroreflected by the magnifying optical system OP into such a narrow retroreflection cone can be received by said detector D.
• the light emitted by the second emitter E2 spaced from the detector D and retroreflected by the magnifying optical system OP in a similar narrow retroreflection cone can not be received by said detector D.
• the detector D can receive only the light emitted by the first emitter E1 adjacent and retroreflected by the magnifying optical system OP.
• the retroreflective object is a conventional retro-reflector OR
• the retroreflective cone of the latter is wide, with an angle R, for example at least equal to 50 mrad.
• the laser emission of the first emitter E1 may consist of a train of first pulses.
• the laser emission of the second emitter E2 may be constituted by a train of second pulses.
• the detector D is able to form first and second images of the scene in which the retroreflective objects OP and OR are located in synchronism with said first and second pulses, respectively.
• both said raw "images formed by said second image detector D comprises image Tobject OR illuminated by said first and second laser pulses, respectively;
• the retroreflective object is a magnifying optical system OP
• only said first images comprise the image of the object OP illuminated by said first laser pulses, said second images not being able to comprise the image of the object OP. illuminated by said second laser pulses.
• Said first and second laser pulses may have the same emission wavelength.
• they are temporally offset and said first and second pulses can form a sequence in which they are entangled, a first laser pulse being interposed between two second pulses and vice versa.
• said first and second laser pulses can be simultaneous, but they then have different emission wavelengths to which said detector D is also sensitive.
• the comparison made by the detector D, a first and a second images respectively corresponding to a first and a second pulse laser, simultaneous or temporally close to each other allows to consider that: - if the first image and the second image both include the image of the retroreflective object, it is a reflex reflector; and
• the first image has the image of the retroreflective object, it is a magnifying optical system.
• L-experiment has shown that the foregoing was verified when the transverse deviation x between the second emitter E2 and the detector D was at least 200 mm and, preferably, of the order of 400 mm.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Electromagnetism (AREA)
• Computer Networks & Wireless Communication (AREA)
• General Physics & Mathematics (AREA)
• Radar, Positioning & Navigation (AREA)
• Remote Sensing (AREA)
• Optical Radar Systems And Details Thereof (AREA)
• Length Measuring Devices By Optical Means (AREA)

Applications Claiming Priority (2)

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• 2007
  • 2007-04-11 FR FR0702630A patent/FR2915001B1/fr not_active Expired - Fee Related
• 2008
  • 2008-04-07 EP EP08787923A patent/EP2140289A2/de not_active Withdrawn
  • 2008-04-07 CA CA002681927A patent/CA2681927A1/fr not_active Abandoned
  • 2008-04-07 US US12/595,218 patent/US20100128992A1/en not_active Abandoned
  • 2008-04-07 RU RU2009141608/28A patent/RU2009141608A/ru not_active Application Discontinuation
  • 2008-04-07 WO PCT/FR2008/000485 patent/WO2008142270A2/fr not_active Ceased
• 2009
  • 2009-09-30 IL IL201265A patent/IL201265A0/en unknown

Non-Patent Citations (1)

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