WO2021241101A1

WO2021241101A1 - Measurement device, control method for measurement device, and program

Info

Publication number: WO2021241101A1
Application number: PCT/JP2021/016567
Authority: WO
Inventors: 宏幸高木; 安寿稲田; 了一高山; 和也久田
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2020-05-27
Filing date: 2021-04-26
Publication date: 2021-12-02
Also published as: JP2023099238A

Abstract

This measurement device comprises: an optical scanner including an optical deflector, a light emission element that emits light of which the frequency changes over time, a splitter that is disposed on an optical path of the light and separates the light into reference light and irradiation light, and a photodetector; and a processing circuit that controls the light emission element, the light deflector, and the photodetector and processes a signal output from the photodetector, wherein the processing circuit allows the optical scanner to emit a line beam, changes an emission direction of the line beam along a direction intersecting a direction in which the line beam extends, allows the photodetector to detect interference light between the reference light and a reflected light generated in the photodetector by irradiating an object with the line beam, and generates and outputs measurement data of the object on the basis of the signal.

Description

Measuring device, measuring device control method, and program

This disclosure relates to a measuring device, a control method of the measuring device, and a program.

Conventionally, there is a LiDAR (Light Detection and Ringing) technology that acquires data related to the distance of an object by irradiating the object with light and detecting the reflected light from the object. A typical example of a measuring device using LiDAR technology includes a light emitting device, a photodetector, and a processing circuit. The light emitting device includes a light deflector that changes the direction of light. The photodetector detects the reflected light from the object and outputs a signal according to the intensity of the reflected light. The processing circuit acquires data on the distance of an object based on the signal output from the photodetector, for example, by TOF (Time Of Flight) technology. Patent Documents 1 to 3 disclose examples of configurations capable of changing the direction of light.

International Publication No. 2013/1682866 Japanese Unexamined Patent Publication No. 2013-016591 International Publication No. 2014/110017

The present disclosure provides a measuring device capable of efficiently acquiring measurement data of an object.

The measuring device according to one aspect of the present disclosure is arranged on a light deflector, a light emitting element that emits light whose frequency changes with time, and the light path, and converts the light into reference light and irradiation light. An optical scanner including a splitter and an optical detector to be separated, a processing circuit that controls the light emitting element, the optical deflector, and the optical detector, and processes a signal output from the optical detector. The processing circuit causes the optical scanner to emit a line beam, and changes the emission direction of the line beam along a direction intersecting the direction in which the line beam extends, and causes the optical detector to emit the line beam. The interference light between the reflected light generated by irradiating the object with the line beam and the reference light is detected, and the measurement data of the object is generated and output based on the signal.

Comprehensive or specific embodiments of the present disclosure may be implemented in recording media such as systems, devices, methods, integrated circuits, computer programs or computer readable recording discs, systems, devices, methods, integrated circuits, etc. It may be realized by any combination of a computer program and a recording medium. The computer-readable recording medium may include a non-volatile recording medium such as a CD-ROM (Compact Disc-Read Only Memory). The device may consist of one or more devices. When the device is composed of two or more devices, the two or more devices may be arranged in one device, or may be separately arranged in two or more separated devices. As used herein and in the claims, "device" can mean not only one device, but also a system of multiple devices.

According to the technology of the present disclosure, it is possible to realize a measuring device capable of efficiently acquiring measurement data of an object.

FIG. 1A is a diagram schematically showing a measuring device according to an exemplary embodiment of the present disclosure. FIG. 1B is a diagram schematically showing a measuring device according to an exemplary embodiment of the present disclosure. FIG. 2 is a flowchart of the operation of FMCW processing executed by the processing circuit. FIG. 3 is a perspective view schematically showing an example of a vehicle in which a measuring device is mounted on the front surface. FIG. 4A is a diagram schematically showing a first example of emitting a plurality of irradiation line beams toward a target scene in front of a vehicle traveling on a road. FIG. 4B is a diagram schematically showing the relationship between the strength of the beat signal and the distance calculated from the frequency of the beat signal in the first example shown in FIG. 4A. FIG. 5A is a diagram schematically showing a second example of emitting a plurality of irradiation line beams toward a target scene in front of a vehicle traveling on a road. FIG. 5B is a diagram schematically showing the relationship between the strength of the beat signal and the distance calculated from the frequency of the beat signal in the second example shown in FIG. 5A. FIG. 6A is a diagram schematically showing a third example of emitting a plurality of irradiation line beams toward a target scene in front of a vehicle traveling on a road. FIG. 6B is a diagram schematically showing the relationship between the strength of the beat signal and the distance calculated from the frequency of the beat signal in the third example shown in FIG. 6A. FIG. 7A is a diagram schematically showing an example of emitting an irradiation flash light toward a target scene in front of a vehicle traveling on a road. FIG. 7B is a diagram schematically showing the relationship between the strength of the beat signal and the distance calculated from the frequency of the beat signal in the example shown in FIG. 7A. FIG. 8 is a flowchart showing a distance measuring operation of a plurality of objects and a vehicle control operation in the present embodiment. FIG. 9 is a diagram schematically showing a measuring device according to the first modification. FIG. 10 is a diagram schematically showing a measuring device according to the second modification.

The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, arrangement positions and connection forms of the components, steps, and the order of the steps shown in the following embodiments are examples, and are not intended to limit the technique of the present disclosure. Among the components in the following embodiments, the components not described in the independent claims indicating the highest level concept are described as arbitrary components. Each figure is a schematic diagram and is not necessarily exactly illustrated. Further, in each figure, substantially the same or similar components are designated by the same reference numerals. Duplicate descriptions may be omitted or simplified.

Before explaining the specific embodiment of the present disclosure, the findings underlying the present disclosure will be explained.

Patent Document 1 discloses a configuration in which the direction of emitted light is changed by rotating a mirror by mechanically driving a MEMS (Mechanical System). The mirror is called a MEMS mirror.

Patent Document 2 describes a waveguide provided with an optical waveguide layer in which light is waveguideed inside, a first distributed Bragg reflector formed on the upper surface and the lower surface of the optical waveguide layer, and a waveguide for incidenting light in the waveguide. A light deflection element including a light incident port and a light emitting port formed on the surface of the waveguide for emitting light incident from the light incident port and waveguide in the waveguide is disclosed.

Patent Document 3 discloses an optical phased array having a plurality of nanophotonic antenna elements arranged two-dimensionally. Each antenna element is optically coupled to a variable optical delay line (ie, a phase shifter). In this optical phased array, a coherent optical beam is guided to each antenna element by a waveguide, and the phase of the optical beam is shifted by a phase shifter. This makes it possible to change the amplitude distribution of the far-field radiation pattern.

The light emitting device disclosed in Patent Documents 1 to 3 scans the target scene two-dimensionally with a light beam having a relatively small beam diameter. When there are multiple objects in the target scene, in a conventional measuring device, the processing circuit causes the light emitting device to individually irradiate the plurality of objects with a light beam, and the photodetector to individually irradiate the light beam. The generated reflected light is detected and a signal corresponding to the intensity of the reflected light is output. The processing circuit acquires data on the distances of a plurality of objects by processing the signal by TOF technology. When the signal obtained by individually irradiating a plurality of objects with a light beam is processed by the TOF technique, it takes a lot of time to acquire data on the distances of the plurality of objects.

In TOF technology, it is important to achieve both a wide dynamic range and high resolution in terms of distance when acquiring data related to the distance of an object. In TOF technology, disturbances such as sunlight can be a problem in terms of light sensitivity. In TOF technology, the velocity of an object is calculated from the change in the distance to the object for each scan. Therefore, when applying LiDAR technology to autonomous driving, there may be a delay in detecting the speed of a fast moving object.

In recent years, FMCW (Frequency Modified Continuos Wave) -LiDAR technology has been developed that achieves both a wide dynamic range and high resolution with respect to distance, is less susceptible to disturbance, and can detect the speed of an object moving at high speed. Non-Patent Document 1 discloses an example of FMCW-LiDAR technology. In the FMCW-LiDAR technology, the light emitting device is controlled so that the frequency of the light emitted from the light emitting device changes with time. The light emitted from the light emitting device is separated into irradiation light and reference light. The object light generated by irradiating the object with the irradiation light is incident on the photodetector. The reference light enters the photodetector without passing through an object. Since the object light enters the photodetector later than the reference light, the object light and the reference light have different frequencies when they enter the photodetector. The photodetector detects the interference light in which the object light and the reference light are superimposed and interfere with each other, and outputs a signal indicating the intensity of the interference light. The signal is called a beat signal. The frequency of the beat signal corresponds to the difference between the frequency of the object light and the frequency of the reference light. The difference depends on the distance to the object.

In the FMCW-LiDAR technology, the object light reflected from a plurality of objects having different distances has a plurality of frequency components. Therefore, even when a beat signal is output from a photodetector including a single photodetector, it is possible to acquire data on the distances of a plurality of objects by separating a plurality of frequency components from the beat signal. .. A line beam extending in one direction with a certain degree of spread and a high energy density to some extent is suitable for irradiating a plurality of objects at once.

In the measuring device according to the present disclosure, the measurement data of the object can be efficiently acquired by processing the signal obtained by irradiating the object with the line beam. Hereinafter, the measuring device according to the present disclosure will be briefly described.

The measuring device according to the first item is arranged on an optical path of the light, a light deflector, a light emitting element that emits light whose frequency changes with time, and separates the light into reference light and irradiation light. An optical scanner including a splitter, an optical detector, and a processing circuit that controls the light emitting element, the optical deflector, and the optical detector to process a signal output from the optical detector. Be prepared. The processing circuit causes the optical scanner to emit a line beam, and changes the emission direction of the line beam along a direction intersecting the direction in which the line beam extends, and causes the photodetector to emit the line beam with the line beam. Interference light between the reflected light generated by irradiating the object and the reference light is detected, and measurement data of the object is generated and output based on the signal.

This measuring device can efficiently acquire the measurement data of the object by detecting the interference light between the reflected light obtained by irradiating the object with the line beam and the reference light.

The measuring device according to the second item is the measuring device according to the first item, in which the photodetector is a single photodetector.

With this measuring device, the rough position of an object can be known by a single photodetector.

The measuring device according to the third item includes a plurality of photodetecting elements in which the photodetector is arranged in the direction in which the line beam extends in the measuring device according to the first item.

With this measuring device, it is possible to know the position of the object in the direction in which the line beam extends.

The measuring device according to the fourth item is the measuring device according to the first item, wherein the optical scanner sets the direction in which the line beam extends as the first direction, and sets the emission direction of the line beam as the first direction. The first mode of changing along the second direction intersecting the directions and the direction in which the line beam extends are set to the second direction, and the emission direction of the line beam is changed along the first direction. It is possible to switch between the second mode and the second mode.

With this measuring device, in scanning with a line beam, the direction in which the line beam extends and the direction in which the line beam is changed can be switched between each other.

The measuring device according to the fifth item is the measuring device according to the first item, wherein the optical scanner sets the direction in which the line beam extends as the first direction, and sets the emission direction of the line beam as the first direction. The first mode in which the light beam is changed along the second direction intersecting the directions and the emission direction of the light beam whose spread in the first direction is smaller than that of the line beam are the first direction and the second direction. It is possible to switch between a second mode that changes along the direction.

With this measuring device, it is possible to switch between scanning with a line beam and scanning with an optical beam.

The measuring device according to the sixth item is the measuring device according to the first item, wherein the optical scanner sets the direction in which the line beam extends as the first direction, and sets the emission direction of the line beam as the first direction. It is possible to switch between a first mode that changes along a second direction that intersects the direction and a second mode that emits a flash light having a wider spread in the second direction than the line beam. be.

With this measuring device, it is possible to switch between scanning with a line beam and scanning with a flash light.

In the measuring device according to the fourth or fifth item, the processing circuit causes the optical scanner to execute the measurement operation in the first mode, and the measuring device according to the seventh item is the first mode. Based on the measurement data acquired by the above, it is determined whether or not it is necessary to switch to the measurement operation by the second mode, and it is determined that it is necessary to switch to the measurement operation by the second mode. Then, the optical scanner is made to execute the measurement operation in the second mode.

With this measuring device, it is possible to perform scanning with another line beam or scanning with an optical beam as needed, based on the measurement data acquired by scanning with a line beam.

The measuring device according to the eighth item is acquired by the second mode in the measuring device according to the sixth item, in which the processing circuit causes the optical scanner to execute the measurement operation in the second mode. Based on the measured data, it is determined whether or not it is necessary to switch to the measurement operation according to the first mode, and in response to the determination that it is necessary to switch to the measurement operation according to the first mode, the above The optical scanner is made to execute the measurement operation in the first mode.

With this measuring device, it is possible to perform a scan with a line beam as needed based on the measurement data acquired by scanning with a flash light.

The measuring device according to the ninth item is the measuring device according to any one of the fourth to sixth items. One of the measurement operations according to the second mode is selected, and the optical scanner is made to perform the measurement operation according to the selected mode.

With this measuring device, it is possible to execute a measurement operation in a mode selected as necessary based on signals from other sensors.

In the present disclosure, all or part of a circuit, unit, device, member or part, or all or part of a functional block in a block diagram is, for example, a semiconductor device, a semiconductor integrated circuit (IC), or an LSI (lage scale integration). ) Can be performed by one or more electronic circuits. The LSI or IC may be integrated on one chip, or may be configured by combining a plurality of chips. For example, functional blocks other than the storage element may be integrated on one chip. Here, it is called LSI or IC, but the name changes depending on the degree of integration, and it may be called system LSI, VLSI (very large scale integration), or ULSI (ultra large scale integration). Field Programmable Gate Array (FPGA), which is programmed after the LSI is manufactured, or reconfigurable logistic device, which can reconfigure the connection relationship inside the LSI or set up the circuit partition inside the LSI, can also be used for the same purpose.

Furthermore, all or part of the function or operation of a circuit, unit, device, member or part can be executed by software processing. In this case, the software is recorded on a non-temporary recording medium such as one or more ROMs, optical discs, hard disk drives, etc., and when the software is run by a processor, the functions identified by the software It is executed by a processor and peripheral devices. The system or device may include one or more non-temporary recording media on which the software is recorded, a processor, and the required hardware device, such as an interface.

In the present disclosure, "light" refers to electromagnetic waves including not only visible light (wavelength of about 400 nm to about 700 nm) but also ultraviolet rays (wavelength of about 10 nm to about 400 nm) and infrared rays (wavelength of about 700 nm to about 1 mm). means.

Hereinafter, a more specific embodiment of the present disclosure will be described.

(Embodiment)
First, a measuring device according to an exemplary embodiment of the present disclosure will be described with reference to FIGS. 1A and 1B. 1A and 1B are diagrams schematically showing a measuring device 100 according to an exemplary embodiment of the present disclosure. The measuring device 100 is a distance measuring device, and measures a distance to an object by irradiating the object with light and detecting reflected light. The measuring device 100 can change the emission direction of light. FIG. 1A shows a state in which the measuring device 100 emits light in a certain direction. FIG. 1B shows a state in which the measuring device 100 emits light in another direction.

In the following description, the coordinate system consisting of the X-axis, the Y-axis, and the Z-axis, which are orthogonal to each other shown in FIGS. 1A and 1B, is used. The direction of the arrow on the X axis is referred to as "+ X direction", and the opposite direction is referred to as "-X direction". The same applies to the Y-axis and the Z-axis. These axes and orientations are used for convenience only and are not intended to limit the placement or orientation of the measuring device 100 in practice.

The measuring device 100 according to the present embodiment detects the reflected light generated by irradiating an object (not shown) with light. The measuring device 100 acquires data on the distance and / or velocity of the object by processing the signal obtained by the detection of the reflected light. The data is also referred to as "measurement data". The measuring device 100 according to the present embodiment includes a light emitting device 10, an optical system 20, a photodetector 30, and a processing circuit 40. A configuration including a light emitting device 10, an optical system 20, and a photodetector 30 is referred to as an "optical scanner 50". The optical scanner 50 emits light toward space and detects reflected light from an object. Optical system 20, a beam splitter 22, first lens 24 _1, the second lens 24 _2, and a mirror 26. In the present specification, the processing circuit is also referred to as "FMCW processing circuit". In the present specification, the "FMCW processing circuit" means an electronic circuit that performs FMCW processing described later.

In the example shown in FIGS. 1A and 1B, the light emitting device 10, a beam splitter 22, first lens 24 _1, and the mirror 26 are disposed in this order along the + Y direction. The light emitting surface of the light emitting device 10 is parallel to the XZ plane. The reflecting surface of the beam splitter 22 is perpendicular to the XY plane and is tilted 45 ° clockwise with respect to the Y axis when viewed from the + Z direction. The optical axis of the first lens 24 ₁ is parallel to the Y axis. The reflective surface of the mirror 26 is parallel to the XZ plane. Photodetector 30, the second lens 24 _2, and the beam splitter 22 are disposed in this order along the + X direction. The photodetector surface of the photodetector 30 is parallel to the YZ plane. The arrangement relationship such as the inclination of the components shown in FIGS. 1A and 1B can be appropriately adjusted according to the application.

The light emitting device 10 emits 10 L of light. The light emitting device 10 may include a light emitting element such as a laser diode that emits a continuous wave laser beam having a single frequency. Instead of a single frequency continuous wave laser beam, a pulse wave laser beam having an optical frequency comb may be used. An optical frequency comb is a comb-shaped frequency spectrum formed from a plurality of discrete evenly spaced lines.

The frequency of the light 10L emitted from the light emitting device 10 can be selected according to the application. When the distance to each of a plurality of objects is measured by infrared rays, the frequency of the light 10L can be, for example, 120 THz (wavelength 2.5 μm) or more and 428 THz (wavelength 700 nm) or less. The frequency of the light 10L may be a frequency in the visible region, that is, 428 THz (wavelength 700 nm) or more and 749 THz (wavelength 400 nm) or less. The frequency of the light 10L may be 120 THz (wavelength 2.5 μm) or less.

The light emitting device 10 includes a light emitting element having a variable frequency. The frequency of the light 10L may change depending on, for example, the current injected into the light emitting element included in the light emitting device 10 or the temperature of the light emitting element. In this embodiment, since the FMCW-LiDAR technology is used, the light emitting device 10 is controlled by the processing circuit 40 so that the frequency of the light 10L changes with time.

The light emitting device 10 may be able to change the shape of the light 10L. The light 10L can be, for example, a flash light that spreads over a wide area, a line beam having a beam shape extending in one direction, or a light beam having a relatively small beam diameter. In the present specification, the term "light beam" is used to refer to a light beam having a relatively small beam diameter, and is used separately from a line beam and a flash light. The light emitting device 10 includes a light emitting element that emits flash light, a light emitting element that emits a line beam, and a light emitting element that emits a light beam, and may emit light 10L from an appropriate light emitting element depending on the application.

The spread of the flash light is larger than the spread of the line beam, and the spread of the line beam is larger than the spread of the light beam. The flash light has a larger spread than the line beam in the direction in which the line beam intersects in the extending direction. The light beam has a smaller spread than the line beam in the direction in which the line beam extends. The energy density of the light beam is higher than the energy density of the line beam, and the energy density of the line beam is higher than the energy density of the flash light. The flash light, which has a relatively large spread, is suitable for irradiating a plurality of objects at once. A light beam with a relatively high energy density is suitable for irradiating a long-distance object. The line beam has the advantages of both light beam and flash light.

The light emitting device 10 includes a light deflector that deflects the light 10L emitted from the light emitting element. The optical deflector changes at least one of the components parallel to the X direction and the components parallel to the Z direction in the direction of the light 10L. The optical deflector may change the direction of the light 10L by mechanical drive such as a MEMS mirror. Alternatively, the optical deflector may change the direction of the light 10L by changing optical parameters such as the refractive index without using mechanical drive. The optical deflector may include, for example, a first reflective layer, a second reflective layer having a higher reflectance than the first reflective layer, and an optical waveguide layer located between them. The light propagating in the optical waveguide layer is emitted to the outside through the first reflective layer. By changing the refractive index of the optical waveguide layer, the direction of the light emitted to the outside through the first reflective layer can be changed. The direction of the light 10L emitted from the light emitting device 10 is different between the example shown in FIG. 1A and the example shown in FIG. 1B. In the examples shown in FIGS. 1A and 1B, the directions of the light 10L are inclined clockwise and counterclockwise with respect to the Y axis in the XY plane when viewed from the + Z direction, respectively.

The beam splitter 22 included in the optical system 20 is located on the optical path of the light 10L. The beam splitter 22 can be, for example, a cube-type beam splitter including two joined right-angle prisms. One right-angled prism has an optical thin film on its slope. An example of a cube-type beam splitter is a polarization-independent beam splitter cube. Alternatively, the beam splitter 22 may be, for example, a plate-type beam splitter having flat glass provided with an optical thin film on the surface.

The beam splitter 22 separates the light 10L emitted from the light emitting device 10 into the first light 10L ₁ and the second light 10L _2. The first light 10L ₁ is a component of the light 10L that has passed through the beam splitter 22. The second light 10L ₂ is a component of the light 10L reflected by the beam splitter 22. The directions of the first light 10L ₁ and the second light 10L ₂ change according to the direction of the light 10L emitted from the light emitting device 10. In the beam splitter 22, _{the intensity ratio of the first light 10L 1} to the second light 10L ₂ can be, for example, 50:50. The ratio of the intensities of the first light 10L ₁ and the second light 10L ₂ may be changed according to the reflectance of the light at the object. The size and position of the beam splitter 22 is designed to cover the entire angular range in which the direction of the light 10L changes.

The first lens 24 ₁ included in the optical system 20, the second lens 24 _2, and the mirror 26 is located in the first optical path of the light 10L _1. The first lens 24 ₁ and the second lens 24 _2, for example, be a condenser lens. In the present embodiment, the focus of the first lens 24 ₁ is present in two locations. One focal point is in the light emitting surface of the light emitting device 10. This focal point is referred to as "first focal point F _1". Other focal point coincides with the focal point of the second lens 24 _{and second} beam splitter 22 side. This focal point is referred to as "second focal point F _2". The first focal point F ₁ and the second focal point F ₂ are mirror-symmetric with respect to the beam splitter 22. The mirror 26 reflects the light propagating along the + Y direction toward the −Y direction. The mirror 26 can be formed from, for example, a metal or a dielectric multilayer film.

Light 10L is emitted from the focus _{F 1} at the light emitting plane of the light emitting device 10. First light 10L ₁ that is separated from the light 10L by the beam splitter 22 is transmitted through the first lens 24 ₁ propagates along the + Y direction, is reflected by the mirror 26. First light 10L ₁ reflected by the mirror 26 propagates along the -Y direction, the first lens 24 ₁ again transmitted through and reflected by the beam splitter 22. First light 10L ₁ reflected by the beam splitter 22, passes through the second focal point _{F 2} passes through the second lens 24 _2, and enters the optical detector 30 propagates along the -X direction. _{The second light 10L 2} separated from the light 10L by the beam splitter 22 propagates toward the object. Third light 10L ₃ caused by the object at the second light 10L ₂ is irradiated, and the second light 10L ₂ propagates in the opposite direction, passes through the beam splitter 22. Third light 10L ₃ which has passed through the beam splitter 22, passes through the second focal point _{F 2} passes through the second lens 24 _2, and enters the optical detector 30 propagates along the -X direction. The first light 10L ₁ and the third light 10L ₃ are superimposed and interfere with each other, and are incident on the photodetector 30 as _{the fourth light 10L 4.}

The optical system 20 separates the light 10L into the first light 10L ₁ and the second light 10L ₂ _{, and photodetects the fourth light 10L 4 in} which the first light 10L ₁ and the third light 10L ₃ interfere with each other. The configuration is not limited to the configuration shown in FIGS. 1A and 1B as long as it can be incidentally incident on the vessel 30. For example, the optical system 20 may include an optical fiber.

Photodetector 30 detects the fourth light 10L _4, and outputs a signal corresponding to the intensity of the fourth light 10L _4. As shown in FIGS. 1A and 1B, _{the position where the fourth light 10L 4} is incident on the photodetector 30 changes depending on the direction of the light 10L. The photodetector 30 includes one or more photodetectors. The photodetector 30 may include, for example, an image sensor having a plurality of photodetectors arranged two-dimensionally. Alternatively, the photodetector 30 may include a line sensor having a plurality of photodetectors arranged one-dimensionally, or may include a single photodetector. The photodetector can be, for example, a Si avalanche photodetector.

Optical detector 30, may include an image sensor having a plurality of light detection elements arranged two-dimensionally, the second lens 24 _2, maintaining the position in the Y and Z directions of the interference light 10L ₄ incident As it is, the interference light 10L ₄ is incident on the image sensor along the -X direction. While the optical detector 30, if it contains a line sensor having a plurality of light detection elements arranged along the Y direction, the second lens 24 _2, maintaining the position in the Y-direction of the interference light 10L ₄ incident, The interference light 10L ₄ is focused on the line sensor in the XZ plane. Similarly, maintaining an optical detector 30, if it contains a line sensor having a plurality of light detection elements arranged along the Z direction, the second lens 24 _2, the position in the Z direction of the interference light 10L ₄ incident While still, the interference light 10L ₄ is focused on the line sensor in the XY plane.

The second lens 24 ₂ may be composed of one lens, or may be composed of a plurality of lenses. For example, when the optical detector 30 comprises a line sensor extending along the Y direction, the second lens 24 _2, the optical path of the interference light 10L _4, a first cylindrical lens extending in the Z-direction, extending in the Y direction direction It may include a second cylindrical lens. The first cylindrical lens maintains the position of the interference light 10L _{4 in} the Y direction. _{The second cylindrical lens focuses the interference light 10L 4} that has passed through the first cylindrical lens on the line sensor in the XZ plane. The same applies to the case where the photodetector 30 includes a line sensor extending along the Z direction.

If the light detector 30 comprises a single photodetector element, the second lens 24 ₂ is removed, the light detector 30 is arranged such that the second focal point F ₂ is located to the light detection surface. The interference light 10L ₄ is incident _{on the second focal point F 2} regardless of the emission direction of the light 10L.

The third light 10L ₃ is incident on the photodetector 30 later than _{the first light 10L 1} by the time required for the round trip between the measuring device 100 and the object. As a result, the _{frequency of the third light 10L 3} is different from the frequency of the first light 10L _1. Due to the different frequencies, beats occur in _{the fourth light 10L 4.} The above signal output from the photodetector 30 is a beat signal. In the present specification, the first light is referred to as "reference light", the second light is referred to as "irradiation light", the third light is referred to as "object light", and the fourth light is referred to as "interference light". It is called.

The processing circuit 40 controls the light emitting device 10 and the photodetector 30, and processes the signal output from the photodetector 30. The control of the light emitting device 10 may be, for example, control of the frequency, shape, direction, and emission timing of the light emitted from the light emitting device 10, and the position of the light emitting device 10. The control of the photodetector 30 may be, for example, control of the detection timing and the position of the photodetector 30.

The operation of the FMCW processing of the processing circuit 40 will be described below with reference to FIG. FIG. 2 is a flowchart of the operation of the FMCW processing executed by the processing circuit 40. The processing circuit 40 executes the operations of steps S101 to S103 below.

<Step S101>
In step S101, the processing circuit 40 causes the light emitting device 10 to emit the light 10L whose frequency f (t) changes with time. When the optical path length of the reference light 10L ₁ is sufficiently short, the frequency _{f r} of the reference light 10L ₁ at the timing t = _{t 0} is detected by the light detector 30, the frequency f (t of light 10L in the timing It can be considered equal to _0). Assuming that the time until the irradiation light 10L ₂ is emitted toward the object, reflected by the object, and returned as _{the object light 10L 3} is Δt, the frequency f _о _{of the object light 10L 3} is f (t ₀ )-[df. (T) / dt] It is represented by _{t = t0 Δt.} [Df (t) / dt] _{t = t0} represents the time change rate of the frequency f (t) at the time t = t _0. The processing circuit 40 may adjust the position of the light emitting device 10 by, for example, an actuator. By this adjustment, it is possible to compensate for the deviation between the first focal point F ₁ and the light emitting surface of the light emitting device 10.

<Step S102>
In step S102, the processing circuit 40 causes the photodetector 30 to output a beat signal by detecting the _{interference light 10L 4.} The frequency of the beat signal is _{expressed by} the frequency difference Δf = _fr −f _о = [df (t) / dt] _{t = t0} Δt _{between the frequency fr} _{of the reference light 10L 1} and the frequency f о of the object light 10L _3. Will be done. The processing circuit 40 may adjust the position of the photodetector 30 by, for example, an actuator. By this adjustment, when the photodetector 30 includes a single photodetector as described above, it is possible to compensate for the deviation between _{the second focal point F 2 and the photodetector surface of the photodetector 30.} As a result, the strength of the beat signal can be improved.

<Step S103>
In step S103, the processing circuit 40 processes the beat signal to generate and output data relating to the distance and / or velocity of the object. The data may be displayed on a display or output as audio from a speaker, for example. Assuming that the distance from the measuring device 100 to the object is d and the speed of light in the air is c, Δt = 2d / c. And the frequency _{f r} of the reference light 10L _1, the frequency difference Δf = (2d / c) [ df (t) / dt] t = t0 and the frequency f _o of the object beam 10L _3, generates the data relating to an object distance d can do. For example, when [df (t) / dt] _{t = t0} = 125 THz / s and the distance d is 5 mm or more and 50 m or less, the frequency difference Δf is 4.17 kHz or more and 4.17 MHz. This frequency difference Δf can be accurately measured by, for example, a spectrum analyzer or an oscilloscope with a resolution on the order of several Hz to several tens of MHz. Therefore, according to the measuring device 100 according to the present embodiment, it is possible to achieve both a wide dynamic range and high resolution with respect to the distance in the acquisition of data regarding the distance of the object. When the object is moving, the frequency difference Δf is shifted by the Doppler effect, so that data regarding the velocity of the object can be generated.

(Distance measurement of multiple objects with a line beam)
Next, distance measurement of a plurality of objects by a line beam using the FMCW-LiDAR technique will be described. The processing circuit 40 in the present embodiment causes the optical scanner 50 to emit a line beam that scans the space. Specifically, the processing circuit 40 causes the light emitting device 10 to emit the line beam 10L, and the emission direction of the line beam 10L changes regularly or irregularly along the direction in which the line beam 10L extends. Let me. The optical deflector can change the emission direction of the line beam 10L in this way. Further, the optical deflector has a first mode in which the direction in which the line beam 10L extends is set to the first direction, and the emission direction of the line beam 10L is changed along the second direction intersecting the first direction. It is possible to switch between a second mode in which the direction in which the line beam 10L extends is set to the second direction and the emission direction of the line beam 10L is changed along the first direction.

When the line beam 10L emitted from the light emitting device 10 extends in the X direction and the emission direction changes along the Z direction, the irradiation line beam 10L ₂ separated from the line beam 10L by the beam splitter 22 is mainly Y. It extends in the direction and its exit direction changes along the Z direction. The irradiation line beam 10L ₂ extends in a direction different from the direction in which the line beam 10L extends. When the line beam 10L emitted from the light emitting device 10 extends in the Z direction and its emission direction changes along the X direction, the irradiation line beam 10L ₂ separated from the line beam 10L by the beam splitter 22 extends in the Z direction. , The emission direction changes along the Y direction. The irradiation line beam 10L ₂ extends in the same direction as the line beam 10L extends.

The processing circuit 40 causes the photodetector 30 to detect the interference light 10L ₄ _{between the plurality of object light beams 10L 3} and the reference light 10L ₁ generated by irradiating the plurality of objects with the irradiation line beam 10L _2. To output a beat signal. A beat signal can also be generated by the interference of a plurality of object light beams 10L _{2 with each other, but this effect is small.} The energy density of the irradiation line beam 10L ₂ decreases as the distance increases. On the other hand, the reference light 10L ₁ is incident on the photodetector 30 located near the light emitting device 10 while maintaining a high energy density. The beat signal corresponds to the multiplication of the electric field components of two lights. Therefore, the beat signals between the plurality of object light beams 10L ₃ are very small and can be ignored. As a result, most of the signals output from the photodetector 30 are beat signals of _{the plurality of object light beams 10L 3} and the reference light 10L _1.

The processing circuit 40 can generate and output data on the distance and / or velocity of a plurality of objects at once from the beat signal. The photodetector 30 for detecting the interference light 10L ₄ does not need to include an image sensor and may include a line sensor extending in the same direction as the _{irradiation line beam 10L 2 or a single photodetector.} In this case, since the number of photodetecting elements may be small, the time for generating data regarding the distance and / or speed of a plurality of objects can be significantly shortened as compared with an image sensor having a maximum frame rate of about 30 fps.

(Scan of target scene)
Next, an example of scanning the target scene with the line beam in the present embodiment will be described with reference to FIGS. 3 to 6B.

FIG. 3 is a perspective view schematically showing an example of a vehicle 200 in which a measuring device 100 is mounted on the front surface. In the example shown in FIG. 3, the traveling direction of the vehicle 200 is parallel to the X direction, the vehicle height direction is parallel to the Y direction, and the direction crossing the road is parallel to the Z direction. The vehicle height direction is a direction perpendicular to the road surface and a direction away from the road surface. In the example shown in FIG. 3, the measuring device 100 in the vehicle 200 emits the irradiation line beam 10L ₂ extending in the vehicle height direction toward the target scene in front of the vehicle 200. The emission direction of the irradiation line beam 10L ₂ changes along the direction across the road, as represented by the double-headed arrow. The mounting position of the measuring device 100 on the vehicle 200 is not limited to the front surface thereof, but may be the upper surface, the side surface, or the rear surface thereof. The mounting position is appropriately determined according to where the target scene is.

FIG. 4A is a diagram schematically showing a first example of emitting a _{plurality of irradiation line beams 10L 2} toward a target scene in front of a vehicle 200 traveling on a road. The target scene is surrounded by a thick solid rectangle. In the target scene, a preceding vehicle is running on the road, and there are pedestrians on the sidewalk beside the road. There are three roadside trees on the sidewalk. The plurality of objects in the target scene are pedestrians, three roadside trees, and a preceding vehicle in ascending order of distance. The distances to pedestrians, leftmost, central, and rightmost roadside trees, as well as preceding vehicles, are d ₁ to d ₅ , respectively. As shown in FIG. 4A, when looking ahead from the vehicle 200, the road surface gradually changes toward the vehicle height direction. The road surface changes continuously, whereas an object such as a person or a car on the road surface changes discontinuously with respect to the road surface. Therefore, it is possible to detect the object by irradiating the object with the irradiation line beam 10L _2.

In the example shown in FIG. 4A, _{the emission direction of the irradiation line beam 10L 2} extending in the Y direction changes along the Z direction. The dashed ellipse shown in FIG. 4A represents the irradiation spots of _{the first irradiation line beam 10L 2a} and the fourth irradiation line beam 10L _2d extending in the Y direction emitted in four different directions. The distances in the upper part, the middle part, and the lower part of the irradiation line beam 10L _{2 in} the irradiation spot do not change so much even if the emission direction changes along the Z direction. _{Therefore, when the target scene is scanned in the horizontal direction with the irradiation line beam 10L 2} extending in the vertical direction, there is an advantage that the resolution of the distance in the horizontal direction is high.

In the example shown in FIG. 4A, _{the irradiation spot of the first irradiation line beam 10L 2a} includes the roadside tree at the left end. The irradiation spot of the second irradiation line beam 10L _2b includes a central roadside tree. The irradiation spot of the third irradiation line beam 10L _2c includes a pedestrian and a roadside tree on the right end. The irradiation spot of the fourth irradiation line beam 10L _2d includes the preceding vehicle. The first irradiation line beam 10L _2a to the fourth irradiation line beam 10L _2d may be emitted toward the target scene in this order or _{vice versa. For example, the third irradiation line beam 10L 2c} and the second irradiation line beam 10L may be emitted. _2b , the fourth irradiation line beam 10L _2d , and the first irradiation line beam 10L _2a may be emitted in an irregular order. In the example shown in FIG. 4A, the photodetector 30 including a single photodetector detects the interference light 10L ₄ as described above.

FIG. 4B is a diagram schematically showing the relationship between the strength of the beat signal and the distance calculated from the frequency of the beat signal in the first example shown in FIG. 4A. The four figures in FIG. 4B show the beat signals generated by _{the first irradiation line beam 10L 2a} to the fourth irradiation line beam 10L _2d. The first irradiation line beam 10L _2a, the second irradiation line beam 10L _2b , and the fourth irradiation line beam 10L _2d produce a single peak at distance d ₂ , distance d ₃ , and distance d _{5, respectively.} On the other hand, the third irradiation line beam 10L _2c causes two peaks of distance d ₁ and distance d _4. The measuring device 100 according to the present embodiment can measure the distances to the plurality of objects at once by irradiating the plurality of objects with _{one irradiation line beam 10L 2.} According to the measuring device 100 according to the present embodiment, a single photodetection element can be used to roughly position a plurality of objects in a short time from the known emission angles of _{the first irradiation line beam 10L 2a} to the fourth irradiation line beam 10L _2d. You can find out at.

FIG. 5A is a diagram schematically showing a second example of emitting a _{plurality of irradiation line beams 10L 2} toward a target scene in front of the vehicle 200 traveling on a road. The second example differs from the first example in that the photodetector 30 including the line sensor extending in the Y direction detects the interference light 10L ₄ as described above. The interference light 10L ₄ is incident on a plurality of photodetecting elements included in the line sensor. The five dotted ellipses in each irradiation line beam shown in FIG. 5A represent the locations corresponding to the photodetection elements 40e from the photodetection elements 40a arranged in the Y direction included in the line sensor.

FIG. 5B is a diagram schematically showing the relationship between the strength of the beat signal and the distance calculated from the frequency of the beat signal in the second example shown in FIG. 5A. FIG. 5B shows a beat signal output from each photodetector by the third irradiation line beam 10L _2c. In the example shown in FIG. 5B, the light detecting element 40c from the light detecting element 40a outputs a beat signal of the distance _{d 4,} the light-detecting element 40d and the light detecting element 40e outputs a beat signal of the distance _{d 1.} From the photodetection element 40a, the photodetection element 40c can know the more accurate position of the roadside tree at the right end, and the photodetection element 40d and the photodetection element 40e can know the more accurate position of the pedestrian. According to the measuring device 100 according to the present embodiment, the line sensor can more accurately know the three-dimensional positions of a plurality of objects.

The measuring device 100 according to the present embodiment may include a photodetector 30 including both a single photodetector and a line sensor. In the measuring apparatus 100, by changing the optical path of the interference light 10L _4, it is possible to detect the interference light 10L ₄ is switched to each other and a line sensor a single light-detecting element according to the application. _{The processing circuit 40 causes a single photodetection element to detect the interference light 10L 4} when the rough position of a plurality of objects is known, and causes the line sensor to more accurately know the three-dimensional position of the plurality of objects. Interference light 10L ₄ is detected. Alternatively, a photodetector 30 that does not include a single photodetector and includes a line sensor can also detect the interference light 10L ₄ depending on the application. When the processing circuit 40 knows the rough positions of a plurality of objects, the processing circuit 40 averages a plurality of beat signals output from each of the plurality of photodetectors included in the line sensor, and obtains the three-dimensional positions of the plurality of objects. To know exactly, the plurality of beat signals are used as they are.

FIG. 6A is a diagram schematically showing a third example of emitting a _{plurality of irradiation line beams 10L 2} toward a target scene in front of the vehicle 200 traveling on a road. The third example differs from the first example in that from the first irradiation line beam 10L _2a extending in the Y direction to the fourth irradiation line beam 10L _2d and the fifth irradiation line beam 10L _{2e extending in the Z direction.} The eighth irradiation line beam 10L _2h is emitted toward the target scene. _{When the target scene is scanned in the vertical direction with the irradiation line beam 10L 2} extending in the horizontal direction, there is an advantage that a high-intensity beat signal can be obtained because the lower side in the target scene is a short distance. In the third example, as in the first example, the photodetector 30 including a single photodetector detects the interference light 10L ₄ as described above.

The irradiation spot of the fifth irradiation line beam 10L _2e mainly includes the upper part of the roadside tree at the right end and the upper part of the preceding vehicle. The irradiation spot of the sixth irradiation line beam 10L _2f mainly includes the upper part of the roadside tree on the left end, the upper part of the roadside tree in the center, the central part of the roadside tree on the right end, and the lower part of the preceding vehicle. The irradiation spot of the 7th irradiation line beam 10L _2g mainly includes the central part of the leftmost roadside tree, the lower part of the central roadside tree, and the lower part of the rightmost roadside tree. The irradiation spot of the eighth irradiation line beam 10L _2h mainly includes the lower part of the roadside tree at the left end and pedestrians.

FIG. 6B is a diagram schematically showing the relationship between the strength of the beat signal and the distance calculated from the frequency of the beat signal in the third example shown in FIG. 6A. The four figures above FIG. 6B are the same as the four figures in FIG. 4B, and the four figures below FIG. 6B show the beat signals generated by _{the fifth irradiation line beam 10L 2e} to the eighth irradiation line beam 10L _2h. Is shown. By the fifth illumination line beam _{10L _2e,} 2 peaks in the distance _{d 4} and the distance _{d 5} appears. The sixth irradiation line beam 10L _2f causes four peaks at _a distance d ₂ to a distance d _5. With the 7th irradiation line beam 10L _2g _, three peaks of a distance d ₂ to a distance d _{4 appear.} The eighth irradiation line beam 10L _2h causes two peaks at _a distance d ₁ and a distance d _2.

The peak at the distance d ₁ appears by the third irradiation line beam 10L _2c and the eighth irradiation line beam 10L _2h. Therefore, it can be seen that the pedestrian at the distance d ₁ is at a position where the third irradiation line beam 10L _2c and the eighth irradiation line beam 10L _{2h overlap.} Similarly, the roadside tree at the left end of the _{distance d 2} _{has the first irradiation line beam 10L 2a} , the sixth irradiation line beam 10L _2f, the seventh irradiation line beam 10L _2g , and the eighth irradiation line beam 10L _2h , respectively. It can be seen that they exist at overlapping positions. Distance central trees of _{d 3} is found to be present and the second irradiation line beam _{10L 2b,} a position and each overlaps the sixth illumination line beam _{10L 2f} and seventh irradiation line beam _{10L 2 g.} Right edge of the trees of the distance _{d 4} is a third irradiation line beam _{10L 2c,} fifth illumination line beam _{10L 2e,} the sixth illumination line beam _{10L 2f,} and the seventh radiation line beam _{10L 2 g} each and overlap the position of the It turns out that it exists. It can be seen that the preceding vehicle having a distance d ₅ exists at a position where the fourth irradiation line beam 10L _2d , the fifth irradiation line beam 10L _2e, and the sixth irradiation line beam 10L _{2f overlap each other.}

In the first example shown in FIG. 4A, it was not possible to know the position of _{the object in the irradiation spot of the irradiation line beam 10L 2.} On the other hand, in the third example shown in FIG. 6A, the target scene is scanned in the Z direction by the irradiation line beam extending in the Y direction, and by scanning in the Y direction by the irradiation line beam extending in the Z direction. , It is possible to know the three-dimensional position of an object more accurately. According to the measuring device 100 according to the present embodiment, _{from the known emission angles of the first irradiation line beam 10L 2a} to the eighth irradiation line beam 10L _2h , the three-dimensional position of the object even if it is a single photodetector. Can be known more accurately.

Next, an example of irradiating the target scene with the flash light in the present embodiment will be described with reference to FIGS. 7A and 7B.

FIG. 7A is a diagram schematically showing an example in _{which the irradiation flash light 10L 2} is emitted toward the target scene in front of the vehicle 200 traveling on the road. The broken line ellipse shown in FIG. 7A represents the irradiation spot of the irradiation _{flash light 10L 2.} In the example shown in FIG. 7A, the photodetector 30 detects the interference light 10L ₄ by a single photodetector as described above.

FIG. 7B is a diagram schematically showing the relationship between the strength of the beat signal and the distance calculated from the frequency of the beat signal in the example shown in FIG. 7A. In the example shown in FIG. 7B, the irradiation flash light causes five peaks at _{a distance d 2} to a distance d _5. According to the measuring device 100 according to the present embodiment, the distances to a plurality of objects can be measured at one time by irradiating the plurality of objects with the flash light.

Next, with reference to FIG. 8, the distance measuring operation and the distance measuring operation of a plurality of objects in the present embodiment based on the results obtained from the _{irradiation line beam 10L 2} _{shown in FIG. 6A and the irradiation flash light 10L 2} shown in FIG. 7A. An example of the control operation of the vehicle 200 will be described. FIG. 8 is a flowchart showing a distance measuring operation of a plurality of objects and a control operation of the vehicle 200 in the present embodiment. The processing circuit 40 in this embodiment executes the operations of steps S201 to S207 below. In the following description, the photodetector 30 includes a single photodetector.

<Step S201>
As shown in FIG. 7A, the processing circuit 40 causes the light emitting device 10 to emit the irradiation flash light toward the target scene, and causes the photodetector 30 to emit a plurality of irradiation flash lights by a single photodetector. The interference light 10L ₄ of the object light beam 10L ₃ and the reference light 10L ₁ is detected and a signal is output. As shown in FIG. 7B, the processing circuit 40 generates and outputs data regarding the distances of a plurality of objects in the target scene based on the signal.

<Step S202>
The processing circuit 40 determines whether or not the object exists at a short distance of the vehicle 200 based on the result of the distance measurement of the object in step S201. The short distance in this step can be, for example, in the range of 0.5 m or more and 20 m or less. When the object exists at a short distance, that is, yes, the processing circuit 40 executes the operation of step S203. When the object does not exist at a short distance, that is, no, the processing circuit 40 executes the operation of step S204.

<Step S203>
The processing circuit 40 transmits a collision avoidance signal to the control circuit of the vehicle 200. Even if it is not known where the object is in the target scene, it is possible to prevent the vehicle 200 from colliding with the object by a collision avoidance action such as stopping.

<Step S204>
As shown in FIG. 6A, the processing circuit 40 causes the light emitting device 10 to scan the target scene in the Z direction with an irradiation line beam extending in the Y direction, and causes the photodetector 30 to scan the target scene with an irradiation line by a single photodetector. The object light beam 10L ₃ generated by the beam 10L ₂ and the interference light 10L ₄ of the reference light 10L ₁ are detected and a signal is output. As shown in the four figures above FIG. 6B, the processing circuit 40 generates and outputs data regarding the distance of an object in the target scene based on the signal.

<Step S205>
The processing circuit 40 determines whether or not the object exists at a short distance of the vehicle 200 based on the result of the distance measurement of the object in step S204. The short distance in this step can be, for example, in the range of 20 m or more and 40 m or less. When the object exists at a short distance, that is, yes, the processing circuit 40 executes the operation of step S206. When the object does not exist at a short distance, that is, no, the processing circuit 40 executes the operation of step S207.

<Step S206>
The processing circuit 40 transmits a collision avoidance signal to the control circuit of the vehicle 200. If the rough position of the object in the target scene is known, it is possible to prevent the vehicle 200 from colliding with the object by a collision avoidance action such as moving away from the rough position to the left or right or stopping.

<Step S207>
As shown in FIG. 6A, the processing circuit 40 causes the light emitting device 10 to scan the target scene in the Y direction with the irradiation line beam 10L extending in the Z direction, and irradiates the photodetector 30 with a single photodetector. The interference light 10L ₄ _{of the object light beam 10L 3} and the reference light 10L ₁ generated by the line beam 10L is detected and a signal is output. As shown in the lower figure of FIG. 6B, the processing circuit 40 generates and outputs data regarding the distance of an object in the target scene based on the signal. From the results of distance measurement of the object in steps S204 and S207, the three-dimensional position of the object can be known more accurately.

Instead of step S207, the processing circuit 40 causes the light emitting device 10 to scan the target scene in the Y direction and the Z direction with an irradiation light beam having a smaller spread than the irradiation line beam 10L, and causes the photodetector 30 to simply scan the target scene. A single photodetector may detect the interference light 10L ₄ _{of the object light beam 10L 3} and the reference light 10L ₁ generated by the irradiation light beam and output a signal. The processing circuit 40 generates and outputs data regarding the distance of an object in the target scene based on the signal. From the known emission angle of the irradiation light beam, the three-dimensional position of the object can be known more accurately.

The operations of the processing circuit 40 in steps S204 and S207 are summarized as follows. Processing circuit 40, together with the emit irradiation line beam 10L ₂ in the optical scanner 50, the emission direction of the illumination line beam 10L _2, is varied along a direction intersecting the direction in which the irradiation line beam 10L ₂ extends. The processing circuit 40 causes the photodetector 30 to detect the interference light 10L ₄ _{between the object light 10L 3} and the reference light 10L ₁ generated by irradiating the object with the irradiation line beam 10L ₂ , from the photodetector 30. Based on the output signal, the measurement data of the object is generated and output.

The operation of the processing circuit 40 when no is selected in step S202 and step S205 is summarized as follows. The processing circuit 40 causes the optical scanner 50 to execute the measurement operation in a certain mode, and determines whether or not it is necessary to switch to the measurement operation in another mode based on the measurement data acquired in the mode. After that, the processing circuit 40 causes the optical scanner 50 to execute the measurement operation in the other mode in response to the determination that it is necessary to switch to the measurement operation in the other mode.

In the case of step S202, one of the above modes may be, for example, scanning with irradiation flash light. The other mode described above may be a scan along the second direction with an irradiation line beam extending in the first direction. In the case of step S205, one of the above modes may be, for example, a scan along a second direction with an irradiation line beam extending in the first direction. The other mode described above may be, for example, a scan along the first direction with an irradiation line beam extending in a second direction, or a scan along the first and second directions with an irradiation light beam. When the photodetector 30 includes a line sensor extending in the Y direction, the position of the object in the Y direction can be known by the _{irradiation flash light 10L 2 in step S201.} Therefore, in step S203, the collision avoidance action of the vehicle 200 can be executed more accurately. Further, in step S204, as shown in FIG. 5A, the irradiation line beam 10L ₂ can more accurately know the three-dimensional position of the object. Therefore, in step S206, the collision avoidance action of the vehicle 200 can be executed more accurately, and the operation of step S207 can be omitted.

As described above, the measuring device 100 according to the present embodiment is capable of a plurality of types of measuring operations having different degrees of light spread and scanning directions. Further, by switching the degree of light spread and the scanning direction according to the situation, the measurement data of the object can be efficiently acquired.

In particular, since the measuring device 100 according to the present embodiment is capable of measuring operation using a line beam, it is possible to realize FMCW-LiDAR capable of roughly distinguishing the positions of a plurality of objects while speeding up the measuring operation. can.

Further, according to the present embodiment, the measuring device 100 quickly provides information to the subsequent system by executing the measuring operation using light having a relatively wide irradiation range and quickly finding an object satisfying a predetermined condition. be able to. Further, by switching the degree of light spread and the scanning direction to perform the next measurement operation, more detailed measurement data of the object can be obtained. As an example, the processing circuit 40 executes the same measurement operation as the measurement operation using the irradiation line beam 10L by using the irradiation flash light 10L in step S201 before the measurement operation using the irradiation line beam 10L in step S204. Then, based on the result of the measurement operation, it is determined whether or not to execute the measurement operation in step S204. By the measurement operation using the irradiation flash light 10L, the collision avoidance action of the vehicle 200 can be quickly executed.

(First modification)
Next, with reference to FIG. 9, a first modification of the measuring device 100 according to the present embodiment will be described. FIG. 9 is a diagram schematically showing the measuring device 300 according to the first modification. In the measuring device 300 according to the present modification, the configuration of the optical scanner 50 is different from that of the measuring device 100 according to the present embodiment. Specifically, the measuring device 300 according to this modification includes a light emitting element 10 ₁ having a variable frequency, an optical deflector 10 _2, and a beam splitter 22. Beam splitter 22, the light emitting element 10 ₁ is disposed on the optical path between the optical deflector 10 _2.

The beam splitter 22 separates the light 10L from the light _{emitting element 10 1} _{into the reference light 10L 1} and the irradiation light 10L _2. Irradiation light 10L ₂ separated by the beam splitter 22, for example, it is deflected by the optical deflector 10 ₂ including MEMS mirror, is emitted towards the space. Object light 10L ₃ reflected back by the object is deflected again by the light deflector 10 _2. The photodetector 30 detects the interference light L ₄ _{between the reference light 10L 1} and the object light 10L ₃ .

(Second modification)
Next, with reference to FIG. 10, a second modification of the measuring device 100 according to the present embodiment will be described. FIG. 10 is a diagram schematically showing the measuring device 400 according to the second modification. The measuring device 400 according to this modification includes the measuring device 100 or the measuring device 300 described above, and another sensor 150. In the above-described embodiment, when switching the measurement operation mode of the measuring device, the optical scanner 50 is first made to execute the measurement operation in one mode, and the measurement operation in another mode is based on the measurement data acquired in the mode. It was determined whether or not it was necessary to switch to. In this modification, when switching the measurement operation mode of the measuring device, it is determined whether or not the mode switching is necessary based on the signal acquired from the other sensor 150.

The processing circuit 40 of the measuring device 400 selects one of a plurality of prepared measurement operation modes based on signals from other sensors. Then, the optical scanner 50 is made to execute the measurement operation in the selected mode.

The other sensor 150 may be, for example, an object recognition system including an image sensor. The measuring device 400 switches the measurement operation mode based on the recognition result of the object recognition system. The recognition result may include information on at least one of the size, position, and type of the object.

(Application example)
The measuring device 100 in the present embodiment can be used, for example, in a distance measuring system for an object. Such a ranging system can be mounted on a moving body such as an automobile, a UAV (Unmanned Aerial Vehicle, so-called drone), or an AGV (Automated Guided Vehicle), and can be used as one of collision avoidance techniques. In the distance measuring system using the measuring device 100 in the present embodiment, the distance distribution of an object can be scanned and detected with a wide dynamic range and high resolution with respect to the distance.

The optical device according to the embodiment of the present disclosure can be used for the purpose of a distance measuring system mounted on a vehicle such as an automobile, a UAV, or an AGV.

10 Light emitting device 10L light 10L ₁ 1st light, reference light 10L ₂ 2nd light, irradiation light 10L ₃ 3rd light, object light 10L ₄ 4th light, interference light 20 Optical system 22 Beam splitter 24 ₁ 1st 1 lens 24 ₂ second lens 26 mirror 30 optical detector 40 processing circuit 50

optical scanner

100, 300, 400 measuring apparatus 200 vehicle 150 other sensors

Claims

With a light deflector,
A light emitting element that emits light whose frequency changes with time,
A splitter arranged on the optical path of the light and separating the light into reference light and irradiation light.
With a photodetector
Including optical scanner,
A processing circuit that controls the light emitting element, the light deflector, and the photodetector and processes a signal output from the photodetector.
Equipped with
The processing circuit is
The optical scanner emits a line beam, and the emission direction of the line beam is changed along a direction intersecting the direction in which the line beam extends.
The photodetector is made to detect the interference light between the reflected light and the reference light generated by irradiating the object with the line beam.
Based on the signal, the measurement data of the object is generated and output.
Measuring device.
The photodetector is a single photodetector.
The measuring device according to claim 1.
The photodetector comprises a plurality of photodetectors arranged in a direction in which the line beam extends.
The measuring device according to claim 1.
The optical scanner is
A first mode in which the direction in which the line beam extends is set to the first direction, and the emission direction of the line beam is changed along a second direction intersecting the first direction.
A second mode in which the direction in which the line beam extends is set to the second direction and the emission direction of the line beam is changed along the first direction.
It is possible to switch between
The measuring device according to claim 1.
The optical scanner is
A first mode in which the direction in which the line beam extends is set to the first direction, and the emission direction of the line beam is changed along a second direction intersecting the first direction.
A second mode in which the emission direction of the light beam having a smaller spread in the first direction than the line beam is changed along the first direction and the second direction.
It is possible to switch between
The measuring device according to claim 1.
The optical scanner is
A first mode in which the direction in which the line beam extends is set to the first direction, and the emission direction of the line beam is changed along a second direction intersecting the first direction.
A second mode that emits a flash light having a wider spread in the second direction than the line beam,
It is possible to switch between
The measuring device according to claim 1.
The processing circuit is
The optical scanner is made to execute the measurement operation in the first mode.
Based on the measurement data acquired in the first mode, it is determined whether or not it is necessary to switch to the measurement operation in the second mode.
In response to the determination that it is necessary to switch to the measurement operation according to the second mode, the optical scanner is made to execute the measurement operation according to the second mode.
The measuring device according to claim 4 or 5.
The processing circuit is
The optical scanner is made to execute the measurement operation in the second mode.
Based on the measurement data acquired in the second mode, it is determined whether or not it is necessary to switch to the measurement operation in the first mode.
In response to the determination that it is necessary to switch to the measurement operation according to the first mode, the optical scanner is made to execute the measurement operation according to the first mode.
The measuring device according to claim 6.
The processing circuit is
Based on the signals from the other sensors, one of the measurement operation in the first mode and the measurement operation in the second mode is selected.
Let the optical scanner perform the measurement operation in the selected mode.
The measuring device according to any one of claims 4 to 6.
A method performed by a computer in a system that includes a measuring device,
The measuring device is
With a light deflector,
A light emitting element that emits light whose frequency changes with time,
A splitter arranged on the optical path of the light and separating the light into reference light and irradiation light.
With a photodetector
Including optical scanner,
A processing circuit that controls the light emitting element, the light deflector, and the photodetector and processes a signal output from the photodetector.
Equipped with
The method is
In addition to emitting a line beam to the optical scanner, the emission direction of the line beam is changed along a direction intersecting the direction in which the line beam extends.
To have the photodetector detect the interference light between the reflected light and the reference light generated by irradiating the object with the line beam.
To generate and output measurement data of the object based on the signal,
How to include.
A computer program executed by a computer in a system that includes a measuring device.
The measuring device is
With a light deflector,
A light emitting element that emits light whose frequency changes with time,
A splitter arranged on the optical path of the light and separating the light into reference light and irradiation light.
With a photodetector
Including optical scanner,
A processing circuit that controls the light emitting element, the light deflector, and the photodetector and processes a signal output from the photodetector.
Equipped with
The computer program is attached to the computer.
In addition to emitting a line beam to the optical scanner, the emission direction of the line beam is changed along a direction intersecting the direction in which the line beam extends.
To have the photodetector detect the interference light between the reflected light and the reference light generated by irradiating the object with the line beam.
To generate and output measurement data of the object based on the signal,
A computer program that runs.