EP2095152A1 - Method and device for detecting an object that can retroreflect light - Google Patents

Method and device for detecting an object that can retroreflect light

Info

Publication number
EP2095152A1
EP2095152A1 EP07870323A EP07870323A EP2095152A1 EP 2095152 A1 EP2095152 A1 EP 2095152A1 EP 07870323 A EP07870323 A EP 07870323A EP 07870323 A EP07870323 A EP 07870323A EP 2095152 A1 EP2095152 A1 EP 2095152A1
Authority
EP
European Patent Office
Prior art keywords
image
wavelength
scene
detection means
detection
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP07870323A
Other languages
German (de)
French (fr)
Inventor
Jean-Louis Duvent
Jean Yves Thomas
Pierre Morin
Bernard Robic
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Compagnie Industriel des Lasers CILAS SA
Original Assignee
Compagnie Industriel des Lasers CILAS SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Compagnie Industriel des Lasers CILAS SA filed Critical Compagnie Industriel des Lasers CILAS SA
Publication of EP2095152A1 publication Critical patent/EP2095152A1/en
Ceased legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F41—WEAPONS
    • F41G—WEAPON SIGHTS; AIMING
    • F41G3/00—Aiming or laying means
    • F41G3/14—Indirect aiming means
    • F41G3/147—Indirect aiming means based on detection of a firing weapon
    • 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
    • G01S7/4876—Extracting wanted echo signals, e.g. pulse detection by removing unwanted signals
    • 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
    • G01S17/88—Lidar systems specially adapted for specific applications
    • G01S17/89—Lidar systems specially adapted for specific applications for mapping or imaging

Definitions

  • the present invention relates to a method and a device for detecting an object capable of retroreflecting light. Although not exclusively, it is particularly suitable for the detection of magnifying optics (including the eye) which exhibit retroreflective properties under the so-called "cat eye effect" principle.
  • the detection of said retro-reflective object is done by comparing an image acquired during illumination by the laser signal and an image acquired out of such illumination, so as to remove the background scene. and displaying the laser echo from the retroreflection by said object.
  • This known technique has the disadvantage of generating false alarms from variations in the scene between the shots of the two images, even if the time interval between them is small. Such variations may be due to movements specific to sensors, to movements of objects in the scene, to a flickering effect of sun reflections, etc ...
  • this prior art is unusable when a movement relative important exists between the sensor and said object to be detected.
  • the present invention aims to overcome this disadvantage.
  • the method for the detection of an object located in a scene the method according to which:
  • said object is illuminated by a laser signal having a first wavelength; forming, through a first filter, whose bandwidth is tuned to said first wavelength, at least a first image of said scene in which said illuminated object is located;
  • a second filter whose bandwidth is tuned to a second wavelength different from said first wavelength, is formed by at least a second image of said scene, in which said illuminated object is located; , so that each first image corresponds to a second image;
  • third images are formed, each of which is the difference between a first image and the corresponding second image, and is remarkable in that:
  • said laser signal illuminating said object is a series of laser pulses
  • said second wavelength is sufficiently close to said first wavelength that the backscattering of sunlight by said scene is at least approximately similar in a first image and in the corresponding second image.
  • pairs of images of the same scene are obtained at the same time and in two different spectral domains, so that one of the images of a couple (the first) represents said scene and the laser echo on said object, while the other image of said pair (the second) represents only said scene without said laser echo.
  • motion effects and flicker effects light are the same in the two images of a couple and are eliminated during the formation of the difference image- Due to the fact that said second wavelength, although different from said first wavelength, is sufficiently close to it that the backscattering of sunlight by said scene is at least approximately similar in a first image and in the corresponding second simultaneous image, similar sensitivities are obtained for the first and second images in the sensor used. to train them.
  • a system for detecting an object in a scene comprising:
  • a transmitter illuminating said object by a laser signal having a first wavelength
  • a receiver comprising: first CCD-type detecting means, looking at the scene in which said object is located through a first filter whose bandwidth is tuned to said first wavelength;
  • first control means adapted to control, by said first detecting means, integrating and reading at least a first image of said scene in which said object illuminated by said transmitter is located;
  • second CCD-type detecting means looking at said scene in which said object is located through a second filter whose bandwidth is tuned to a second wavelength different from said first wavelength;
  • second control means able to control, by said second detection means, the integration and the reading of at least a second image of said scene, in which is said object illuminated by said transmitter, so that each first image corresponds to a second image;
  • processing means for forming the differences between a first image and the corresponding second image is remarkable in that:
  • said transmitter emits a signal consisting of a sequence of laser pulses
  • said first and second control means form a first image and the corresponding second image in strict synchronism with each laser pulse of said sequence; and said second wavelength is sufficiently close to said first wavelength that the backscattering of sunlight by said scene is at least approximately similar in a first image and in the corresponding second image.
  • Said first and second detection means may be respectively formed by individual CCD detectors or by portions of a single common CCD detector.
  • said first control means and said second control means can form a control unit common to said first and second detection means.
  • the system comprises an optical system common to said first and said second detection means.
  • Figure 1 schematically illustrates a system for detecting an object capable of retroreflecting light.
  • Figure 2 shows the block diagram of the receiver of such a detection system according to the present invention.
  • FIG. 3 shows, as a function of time t, timing diagrams illustrating the operation of said detection system according to the present invention.
  • the detection system 1 shown in Figure 1 comprises a laser emitter E and a receiver R close to each other and even integral with each other. Its object is to detect an object OP, for example an optical sighting system, an eye, ..., able to retroreflect the light it receives.
  • the system 1 is directed towards the object OP and its emitter E illuminates it by a series of incident laser pulses ⁇ (see the timing diagram A of FIG. 3) following an incident light path 2, and having a predetermined wavelength ⁇ 1.
  • the said laser pulses are retroreflected towards the detection system 1, following a reflected light path 3.
  • the laser pulses thus retroreflected and seen by the receiver R are designated by the reference ù on the chronogram B of FIG. 3.
  • the receiver R comprises a single optical system OS, pointed towards the object OP and receiving the laser pulses ⁇ retroreflected along the path 3.
  • the receiver R furthermore comprises two detection devices D1 and D2 identical in parallel, CCD type, arranged in the focal plane of the optical system OS and in connection with an electronic control unit and image processing CT, common to both devices D1 and D2. These can be two individual CCD detectors or two parts of the same CCD detector.
  • the light path 3 reaches the detection device D1 through a separator device LD, such as a separator plate or a separator cube, and through a filter F1 tuned to the wavelength ⁇ 1 of the laser pulses ù.
  • a separator device LD such as a separator plate or a separator cube
  • the light path 3 reaches the detection device D2 after reflection on the separator device LD and on a possible mirror M and after passing through a filter F2 tuned to a wavelength ⁇ 2, which is different from the length of d. wave ⁇ 1.
  • the detection devices D1 and D2 may comprise a matrix of photosensitive elements arranged in a cooler.
  • the filters F1 and F2 can also be of the cooled type and be housed in said cooler.
  • the electronic block CT opens an integration window 11 for the detection device D1. and an integration window i2 for the detection device D2.
  • Each integration window 11 and 12 completely contains the corresponding retroreflected laser pulse Ix and starts at the earliest moment when the corresponding incident laser pulse is emitted (situation shown in FIG. 3).
  • the early integration windows it and i2 can be temporally located between the time of the issuance of the incident laser pulse £ ' ⁇ corresponding and this time ⁇ increased the period mentioned above.
  • the opening times of the integration windows 11 and 12 are identical.
  • Reading of the detection devices D1 and D2 by the electronic block CT, after closure of each integration window il and i2, allows to obtain images 11 and 12, respectively (see timing diagrams D and F in Figure 3).
  • the images 11 and 12, associated with the same retroreflected laser pulse I ⁇ are identical except for the presence of the object OP.
  • the image 11, made at the wavelength ⁇ 1 comprises not only the scene in which the object OP is located, but also the latter illuminated by the corresponding incident wavelength laser pulse wavelength ⁇ 1.
  • the image 12 produced at the wavelength ⁇ 2 can not see said illuminated object OP at the wavelength ⁇ 1, so that the image 12 includes only the scene in which the object OP is located. .

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

Abstract

According to the invention, two simultaneous images with different wavelengths (λ1, λ2) are formed in synchronism with each illuminance laser pulse, one of the images corresponding to the wavelength (λ1) of the laser pulses, and the difference between the two images is generated.

Description

Procédé et dispositif pour la détection d'un objet apte à rétroréfléchir la lumière. Method and apparatus for detecting an object capable of retroreflecting light
La présente invention concerne un procédé et un dispositif pour la détection d'un objet apte à rétroréfléchir la lumière. Quoique non exclusivement, elle est particulièrement appropriée à la détection des optiques grossissantes (y compris l'oeil) qui présentent des propriétés de rétroré- flexion en vertu du principe dit "effet œil de chat".The present invention relates to a method and a device for detecting an object capable of retroreflecting light. Although not exclusively, it is particularly suitable for the detection of magnifying optics (including the eye) which exhibit retroreflective properties under the so-called "cat eye effect" principle.
Il est déjà connu, pour détecter un tel objet, d'éclairer celui-ci par un signal laser et de former, à travers un filtre accordé sur la longueur d'onde dudit signal laser, des images de la scène dans laquelle se trouve ledit objet, pendant et entre les éclairements de celui-ci par ledit signal laser. Pour ce faire, il est usuel de mettre en oeuvre des capteurs pourvus de détecteurs matriciels, de type CCD.It is already known, for detecting such an object, to illuminate it by a laser signal and to form, through a filter tuned to the wavelength of said laser signal, images of the scene in which said object is located. object, during and between the illuminations thereof by said laser signal. To do this, it is customary to use sensors provided with matrix detectors, of the CCD type.
Ainsi, dans cette technique connue, la détection dudit objet rétro- réfléchissant se fait en comparant une image acquise lors de l'éclairement par le signal laser et une image acquise hors d'un tel éclairement, de façon à faire disparaître la scène de fond et à faire apparaître l'écho laser provenant de la rétroréflexion par ledit objet.Thus, in this known technique, the detection of said retro-reflective object is done by comparing an image acquired during illumination by the laser signal and an image acquired out of such illumination, so as to remove the background scene. and displaying the laser echo from the retroreflection by said object.
Cette technique connue présente l'inconvénient d'engendrer des fausses alarmes provenant de variations dans la scène entre les prises des deux images, même si l'intervalle temporel entre elles est faible. De telles variations peuvent être dues à des mouvements propres à des capteurs, à des mouvements d'objets de la scène, à un effet de scintillement des reflets de soleil, etc ... A fortiori, cette technique antérieure est inutilisable lorsqu'un mouvement relatif important existe entre le capteur et ledit objet à détecter. La présente invention a pour objet de remédier à cet inconvénient. A cette fin, selon l'invention, le procédé pour la détection d'un objet se trouvant dans une scène, procédé selon lequel :This known technique has the disadvantage of generating false alarms from variations in the scene between the shots of the two images, even if the time interval between them is small. Such variations may be due to movements specific to sensors, to movements of objects in the scene, to a flickering effect of sun reflections, etc ... A fortiori, this prior art is unusable when a movement relative important exists between the sensor and said object to be detected. The present invention aims to overcome this disadvantage. For this purpose, according to the invention, the method for the detection of an object located in a scene, the method according to which:
- on éclaire ledit objet par un signal laser ayant une première longueur d'onde ; - on forme, à travers un premier filtre, dont la bande passante est accordée sur ladite première longueur d'onde, au moins une première image de ladite scène dans laquelle se trouve ledit objet éclairé ;said object is illuminated by a laser signal having a first wavelength; forming, through a first filter, whose bandwidth is tuned to said first wavelength, at least a first image of said scene in which said illuminated object is located;
- on forme, à travers un second filtre, dont la bande passante est accordée sur une seconde longueur d'onde différente de ladite première lon- gueur d'onde, au moins une seconde image de ladite scène, dans laquelle se trouve ledit objet éclairé, de sorte qu'à chaque première image correspond une seconde image ; eta second filter, whose bandwidth is tuned to a second wavelength different from said first wavelength, is formed by at least a second image of said scene, in which said illuminated object is located; , so that each first image corresponds to a second image; and
- on forme des troisièmes images dont chacune d'elles est la différence entre une première image et la seconde image correspondante, est remarquable en ce que :third images are formed, each of which is the difference between a first image and the corresponding second image, and is remarkable in that:
- ledit signal laser éclairant ledit objet est une suite d'impulsions laser ;said laser signal illuminating said object is a series of laser pulses;
- on forme une première image et la seconde image correspondante en synchronisme rigoureux avec chaque impulsion laser de ladite suite ; eta first image and the second corresponding image are formed in strict synchronism with each laser pulse of said sequence; and
- ladite seconde longueur d'onde est suffisamment proche de ladite pre- mière longueur d'onde pour que la rétrodiffusion de la lumière solaire par ladite scène soit au moins approximativement semblable dans une première image et dans la seconde image correspondante.said second wavelength is sufficiently close to said first wavelength that the backscattering of sunlight by said scene is at least approximately similar in a first image and in the corresponding second image.
Ainsi, selon l'invention, on obtient des couples d'images de Ia même scène au même instant et dans deux domaines spectraux diffé- rents, de sorte que l'une des images d'un couple (la première) représente ladite scène et l'écho laser sur ledit objet, alors que l'autre image dudit couple (la seconde) ne représente que ladite scène sans ledit écho laser. Il en résulte alors que les effets de mouvement et les effets de scintillement de la lumière sont les mêmes dans les deux images d'un couple et sont éliminés lors de la formation de l'image de différence- Grâce au fait que ladite seconde longueur d'onde, bien que différente de ladite première longueur d'onde, est suffisamment proche de celle-ci pour que la rétrodiffusion de la lumière solaire par ladite scène soit au moins approximativement semblable dans une première image et dans Ia seconde image simultanée correspondante, on obtient des sensibilités semblables pour les premières et secondes images dans Ie capteur utilisé pour les former. Selon un autre aspect de la présente invention, un système pour la détection d'un objet se trouvant dans une scène, système comportant :Thus, according to the invention, pairs of images of the same scene are obtained at the same time and in two different spectral domains, so that one of the images of a couple (the first) represents said scene and the laser echo on said object, while the other image of said pair (the second) represents only said scene without said laser echo. As a result, motion effects and flicker effects light are the same in the two images of a couple and are eliminated during the formation of the difference image- Due to the fact that said second wavelength, although different from said first wavelength, is sufficiently close to it that the backscattering of sunlight by said scene is at least approximately similar in a first image and in the corresponding second simultaneous image, similar sensitivities are obtained for the first and second images in the sensor used. to train them. According to another aspect of the present invention, a system for detecting an object in a scene, comprising:
- un émetteur éclairant ledit objet par un signal laser ayant une première longueur d'onde ;a transmitter illuminating said object by a laser signal having a first wavelength;
- un récepteur comportant : . des premiers moyens de détection de type CCD, regardant la scène dans laquelle se trouve ledit objet à travers un premier filtre dont la bande passante est accordée sur ladite première longueur d'onde ;a receiver comprising: first CCD-type detecting means, looking at the scene in which said object is located through a first filter whose bandwidth is tuned to said first wavelength;
. des premiers moyens de commande aptes à commander, par lesdits premiers moyens de détection, l'intégration et la lecture d'au moins une première image de ladite scène dans laquelle se trouve ledit objet éclairé par ledit émetteur ;. first control means adapted to control, by said first detecting means, integrating and reading at least a first image of said scene in which said object illuminated by said transmitter is located;
. des seconds moyens de détection de type CCD, regardant ladite scène dans laquelle se trouve ledit objet à travers un second filtre dont la bande passante est accordée sur une seconde longueur d'onde différente de ladite première longueur d'onde ;. second CCD-type detecting means, looking at said scene in which said object is located through a second filter whose bandwidth is tuned to a second wavelength different from said first wavelength;
. des seconds moyens de commande aptes à commander, par lesdits seconds moyens de détection, l'intégration et la lecture d'au moins une seconde image de ladite scène, dans laquelle se trouve ledit objet éclairé par ledit émetteur, de sorte qu'à chaque première image correspond une seconde image ; et. second control means able to control, by said second detection means, the integration and the reading of at least a second image of said scene, in which is said object illuminated by said transmitter, so that each first image corresponds to a second image; and
. des moyens de traitement pour former les différences entre une première image et la seconde image correspondante, est remarquable en ce que :. processing means for forming the differences between a first image and the corresponding second image is remarkable in that:
- ledit émetteur émet un signal constitué d'une suite d'impulsions laser ;said transmitter emits a signal consisting of a sequence of laser pulses;
- lesdits premiers et seconds moyens de commande forment une première image et la seconde image correspondante en synchronisme rigoureux avec chaque impulsion laser de ladite suite ; et - ladite seconde longueur d'onde est suffisamment proche de ladite première longueur d'onde pour que la rétrodiffusion de la lumière solaire par ladite scène soit au moins approximativement semblable dans une première image et dans la seconde image correspondante.said first and second control means form a first image and the corresponding second image in strict synchronism with each laser pulse of said sequence; and said second wavelength is sufficiently close to said first wavelength that the backscattering of sunlight by said scene is at least approximately similar in a first image and in the corresponding second image.
Lesdits premiers et seconds moyens de détection peuvent être respectivement formés par des détecteurs CCD individuels ou bien par des parties d'un unique détecteur CCD commun.Said first and second detection means may be respectively formed by individual CCD detectors or by portions of a single common CCD detector.
Par ailleurs, lesdits premiers moyens de commande et lesdits seconds moyens de commande peuvent former une unité de commande commune auxdits premiers et seconds moyens de détection. Avantageusement, le système comporte un système optique commun auxdits premiers et auxdits seconds moyens de détection.Furthermore, said first control means and said second control means can form a control unit common to said first and second detection means. Advantageously, the system comprises an optical system common to said first and said second detection means.
Lorsque ledit système est destiné à la détection d'un objet apte à rétroréfléchir la lumière, il est avantageux que ledit émetteur et ledit récepteur soient proches l'un de l'autre. Les figures du dessin annexé feront bien comprendre comment l'invention peut être réalisée. Sur ces figures, des références identiques désignent des éléments semblables.When said system is intended for detecting an object capable of retroreflecting light, it is advantageous for said transmitter and said receiver to be close to one another. The figures of the appended drawing will make it clear how the invention can be realized. In these figures, identical references designate similar elements.
La figure 1 illustre schématiquement un système pour la détection d'un objet apte à rétroréfléchir la lumière. La figure 2 montre le schéma synoptique du récepteur d'un tel système de détection conforme à la présente invention.Figure 1 schematically illustrates a system for detecting an object capable of retroreflecting light. Figure 2 shows the block diagram of the receiver of such a detection system according to the present invention.
La figure 3 montre, en fonction du temps t, des chronogrammes illustrant le fonctionnement dudit système de détection conforme à la pré- sente invention.FIG. 3 shows, as a function of time t, timing diagrams illustrating the operation of said detection system according to the present invention.
Le système de détection 1 représenté sur la figure 1 comporte un émetteur laser E et un récepteur R proches l'un de l'autre et même solidaires l'un de l'autre. Il a pour objet de détecter un objet OP, par exemple un système optique de visée, un œil, ..., apte à rétroréfléchir la lumière qu'il reçoit. Pour ce faire, le système 1 est dirigé vers l'objet OP et son émetteur E éclaire celui-ci par une suite d'impulsions laser incidentes £\ (voir le chronogramme A de la figure 3) suivant un trajet lumineux incident 2, et ayant une longueur d'onde λ1 prédéterminée.The detection system 1 shown in Figure 1 comprises a laser emitter E and a receiver R close to each other and even integral with each other. Its object is to detect an object OP, for example an optical sighting system, an eye, ..., able to retroreflect the light it receives. For this purpose, the system 1 is directed towards the object OP and its emitter E illuminates it by a series of incident laser pulses \ (see the timing diagram A of FIG. 3) following an incident light path 2, and having a predetermined wavelength λ1.
L'objet OP étant rétroréfléchissant pour la lumière, lesdites impul- sions laser sont rétroréf léchies en direction du système de détection 1 , en suivant un trajet lumineux réfléchi 3. Les impulsions laser ainsi rétroréf léchies et vues par le récepteur R sont désignées par la référence ù sur le chronogramme B de la figure 3. Bien entendu, si la distance séparant le système de détection 1 de l'objet OP est égale à d, les impulsions laser rétroréfléchies sont retardées d'un délai τ = 2d/c, expression dans laquelle c est la vitesse de propagation de la lumière.Since the object OP is retroreflective for light, the said laser pulses are retroreflected towards the detection system 1, following a reflected light path 3. The laser pulses thus retroreflected and seen by the receiver R are designated by the reference ù on the chronogram B of FIG. 3. Of course, if the distance separating the detection system 1 from the object OP is equal to d, the retroreflected laser pulses are delayed by a delay τ = 2d / c, expression where c is the speed of propagation of light.
Comme le montre schématiquement Ia figure 2, le récepteur R comporte un unique système optique OS, pointé vers l'objet OP et recevant les impulsions laser £τ rétroréfléchies selon le trajet 3. Le récepteur R comporte de plus deux dispositifs de détection D1 et D2 identiques en parallèle, de type CCD, disposés dans le plan focal du système optique OS et en liaison avec un bloc électronique de commande et de traitement d'images CT, commun aux deux dispositifs D1 et D2. Ceux-ci peuvent être deux détecteurs CCD individuels ou bien deux parties d'un même détecteur CCD.As shown schematically in FIG. 2, the receiver R comprises a single optical system OS, pointed towards the object OP and receiving the laser pulses τ retroreflected along the path 3. The receiver R furthermore comprises two detection devices D1 and D2 identical in parallel, CCD type, arranged in the focal plane of the optical system OS and in connection with an electronic control unit and image processing CT, common to both devices D1 and D2. These can be two individual CCD detectors or two parts of the same CCD detector.
Le trajet lumineux 3 atteint le dispositif de détection D1 à travers un dispositif séparateur LD, tel qu'une lame séparatrice ou un cube sépa- rateur, et à travers un filtre F1 accordé sur la longueur d'onde λ1 des impulsions laser £\ et ù.The light path 3 reaches the detection device D1 through a separator device LD, such as a separator plate or a separator cube, and through a filter F1 tuned to the wavelength λ1 of the laser pulses ù.
De plus, le trajet lumineux 3 atteint le dispositif de détection D2 après réflexion sur le dispositif séparateur LD et sur un éventuel miroir M et après traversée d'un filtre F2 accordé sur une longueur d'onde λ2, dif- férente de la longueur d'onde λ1.In addition, the light path 3 reaches the detection device D2 after reflection on the separator device LD and on a possible mirror M and after passing through a filter F2 tuned to a wavelength λ2, which is different from the length of d. wave λ1.
De façon connue, les dispositifs de détection D1 et D2 peuvent comporter une matrice d'éléments photosensibles disposée dans un refroi- disseur. Les filtres F1 et F2 peuvent également être du type refroidi et être logé dans ledit refroidisseur. Comme l'illustrent les chronogrammes C et E de la figure 3, en synchronisme avec l'émission de chaque impulsion laser incidente £\ par l'émetteur E, le bloc électronique CT ouvre une fenêtre d'intégration il pour le dispositif de détection D1 et une fenêtre d'intégration i2 pour le dispositif de détection D2. Chaque fenêtre d'intégration il et i2 contient totalement l'impulsion laser rétroréfléchie correspondante Ix et commence au plus tôt à l'émission de l'impulsion laser incidente £\ correspondante (situation représentée sur la figure 3). Cependant le début des fenêtres d'intégration il et i2 peut être temporellement situé entre l'instant de l'émission de l'impulsion laser incidente £'\ correspondante et cet instant augmenté du délai τ mentionné ci-dessus. De plus, les temps d'ouverture des fenêtres d'intégration il et i2 (quelques dizaines de microsecondes) sont identiques.In known manner, the detection devices D1 and D2 may comprise a matrix of photosensitive elements arranged in a cooler. The filters F1 and F2 can also be of the cooled type and be housed in said cooler. As illustrated by the chronograms C and E of FIG. 3, in synchronism with the emission of each incident laser pulse \ by the emitter E, the electronic block CT opens an integration window 11 for the detection device D1. and an integration window i2 for the detection device D2. Each integration window 11 and 12 completely contains the corresponding retroreflected laser pulse Ix and starts at the earliest moment when the corresponding incident laser pulse is emitted (situation shown in FIG. 3). However the early integration windows it and i2 can be temporally located between the time of the issuance of the incident laser pulse £ '\ corresponding and this time τ increased the period mentioned above. In addition, the opening times of the integration windows 11 and 12 (a few tens of microseconds) are identical.
La lecture des dispositifs de détection D1 et D2 par le bloc électronique CT, après fermeture de chaque fenêtre d'intégration il et i2, permet d'obtenir des images 11 et 12, respectivement (voir les chronogrammes D et F de la figure 3).Reading of the detection devices D1 and D2 by the electronic block CT, after closure of each integration window il and i2, allows to obtain images 11 and 12, respectively (see timing diagrams D and F in Figure 3).
On comprendra aisément que les images 11 et 12, associées à une même impulsion laser rétroréfléchie lκ, sont identiques sauf en ce qui concerne la présence de l'objet OP. En effet, l'image 11 , réalisée à la longueur d'onde λ1 , comporte non seulement la scène dans laquelle se trouve l'objet OP, mais encore ce dernier éclairé par l'impulsion laser incidente £\ correspondante de longueur d'onde λ1 . En revanche, l'image 12 réalisée à la longueur d'onde λ2, ne peut voir ledit objet OP éclairé à la longueur d'onde λ1 , de sorte que l'image 12 ne comporte que la scène dans laquelle se trouve ledit objet OP.It will be readily understood that the images 11 and 12, associated with the same retroreflected laser pulse Iκ, are identical except for the presence of the object OP. In fact, the image 11, made at the wavelength λ1, comprises not only the scene in which the object OP is located, but also the latter illuminated by the corresponding incident wavelength laser pulse wavelength λ1. On the other hand, the image 12 produced at the wavelength λ2 can not see said illuminated object OP at the wavelength λ1, so that the image 12 includes only the scene in which the object OP is located. .
Ainsi, en soustrayant une image 12 de l'image 11 associée, on obtient une image de laquelle ladite scène est éliminée, seul subsistant ledit objet OP éclairé. Il est alors aisé de déterminer la position de l'image dudit objet OP dans l'image de différence ainsi obtenue et, par suite, la position dudit objet OP par rapport audit système de détection 1 . Thus, by subtracting an image 12 from the associated image 11, an image is obtained from which said scene is eliminated, leaving only said illuminated object OP. It is then easy to determine the position of the image of said object OP in the difference image thus obtained and, consequently, the position of said object OP with respect to said detection system 1.

Claims

REVENDICATIONS
1 . Procédé pour Ia détection d'un objet (OP) se trouvant dans une scène, procédé selon lequel :1. A method for detecting an object (OP) in a scene, wherein:
- on éclaire ledit objet par un signal laser ayant une première longueur d'onde (λ1 ) ;said object is illuminated by a laser signal having a first wavelength (λ1);
- on forme, à travers un premier filtre (F1 ), dont la bande passante est accordée sur ladite première longueur d'onde (λ1 ), au moins une première image (11 ) de ladite scène dans laquelle se trouve ledit objet (OP) éclairé ; - on forme, à travers un second filtre (F2), dont la bande passante est accordée sur une seconde longueur d'onde (λ2) différente de ladite première longueur d'onde (λ1 ), au moins une seconde image (12) de ladite scène, dans laquelle se trouve ledit objet (OP) éclairé, de sorte qu'à chaque première image (11 ) correspond une seconde image (12) ; et - on forme des troisièmes images dont chacune d'elles est la différence entre une première image (11 ) et la seconde image correspondante (12), caractérisé en ce que :a first filter (F1), whose bandwidth is tuned to said first wavelength (λ1), is formed, at least a first image (11) of said scene in which said object (OP) is located; enlightened ; forming, through a second filter (F2) whose bandwidth is tuned to a second wavelength (λ2) different from said first wavelength (λ1), at least one second image (12) of said scene, in which there is said illuminated object (OP), so that each first image (11) corresponds to a second image (12); and third images are formed, each of which is the difference between a first image (11) and the corresponding second image (12), characterized in that:
- ledit signal laser éclairant ledit objet (OP) est une suite d'impulsions laser ; - on forme une première image (11 ) et la seconde image correspondante (12) en synchronisme rigoureux avec chaque impulsion laser de ladite suite ; etsaid laser signal illuminating said object (OP) is a series of laser pulses; - forming a first image (11) and the corresponding second image (12) in strict synchronism with each laser pulse of said sequence; and
- ladite seconde longueur d'onde (λ2) est suffisamment proche de ladite première longueur d'onde (λi ) pour que la rétrodiffusion de la lumière solaire par ladite scène soit au moins approximativement semblable dans une première image (11 ) et dans la seconde image correspondante (12) .said second wavelength (λ2) is sufficiently close to said first wavelength (λi) for the backscattering of sunlight by said scene to be at least approximately similar in a first image (11) and in the second corresponding image (12).
2. Système pour la détection d'un objet (OP) se trouvant dans une scène, système comportant : - un émetteur (E) éclairant ledit objet (OP) par un signal laser ayant une première longueur d'onde (λ1 ) ;2. System for detecting an object (OP) in a scene, comprising: a transmitter (E) illuminating said object (OP) by a laser signal having a first wavelength (λ1);
- un récepteur (R) comportant :a receiver (R) comprising:
. des premiers moyens de détection (D 1 ) de type CCD, regardant la scène dans laquelle se trouve ledit objet (OP) à travers un premier filtre (F1 ) dont la bande passante est accordée sur ladite première longueur d'onde (λ1 ) ;. first detection means (D 1) of the CCD type, looking at the scene in which said object (OP) is located through a first filter (F1) whose bandwidth is tuned to said first wavelength (λ1);
. des premiers moyens de commande (CT) aptes à commander, par lesdits premiers moyens de détection (D1 ), l'intégration et la lecture d'au moins une première image (11 ) de ladite scène dans laquelle se trouve ledit objet (OP) éclairé par ledit émetteur (E) ; . des seconds moyens de détection (D2) de type CCD, regardant ladite scène dans laquelle se trouve ledit objet (OP) à travers un second filtre (F2) dont la bande passante est accordée sur une seconde lon- gueur d'onde (λ2) différente de ladite première longueur d'onde (λ1 ) ;. first control means (CT) able to control, by said first detection means (D1), the integration and the reading of at least a first image (11) of said scene in which said object (OP) is located illuminated by said emitter (E); . second detection means (D2) of CCD type, looking at said scene in which said object (OP) is located through a second filter (F2) whose bandwidth is tuned to a second wavelength (λ2) different from said first wavelength (λ1);
. des seconds moyens de commande (CT) aptes à commander, par lesdits seconds moyens de détection (D2), l'intégration et la lecture d'au moins une seconde image (12) de ladite scène, dans laquelle se trouve ledit objet (OP) éclairé par ledit émetteur (E), de sorte qu'à chaque première image (11 ) correspond une seconde image (12) ; et. second control means (CT) able to control, by said second detection means (D2), the integration and the reading of at least a second image (12) of said scene, in which is located said object (OP ) illuminated by said emitter (E), so that each first image (11) corresponds to a second image (12); and
. des moyens de traitement (CT) pour former les différences entre une première image (11 ) et la seconde image (12) correspondante, caractérisé en ce que :. processing means (CT) for forming the differences between a first image (11) and the corresponding second image (12), characterized in that:
- ledit émetteur (E) émet un signal constitué d'une suite d'impulsions Ia- ser ;said emitter (E) emits a signal consisting of a succession of Jaaer pulses;
- lesdits premiers et seconds moyens de commande (CT) forment une première image et la seconde image correspondante en synchronisme rigoureux avec chaque impulsion laser de ladite suite ; et - ladite seconde longueur d'onde (λ2) est suffisamment proche de ladite première longueur d'onde (λ1 ) pour que la rétrodiffusion de la lumière solaire par ladite scène soit au moins approximativement semblable dans une première image (11 ) et dans la seconde image correspondante (12) .said first and second control means (CT) form a first image and the corresponding second image in strict synchronism with each laser pulse of said sequence; and said second wavelength (λ2) is sufficiently close to said first wavelength (λ1) so that the backscattering of sunlight by said scene is at least approximately similar in a first image (11) and in the second corresponding image (12).
3. Système selon la revendication 2, caractérisé en ce que lesdits premiers moyens de détection (D1 ) et lesdits seconds moyens de détection (D2) sont respectivement formés par des détecteurs CCD individuels. 3. System according to claim 2, characterized in that said first detection means (D1) and said second detection means (D2) are respectively formed by individual CCD detectors.
4. Système selon la revendication 2, caractérisé en ce que lesdits premiers moyens de détection (D1 ) et lesdits seconds moyens de détection (D2) sont respectivement formés par des parties d'un détecteur CCD commun.4. System according to claim 2, characterized in that said first detection means (D1) and said second detection means (D2) are respectively formed by portions of a common CCD detector.
5. Système selon l'une des revendications 2 à 4, caractérisé en ce que lesdits premiers moyens de commande et lesdits seconds moyens de commande forment une unité de commande (CT) commune auxdits premiers et seconds moyens de détection (D 1 , D2).5. System according to one of claims 2 to 4, characterized in that said first control means and said second control means form a control unit (CT) common to said first and second detection means (D 1, D 2) .
6. Système selon l'une des revendications 2 à 5, dans lequel ledit récepteur est pourvu d'un système optique (OS) dirigé vers ladite scène, caractérisé en ce que ledit système optique (OS) est commun auxdits premiers et auxdits seconds moyens de détection (D1 , D2).6. System according to one of claims 2 to 5, wherein said receiver is provided with an optical system (OS) directed to said scene, characterized in that said optical system (OS) is common to said first and second means detection (D1, D2).
7. Système selon l'une des revendications 2 à 6, destiné à la détection d'un objet (OP) apte à rétroréfléchir la lumière, caractérisé en ce que ledit émetteur (E) et ledit récepteur (R) sont proches l'un de l'autre. 7. System according to one of claims 2 to 6, for the detection of an object (OP) capable of retroreflecting light, characterized in that said transmitter (E) and said receiver (R) are close to one the other.
EP07870323A 2006-11-28 2007-11-22 Method and device for detecting an object that can retroreflect light Ceased EP2095152A1 (en)

Applications Claiming Priority (2)

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FR0610392A FR2909182B1 (en) 2006-11-28 2006-11-28 METHOD AND DEVICE FOR DETECTING AN OBJECT CAPABLE OF RETROREFLECTING LIGHT
PCT/FR2007/001919 WO2008071866A1 (en) 2006-11-28 2007-11-22 Method and device for detecting an object that can retroreflect light

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US20130003079A1 (en) * 2011-06-29 2013-01-03 Holcombe Wayne T Proximity sensor calibration
US9482617B2 (en) 2012-06-07 2016-11-01 Jeffrey M. Smith Method for optical detection of surveillance and sniper personnel
RU2518533C1 (en) * 2013-04-02 2014-06-10 Александр Абрамович Часовской Optical-location device
US20140333808A1 (en) * 2013-05-10 2014-11-13 BAE Systems Imaging Solutions, Inc. Customizable Image Acquisition Sensor and Processing System

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FR2909182A1 (en) 2008-05-30
US7858920B2 (en) 2010-12-28
IL198279A0 (en) 2009-12-24
FR2909182B1 (en) 2011-06-24
US20100065722A1 (en) 2010-03-18

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