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WO2020020799A1 - Dispositif de détermination à résolution spatiale de la distance et/ou de la vitesse d'un objet - Google Patents

Dispositif de détermination à résolution spatiale de la distance et/ou de la vitesse d'un objet Download PDF

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Publication number
WO2020020799A1
WO2020020799A1 PCT/EP2019/069607 EP2019069607W WO2020020799A1 WO 2020020799 A1 WO2020020799 A1 WO 2020020799A1 EP 2019069607 W EP2019069607 W EP 2019069607W WO 2020020799 A1 WO2020020799 A1 WO 2020020799A1
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WIPO (PCT)
Prior art keywords
awg
optical
output channels
dispersive
light source
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PCT/EP2019/069607
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German (de)
English (en)
Inventor
Peter Westphal
Frank HÖLLER
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Carl Zeiss AG
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Carl Zeiss AG
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Publication of WO2020020799A1 publication Critical patent/WO2020020799A1/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
    • G01S7/4817—Constructional features, e.g. arrangements of optical elements relating to scanning
    • 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
    • G01S17/32—Systems determining position data of a target for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
    • G01S17/34—Systems determining position data of a target for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal
    • 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
    • G01S17/50—Systems of measurement based on relative movement of target
    • G01S17/58—Velocity or trajectory determination systems; Sense-of-movement determination systems
    • 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
    • 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
    • G01S7/4814—Constructional features, e.g. arrangements of optical elements of transmitters alone

Definitions

  • the invention relates to a device for spatially resolved distance and / or speed determination of an object.
  • the device can be used to determine distances of both moving and still objects and in particular to determine the topography or shape of a spatially extended three-dimensional object.
  • LIDAR For optical distance measurement of objects, a measuring principle also known as LIDAR is known, in which an optical signal whose frequency has changed over time is transmitted to the object in question and is evaluated after back-reflection on the object.
  • object can also be understood to mean a complex spatial scenery, for example in road traffic.
  • the object can therefore also consist of many individual objects with different distances and speeds.
  • 15a shows only a schematic representation of a basic structure known per se, in which a signal 1511 emitted by a light source 1510 with a frequency which changes over time (also referred to as “chirp”) is split into two partial signals, this split-up not, for example, via one shown partially transparent mirror takes place.
  • the term “light” also includes invisible radiation.
  • the two partial signals are coupled via a signal coupler 1550 and superimposed on one another at a detector 1560, the first partial signal reaching the signal coupler 1550 and the detector 1560 as a reference signal 1522 without reflection on the object labeled “1540”.
  • the second partial signal arriving at the signal coupler 1550 or the detector 1560 runs as a measurement signal 1521 via an optical circulator 1520 and a scanner 1530 to the object 1540, is reflected back by the latter and thus arrives with a time delay and changes accordingly in comparison to the reference signal 1522 - Different frequency to the signal coupler 1550 and to the detector 1560.
  • the detector signal supplied by the detector 1560 is evaluated relative to the measuring device or the light source 1510 via an evaluation device (not shown), the difference frequency 1531 between the measured signal 1521 and the reference signal 1522, which is detected at a specific point in time and shown in the diagram in FIG. 15b, being characteristic of the Distance of the object 1540 from the measuring device or the light source 1510.
  • the time-dependent frequency profile of the signal 1511 emitted by the light source 1510 can also be such that two sections are present. conditions in which the time derivative of the frequency generated by the light source 1510 is opposite to each other.
  • LIDAR measuring methods based on frequency modulation
  • LIDAR measuring methods based on the direct measurement of the transit time of radiation pulses.
  • the present invention can be used for both LIDAR measurement methods.
  • FOV Field of View
  • a device for spatially resolved distance and / or speed determination of an object has:
  • At least one light source for emitting optical radiation with a time-varying frequency
  • a dispersive unit with at least one dispersive optical element which effects a simultaneous distribution of the optical radiation divided by the unit for spatial division over a plurality of pixels on the object;
  • an evaluation device for determining the distance and / or speed of the object on the basis of the radiation reflected or scattered by the pixels on the object.
  • the invention is based in particular on the concept of realizing a comparatively fast scanning process when scanning as large a field of view (FOV) as possible, which realizes a spatial parallelization with regard to the measurement signals directed to the object and reflected or scattered by this object becomes.
  • FOV field of view
  • the spatial division in turn depending on the specific design of the said, at least one dispersive optical element can be carried out in different ways:
  • FIGS. 1-11 embodiments using an AWG arrangement are described below, in which the light generated by the tunable light source in exemplary embodiments simultaneously on a plurality of AWG 's (in spatially separated from one another, discrete channels) is distributed.
  • FIGS. 1-11 embodiments using an AWG arrangement are described below, in which the light generated by the tunable light source in exemplary embodiments simultaneously on a plurality of AWG 's (in spatially separated from one another, discrete channels) is distributed.
  • the light generated by the tunable light source is spatially divided into a plurality of spatially separate laser lines, with these laser lines then a single dispersive optical element for example in the form of a spectral grating.
  • the device has a plurality of detectors for detecting in each case a superposition signal consisting of radiation divided by the unit, reflected or scattered by the object, and reference radiation emitted by the light source and not reflected or scattered by the object.
  • the device also has at least one deflection element, via which the angle at which light is directed from the dispersive unit to the object can be varied.
  • the dispersive unit has an AWG arrangement which has a plurality of AWGs, each of these AWGs causing a frequency-selective distribution of the measurement signal to a plurality of output channels belonging to the respective AWG, and an imaging system for optically imaging these output channels in the direction of the object.
  • the invention is based on the concept of using an AWG arrangement comprising a plurality of AWGs and realizing the largest possible field of view (FOV) with high two-dimensional spatial resolution, and which AWGs generated by these AWGs due to the dispersive effect, to map spatially separated output channels via an imaging system to the object to be measured with regard to its distance and, if applicable, its speed.
  • the invention includes in this case the concept of stacking s to obtain a saudimensi--dimensional array of output channels, a plurality of AWG ', said output channels in a by the imaging system in the direction of the object surface are Image Files cash.
  • each of these AWG's has at least 10 output channels.
  • the plurality of AWGs are stacked to obtain a two-dimensional arrangement of output channels.
  • this two-dimensional arrangement of output channels lies in a direction through the imaging system Object mappable area.
  • the output channels can be mapped to infinity without the invention being restricted thereto.
  • At least one spreading element for generating secondary output channels is provided at a greater distance from one another compared to primary output channels generated by one AWG each.
  • the (primary) output channels provided by the AWG arrangement can be spatially separated, with the result that the imaging system for optically imaging the secondary output channels in the direction of the object is subject to comparatively lower (enlargement) requirements have to.
  • Said spreading element can be implemented, for example, by additional waveguides, which in embodiments can also be integrated in the wafer structured to form the AWG 's of the AWG arrangement.
  • optical fibers or glass fibers can also be used for the expansion element instead of waveguides.
  • the primary output channels or the secondary output channels lie in a surface that can be imaged by the imaging system in the direction of the object.
  • This surface can in particular have a non-planar shape, in particular a spherical, ellipsoid, parabolic, hyperbolic or cylindrical shape, with the result that the imaging optics used to project the arrangement of (primary or secondary) output channels in the direction of the object are made simpler can be.
  • the device furthermore has a spectral grating for at least partially averaging out speckle patterns.
  • the imaging system is designed as a zoom lens with a variably adjustable field of view.
  • Such an arrangement has the advantage that, in practice, the device can be flexibly adapted (for example to the respective traffic situation or speed).
  • a first possibility for realizing the sequential processing of the AWG's is composed of an additional weight, based on the light or Sig- nalweg upstream AWG in the insert 's.
  • this wavelength range and up to solution S are selected so that additional upstream AWG 'that each "covering" of the of this upstream AWG through the dispersive effect ER- witnessed output channels just a respective AWG the following AWG arrangement with the consequence that with the frequency tuning of the light source also automatically switches the additional upstream AWG sequentially with respect to the further light path between the AWGs of the AWG arrangement.
  • Such an embodiment has the advantage that the use of fundamentally undesirable, mechanically movable components such as deflecting mirrors or the like is also dispensed with, in contrast a comparatively large required tuning range of the light source being accepted.
  • This movable optical element can be equipped, for example, only as an optical fiber, which is shifted from one input light guide of the AWG arrangement to the next input light guide of the AWG arrangement with the aid of a (for example, piezoelectric) drive.
  • the movable optical element can also be a tiltable or displaceable reflective or refractive component such as e.g. comprise a mirror, a lens, a prism or a combination of these components in order to implement a variable coupling into different input light guides of the AWG arrangement by tilting or shifting these component (s).
  • a tiltable or displaceable reflective or refractive component such as e.g. comprise a mirror, a lens, a prism or a combination of these components in order to implement a variable coupling into different input light guides of the AWG arrangement by tilting or shifting these component (s).
  • the light can in this case by corresponding division of power and laser power simultaneous "Operation" more or sämtli- cher AWG's of AWG-arrangement carried out with light, wherein the respective AWG's turn may be allocated from the JE LAN measuring signal and the reference signal superimposing signal generated each separate detectors for detecting the.
  • this configuration has the advantage of a high degree of parallelization and a correspondingly comparatively fast two-dimensional measuring process with an avoidable increase in the tuning range of the light source, but in addition to the required high light output of the light source and also the increase in construction due to the provision of a plurality of detectors Effort is accepted.
  • the device also has a deflection element, via which the respective angle at which light is directed from the AWGs of the AWG arrangement to the object can be varied.
  • a deflection element as a “beam deflector”, which can be realized as a mechanically movable deflection element or also as a polarization-optical or phase-optical deflection element, has the advantage that the incomplete arrangement of pixels or Laser spots can be filled via said beam deflector by bridging a spatial distance between the individual AWGs of the AWG arrangement in the optical imaging of the output channels in the direction of the object.
  • the dispersive unit has a single dispersive optical element.
  • this dispersive optical element is a spectral grating.
  • an anamorphic optical system in particular cylinder optics or toric optics, is arranged between the unit for spatially dividing the optical radiation emitted by the light source and the dispersive optical element or spectral grating. This first anamorphic optical system enables narrow laser lines to be generated on the spectral grating.
  • a second anamorphic optical system in particular a cylindrical optic or a toric optic, is arranged in the optical beam path after the dispersive optical element or spectral grating.
  • This second anamorphic optical system makes it possible to collimate the laser beams emanating from the dispersive optical element or spectral grating in one dimension.
  • the distance and / or speed is determined in an interferometric manner.
  • the distance and / or speed is determined by means of transit time measurements.
  • Figures 1 a-1 b are schematic representations to explain the possible structure of an AWG arrangement used in a device according to the invention
  • Figures 2-3 are schematic representations of the structure of a device according to the invention in exemplary embodiments
  • FIGS. 4-5 are schematic representations of possible tuning schemes in the operation of a device according to the invention.
  • Figure 6 is a schematic representation of the structure of a in
  • FIG. 7 shows a schematic illustration of a possible tuning scheme when using the spreading element from FIG. 6;
  • Figures 8a-8b are graphs for explaining a dung useful in the inventions Gauss's measuring beam (8a) or the result of a simulation performed for this statement ( Figure 8b);
  • Figure 9 is a diagram illustrating a possible
  • FIGS. 10a-10c are schematic representations of further embodiments of the invention using an additional optical deflection element
  • FIG. 11 a-11 c schematic representation of further embodiments of the imaging system that can be used for the invention.
  • FIG. 12-13 show schematic representations of the structure (FIG. 12) and the mode of operation (FIG. 13) of a device according to the invention in a further exemplary embodiment;
  • Figure 14 is a schematic representation of the operation of a device according to the invention in a further exemplary embodiment.
  • FIGS. 15a-15b are schematic representations for explaining the structure and mode of operation of a conventional device for determining the distance.
  • Embodiments of a device according to the invention for spatially resolved distance determination are described below with reference to the schematic representations in FIGS. 1 to 11.
  • FIG. 1 a initially shows, in a highly simplified schematic representation, the structure of an individual AWG, to which electromagnetic radiation with a time-varying frequency is supplied via an input light guide 101 from a light source (not shown in FIGS. 1 a-1 b) ,
  • the radiation enters the AWG waveguide 103 of different lengths via a first free radiation area 102 and, at the end of a second free radiation area 104, interferes constructively at different locations due to the different phase delays caused in the waveguides 103.
  • a plurality M (where M is preferably at least 10 and may be, in embodiments of the invention, at least 100).
  • FIG. 1 b not only an AWG, but a stack of a plurality of N AWG's used, again with N examples may be play, 5.
  • the number N determines the degree of parallelization of the LIDAR measurements, which can therefore be selected within wide limits.
  • a (for example spherical) shape of the end face in question can be advantageous in view of the fact that the imaging optics used for projecting the arrangement of output channels in the direction of the object can possibly be made simpler, since, for example, part of the required optical Effect can already be taken over by said geometry of the end face and / or the correction of an image field curvature by the subsequent optical system can be dispensed with.
  • FIG. 2 shows an overall view of a device according to the invention in a first embodiment.
  • Electromagnetic radiation with a time-varying frequency is emitted by a tunable light source or a laser (possibly with an optical amplifier) via an optical beam splitter 202, in part as a measurement signal via the AWG arrangement 205 according to the invention (for example with the structure shown in FIG. 1b) and an imaging system 206 for imaging the provided output channels is directed onto an object 210 to be measured with regard to its distance and possibly its speed.
  • 204 denotes a unit for the sequential distribution of the light generated by the light source 201 over the AWG ' s of the AWG arrangement 205, this unit 204 in turn as an AWG, as a grating or as a movable optical element (for example as Slidable optical fiber, as a micromechanically actuated mirror or as a refractive optical element such as a lens or a prism) can be configured.
  • the overlay signal generated at the detector 203 by superimposing the reference signal and the measurement signal is evaluated in a control and evaluation unit 207 to determine the distance and, if appropriate, the speed of the object 210.
  • One AWG of the AWG arrangement 205 after the other is “processed” successively via said unit 204 and, as a result, a two-dimensional scanning of the object 210 is achieved by means of the AWG arrangement 205.
  • “209” denotes an optional spectral grating in the device according to the invention, by means of which speckle patterns, which can be attributed to the spatial coherence of the light generated by the light source 201 and have a random character, can be suppressed or at least partially averaged out .
  • Such coherent disturbances which occur in the form of speckle patterns and which, without further measures, lead to an undesired dependence of the measured intensity values on the respective object location, are in this case achieved by a lateral movement of the measuring beam attained by the dispersion of the spectral grating 209 Frequency tuning of the light source 201 averaged.
  • the dispersion of the spectral grating 209 (in ° / Hz) can e.g. should be selected so that the lateral movement of the measuring beam during a complete frequency sweep is in the range of 2-5 beam diameters.
  • the spectral grating 209 described above according to FIG. 2 is arranged on the light exit side of the imaging system 206, the invention is not limited to this. In further embodiments, this (basically optional) spectral grating 209 can also be arranged at another position following the AWG arrangement 205 in the beam path.
  • unit 204 for sequential distribution of the light generated by the light source 201 also has this as AWG supply additional upstream AWG in comparison with the AWG's of AWG assembly 205, a coarser spectral resolution, whereby in particular the first channel of the additional upstream AWG's covers the first AWG, so that after processing of the individual output channels of the first AWG's of the AWG-assembly 205, a switch on the upstream additional AWG to the second AWG AWG assembly 205 (with a corresponding waste processing of its output channels), etc.
  • mechanically moving elements such deflection can mirrors, lenses or prisms to the realization of the switching between the individual AWG 's of the AWG-assembly 205 omitted, but a requested from the upstream additional AWG, correspondingly large tuning range of the light source is required 201 ,
  • the unit 204 is configured in the form of at least one movable optical element, such an increase in the tuning range of the light source 201 can be dispensed with.
  • FIG. 3 shows a further possible embodiment of the invention, in which, in comparison to FIG. 2, analogous or essentially functionally identical components are denoted by reference numerals increased by “100”.
  • Fig. 3 2 differs from that of FIG. Characterized in that a simultaneous processing of the AWG's is carried out of the AWG array 305th
  • a light source 301 that can be tuned serves first for this purpose following unit 308 for simultaneous distribution of ER- testified from the light source 301 light on the AWG 's 305 of the AWG array Consequently, a parallelized measurement over a plurality of the respective AWG's done associated detectors 303rd "302" denotes a corresponding number of optical beam splitters, via which the radiation from light source 301, as described above, is distributed in part via AWG arrangement 305 and imaging system 306 to object 310 (as well as reflected or scattered) Measurement signal returned) and the rest is coupled out as a reference signal and superimposed on the detectors 303 with the respective measurement signal.
  • Each of the detectors 303 used simultaneously can have two photodiodes, each with associated transimpedance amplifiers, wherein the detectors 303 can also be accommodated in a common integrated optics.
  • the photodiodes can also be designed as individual or matrix-like avalanche photodiodes.
  • N optical beam splits are also required, since N measuring beams are present at the same time.
  • the N interferometric beam splits or beam mergers can also be carried out using a single beam splitter plate.
  • the time-dependent frequency profile of the signal emitted by the light source to obtain additional information regarding the relative speed between the object and the measuring device or the light source is such that there are two sections in which the time derivative of the the frequency of the generated light source is opposite to each other.
  • effects of the Doppler effect can be recorded and taken into account in a manner known per se.
  • the light source is further tuned by 10 GHz within the shortest possible time Tzw in order to switch to the next (vertical) pixel.
  • a change in frequency Af corresponds to a change in angle by DQ, and this change in angle can be suitably selected by designing the optical imaging system.
  • B 1 GHz, which is less by a factor of 10
  • the tuning scheme according to FIG. 4 is particularly advantageous if a comparatively low value of the lateral speed of the laser beam on the object is desired (e.g. because otherwise too many random interference phases would be impressed on the object surface by the measurement signal).
  • FIG 5 shows an alternative tuning scheme for the temporal change in the frequency of the light source.
  • the measurements with a time-increasing frequency (“chirp-up measurements”) for all pixels are carried out directly one after the other, whereas, on the other hand, the measurements with a time-decreasing frequency (“chirp-down measurements”) are only carried out subsequently for all pixels , B ⁇ Af also applies here.
  • the tuning scheme according to FIG. 5 has the advantage that the same tuning rate df / dt can be used at any time, only the sign being reversed after half the time. It is assumed that the object to be measured moves only negligibly during the entire tuning, so that the assignment of the individual "chirp-up" and “chirp-down” measurements does not lead to errors when considering the Doppler effect.
  • the tuning scheme shown in FIG. 5 can correspond to a vertical scan or the scan of the N * M pixels, ie the entire field of view (FOV).
  • FIG. 6 shows a further embodiment of the invention, in which, in comparison to FIG. 1, analogous or essentially functionally identical components are designated with reference numerals increased by “500”.
  • FIG. 6 differs from that of FIG. 1 a-1 b by an additional spreading element 620, which serves to determine the distance between the output channels generated by one AWG each before they are projected onto the imaging system in the direction of the object to enlarge.
  • the spreading element 620 is used to generate secondary output channels with a greater distance from one another compared to primary output channels generated by one AWG each.
  • the secondary output channels generated by the spreading element 620 lie in a surface that can be imaged in the direction of the object by the subsequent imaging system, wherein this surface can also have a non-flat, in particular a spherical, ellipsoid, parabolic, hyperbolic or cylindrical shape.
  • this has the advantage that the imaging optics used to project the arrangement of (primary or secondary) output channels in the direction of the object can be made simpler.
  • the additional spreading element 620 has a stack of N planar individual elements for channel spreading, the light guides of the spreading element 620 being optically coupled to the output channels of the AWG arrangement.
  • the light guides consist of wise from waveguides in a planar photonic structure.
  • optical fibers or glass fibers can also be used for the spreading element 620 instead of waveguides.
  • the use of the spreading element 620 makes it possible to cover a larger solid angle range on the one hand and on the other hand to reduce the angular velocity of the measuring beam on the object during the individual distance measurements, which in turn reduces phase fluctuations and increases the achievable depth resolution or peak widths in the measured distance spectrum can be reduced.
  • the use of the spreading element 620 leads to a changed “frequency-angle assignment” during the scanning process, as indicated in the schematic tuning scheme of FIG. 7.
  • FIG. 8b shows the result of an exemplary simulation calculation in supply grundelegung a Gauss's measuring beam in accordance with FIG. 8a.
  • a beam diameter at the exit of the optical system of 15 mm and a wavefront radius at the exit of the optical system of 1000 m are taken as a basis, a beam diameter of 19 mm is obtained at a distance of 100 m.
  • the lateral velocity of the measuring beam at a distance of 100 m is assumed to be 10 km / s, for example.
  • the simulation shows that a distance measurement of up to 200 m with a high signal / noise ratio (SNR> 10) is possible with the parameters mentioned.
  • FIG. 9 shows a diagram to illustrate a possible application of the device according to the invention in road traffic. Since there is a maximum range as well as with a straight view ("901" in Fig. 9) the most accurate possible longitudinal speed measurement arrives, the device according to the invention can be used and designed for this solid angle such that a minimum range of 200 m is achieved. Since covering a large horizontal angular range (> 100 °) with a long range and high lateral resolution is technologically difficult with a single measuring device, at least two further measuring devices can be used for the lateral viewing directions. Since the lateral viewing directions ("902" and "903" in Fig. 9) tend to depend on a large angular range rather than a long range, the other measuring devices can be adapted to these requirements.
  • the range can be limited to 70 m here in order to keep the technical outlay and the optical power to be emitted comparatively low.
  • the measurement in the lateral viewing directions 902 and 903 can also be carried out using a device according to the invention or
  • TOF runtime-of-flight
  • the device in addition to the AWG arrangement 1010 according to the invention and the imaging system 1020, the device has a deflection element 1030, by means of which the respective angle at which light is directed from the AWGs of the AWG arrangement 1010 to the object can be varied.
  • This deflector 1030 allows, as a result, without limiting the field of view (FOV), which eg * may be 20 ° 20 °, the required arrival number N of the inventive AWG arrangement existing AWG 's to a moderate level (for example to restrict 5 to 50), since Any remaining spatial distance between each AWG 's of the AWG array 1010 can be bridged in the optical imaging of the output channels in the direction of the object, as indicated in FIG. 10a.
  • FOV field of view
  • the deflection element 1030 can be a mechanically movable optical element, wherein both reflective elements (for example a mirror that can be adjusted via at least one solid-state joint) and refractive optical elements (for example lenses or prisms) can be used.
  • reflective elements for example a mirror that can be adjusted via at least one solid-state joint
  • refractive optical elements for example lenses or prisms
  • OPA optical Phased Array
  • LCPG Liquid Crystal Polarization Grating
  • the implementation of the above-described “filling” of the pattern of laser spots or pixels generated by the AWG arrangement can be carried out in one or two dimensions (ie with deflection of the radiation arriving from the AWG arrangement in one spatial direction or in two to one another vertical spatial directions).
  • the laser spot or pixel density in the vertical direction can also be increased with a two-dimensional deflection element.
  • the deflection element 1030 described above according to FIG. 10a is only for said gaps in the generated pattern of laser spots or pixels is required, the angular ranges to be set via the deflection element 1030 are comparatively small and can be of the order of 1 °. Furthermore, due to the fact that with each new deflection angle N set via the deflection element 1030, “new” columns of laser spots or pixels are generated on the object, the setting of the beam deflection can be carried out comparatively slowly (relative to a scanner that individually controls each laser spot) ) respectively.
  • FIG. 10b and 10c show schematic representations to explain possible concrete exemplary embodiments using the LCPG deflection mentioned above.
  • a comparatively less dense AWG arrangement 1011 with comparatively coarser angular steps of 0.9 ° each, which completely covers the field of view to be scanned (FoV) in the horizontal direction is used in combination with two LCPG arrangements (each LCPG arrangement).
  • Arrangement consists of at least two LCPGs and can generate at least two deflection angles).
  • One of these LCPG arrangements generates 6-7 angular steps of 3.2 ° each in the vertical direction, and the other LCPG arrangement generates 8-9 angular steps of 0.1 ° each in the horizontal direction.
  • a field of view (FoV) of approx. 20 ° can be covered two-dimensionally with 0.1 ° intermediate steps during the scanning process.
  • a comparatively dense AWG arrangement 1012 with comparatively smaller angular steps of 0.1 ° each, which only covers an angular range of 2.5 ° in the horizontal direction from the field of view to be scanned (FoV) is used in combination with two LCPG arrangements ( where again each LCPG arrangement consists of at least two LCPGs and can generate at least two deflection angles).
  • Each LCPG arrangement generates 6-7 angular steps of 3.2 ° each in the vertical direction, and the other of these LCPG arrangements generates 8-9 angular steps of 2.5 ° each in the horizontal direction.
  • a FoV of approx. 20 ° with 0.1 ° intermediate steps can be two-dimensional in the scanning process. be covered regionally.
  • “1035” in FIG. 10a is a fundamentally optional spectral grating which serves to at least partially find out speckle patterns (due to the spatial coherence of the light) (analogous to the embodiments of FIGS. 2 and FIG. 3).
  • FIG. 11 a shows an exemplary imaging system 1120 for generating different beam directions as a function of the lateral position of the AWG output channels.
  • Other suitable imaging systems can also include optical elements behind the deflection element 1030.
  • the imaging system can also be designed as a zoom lens with a variably adjustable field of view, as a result of which the device can be flexibly adapted (for example to the respective traffic situation or to the speed of the vehicle with the device according to the invention) ,
  • FIG. 11 b shows an exemplary optical imaging system with a spherical radiation surface 1100 or end surface shown enlarged in FIG. 11 c, in which the AWG output channels or the secondary output channels provided by a spreading element according to FIG. 6 are located.
  • the spherical shape of the radiation surface 1100 can be advantageous in view of the fact that the imaging optics 1110 used for projecting the arrangement of output channels in the direction of the object can be made simpler, since part of the required optical effect is already taken over by said geometry of the radiation surface 1100 and / or the correction of a field curvature by the subsequent optical system 1110 can be dispensed with.
  • a diffraction-limited imaging quality over the entire field of view can be achieved with a comparatively simple optical imaging system 1110.
  • the invention was described in the above-mentioned exemplary embodiments predominantly on the assumption of an interferometric signal evaluation, since it is particularly suitable for this. Nevertheless, the invention can also be used for distance and / or speed determinations based on transit time measurements of radiation pulses.
  • the device according to FIG. 12 has a tunable light source 1201 (possibly with an optical amplifier) and a plurality N of optical beam splitters, designated “1203”, to the extent analogous to FIG. 3, with these beam splitters having the correspondingly divided optical radiation or laser power of the light source 1201 is supplied.
  • PIC photonically integrated circuit
  • the device according to FIG. 12 does not have an AWG arrangement for the purpose of parallelizing the scanning process, but rather a single dispersive optical element 1206, which according to FIG is designed as a spectral grating with grating lines running in the horizontal direction.
  • a single dispersive optical element 1206 which according to FIG is designed as a spectral grating with grating lines running in the horizontal direction.
  • an optical system 1205 in the form of an anamorphic optics (in particular cylindrical optics) which, as shown only schematically in FIG. 13, causes laser lines (correspondingly to the dispersive optical element or the spectral grating) 13), which are horizontally focused and vertically collimated.
  • the partial beams in a focal plane are converted into (spatial) laser lines via the optical system 1205, which have a lateral distance D> 0 in the focal plane.
  • all N laser lines are simultaneously deflected in angle by the dispersive optical element 1206.
  • a (balanced) detector 1204 belongs to each laser line, so that the N measuring beams can be read out simultaneously.
  • a first part of each of the partial beams thus reaches the optical system 1205, while a second part reaches the detection system comprising detectors 1204 and serves as reference radiation.
  • the overlay signals generated by the detectors 1204 by superimposing the reference signal and the measurement signal are evaluated in a control and evaluation unit 1208 to determine the distance and, if appropriate, the speed of the object 1210.
  • the dispersive element 1206 ensures that the N measuring beams scan the field of view (FoV) in a spatial dimension (vertical in the example), this scanning being able to take place step by step or continuously.
  • OPA optical phased array
  • a spatial one can also be used as the dispersive optical element 1206
  • the dispersive optical element 1206 in the form of the spectral grating causes a deflection in the vertical direction when the wavelength or frequency of the light source 1201 is tuned as a result of dispersion for incident light.
  • a collimation in the horizontal direction is then achieved via a second optical system 1207 (which can also be designed as an anamorphic system) following the dispersive optical element 1206 in the beam path.
  • a (for example mechanically movable) deflection element 1209 is preferably also provided in the beam path after the dispersive optical element 1206, by means of which the angle at which light is directed to the object 1210 can be varied analogously to the deflection element 1030 from FIG spatial distance which the laser lines according to FIG.
  • the deflection element 1209 can also be arranged in front of the second optical system 1207 in relation to the optical beam path.
  • the deflection element 1209 can be used to deflect the measurement radiation perpendicularly to the specular angle deflection (caused by the dispersive optical element 1206). In this way, a sub-pixel resolution can be achieved in the exemplary embodiment by means of said deflection element 1209 — as is also indicated schematically in FIG. 13 by dashed vertical lines — by additional horizontal deflection. For example only, angular steps of 1 ° each can be set between the angular steps of 0.2 ° each, which are finer from the dispersive optical element 1206 or spectral grating, via the deflection element 1209 according to FIG. 13.
  • Such a VIPA can be constructed in a manner known per se from a semi-cylindrical lens and a glass plate subsequently tilted in the beam path, with “line-focused” light entering the glass plate via the semi-cylindrical lens and exiting from it at deflection angles dependent on the wavelength.
  • the bottom line of laser lines corresponds to the measurement beams coupled into the VIPA, a collimated beam ultimately being obtained again via a plurality of reflections.
  • the reflectivity curve in the VIPA should preferably be designed so that the distribution of intensity is as symmetrical as possible (for example, Gaussian) at the VIPA output.
  • Device for spatially resolved distance and / or speed determination of an object with at least one light source (201, 301) for emitting an optical signal with a time-varying frequency; an evaluation device for determining a distance and / or a speed of the object (210, 310) on the basis of a measurement signal originating from the signal, reflected or scattered on the object; an AWG arrangement (100, 205, 305, 1010) which has a plurality of AWGs, each of these AWGs having a frequency-selective distribution of the Measurement signal caused to a plurality of output channels belonging to the respective AWG; and an imaging system (206, 306, 1020) for optically imaging these output channels in the direction of the object (210, 310).
  • a unit (204, 308) for the selective distribution of the light generated by the light source on the AWG's of the AWG arrangement (205, 305 ) is provided.
  • this unit (308) is designed for the simultaneous distribution of the light generated by the light source (301) over the AWG's.
  • Device according to sentence 8 characterized in that it has a plurality of detectors (303) each assigned to one of the AWGs for detecting a superposition signal generated from the respective measurement signal and a reference signal.
  • each of these AWG's has at least 10 output channels.
  • Device characterized in that it also has at least one deflection element (1030), via which the angle at which light is directed from the AWG's of the AWG arrangement (1010) to the object can be varied is.
  • this deflection element (1030) is a phase-optical or polarization-optical deflection element.
  • Device characterized in that at least one spreading element (620) is provided between the AWG arrangement and the imaging system to enlarge the distance between the output channels generated by one AWG each.
  • Device according to one of the preceding sentences, characterized in that the imaging system is designed as a zoom lens (1120) with a variably adjustable field of view. 17. Device according to one of the sentences 1 to 16, characterized in that the distance and / or speed is determined in an interferometric manner.

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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)
  • Optical Radar Systems And Details Thereof (AREA)

Abstract

L'invention concerne un dispositif de détermination à résolution spatiale de la distance et/ou de la vitesse d'un objet, comprenant : au moins une source lumineuse (301, 1201) pour émettre un rayonnement optique présentant une fréquence variant dans le temps ; une unité (308, 1202) pour diviser spatialement le rayonnement optique émis par la source lumineuse (301, 1201) ; une unité dispersive comportant au moins un élément optique dispersif, qui provoque une distribution simultanée du rayonnement optique divisé spatialement par l'unité (308, 1202) sur une pluralité de pixels sur l'objet (310, 1210) ; et un dispositif d'évaluation (307, 1208) pour déterminer la distance et/ou la vitesse de l'objet (310, 1210) en fonction des pixels du rayonnement réfléchi ou dispersé sur l'objet (310 , 1210).
PCT/EP2019/069607 2018-07-24 2019-07-21 Dispositif de détermination à résolution spatiale de la distance et/ou de la vitesse d'un objet Ceased WO2020020799A1 (fr)

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DE102019135753B3 (de) * 2019-12-23 2020-10-29 Carl Zeiss Ag Optische Scanvorrichtung, Verwendung derselben und LIDAR-System

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20150378187A1 (en) * 2014-06-28 2015-12-31 John Heck Solid state lidar circuit
US20180024246A1 (en) 2016-07-21 2018-01-25 Lg Electronics Inc. Lidar apparatus for vehicles
WO2018107237A1 (fr) 2016-12-16 2018-06-21 Baraja Pty Ltd Estimation de profil spatial d'environnement

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US8098185B2 (en) * 2006-11-13 2012-01-17 Battelle Memorial Institute Millimeter and sub-millimeter wave portal

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20150378187A1 (en) * 2014-06-28 2015-12-31 John Heck Solid state lidar circuit
US20180024246A1 (en) 2016-07-21 2018-01-25 Lg Electronics Inc. Lidar apparatus for vehicles
WO2018107237A1 (fr) 2016-12-16 2018-06-21 Baraja Pty Ltd Estimation de profil spatial d'environnement

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