WO2018198115A1 - Agencement optique et procédé pour utilisation dans le balayage continu d'un capteur optique - Google Patents

Agencement optique et procédé pour utilisation dans le balayage continu d'un capteur optique Download PDF

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Publication number
WO2018198115A1
WO2018198115A1 PCT/IL2018/050448 IL2018050448W WO2018198115A1 WO 2018198115 A1 WO2018198115 A1 WO 2018198115A1 IL 2018050448 W IL2018050448 W IL 2018050448W WO 2018198115 A1 WO2018198115 A1 WO 2018198115A1
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WO
WIPO (PCT)
Prior art keywords
optical
signals
arrangement
scanning
optical arrangement
Prior art date
Application number
PCT/IL2018/050448
Other languages
English (en)
Inventor
Dan Alon
Noam Cohen
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 WO2018198115A1 publication Critical patent/WO2018198115A1/fr

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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
    • 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
    • G01S7/4812—Constructional features, e.g. arrangements of optical elements common to transmitter and receiver transmitted and received beams following a coaxial path
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/47—Scattering, i.e. diffuse reflection
    • 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
    • G01S17/10—Systems determining position data of a target for measuring distance only using transmission of interrupted, pulse-modulated waves
    • G01S17/26—Systems determining position data of a target for measuring distance only using transmission of interrupted, pulse-modulated waves wherein the transmitted pulses use a frequency-modulated or phase-modulated carrier wave, e.g. for pulse compression of received signals

Definitions

  • the present disclosure generally relates to systems implementing coherent detection. More particularly, the present disclosure relates to systems utilizing depth sensing sensors.
  • Optical coherent detection is a method of extracting information encoded as modulation of the phase and/or frequency of electromagnetic radiation in the wavelength band of visible or infrared light.
  • the received light signal is compared with a brighter standard or reference light, often called a "local oscillator” (LO) , by analogy with a superhetrodyne receiver.
  • LO local oscillator
  • the comparison of the two light signals is typically accomplished by combining them in a non linear element such as a photodiode detector.
  • the two light frequencies may be similar enough that their difference or beat frequency produced by the detector is in the radio or microwave band that can be conveniently processed by electronic means.
  • an optical arrangement for use in a coherent detection system, wherein the optical arrangement comprises a light beam generating source configured to convey a series of modulated optical signals, an optical receiver, a plurality of optical sensors (e.g. detectors) and means configured to enable continuously scanning of optical energy across the plurality of optical sensors (e.g. a large optical sensors' array), and wherein the arrangement is characterized in that: a) part of the optical energy generated by the light beam generating source (i.e.
  • part of the optical energy generated by the light beam generating source is directed towards an optical transmitter for transmitting optical signals that are reflected off objects that are present within the field of view, thereby ensuring that while continuously scanning optical energy across the plurality of optical sensors, each time a different portion of the plurality of optical sensors is simultaneously illuminated by both reference light signals and the signals reflected from objects that are present within the field of view, while the optical arrangement is operative.
  • reference light signal and "LO signal” as used herein throughout the specification and claims is used to denote bright standard or reference light, that is used for comparing it with a weaker received light signal.
  • the term “Local Oscillator” is used by analogy with superhetrodyne detection systems.
  • the information carried by the received light is encoded as an amplitude, frequency and/or phase shift from the reference signal.
  • the received signal and the reference signal may be introduced to a nonlinear signal-processing device (such as a photodiode) usually referred to as a mixing device ⁇ e.g. a multiplier or square law detector), to yield an output signal.
  • continuous scanning as used herein throughout the specification and claims is used to denote a scanning process having one or more degrees of freedom (length, width, angles etc.) where the scanning is carried out at an essentially constant speed. i.e. without staring, stopping, pausing, or slowing, when the optical arrangement is operative.
  • optical transmitter as used herein through the specification and claims, is used to denote an arrangement comprising at least one optical element designed to collect optical energy and shape it to illuminate a pre-defined field of view .
  • optical receiver as used herein through the specification and claims, is used to denote an arrangement comprising at least one optical element designed to collect optical energy and focus it onto an optical sensor array plane. Subject to the limitations of the optical arrangement and the sensor directivity, each sensing element within the array views a unique portion of the field of view.
  • the optical receiver is designed to facilitate collection of the reflected signals and to reflect the field of view onto the plurality of optical sensors (e.g. a sensors' array) .
  • optical spot critical dimension and scanning velocity that are applied. For example, they should be applied in a manner that would comply with the following limitation : where V is the scanning velocity;
  • D is the critical dimension of the optical spot size
  • T is the time duration of the modulated signal length; and t is the maximal allowed time of flight from the transmitter to the field of view and back to the receiver.
  • Scanning can be accomplished by various means that can roughly be divided into two general categories: a) mechanical scanning means that comprise moving parts which are configured to enable spinning, rotating, sliding, shifting, bending, tilting etc. of the optical energy. This group also comprises micro moving parts such as MEMs, piezo electric actuators and the like, b) Scanning means (or beam steering) that do not comprise moving parts, and the scanning is carried out by varying the physical properties of materials over time. This group comprises photo acoustic devices, index of diffraction manipulations through E field, temperature control and the like.
  • the optical arrangement is configured to enable scanning only received (Rx) signals, while the LO signals are used to statically illuminate all optical sensors of the plurality of optical sensors (the entire sensors' array) .
  • the optical arrangement is configured to enable scanning only LO signals, while the received (Rx) signals are used to statically illuminate all optical sensors of the plurality of optical sensors (the entire sensors' array) .
  • the optical arrangement is configured to enable simultaneous scanning of both LO signals and received (Rx) signals, while ensuring that both the LO signals and the received signals are aligned to illuminate the same optical sensors from among the plurality of optical sensors (the same sub-array of the sensors ' array) .
  • the optical arrangement is configured to enable scanning essentially all of the optical energy across the plurality of the optical sensors and direct the energy reflected therefrom towards the transmitter.
  • the reciprocity of light propagation will insure that the received signals will return to the appropriate illuminated sub-array of pixels.
  • the light beam emitted from the optical transmitter is emitted in a pre-defined pattern.
  • the light beam generation source is a gas laser.
  • the plurality of optical sensors (e.g. the optical sensors' array) comprises photo diodes.
  • the plurality of optical sensors (e.g. the optical sensor's array) comprises rectifying antennas (rectennas) .
  • the optical arrangement further comprises a processor, wherein the processor is configured to execute a sub-array data analysis algorithm, which in turn is configured to accommodate specific signals' modulation types, according to each sub-array's relative location within the array.
  • the optical arrangement further comprises a processor, wherein the processor is configured to combine results obtained from a plurality of scanning operations, in order to obtain a unified result (e.g. a full frame) .
  • FIG . 1 illustrates a prior art technique by which an optical sensor is scanned by steps
  • FIG . 2 demonstrates an embodiment of the solution provided by the present invention by which a continuous scanning of the Rx signals is carried out while maintaining a static LO signal that illuminates the entire pixel array;
  • FIG . 3 illustrates an example of a linear frequency modulated signal that is used to continuously scan the sub-arrays of the optical sensor demonstrated in FIG. 2;
  • FIG . 4 demonstrates an embodiment which illustrates an optical arrangement construed in accordance with an embodiment of the present invention
  • FIG . 5 illustrates an embodiment by which all of the available energy is used to scan the sensors' array and the reflected energy is forwarded to the optical transmitter; and
  • FIG . 6 presents a flow chart demonstrating a method carried out in accordance with an embodiment of the present invention.
  • FIG. 1 illustrates a prior art scanning technique, whereby the optical sensor is scanned by steps (i.e. using scan and stare technique for each step) , while keeping a sub-array of the sensors statically illuminated during each such step.
  • FIG. 2 demonstrates an embodiment of the solution provided by the present invention, by which a continuous scanning of the Rx signals is carried out, while at the same time a static LO signal that illuminates the entire pixel array is maintained.
  • sensor 400 comprises an array of pixels 410, optical LO signal 470 illuminates statistically the entire array, and the received optical energy (Rx) 420 illuminates sub- arrays of pixels.
  • the light beam of the received signals (Rx) continuously scans across the sensor in the direction designated 480, at a speed assuring that sub- array 430 remains illuminated for the duration of the symbol length.
  • the time required to move spot 420 from its left edge (430) to its right edge (440) is equal to or greater than the symbol length and flight time.
  • the sub-arrays of pixels designated by 450 and 460 are illuminated at different times.
  • FIG. 3 illustrates an example of a linear frequency modulated signal 500, that is used to continuously scan the sub- arrays of the optical sensor shown in FIG. 2.
  • Sub-array 440 being the first illuminated array in this example, is illuminated by signal 510.
  • the illumination time of the next sub-array, 450 begins at a time delay relative to the time at which sub-array 440 began its illumination, and therefor sub- array 450 is illuminated by signal 520.
  • the illumination of sub-array 460 takes place in a further delay with respect to sub-array 450 so it is illuminated by signal 530.
  • the delays in the illumination of the various sub-arrays are preferably predetermined by the system specific scanning parameters. In some modulation techniques, algorithmic compensation for the known delay, might be required.
  • FIG. 4 demonstrates another embodiment which illustrates an optical arrangement construed in accordance with an embodiment of the present invention, where essentially all of the optical energy is continuously scanned across the optical sensor and the reflected energy is presented to an optical transmitter.
  • available optical energy 100 which is comprised within the optical beam generated by the light source, is conveyed to the optical sensor 121 which, in the present example is printed on the surface of sensor die 120.
  • This conveyance of optical energy is preferably done in a controlled manner in order to enable establishing a predetermined phase and spot size.
  • the desired phase and spot size are typical of a Gaussian beam waist created by lens 110 which is located along the optical path of the light beam.
  • the surface of the sensor 121 is designed to reflect the optical power and consequently to illuminate the system field of view.
  • the proposed system configuration may preferably be such that it ensures (by implementing a proper design) that the field of view and the illuminated field are essentially identical, thus eliminating losses that would otherwise occur due to the phenomenon known as parallax.
  • radiation pattern 140 is reflected from the surface of sensor 121 in a way designed to match the aperture of lens 150.
  • Lens 150 is designed so as to shape the transmitted beam to illuminate the field of view 160.
  • the arrangement further comprises a beam shaping means which is operative on the LO signal before the latter is introduced to the detector die.
  • This beam shaping operation enables matching the beam profile with the sensor array shape. For example, if the sensor array is in an essentially rectangular shape, the LO beam profile can be made rectangular to ensure that all of the available energy would indeed be delivered to the sensor. Another potential use may be for example, spreading the beam energy uniformly across the optical sensor die.
  • Such a shaping operation may be done by lenses (110 in FIG.
  • FIG. 5 illustrates an embodiment by which all of the available energy is used to scan the sensors' array, and the reflected energy is conveyed to the optical transmitter. Reciprocity of light propagation insures that the Rx signal returns to the illuminated area.
  • sensor 400 comprises an array of pixels 410.
  • the optical energy 420 illuminates a sub array of pixels 430.
  • the beam continuously scans across the sensor at a rate that ensures that sub array 430 remains illuminated for the duration of a symbol length.
  • the time required to move spot 420 from its left edge 430 to its right edge 440 is equal to or greater than the time period of a symbol length. It can be seen that subsequent sub-arrays will be illuminated at different phases of the symbol. However, the phase of each sub array is predetermined, allowing compensation to be affected during signal processing.
  • scanning is implemented in prior art systems in order to manipulate the field of view of their respective sensors' array (thereby shifting light from one region of the field of view to another) , whereas according to the present invention solution, the field of view of each pixel remains constant.
  • the scanning carried out in the present solution allows to concentrate the available optical energy on fewer pixels, and consequently improving the system sensitivity .
  • the optical power is steered to illuminate a portion of the sensor.
  • the scanning rate and the spot size are designed to ensure that each pixel remains continuously illuminated for the duration of the coherent system symbol length.
  • each column (or row) of pixels is exposed to the transmitted symbol at different times (i.e. out of phase) . Because the phase of exposure is predetermined, this can be accounted for during signal processing.
  • the continuous scanning carries on until the entire sensor has been illuminated.
  • results from the scanning process are combined (or stitched together) into a single image representing the full field of view.
  • Steps (A) through (D) are repeated at a given frame rate.
  • FIG. 6 presents a flow chart demonstrating a method carried out in accordance with an embodiment of the present invention.
  • a light beam is generated by a light source and is optionally modulated.
  • Part of the modulated light beam is conveyed towards an optical sensor for use as a reference light signal thereat in the coherent detection process, and the shape of that part of the modulated light beam is adapted to match that of the shape of the optical sensor (step 610) .
  • that part of the modulated light beam may be shaped to match a sub-array of sensors comprised in the optical sensor.
  • Another part of the modulated light beam is conveyed towards an optical transmitter, and the shape of that part of the modulated light beam is adapted to match the Field of View (FOV) of the optical transmitter (step 620) .
  • FOV Field of View
  • that part of the modulated light beam may be shaped to match a sub- array of sensors.
  • the optical signals are continuously scanned across the sensors' array in a manner that would allow each sensor of that array to be simultaneously illuminated by both LO and Rx signals for the whole period of time that is comprised of the signal length and its time of flight (step 630) .
  • step 640 a coherent detection of signals being reflected off targets that are located within a pre-defined sub- FOV (field of view) is carried out, and information that relates to their distance and velocity relative to the detector is extracted therefrom.
  • FOV field of view
  • An appropriate detection algorithm associated with each sub array of pixels is adapted to match the specific modulation scheme of the signals it receives, where the adaptation is based on its relative position in the scanning sequence (step 650) .
  • the data received during the continuous scanning process is compiled (stitch together) thereby enabling to obtain information on the objects that are present within the entire field of view (step 660) .

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Remote Sensing (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Electromagnetism (AREA)
  • Analytical Chemistry (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • General Health & Medical Sciences (AREA)
  • Biochemistry (AREA)
  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

La présente invention concerne un agencement optique pour utilisation dans un système de détection cohérent. Cet agencement comprend une source de génération de faisceau lumineux pour transporter une série de signaux optiques modulés, un récepteur optique, une pluralité de capteurs optiques et des moyens pour permettre un balayage continu d'énergie optique à travers les capteurs optiques. L'agencement est caractérisé en ce que : a) une partie de l'énergie optique générée par la source de génération de lumière est transportée vers les capteurs optiques pour une utilisation en tant que signaux de lumière de référence ; et b) une partie de l'énergie optique générée par la source de génération de lumière est dirigée vers un émetteur optique pour émettre des signaux optiques qui sont réfléchis par des objets présents dans le champ de visée. Par conséquent, au moins une partie des capteurs optiques est éclairée simultanément par des signaux lumineux de référence et par les signaux réfléchis par des objets présents dans le champ de visée.
PCT/IL2018/050448 2017-04-23 2018-04-22 Agencement optique et procédé pour utilisation dans le balayage continu d'un capteur optique WO2018198115A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US201762488776P 2017-04-23 2017-04-23
US62/488,776 2017-04-23
US201762521591P 2017-06-19 2017-06-19
US62/521,591 2017-06-19

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PCT/IL2018/050448 WO2018198115A1 (fr) 2017-04-23 2018-04-22 Agencement optique et procédé pour utilisation dans le balayage continu d'un capteur optique

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5155363A (en) * 1989-09-13 1992-10-13 Hans Steinbichler Method for direct phase measurement of radiation, particularly light radiation, and apparatus for performing the method
US6075603A (en) * 1997-05-01 2000-06-13 Hughes Electronics Corporation Contactless acoustic sensing system with detector array scanning and self-calibrating
US6396587B1 (en) * 1999-06-26 2002-05-28 Carl-Zeiss-Stiftung Method for recording depth profiles in a specimen and apparatus therefor
US7262861B1 (en) * 2004-05-24 2007-08-28 Mrl Laboratories, Llc Ultrasound single-element non-contacting inspection system

Family Cites Families (7)

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Publication number Priority date Publication date Assignee Title
DE3886966T2 (de) * 1987-03-20 1994-08-18 Digital Optronics Corp Bildsystem in drei Dimensionen mit kohärenter optischer Detektion.
US4824251A (en) * 1987-09-25 1989-04-25 Digital Signal Corporation Optical position sensor using coherent detection and polarization preserving optical fiber
EP0367407A3 (fr) * 1988-10-14 1990-06-13 British Aerospace Public Limited Company Procédé et appareil de contrôle de l'alignement d'un faisceau laser transmis à un terminal transmetteur/récepteur optique par détection cohérente
EP0943075B1 (fr) * 1996-12-04 2005-06-01 The Research Foundation of city college of New York Systeme et procede d'execution de mesures optiques choisies
DE102007025891A1 (de) * 2007-06-01 2008-12-11 Johann Wolfgang Goethe-Universität Frankfurt am Main Vorrichtung und Verfahren zur Erzeugung und Erfassung kohärenter elektromagnetischer Strahlung im THz-Frequenzbereich
WO2009046717A2 (fr) * 2007-10-09 2009-04-16 Danmarks Tekniske Universitet Système de lidar cohérent basé sur un laser à semi-conducteur et un amplificateur
US7989859B2 (en) * 2008-02-08 2011-08-02 Omnivision Technologies, Inc. Backside illuminated imaging sensor with silicide light reflecting layer

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5155363A (en) * 1989-09-13 1992-10-13 Hans Steinbichler Method for direct phase measurement of radiation, particularly light radiation, and apparatus for performing the method
US6075603A (en) * 1997-05-01 2000-06-13 Hughes Electronics Corporation Contactless acoustic sensing system with detector array scanning and self-calibrating
US6396587B1 (en) * 1999-06-26 2002-05-28 Carl-Zeiss-Stiftung Method for recording depth profiles in a specimen and apparatus therefor
US7262861B1 (en) * 2004-05-24 2007-08-28 Mrl Laboratories, Llc Ultrasound single-element non-contacting inspection system

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