WO2019155458A1 - Prévention de dommages de capteurs dans des systèmes optiques - Google Patents

Prévention de dommages de capteurs dans des systèmes optiques Download PDF

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Publication number
WO2019155458A1
WO2019155458A1 PCT/IL2019/050110 IL2019050110W WO2019155458A1 WO 2019155458 A1 WO2019155458 A1 WO 2019155458A1 IL 2019050110 W IL2019050110 W IL 2019050110W WO 2019155458 A1 WO2019155458 A1 WO 2019155458A1
Authority
WO
WIPO (PCT)
Prior art keywords
optical
target
signal
optical signal
reflected
Prior art date
Application number
PCT/IL2019/050110
Other languages
English (en)
Inventor
Joel BIBERMAN
Irad Leiser
Dan Alon
Noam Cohen
Itamar GURMAN
Amir Porat
Original Assignee
Oryx Vision Ltd.
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 Oryx Vision Ltd. filed Critical Oryx Vision Ltd.
Publication of WO2019155458A1 publication Critical patent/WO2019155458A1/fr

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
    • G02B27/283—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising used for beam splitting or combining
    • 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
    • G01S17/06—Systems determining position data of a target
    • G01S17/08—Systems determining position data of a target for measuring distance only
    • 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
    • G01S7/481—Constructional features, e.g. arrangements of optical elements
    • G01S7/4811—Constructional features, e.g. arrangements of optical elements common to transmitter and receiver
    • 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
    • G01S7/491—Details of non-pulse systems
    • G01S7/4912—Receivers
    • G01S7/4918—Controlling received signal intensity, gain or exposure of sensor
    • 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
    • G01S7/499—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00 using polarisation effects

Definitions

  • the present disclosure generally relates to the field of optics. More particularly, the present disclosure relates to protecting sensors in optical detection systems.
  • Radar systems are often used to determine parameters associated with am object. Radio waves (pulsed or continuous) that are transmitted from the system's transmitter, are reflected from the object and return to the system's receiver, giving information, for example, about the object's location and speed ,
  • the detection of received information is conducted by measuring the voltage induced on the antenna terminals (or sensor) by the reflected signals, where a signal may be an electromagnetic wave, an ultrasonic wave, an optical signal or any other applicable type of transmitted energy.
  • FIG. 1 presents a prior art coherent detection system.
  • the voltage developing across the sensor includes the following contributions :
  • Vsensor Veias + VLO + VRX wherein :
  • Vei as - is an optional term and its value depending on the sensor mode of operation
  • V L0 - is an optional term which is used as a reference signal in coherent systems.
  • VRX - is the voltage induced at the sensor by the reflected signal .
  • V B ias and V L o are terms that may be optimized so as to increase the sensor sensitivity, so that the only variable and un-predictable term is V RX , which is highly depended on the target properties.
  • the optical sensors are susceptible to damages that might occur at times when the target object has highly reflective surface (s), Under such circumstances, a damage might occur to the receiving sensor when the voltage induced on the sensor by the reflected light is equal to or greater than the sensor's breakdown voltage .
  • Reflection of light off surfaces can carried out either in a mirror-like mechanism and/or by retaining the energy, but losing the phase, depending on the characteristics of the surface.
  • Highest risk for a sensor damage occurs when a surface, having a strong specular component, is positioned at an angle in which it would reflect the transmitted energy back to the sensor .
  • the present invention seeks to provide, among others, a solution to the problem of how to prevent damages to such systems' sensors without compromising their sensitivity.
  • an optical arrangement for use in an optical detection system wherein the optical arrangement comprises:
  • a light beam generating source for generating an optical signal
  • optical arrangement is characterized in that at least part of the optical signal arrives to the transmitter for its transmission towards a target, after it has been elliptically polarized.
  • the optical arrangement further comprising a filter for preventing conveyance of signals that are counter elliptically polarized, arriving from a target comprising one or more highly reflective surfaces and received by the receiver, to the sensor.
  • signals that are reflected from a target having one or more highly reflective surfaces positioned perpendicular to the transmitted optical signal will be reflected at a counter elliptic polarization, whereas if the target comprises highly diffusive surfaces, part of the reflected signal will be reflected from the target towards the receiver at a random polarization, which is different from a counter elliptical polarization and will not be blocked by that filter, as it is configured to prevent conveyance of signals that are counter elliptically polarized.
  • the randomly polarized signals will not have an adverse effect upon the sensor.
  • the optical arrangement further comprises a splitter configured to split the optical signal after it has been elliptically polarized into two parts, wherein the first part is conveyed to the sensor for use as a reference signal thereat, and the second part is conveyed to the transmitter to be transmitted towards the target as an optical signal.
  • the elliptical polarization is a circular polarization.
  • the optical arrangement provided is adapted to operate in a non-coherent optical detection system, and further comprises at least one linear polarizer, and wherein the optical signal generated by the light beam generating source is linearly polarized by one of the at least one linear polarizer.
  • the elliptic polarizer is configured to elliptically polarize the first part of the linearly polarized optical signal, and to block the signal reflected from the target and which arrives at a counter elliptic polarization to the receiver.
  • a method for use in an optical detection system comprising the steps of: (i) generating an optical signal by a light beam generating source ;
  • the elliptical polarization is a circular polarization .
  • the method is adapted for use in a non-coherent optical detection system, and the method further comprising the step of linearly polarizing at least part of the optical signal generated by the light beam generating source.
  • the method further comprising a step of elliptically polarizing a first part of the linearly polarized optical signal, and blocking the signal reflected from the target which arrives at a counter elliptic polarization to the system receiver, by an elliptic polarizer.
  • FIG. 1 demonstrates a prior art coherent detection system
  • FIG. 2A presents an example of a system for coherent detection, wherein the optical signal is transmitted to and reflected from a target which is a specular target;
  • FIG. 2B demonstrates an example of a system for coherent detection, wherein the optical signal is transmitted to and reflected from a target which is a diffusive target;
  • FIG. 3 illustrates an embodiment of the present disclosure by which the signal generated by a light beam generating source, is first linearly polarized by a linear polarizer
  • FIG. 4 illustrates a non-coherent optical detection system construed in accordance with an embodiment of the present invention.
  • FIG. 5 presents a flow chart demonstrating a method carried out in accordance with an embodiment of the present invention.
  • one of the main objects of the present disclosure is to provide a solution to protect optical sensor from being damaged due to energy reflected from highly reflected specular targets, positioned such that the incident energy is reflected to the receiver.
  • the solution proposed herein offers means and a method to filter energy reflected from specular targets with minimal attenuation of reflections from all other target types, such as diffusive targets.
  • FIG. 2A and FIG. 2B exemplify an example of a system 200 for coherent detection, in which the signal is reflected from a target 250 towards an optical arrangement 210.
  • target 250 is a specular target and the signal reflected from the target is in a counter circular polarization
  • target 250 is a diffusive target and the signal reflected from this target is scattered, so that a portion of the signal is reflected backwards towards optical arrangement 210 with a random polarization .
  • a circularly polarrzed wave may be in either a right circular polarization in which the electric field vector rotates in a right-hand direction with respect to the direction of propagation, or alternat ively in a left circular polarization in which the electric field vector rotates in a left-hand direction with respect to the direction of propagation .
  • the direction (handedness) of the polarized light is also reversed when the light is reflected off a surface at a normal incidence.
  • the rotation of the plane of polarization of the reflected light is identical to that of the incident field.
  • the same rotation direction that would be described as "right handed” for the incident beam becomes now “left-handed” for propagation in the reverse direction, and vice versa.
  • the ellipticity of polarization is preserved.
  • the light beam generated at the light beam generating source 220 is right hand circularly polarized ("RHCP") by a circular polarizer 230 and then conveyed to a splitter 240, where part of the RHCP light is conveyed towards transmitter 250 while the other part is conveyed towards an optical sensor 290.
  • the part of the RHCP light which is conveyed towards transmitter 250 is then transmitted by transmitter 250 towards the specular perpendicular target, and upon hitting target 250, is reflected off the surface at a normal incidence.
  • the direction (handedness) of the polarized light is reversed.
  • the LHCP reflected light reaches receiver 270 and then conveyed towards optical sensor 290 via optical filter 280 which filters out the LHCP light, so that the induced voltage, V RX , reaching the optical sensor in case of specular target, as in this example, should theoretically be equal to zero, and according to a general rule of thumb, is reduced to the value of -40dB from the original V RX received from the target, had optical filter 280 not been installed along the optical path and located prior to the optical sensor 290.
  • FIG. 2B illustrates another embodiment of system 200 for coherent detection, wherein the signal is again reflected from target 250, which, in the present case is a non-specular target, i.e. a diffusive target, towards the optical arrangement 210 in a counter circular polarization.
  • target 250 which, in the present case is a non-specular target, i.e. a diffusive target, towards the optical arrangement 210 in a counter circular polarization.
  • the light generated in the example illustrated in FIG. 2B undergoes a similar process, namely, the light beam is generated by light beam generating source 220 and then is right hand circularly polarized ("RHCP") by the circular polarizer 230 and conveyed to splitter 240, where part of the RHCP light is conveyed towards a transmitter 250 whereas the other part is conveyed towards an optical sensor 290.
  • the part of the RHCP light which is conveyed towards transmitter 250 is then transmitted by the transmitter 250 towards target 250, and upon hitting target 250, is reflected off its surface.
  • target 250 is a diffusive target
  • the reflected signal is scattered, and a portion of the signal is reflected backwards towards optical arrangement 210 with a random polarization.
  • the reflected signal would not be polarized in a counter circular polarization.
  • the direction of polarization as affected by circular polarizer 230 is irrelevant as long as the optical filter 280 of optical arrangement 210 is configured to filter out (i.e. to block) the polarization which is a counter polarization to that induced by circular polarizer 230.
  • the filter would have no effect, (or practically a negligible one), while the received signal amplitude remains unchanged.
  • the generated light is circularly polarized.
  • the generated light is RHCP and that the antennas are also RHCP. Consequently, one is able to achieve a perfect (or near perfect) match for the L.O (local oscillator) signal and a low loss due to filtering of the reflected signal if it is LHCP .
  • L.O local oscillator
  • FIG. 3 illustrates another embodiment of the present disclosure by which the light beam generated by the signal generating source 310 is linearly polarized by a first linear polarizer 320. The linearly polarized signal is conveyed to L.O.
  • the splitter 330 after which part of the signal is forwarded towards transmitter 350 (which can be for example a lens, a mirror, etc.) via circular polarizer 340 (RHCP in this example), while the other part is conveyed from L.O. splitter 330 via a second linear polarizer 360 to sensor 370.
  • the sensor may either be an antenna having no specific polarization, a photodiode or any other type of a scalar sensor such as a bolometer.
  • a passive filter (not shown in this FIG.) may be used to block the reflected signal.
  • the same element (e.g. circular polarizer) 340 may be used for both, circularly polarizing the signal conveyed towards the transmitter and also to block the signal conveyed from the receiver 380 (which can be for example a lens) to the sensor (after being reflected at LHCP from a highly reflective target) by using a simple array of mirrors.
  • This set up results in a perfect polarization matching for the L.O as well as in a relatively very simple and cheap system.
  • FIG. 4 demonstrates a non-coherent optical detection system (such as a camera, a Ildar etc.), wherein the signal generated at signal source 410 is first linearly polarized by a linear polarizer 420, followed by an elliptic polarizer such as a righthand circular polarizer 430, and the RHCP signal is then transmitted by transmitter 440 towards a specular target. The transmitted signal is then reflected from the target as an LHCP signal, which is received by the system receiver 450 and then conveyed to the system's sensor 470 via an LHCP filter 460, configured to block LHCP signals.
  • FIG. 5 exemplifies an example of one embodiment for a method of carrying out the present disclosure.
  • the first step in accordance with this example is generating a light beam by a signal source (step 500) .
  • polarizing the signal by a circular polarizer step 510) and splitting the signal (step 520) into two parts.
  • the first circularly polarized portion of the signal is conveyed to a transmitter and the second circularly polarized portion of the signal - to a sensor.
  • the transmitter transmits the circularly polarized signal towards a target (step 530) .
  • the target in this example is a specular target having one or more highly reflective surfaces and located normal to the signal propagation direction
  • the signal arriving at the target is reflected with a counter circular polarization (step 540), and reaches the system's receiver (step 550) .
  • the signal received is conveyed to a sensor via a counter circular polarization filter, which is configured to block arriving signals having counter circular polarization (step 560) .
  • a counter circular polarization filter which is configured to block arriving signals having counter circular polarization (step 560) .
  • the outcome of the sensor is determined (step 570) .

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Electromagnetism (AREA)
  • Optics & Photonics (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
  • Optical Radar Systems And Details Thereof (AREA)

Abstract

Un agencement optique selon l'invention comprend : une source de génération de faisceau lumineux pour générer un signal optique ; un polariseur elliptique (par exemple, un polariseur circulaire) ; un émetteur ; un récepteur ; et un capteur, et l'agencement optique étant caractérisé en ce qu'au moins une partie du signal optique arrive à l'émetteur pour son émission vers une cible, après qu'elle a été polarisée de manière elliptique.
PCT/IL2019/050110 2018-02-06 2019-01-28 Prévention de dommages de capteurs dans des systèmes optiques WO2019155458A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US201862626703P 2018-02-06 2018-02-06
US62/626,703 2018-02-06

Publications (1)

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WO2019155458A1 true WO2019155458A1 (fr) 2019-08-15

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Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19801632A1 (de) * 1997-10-24 1999-05-06 Pepperl & Fuchs Reflexlichtschranke, insbesondere zur Erkennung transparenter, polarisierender Materialien, sowie ein Verfahren zur Verbesserung der Störsicherheit von Reflexlichtschranken
JPH11342765A (ja) * 1998-06-02 1999-12-14 Hino Motors Ltd 居眠り検出装置
WO2005104009A1 (fr) * 2004-04-22 2005-11-03 Omniperception Limited Systeme de reconnaissance de visage
EP2252859B1 (fr) * 2008-03-19 2012-12-19 Raytheon Company Imagerie 3d de type ladar à balayage rapide avec formation de faisceau numérique compact
US20140121532A1 (en) * 2012-10-31 2014-05-01 Quaerimus, Inc. System and method for prevention of diabetic foot ulcers
EP3193318A1 (fr) * 2016-01-18 2017-07-19 Autoliv Development AB Système de surveillance de conducteur et procédé de surveillance de conducteur pour un véhicule automobile
WO2017175211A1 (fr) * 2016-04-06 2017-10-12 Oryx Vision Ltd. Système et procédé de détection de profondeur
EP3243966A1 (fr) * 2016-05-13 2017-11-15 Toto Ltd. Appareil de décharge d'eau et capteur photoélectrique

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19801632A1 (de) * 1997-10-24 1999-05-06 Pepperl & Fuchs Reflexlichtschranke, insbesondere zur Erkennung transparenter, polarisierender Materialien, sowie ein Verfahren zur Verbesserung der Störsicherheit von Reflexlichtschranken
JPH11342765A (ja) * 1998-06-02 1999-12-14 Hino Motors Ltd 居眠り検出装置
WO2005104009A1 (fr) * 2004-04-22 2005-11-03 Omniperception Limited Systeme de reconnaissance de visage
EP2252859B1 (fr) * 2008-03-19 2012-12-19 Raytheon Company Imagerie 3d de type ladar à balayage rapide avec formation de faisceau numérique compact
US20140121532A1 (en) * 2012-10-31 2014-05-01 Quaerimus, Inc. System and method for prevention of diabetic foot ulcers
EP3193318A1 (fr) * 2016-01-18 2017-07-19 Autoliv Development AB Système de surveillance de conducteur et procédé de surveillance de conducteur pour un véhicule automobile
WO2017175211A1 (fr) * 2016-04-06 2017-10-12 Oryx Vision Ltd. Système et procédé de détection de profondeur
EP3243966A1 (fr) * 2016-05-13 2017-11-15 Toto Ltd. Appareil de décharge d'eau et capteur photoélectrique

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