WO2023248798A1 - Laser radar - Google Patents

Abstract

A laser radar (1) comprises: a scanning unit (10) that scans using a plurality of laser beams, in which angles formed with respect to a rotation axis (R10) are different from each other by a predetermined angle, while rotating the laser beams about the rotation axis (R10), and that individually receives reflected beams, of the plurality of laser beams, from an object; and a guiding unit (200) that guides, at a predetermined rotational position, the plurality of laser beams emitted from the scanning unit (10) to a plurality of photodetectors of the scanning unit (10) through approximately the same optical path length.

Description

laser radar

The present invention relates to a laser radar that detects objects using laser light.

In recent years, laser radars that detect objects using laser light have been installed in intrusion detection systems, cars, robots, etc. This type of laser radar projects a laser beam onto a target area and detects the presence or absence of an object in the projection direction based on the reflected light. Further, this type of laser radar may also have a function of measuring the distance to an object based on the time required from the timing of projecting the laser beam to the timing of receiving the reflected light.

This type of laser radar uses a configuration in which the projection direction of laser light is rotated about a rotation axis. Thereby, objects around the laser radar can be detected. In this case, an arrangement may further be arranged for monitoring the operation of the laser radar at a predetermined rotational position. For example, a mirror that returns the projected laser light to the light receiving element of the laser radar under intended conditions without hitting the object to be detected is arranged at this rotational position. Such a configuration is described, for example, in Patent Document 1 below.

Japanese Patent Application Publication No. 2011-75287

With the above configuration, an abnormality in the light emitting element and the light receiving element can be detected from the output of the light receiving element at the rotational position where the mirror is arranged. Furthermore, with the above configuration, by measuring the distance at the rotational position where the mirror is placed, it is possible to correct the deviation in the distance measurement value. That is, the distance measured at this rotational position is compared with the optical path length (reference value) of the laser beam fed back by the mirror, and a deviation in the distance measurement value at this rotational position is detected. Based on the deviation detected in this way, the distance actually measured at a rotational position other than this rotational position is corrected.

In addition, in the configuration in which the projection direction of the laser beam is rotated about the rotation axis as described above, a plurality of laser beams are projected from the laser radar and the angles formed with the rotation axis differ by a predetermined angle, and the reflection of these laser beams. A configuration is used in which light is received by each of a plurality of light receiving elements. Thereby, the range of object detection can be further expanded in the direction parallel to the rotation axis.

However, in this configuration, when the mirror is placed at a predetermined rotational position as described above in order to monitor the operating status of the device, the optical path lengths of the laser beams reflected by the mirror and returned to each other are different from each other. It turns out to be a problem. Due to these differences in optical path length, the amount of light received by each laser beam differs from each other, so it is necessary to detect abnormalities in the light emitting element and light receiving element for each laser beam individually based on the output from the light receiving element. . Furthermore, if the optical path length differs between laser beams, it is necessary to detect the deviation in the distance measurement value and correct the distance measurement accordingly for each laser beam. This increases the processing load on the device, leading to an increase in cost.

In view of such problems, the present invention provides a laser beam that is capable of monitoring the operation of a device through simpler processing in a configuration in which a plurality of laser beams rotate about a rotation axis, each having a predetermined angle different from the rotation axis. The purpose is to provide radar.

A laser radar according to a main aspect of the present invention rotates and scans a plurality of laser beams whose angles with a rotation axis differ by a predetermined angle, respectively, and scans the plurality of laser beams by rotating them about the rotation axis, and detects reflected light from an object of the plurality of laser beams. a scanning unit that individually receives the laser beams; and a guide that guides the plurality of laser beams emitted from the scanning unit to the plurality of photodetectors of the scanning unit at a predetermined rotational position, respectively, with optical path lengths that are substantially the same as each other. It is equipped with a section and a section.

According to the laser radar according to this aspect, the guiding section guides the plurality of laser beams to the photodetector with optical path lengths that are substantially the same. As a result, the processing for each laser beam can be shared, and the operation of the device can be monitored using simpler processing.

As described above, according to the present invention, in a configuration in which a plurality of laser beams rotate about the rotation axis, the angles formed with the rotation axis differ by a predetermined angle, it is possible to monitor the operation of the device by simpler processing. We can provide laser radar.

The effects and significance of the present invention will become clearer from the description of the embodiments shown below. However, the embodiment shown below is merely one example of implementing the present invention, and the present invention is not limited to what is described in the embodiment below.

FIG. 1 is a perspective view schematically showing the configuration of a laser radar according to an embodiment. FIG. 2 is a perspective view schematically showing the configuration of the optical system according to the embodiment. FIG. 3A is a side view schematically showing the configuration of the projection optical system according to the embodiment. FIG. 3(b) is a side view schematically showing the configuration of the light receiving optical system according to the embodiment. FIG. 4 is a plan view schematically showing the configuration of the laser radar according to the embodiment. FIG. 5 is a perspective view showing the configuration of the first reflecting member and the second reflecting member according to the embodiment. FIG. 6 is a perspective view showing the configuration of a light shielding member and a structure according to the embodiment. FIG. 7(a) is a perspective view showing the configuration of the guide section according to the embodiment. FIG. 7(b) is a perspective view showing the C1-C2 cross section of FIG. 7(a) according to the embodiment. FIGS. 8A and 8B are diagrams showing the configuration of the guiding section and the optical path of the laser beam when viewed in the negative direction of the y-axis, according to the embodiment. FIG. 9 is a block diagram showing the configuration of the circuit section of the laser radar according to the embodiment. FIG. 10A is a diagram schematically showing the emission timing of laser light according to the embodiment. FIG. 10(b), FIG. 10(c), and FIG. 10(d) are diagrams schematically showing detection signals of the photodetector at temperature Tm1 according to the embodiment. FIG. 11 is a graph schematically showing the relationship between pulse width and distance correction amount according to the embodiment. FIGS. 12(a) and 12(b) are diagrams schematically showing the reflective surfaces of the guide portions according to comparative examples. FIGS. 13(a) and 13(b) are diagrams schematically showing the reflective surface of the guiding section according to the embodiment. FIGS. 14(a) and 14(b) are diagrams schematically showing the reflective surface of the guiding section according to the embodiment. FIGS. 15(a) and 15(b) are diagrams schematically showing the configurations of the guiding section and the optical system according to the embodiment. FIGS. 16(a) and 16(b) are diagrams schematically showing reflective surfaces of guide portions according to a comparative example and an embodiment, respectively. FIG. 17A is a diagram schematically illustrating the configuration of the guide section when two sets of reflective surfaces are used, according to Modification Example 1. FIG. 17(b) is a diagram schematically showing the configuration of the guiding section when an ND filter is used according to modification example 2. FIGS. 18(a) and 18(b) are diagrams schematically showing the configuration of the guiding section when an ND filter is used according to modification example 2. FIG. FIGS. 19(a) to 19(c) are diagrams schematically showing the configuration of a guiding section according to modification example 3. FIG. 20(a) and 20(b) are diagrams schematically showing a configuration when a prism is used according to modification example 4. FIG. 21 is a diagram schematically showing a configuration when an optical fiber is used according to modification example 5. 22(a) and 22(b) are diagrams schematically showing the configuration of a light shielding member according to modification example 6. FIG. FIG. 23 is a side view schematically showing the configuration of a projection optical system according to another modification.

However, the drawings are solely for illustrative purposes and do not limit the scope of the invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view schematically showing the configuration of a laser radar 1.

In FIG. 1, for convenience, X, Y, and Z axes that are orthogonal to each other are added. The Z-axis positive direction is the height direction of the laser radar 1.

The laser radar 1 includes a scanning section 10, a supporting section 20, and a guiding section 200. The scanning unit 10 rotates and scans the laser beam about the rotation axis R10, and receives reflected light from an object. The scanning section 10 includes a fixed section 11, a rotating section 12, and an optical system 100. In FIG. 1, the positions of the rotating part 12 and the optical system 100 are shown by broken lines and dotted lines, respectively, for convenience.

The rotating part 12 is rotated by a motor in the fixed part 11 about a rotating axis R10 parallel to the Z-axis direction. The rotating direction of the rotating part 12 is clockwise when viewed in the negative direction of the Z-axis. The optical system 100 is installed inside the rotating section 12, and rotates in the circumferential direction of the rotation axis R10 as the rotating section 12 rotates. The optical system 100 emits a plurality of laser beams in a direction away from the rotation axis R10, each having a predetermined angle different from the rotation axis R10, and emits reflected light reflected by an object existing at a scanning position of these laser beams. Receive light. The side surface of the rotating part 12 is made of a member through which the laser beam emitted from the optical system 100 and the reflected light reflected by the object pass through. Note that an opening may be formed on the side surface of the rotating part 12 for the laser beam to pass through. The configuration of the optical system 100 will be explained later with reference to FIG. 2.

The support portion 20 is an L-shaped member when viewed in the X-axis direction. The support portion 20 includes a horizontal portion 21 extending in the Y-axis direction and a vertical portion 22 extending in the vertical direction (Z-axis direction). One end of the horizontal portion 21 and one end of the vertical portion 22 are connected. The other end of the horizontal part 21 supports the upper end of the rotating part 12 so that the rotating part 12 can rotate, and the other end of the vertical part 22 is installed on the outer periphery of the fixed part 11.

The guide section 200 is installed inside the vertical section 22 (on the side facing the rotating section 12). The guiding unit 200 guides the plurality of laser beams emitted from the plurality of light sources 111 (see FIG. 2) of the optical system 100 at a predetermined rotational position of the optical system 100 with substantially the same optical path length. Each of the light beams is guided to a plurality of photodetectors 122 (see FIG. 2). The configuration of the guiding section 200 will be explained later with reference to FIGS. 5 to 7(a).

When the laser radar 1 detects an object, laser light is emitted from the light source 111 (see FIG. 2) of the optical system 100 to the outside of the laser radar 1. The laser light emitted from the optical system 100 is emitted radially with respect to the rotation axis R10, as shown by the dashed-dotted arrow. The laser light (reflected light) reflected by an object present at the scanning position of the laser light is received by the photodetector 122 (see FIG. 2) of the optical system 100, as shown by the dashed arrow. The optical axis of the laser beam projected from the laser radar 1 rotates around the rotation axis R10 due to the rotation of the rotating part 12 around the rotation axis R10. Along with this, the scanning position of the laser beam also moves.

The laser radar 1 determines whether an object exists at the scanning position based on whether or not reflected light is received. Further, the laser radar 1 measures the distance to the object present at the scanning position based on the time difference (time of flight) between the timing of projecting the laser beam and the timing of receiving the reflected light. By rotating the rotating part 12 around the rotation axis R10, the laser radar 1 can detect objects existing in the surrounding range excluding the position of the supporting part 20.

In addition to detecting the presence or absence of an object to the scanning position and measuring the distance, the laser radar 1 projects a laser beam onto the guiding section 200 at a predetermined timing and receives reflected light from the guiding section 200. The laser radar 1 determines whether an abnormality has occurred in the light source 111 and the photodetector 122 (see FIG. 2) based on the amount of reflected light received from the guide section 200. Further, the laser radar 1 corrects the distance measurement value (distance measurement value) at the scanning position based on the detection signal of the reflected light from the guiding section 200. Correction of the measured distance value will be explained later with reference to FIGS. 10(a) to 11.

FIG. 2 is a perspective view schematically showing the configuration of the optical system 100.

In FIG. 2, the same X, Y, and Z axes as in FIG. The optical system 100 is shown when the laser beam emission direction is in the negative direction of the Y-axis. In FIG. 2, the laser light emitted from each light source 111 and heading toward the scanning position is shown by a dashed line, and the laser light (reflected light) reflected from the scanning position is shown by a broken line.

The optical system 100 includes a projection optical system 110 that projects a laser beam, and a light receiving optical system 120 that receives the reflected light of the laser beam reflected by an object. The projection optical system 110 includes nine light sources 111 and a collimator lens 112. Projection optical system 110 projects nine laser beams. The light receiving optical system 120 includes a condensing lens 121 and nine photodetectors 122. The light receiving optical system 120 guides nine reflected lights to nine photodetectors 122.

The output optical axis of the central light source 111 among the nine light sources 111 and the optical axis 112a of the collimator lens 112 are aligned. The optical axis 112a of the collimator lens 112 (the optical axis of the projection optical system 110) and the optical axis 121a of the condenser lens 121 (the optical axis of the light receiving optical system 120) are spaced apart from each other in the X-axis direction.

The light source 111 is a semiconductor laser element that emits laser light of a predetermined wavelength. The nine light sources 111 are installed on the substrate 113 so as to be lined up in the Z-axis direction at predetermined intervals. The optical axis of the central light source 111 is parallel to the Y axis. The optical axes of the light sources 111 at both ends are tilted by the same angle from being parallel to the Y axis to approach the optical axis of the light source 111 at the center. That is, the central light source 111 is installed so that its emitting end surface is parallel to the X-Z plane, and the other light sources 111 are installed so that their emitting end surfaces are slightly parallel to the X-Y plane from being parallel to the X-Z plane. It is set up so that it is tilted.

The collimator lens 112 converts the laser beams emitted from the nine light sources 111 into parallel beams. The nine laser beams converted into parallel beams by the collimator lens 112 are projected onto the scanning position and reflected by an object present at the scanning position. The nine laser beams (nine reflected beams) reflected by the object enter the Y-axis negative side surface (incident surface) of the condenser lens 121.

The condensing lens 121 has a circular shape with a part cut out in plan view. The cut surface 121b of the condenser lens 121 is parallel to the YZ plane and is located on the negative side of the X-axis with respect to the optical axis 121a. The cut surface 121b is adjacent to the collimator lens 112 in the X-axis direction. The condensing lens 121 condenses the nine reflected lights onto the corresponding photodetectors 122, respectively. Since the condenser lens 121 has such a shape, the nine light sources 111 and collimator lenses 112 and the condenser lens 121 can be arranged close to each other. This makes it easier to properly guide reflected light from a nearby object to the photodetector 122.

The nine photodetectors 122 are installed on the substrate 123 so as to be lined up in the Z-axis direction at predetermined intervals. The nine photodetectors 122 each receive the corresponding reflected light and output a detection signal according to the amount of received light. Photodetector 122 is, for example, an avalanche photodiode.

FIG. 3(a) is a side view schematically showing the configuration of the projection optical system 110.

The same X, Y, and Z axes as in FIG. 2 are also added to FIG. 3(a). In FIG. 3(a), the emission optical axes of the laser beams emitted from the nine light sources 111 are shown by dashed-dotted lines. The output optical axes of the nine laser beams intersect near the incident surface (the surface on the positive side of the Y-axis) of the collimator lens 112.

FIG. 3(b) is a side view schematically showing the configuration of the light receiving optical system 120.

The same X, Y, and Z axes as in FIG. 2 are also added to FIG. 3(b). In FIG. 3(b), the optical axes of the nine reflected lights reflected by the object are shown by broken lines. The nine reflected lights condensed by the condensing lens 121 are incident on the nine photodetectors 122, respectively.

FIG. 4 is a plan view schematically showing the configuration of the laser radar 1. In FIG. 4, illustration of the support portion 20 is omitted for convenience.

The optical system 100 rotates about the rotation axis R10 as the center of rotation in accordance with the rotation of the rotation unit 12. At this time, the optical system 100 projects nine laser beams in a direction away from the rotation axis R10 (radially when viewed in the Z-axis direction). The nine laser beams projected from the optical system 100 overlap when viewed in the Z-axis direction. The optical system 100 projects nine laser beams while rotating at a predetermined speed, and receives nine reflected beams from the scanning position. Thereby, the presence or absence of objects existing around the laser radar 1 is detected and the distance is measured.

Further, when the laser beam emission position in the optical system 100 is positioned in front of the guiding section 200 (on the positive side of the Y axis), the laser beam emitted from the optical system 100 is reflected by the guiding section 200, and the laser beam emitted from the optical system 100 is Light is received. Thereby, the laser radar 1 determines whether an abnormality has occurred in the light source 111 and the photodetector 122, and corrects the distance measurement value (distance measurement value) at the scanning position, as will be described later.

Next, the assembly procedure of the guide section 200 will be described with reference to FIGS. 5 to 7(a).

For convenience, x, y, and z axes that are orthogonal to each other are added to FIGS. 5 to 7(a). The x-axis direction is the same axis as the X-axis shown in FIG. 1, and the y-axis and z-axis are the axes obtained by rotating the Y-axis and Z-axis shown in FIG. 1 by 45 degrees around the X-axis, respectively. .

FIG. 5 is a perspective view showing the configurations of the first reflecting member 210 and the second reflecting member 220.

The first reflecting member 210 is formed with reflecting surfaces 211 and 212, a cylindrical surface 213, holes 214 and 215, two installation surfaces 216, and an installation surface 217.

The reflective surfaces 211 and 212 have a conical side surface shape. The reflective surface 211 has a shape in which the radius of the curved surface decreases as it advances in the negative direction of the x-axis, and the diameter of the curved surface 212 has a shape that decreases in the diameter of the curved surface as it advances in the positive direction of the x-axis. The reflective surfaces 211 and 212 have shapes that are substantially symmetrical to each other in the x-axis direction.

The reflectance of the reflective surface 211 is lower than the reflectance of the reflective surface 212 of the second reflective member 220. For example, the reflectance of the reflective surfaces 211, 212 can be adjusted by using different materials for the reflective surfaces 211, 212. The cylindrical surface 213 has a cylindrical side shape and is formed between the reflective surfaces 211 and 212.

The holes 214 and 215 are formed at the end of the first reflecting member 210 on the negative side of the x-axis, and pass through the end of the negative side of the x-axis of the first reflecting member 210 in the x-axis direction. The two installation surfaces 216 are formed near the ends of the first reflecting member 210 on the x-axis negative side and the x-axis positive side. The installation surface 216 is composed of a surface shaped like a side surface of a cylinder and a surface parallel to the xz plane. The installation surface 217 is formed on the negative side of the z-axis of the reflective surface 211 and the cylindrical surface 213, and includes a surface inclined to the xz plane and a surface parallel to the XZ plane.

The second reflecting member 220 is formed with a reflecting surface 221, a protrusion 222, a hole 223, and installation surfaces 224 and 225.

The reflective surface 221 has a conical side surface shape. The reflective surface 221 has a shape in which the radius of the curved surface decreases as it advances in the negative direction of the x-axis. The reflectance of the reflective surface 221 is higher than the reflectance of the reflective surface 211 of the first reflective member 210. For example, a material having a higher reflectance than the material applied to the reflective surface 211 is applied to the reflective surface 221. In this case, a material that provides the desired reflectance for the reflective surface 221 is selected.

The protrusion 222 and the hole 223 are formed at the end of the second reflecting member 220 on the negative side of the x-axis. The installation surface 224 is composed of a surface shaped like a cylindrical side surface and a surface parallel to the xz plane. The installation surface 225 is composed of a surface inclined to the xz plane and a surface parallel to the xz plane.

During assembly, the protrusion 222 is passed through the hole 214 and the installation surface 225 is installed on the installation surface 217. In this state, the holes 215 and 223 are screwed together. As a result, the structure 240 shown in FIG. 6 is completed.

FIG. 6 is a perspective view showing the configuration of the light shielding member 230 and the structure 240.

In the structure 240, the installation surface 216 and the installation surface 224 on the negative side of the x-axis are connected without a step difference. An opening 241 is formed in a portion surrounded by the installation surface 216 and the installation surface 224. The reflective surface 211 is exposed to the outside through the opening 241. Furthermore, in the structure 240, an opening 242 is formed between the end of the second reflecting member 220 on the positive side of the x-axis and the cylindrical surface 213. The reflective surface 211 is opened in the positive x-axis direction through the opening 242 and faces the reflective surface 212 in the x-axis direction. Further, in the structure 240, the reflective surface 221 also faces the reflective surface 212 in the x-axis direction.

The light shielding member 230 is composed of a cylindrical side surface and a surface parallel to the xz plane. The light shielding member 230 is a limiter for limiting the amount of laser light emitted from the light source 111 and incident on the photodetector 122. Apertures 231, 232, and 233 are formed in the light shielding member 230.

The openings 231, 232, and 233 penetrate the light shielding member 230. The openings 231 and 232 have a rectangular shape when viewed in a direction parallel to the yz plane (for example, the Y-axis direction in FIG. 1). The openings 231 and 232 have a shape in which the lengths in the y-axis direction and the z-axis direction are longer than in the x-axis direction. The lengths of the apertures 231 and 232 in the y-axis direction and the z-axis direction are set such that the optical axes of the nine laser beams emitted from the optical system 100 are positioned within the apertures 231 and 232. The length of the opening 233 in the y-axis direction and the z-axis direction is the same as the length of the openings 231 and 232 in the y-axis direction and the z-axis direction, and the length in the x-axis direction is the same as that of the openings 231 and 232 in the x-axis direction. It has a shape that is longer than its length.

During assembly, the light shielding member 230 is installed on the installation surfaces 216 and 224 of the structure 240 with adhesive or the like. As a result, the guide portion 200 is completed as shown in FIG. 7(a).

FIG. 7(a) is a perspective view showing the configuration of the guiding section 200.

The opening 231 of the light shielding member 230 is located in front of the opening 241 of the structure 240 and the reflective surface 211 shown in FIG. The opening 232 of the light shielding member 230 is located in front of the reflective surface 221, and the opening 233 is located in front of the reflective surface 212. Depending on the size of the openings 231 and 232, the amount of laser light that enters the photodetector 122 via the guide section 200 can be adjusted.

With reference to FIGS. 7(b) to 8(b), the optical path of the laser beam that enters the guide portion 200 from the apertures 231 and 232 will be described.

FIG. 7(b) is a perspective view showing the C1-C2 cross section of FIG. 7(a). FIGS. 8A and 8B are diagrams showing the configuration of the guide section 200 and the optical path of the laser beam when viewed in the negative direction of the y-axis. In FIGS. 7(b) to 8(b), the optical axis of the laser beam that passes through the position where the positive side of the y-axis is open is shown by a solid line, and the optical axis of the laser beam that is hidden by the guiding part 200 is shown as a solid line. , shown by the dotted line.

When the rotational position of the plurality of laser beams emitted by the optical system 100 is positioned at a position corresponding to the aperture 231, the plurality of laser beams enter the reflective surface 211 via the aperture 231 and the aperture 241 (see FIG. 6). The laser light incident on the reflective surface 211 is reflected by the reflective surface 211 in the positive direction of the x-axis. The reflected light reflected by the reflective surface 211 passes through the opening 242 as shown in FIG. 7(b), and enters the reflective surface 212 as shown in FIG. 8(a). The reflected light incident on the reflective surface 212 is reflected by the reflective surface 212, passes through the aperture 233, travels in a direction parallel to the yz plane, and heads toward the condenser lens 121. In this case, as shown in FIG. 8(a), although the optical axis of the reflected light passing through the aperture 233 and the optical axis 121a of the condensing lens 121 are shifted in the x-axis direction, the reflected light is condensed. The light is focused by a lens 121 and guided to a photodetector 122.

When the rotational position of the plurality of laser beams emitted by the optical system 100 is positioned at a position corresponding to the aperture 232, the plurality of laser beams enter the reflective surface 221 through the aperture 232. The laser light incident on the reflective surface 221 is reflected by the reflective surface 221 in the positive direction of the x-axis. The reflected light reflected by the reflective surface 221 enters the reflective surface 212 as shown in FIG. 8(b). The reflected light incident on the reflective surface 212 is reflected by the reflective surface 212, passes through the aperture 233, travels in a direction parallel to the yz plane, and heads toward the condenser lens 121. In this case, as shown in FIG. 8(b), the optical axis of the reflected light that has passed through the aperture 233 and the optical axis 121a of the condensing lens 121 match in the x-axis direction, and the reflected light is condensed. The light is focused by a lens 121 and guided to a photodetector 122.

FIG. 9 is a block diagram showing the configuration of the circuit section 30 of the laser radar 1.

The circuit section 30 includes a control circuit 31, a drive circuit 32, and a processing circuit 33. The drive circuit 32 is connected to nine light sources 111, and the processing circuit 33 is connected to nine photodetectors 122.

The control circuit 31 includes an arithmetic processing unit such as a CPU or FPGA, and a memory, and controls each part according to a program stored in the memory. The drive circuit 32 causes the nine light sources 111 to simultaneously emit pulsed light in accordance with the control from the control circuit 31. The processing circuit 33 performs processing such as amplification and noise removal on the analog detection signals output from the nine photodetectors 122, converts the processed detection signals into digital signals, and outputs the digital signals to the control circuit 31. .

The control circuit 31 determines that an object is present in the projection direction of the laser beam if reflected light is detected by the corresponding photodetector 122 within a certain period of time after the light source 111 emits pulsed light, and further, The distance to the object is calculated based on the time difference between the pulse emission timing and the reflected light detection timing. In this way, detection of the presence or absence of an object in the projection direction and calculation of the distance to the object are performed every predetermined rotation angle (for example, 1°) of the rotating section 12.

The object detection results (presence or absence of the object and distance to the object) obtained by the circuit section 30 of the optical system 100 are sent to the circuit section on the fixed section 11 side via a communication section (for example, a non-contact communication section) at any time. and further transmitted from the circuit section on the fixed section 11 side to an external device. External devices include, for example, intrusion detection systems, cars, robots, and the like.

Next, distance correction performed during distance detection will be explained.

FIG. 10(a) is a diagram schematically showing the emission timing of laser light.

Based on the control signal from the control circuit 31, the drive circuit 32 causes the light source 111 to emit laser light, for example, at time Ts. The reflected light reflected by the object at the scanning position is received by the corresponding photodetector 122, and the photodetector 122 outputs a wave-shaped detection signal as shown in FIG. 10(b).

FIG. 10(b) is a diagram schematically showing the detection signal of the photodetector 122.

The photodetector 122 outputs a detection signal according to the amount of reflected light it receives. At this time, if the left side (rise side) time is T0 among the times when the light intensity reaches the threshold Lth, the control circuit 31 determines the distance D0 to the object at the scanning position based on the time from time Ts to time T0. Calculate.

Here, the amount of reflected light changes depending on the reflectance of the object at the scanning position. For example, if the reflectance of the object is the reference value, a detection signal like that shown in FIG. A detection signal like this is obtained. In the cases of FIGS. 10(c) and 10(d), if the distance is calculated in the same manner as in FIG. 10(b), a distance longer than the actual distance will be calculated. That is, in the case of FIG. 10(c), the distance D1 is calculated based on the time from time Ts to time T1, and in the case of FIG. 10(d), the distance D2 is calculated based on the time from time Ts to time T2. be done. In this way, in the cases of FIGS. 10(c) and 10(d), the calculated distances D1 and D2 are separated from the appropriate distance D0.

Therefore, in order to make the calculated distance value appropriate, the distance value is corrected according to the slope (rise angle) of the detection signal. Specifically, the control circuit 31 estimates the slope of the detection signal from the pulse width based on the threshold value Lth, and calculates the distance correction amount according to the estimated slope. For example, in the case of FIG. 10(c), the control circuit 31 corrects the distance based on the reference relational expression that defines the relationship between the pulse width and the distance correction amount based on the pulse width w1 obtained from the detection signal. An appropriate distance D0 is calculated by obtaining the distance correction amount A1 of and subtracting the distance correction amount A1 from the distance D1. Similarly, in the case of FIG. 10(d), the control circuit 31 obtains the distance correction amount A2 for correcting the distance from the above-mentioned reference relational expression based on the pulse width w2 obtained from the detection signal, and An appropriate distance D0 is calculated by subtracting the distance correction amount A2 from D2.

In this way, the distance measurement value can be corrected by correction based on the pulse width of the detection signal. However, when the environmental temperature of the laser radar 1 changes, the characteristics of the light source 111 and the photodetector 122 change, and the detection signal output from the photodetector 122 changes. Therefore, if the distance correction amounts obtained from the above-mentioned standard relational expressions (distance correction amounts A1 and A2 in the case of FIGS. 10(c) and (d)) are used as they are, there will be a difference between them and the true distance correction amount. may occur.

In order to cope with this, the control circuit 31 modifies the relational expression between the pulse width and the distance correction amount based on the detection signal of the reflected light from the guiding section 200.

FIG. 11 is a graph schematically showing the relationship between pulse width and distance correction amount.

The solid line in FIG. 11 shows the relationship between the pulse width and the distance correction amount when the environmental temperature of the laser radar 1 is at the reference temperature Tm1.

The control circuit 31 projects a laser beam onto the low-reflectance reflective surface 211 and the high-reflectance reflective surface 221, and acquires two detection signals as in FIGS. 10(c) and 10(d). At this time, the light shielding member 230 limits the amount of laser light that enters the photodetector 122. Thereby, saturation of the output of the photodetector 122 can be suppressed, and the waveform of the detection signal of the photodetector 122 can be smoothly varied according to the difference in reflectance between the reflective surfaces 211 and 221.

The control circuit 31 describes the distances D11 and D12 when the laser beam is projected onto the low reflectance reflecting surface 211 and the high reflectance reflecting surface 221, respectively, with reference to FIGS. 10(c) and 10(d). Calculated by processing. In this case, the control circuit 31 obtains the distance correction amount used for each distance calculation from the reference temperature relational expression (reference relational expression) shown by the solid line in FIG. 11 .

Here, the optical path length from the light source 111 to the photodetector 122 when passing through the reflective surface 211 (distance D01), and the optical path length from the light source 111 to the photodetector 122 when passing through the reflective surface 221 (distance D02) ) are known respectively. The control circuit 31 calculates a difference A11 from the difference between the known distance D01 and the calculated distance D11, and calculates a difference A12 from the difference between the known distance D02 and the calculated distance D12.

The control circuit 31 corrects the relational expression of the reference temperature from these differences A11 and A12, and determines the relational expression used for measurement. In the example of FIG. 11, when the environmental temperature is Tm2 higher than temperature Tm1 (reference temperature), the relational expression shown by the dotted line is determined as the relational expression used for measurement. Further, when the environmental temperature is a temperature Tm3 lower than the temperature Tm1 (reference temperature), the relational expression shown by the broken line is determined as the relational expression used for measurement.

The control circuit 31 obtains the distance correction amount during actual distance measurement based on the relational expression determined in this way. For example, when the environmental temperature is temperature Tm2, the control circuit 31 obtains the distance correction amount A3 when the pulse width during distance measurement is w5, and when the environmental temperature is temperature Tm3, the control circuit 31 obtains the distance correction amount A3. When the pulse width during distance measurement is w5, a distance correction amount A4 is obtained. The control circuit 31 uses the distance correction amount thus obtained to calculate the distance at each scanning position by the process shown in FIGS. 10(c) and 10(d).

By the way, if the optical path length from the light source 111 to the photodetector 122 via the guide section 200 differs for each laser beam, the known optical path lengths (the above distances D01 and D02) cannot be used in common. . Furthermore, if the optical path length differs for each laser beam, the degree of spread of each laser beam will vary, and therefore the amount of reflected light guided to the photodetector 122 will vary. When such a variation in the amount of light occurs, it becomes necessary to change the threshold value Lth for each laser beam. Further, when determining whether or not an abnormality has occurred in the light source 111 and the photodetector 122 based on the amount of reflected light received via the guide section 200, the magnitude of the light amount can be determined using a common threshold value. It disappears. Therefore, processing based on reflected light becomes complicated.

On the other hand, in this embodiment, the optical system 100 and the guiding section 200 are arranged so that the optical path length from the light source 111 to the photodetector 122 via the guiding section 200 is approximately the same for each laser beam. It is configured. This suppresses variations in the amount of reflected light guided to the photodetector 122 via the guide section 200.

Therefore, when determining whether an abnormality has occurred in the light source 111 and the photodetector 122 based on the amount of received reflected light, the magnitude of the amount of light can be determined using a common threshold value. Furthermore, when performing distance correction, the pulse width can be obtained using a common threshold Lth, and the relational expression between the pulse width and the distance correction amount can be obtained using a common optical path length (distances D01 and D02 above). . Therefore, since the processing for each laser beam can be shared, the operation of the laser radar 1 can be monitored with simpler processing.

FIGS. 12(a) and 12(b) are diagrams schematically showing reflective surfaces 301, 302, and 311 of the guiding section 300 according to a comparative example.

FIG. 12(a) shows the reflective surfaces 301 and 302 in a transparent state when the guiding section 300 is viewed in the negative direction of the X-axis, and FIG. 12(b) shows the guiding section 300 in the negative direction of the X-axis. The reflective surfaces 311, 302 are shown in perspective when viewed in the direction. The reflective surfaces 301 and 311 reflect the laser light from the light source 111 in the positive direction of the X-axis, and the reflective surface 302 reflects the reflected light from the reflective surfaces 301 and 311 toward the condenser lens 121. . In FIGS. 12(a) and 12(b), the optical axis of the laser beam emitted from the optical system 100 toward the guide section 300 is shown by a dashed line.

As shown in FIGS. 12(a) and 12(b), in the case of the comparative example, the reflective surfaces 301 and 302 have a planar shape. In this case, since the reflection positions of the nine laser beams on the reflective surface 301 are aligned along a straight line, the optical path length of each laser beam from the output surface of the collimator lens 112 to the reflective surface 301 varies. Similarly, since the reflection positions of the nine laser beams on the reflective surface 311 are aligned along a straight line, the optical path length of each laser beam from the output surface of the collimator lens 112 to the reflective surface 311 varies.

Therefore, in the comparative example, variations occur in the optical path length from the light source 111 to the photodetector 122 via the guide section 300, and due to such variations in the optical path length, the amount of reflected light guided to the photodetector 122 decreases. There are also variations. Furthermore, in the comparative example, since the reflective surface of the guide section 300 is a flat surface, the angle of incidence of each laser beam on the reflective surface varies, and as a result, the angle of incidence on the photodetector 122 also varies. Therefore, the variation in the amount of reflected light guided to the photodetector 122 becomes even larger.

FIGS. 13(a) and 13(b) are diagrams schematically showing reflective surfaces 211 and 212 of the guiding section 200, respectively, according to the embodiment.

FIG. 13(a) shows the shape of a cross section when the reflective surface 211 is cut along a plane parallel to the rotation axis R10 and including the optical axes of nine laser beams incident on the reflective surface 211 from the aperture 231. There is. In addition, in FIG. 13(b), the reflective surface 212 is cut by a plane that is parallel to the rotation axis R10 and includes the optical axes of nine laser beams that are reflected by the reflective surfaces 211 and 212 after entering from the aperture 231. The cross-sectional shape is shown.

As shown in FIGS. 13(a) and 13(b), the reflective surfaces 211 and 212 are concave in the shape of a circular arc in the direction away from the rotation axis R10. In other words, the shapes of the reflective surfaces 211 and 212 at the laser beam incident position are curved in an arc shape in the laser beam incident direction when viewed in the rotation direction around the rotation axis R10.

FIGS. 14(a) and 14(b) are diagrams schematically showing the reflective surfaces 221 and 212 of the guiding section 200, respectively, according to the embodiment.

FIG. 14(a) shows the shape of a cross section when the reflective surface 221 is cut along a plane parallel to the rotation axis R10 and including the optical axes of nine laser beams incident on the reflective surface 221 from the aperture 232. There is. In addition, in FIG. 14(b), the reflective surface 212 is cut by a plane that is parallel to the rotation axis R10 and includes the optical axes of nine laser beams that are reflected by the reflective surfaces 221 and 212 after entering from the aperture 232. The cross-sectional shape is shown.

As shown in FIGS. 14(a) and 14(b), the reflective surfaces 221 and 212 are concave in the shape of a circular arc in the direction away from the rotation axis R10. In other words, the shapes of the reflecting surfaces 221 and 212 at the laser beam incident position are curved in an arc shape in the laser beam incident direction when viewed in the rotation direction around the rotation axis R10.

Here, as shown in FIGS. 13(a) and 13(b), the shapes of the reflective surfaces 211 and 212 are such that nine laser beams emitted from the optical system 100 are directed from the corresponding light sources 111 to the reflective surfaces. 211 and 212 to the corresponding photodetector 122 are adjusted so that the optical path lengths are approximately the same. Further, as shown in FIGS. 14(a) and 14(b), the shapes of the reflecting surfaces 221 and 212 are such that nine laser beams emitted from the optical system 100 are directed from the corresponding light sources 111 to the reflecting surfaces 221 and 212. , 212 to the corresponding photodetector 122 are adjusted so that the optical path lengths are approximately the same.

In this way, by adjusting the shapes of the reflective surfaces 211, 212, and 221 when viewed in the direction of rotation about the rotation axis R10 by curving them in an arc shape in the incident direction of the laser beam, the optical system 100 can be When the nine emitted laser beams are guided by the guiding section 200, the optical path lengths of the nine laser beams can be made substantially the same.

The shape of the reflecting surfaces 211, 212, 221 when viewed in the direction of rotation around the rotation axis R10 does not have to be a perfect circular arc, but in order to make the optical path lengths of all laser beams approximately the same, It may be slightly deformed. Further, the shapes of the reflecting surfaces 211 and 212 when viewed in the direction of rotation around the rotation axis R10 do not have to be the same, and may be slightly different in order to make the optical path lengths of all laser beams approximately the same. You can leave it there. Similarly, the shapes of the reflecting surfaces 221 and 212 when viewed in the direction of rotation around the rotation axis R10 do not have to be the same, but may be slightly different in order to make the optical path lengths of all laser beams approximately the same. You may do so.

Furthermore, in this embodiment, when the guiding section 200 guides the laser beam to the photodetector 122, the laser beam is reflected by a pair of two reflecting surfaces. Therefore, reflected light can be efficiently guided to the photodetector 122. This effect will be explained with reference to FIGS. 15(a) and 15(b).

FIGS. 15(a) and 15(b) are diagrams schematically showing the configurations of the guiding section 200 and the optical system 100 according to the embodiment.

15(a) shows a state in which the light source 111 and the collimator lens 112 face the reflective surface 211, and FIG. 15(b) shows a state in which the light source 111 and the collimator lens 112 face the reflective surface 221. There is. In FIGS. 15A and 15B, the reflective surfaces 211, 212, and 221 of the guide section 200 are shown in a transparent state.

As shown in FIGS. 15(a) and 15(b), in the embodiment, a reflective surface 212 is arranged opposite to the reflective surface 211, and a reflective surface 212 is arranged opposite to the reflective surface 221. As a result, the laser beam incident on the reflective surface 211 can be reflected by the two reflective surfaces 211 and 212 in directions different by 90 degrees, and can be reflected in directions different by 90 degrees by the two reflective surfaces 221 and 212. can be done. Therefore, when viewed in the Z-axis direction, the reflected light reflected by the reflective surface 212 is parallel to the direction of the optical axis 121a of the condenser lens 121 (Y-axis direction), so that the reflected light is directed to the photodetector 122. Can be guided efficiently.

Furthermore, in this embodiment, the reflected light reflected by the reflective surfaces 211 and 221 can be reflected by one reflective surface 212 and guided to the photodetector 122. This effect will be explained with reference to FIGS. 16(a) and 16(b).

FIGS. 16(a) and 16(b) are diagrams schematically showing reflective surfaces of guiding parts according to a comparative example and an embodiment, respectively.

FIG. 16(a) shows reflective surfaces 301, 302, 311, and 312 in a transparent state when the guiding section 300 according to the comparative example is viewed in the negative Z-axis direction, and FIG. 16(b) shows reflective surfaces 301, 302, 311, and 312 in a transparent state. , reflective surfaces 211, 212, and 221 are shown in a transparent state when the guiding section 200 according to the embodiment is viewed in the negative Z-axis direction. In FIGS. 16A and 16B, illustration of the collimator lens 112, the condensing lens 121, and the light shielding member 230 is omitted for convenience. For convenience, FIGS. 16A and 16B show the light source 111, the photodetector 122, and the optical path of the laser beam when the light source 111 is in two rotational positions facing the reflective surfaces 211 and 221, respectively. It is shown.

As shown in FIG. 16(a), in the case of the comparative example, reflective surfaces 311 and 312 are arranged corresponding to reflective surfaces 301 and 302, respectively. In this case, since the four reflective surfaces 301, 302, 311, and 312 are lined up in the X-axis direction, the width of the guiding section 300 in the X-axis direction becomes long.

On the other hand, as shown in FIG. 16(b), in the case of the embodiment, the reflected light reflected by the reflective surface 211 and the reflected light reflected by the reflective surface 221 are both reflected by the reflective surface 212. That is, one reflective surface 212 is arranged corresponding to both of the two reflective surfaces 211 and 221. In this case, the number of reflective surfaces aligned in the X-axis direction is reduced compared to the comparative example, so the width of the guide section 200 in the X-axis direction can be reduced.

<Effects of embodiment>
As described above, according to the embodiment, the following effects are achieved.

As described with reference to FIGS. 13(a) to 14(b), the guiding unit 200 allows the plurality of laser beams emitted from the scanning unit 10 to be detected by a plurality of optical paths with substantially the same optical path length. They are each guided to a vessel 122. Thereby, when determining whether an abnormality has occurred in the light source 111 and the photodetector 122 based on the amount of received reflected light, the magnitude of the amount of light can be determined using a common threshold value. Furthermore, when performing distance correction, the pulse width can be obtained using a common threshold Lth, and the relational expression between the pulse width and the distance correction amount can be obtained using a common optical path length (distances D01 and D02 above). . Therefore, since the processing for each laser beam can be shared, the operation of the laser radar 1 can be monitored by simpler processing.

As shown in FIG. 13(a), when the reflective surface 211 is cut along a plane that is parallel to the rotational axis R10 and includes the optical axis of the laser beam incident on the reflective surface 211, the shape of the cross section is far from the rotational axis R10. It is concave in the shape of a circular arc. In other words, the reflective surface 211 has a shape curved into an arc in the direction of incidence of the laser beam when viewed in the direction of rotation about the rotation axis R10. Thereby, the optical path lengths of the plurality of laser beams up to the reflecting surface 211 can be made close to each other with a simple configuration.

As shown in FIGS. 8A and 8B, the reflective surfaces 211 and 221 direct the incident laser beams from the optical axis 112a of the collimator lens 112 (the optical axis of the projection optical system 110) to the condenser lens 121. is reflected in the direction toward the optical axis 121a (optical axis of the light receiving optical system 120). The reflective surface 212 (second reflective surface) reflects the plurality of laser beams reflected by the reflective surfaces 211 and 221 in a direction along the optical axis 121a of the condenser lens 121 (optical axis of the light receiving optical system 120). The light is guided to a plurality of photodetectors 122, respectively. As shown in FIGS. 13(b) and 14(b), the reflecting surface 212 ( The cross-sectional shape of the second reflective surface (second reflective surface) when cut is an arc-shaped concave shape in the direction away from the rotation axis R10. In other words, the reflective surface 212 (second reflective surface) has an arc-shaped shape curved in the same direction as the reflective surface 211.

According to this configuration, as shown in FIGS. 15(a) and 15(b), at the rotational position (predetermined rotational position) where the optical system 100 faces the guide section 200, the plurality of laser beams are directed to the condenser lens 121. The light can be made incident on the condenser lens 121 in the direction along the optical axis 121a. This allows the photodetector 122 to output a detection signal of sufficient magnitude, making it possible to appropriately monitor the state of the device. Furthermore, by curving the shape of the reflective surface 212 into an arc in the same direction as the reflective surface 211, the optical path lengths from the reflective surface 212 to the corresponding photodetectors 122 can be made closer to each other for a plurality of laser beams. can.

The plurality of laser beams are incident on the reflective surface 221 (third reflective surface) at a position shifted by a predetermined rotation angle from a predetermined rotation position. As shown in FIG. 14(a), the reflective surface 221 (third reflective surface) is a plane that is parallel to the rotation axis R10 and includes the optical axis of the laser beam incident on the reflective surface 221 (third reflective surface). The cross-sectional shape when cut is a circular arc-shaped concave shape in the direction away from the rotation axis R10. In other words, the reflective surface 221 (third reflective surface) has a shape curved into a circular arc in the direction of incidence of the laser beam when viewed in the rotation direction around the rotation axis R10. The reflective surface 221 (third reflective surface) reflects the plurality of incident laser beams toward the reflective surface 212 (second reflective surface). According to this configuration, the amount of laser light that enters the photodetector 122 via the reflective surface 211 and the amount of laser light that enters the photodetector 122 via the reflective surface 221 are made different from each other. Thereby, as explained with reference to FIG. 11, the relational expression between the pulse width and the distance correction amount can be obtained with high accuracy.

The reflective surface 211 and the reflective surface 221 (third reflective surface) have different reflectances from each other. According to this configuration, the amount of laser light that enters the photodetector 122 via the reflective surface 211 and the amount of laser light that enters the photodetector 122 via the reflective surface 221 can be adjusted with a simple configuration. can be made different from each other.

The guiding section 200 includes a light blocking member 230 (limiting body) for limiting the amount of laser light emitted from the light source 111 and entering the photodetector 122. According to this configuration, saturation of the output of the photodetector 122 can be suppressed, and the waveform of the detection signal of the photodetector 122 can be smoothly varied according to the reflectance of the reflective surfaces 211 and 221. Therefore, the distance correction as described above can be performed appropriately.

Openings 231 and 232 are formed in the light shielding member 230 (limiting body). According to this configuration, the amount of laser light incident on the photodetector 122 can be adjusted depending on the size of the apertures 231 and 232. Therefore, the waveforms of the two detection signals based on the laser beams that have passed through the reflective surfaces 211 and 221 can be adjusted to desired waveforms.

The openings 231 and 232 are narrow slits in the rotation direction of the plurality of laser beams. According to this configuration, since the incident area of the laser beam onto the reflective surfaces 211, 212, and 221 can be restricted in the X-axis direction, the reflective surfaces 211, 212, and 221 can be made smaller in the X-axis direction, and the guide section 200 can be made compact. .

<Change example 1>
In the above embodiment, one reflective surface 212 is arranged corresponding to both the reflective surfaces 211 and 221, but the reflective surfaces 212a and 212b are arranged corresponding to the reflective surfaces 211 and 221, respectively, as shown below. Good too.

FIG. 17(a) is a diagram schematically showing the configuration of the guiding section 200 when two reflective surfaces 212a and 212b are used. For convenience, FIG. 17A shows the light source 111, the photodetector 122, and the optical path of the laser beam when the light source 111 is in two rotational positions facing the reflective surfaces 211 and 221, respectively.

In this modified example, a reflective surface 212a is arranged opposite to the reflective surface 211, and a reflective surface 212b is arranged opposite to the reflective surface 221. The reflective surfaces 212a and 212b both have a conical side surface shape, similar to the reflective surface 212 of the above embodiment. The reflective surfaces 212a and 212b are formed as separate reflective surfaces.

Also in this case, the reflected light reflected by the reflective surfaces 211 and 221 can be reflected by the reflective surfaces 212a and 212b, respectively, and properly guided to the photodetector 122. Further, the optical path lengths from the nine light sources 111 to the photodetector 122 via the guide section 200 can be made substantially the same.

<Change example 2>
In the above embodiment, the light shielding member 230 is used as a limiter for limiting the amount of laser light emitted from the light source 111 and incident on the photodetector 122, but the limiter is not limited to this, for example, an ND filter is used as a limiter. may be used.

FIG. 17(b) is a diagram schematically showing the configuration of the guiding section 200 when an ND filter is used as the restrictor. For convenience, FIG. 17B shows the light source 111, the photodetector 122, and the optical path of the laser beam when the light source 111 is in two rotational positions facing the reflective surfaces 211 and 221, respectively. In the configuration of FIG. 17(b), ND filters 251 and 252 are disposed upstream of the reflective surfaces 211 and 221, respectively, and the light shielding member 230 is omitted.

In this case, the amount of laser light that enters the photodetector 122 via the reflective surface 211 can be set by the reflectance of the reflective surfaces 211 and 212 and the transmittance of the ND filter 251. The amount of laser light incident on the detector 122 can be set by the reflectance of the reflective surfaces 221 and 212 and the transmittance of the ND filter 252. The amounts of light from these two paths are set to differ by a predetermined difference so that the correction described with reference to FIG. 11 can be performed. As long as these amounts of light differ by a predetermined difference, the reflectances of the reflecting surfaces 211 and 221 may be higher or the same, and the transmittance of the ND filters 251 and 252 may be higher. Either one of them may be higher, or they may be the same.

Furthermore, an ND filter may be installed at a position facing only one of the reflective surface 211 and the reflective surface 221.

For example, as shown in FIG. 18(a), the ND filter 251 may be placed only at a position facing the reflective surface 211. In this case, the amount of laser light that enters the photodetector 122 via the reflective surface 211 can be set by the reflectance of the reflective surfaces 211 and 212 and the transmittance of the ND filter 251. The amount of laser light incident on the detector 122 can be set by the reflectance of the reflective surfaces 221 and 212. Also in this case, the amount of laser light that enters the photodetector 122 via the reflective surface 211 and the amount of laser light that enters the photodetector 122 via the reflective surface 221 are different by a predetermined difference. The reflectances of the reflective surfaces 211 and 221 and the reflectance of the ND filter 251 are set so as to. Note that in this configuration, the reflectances of the reflective surfaces 211 and 221 may be different from each other or may be the same.

Similarly, the ND filter 252 may be placed only at a position facing the reflective surface 221. In this case, the amount of laser light that enters the photodetector 122 via the reflective surface 211 can be set by the reflectance of the reflective surfaces 211 and 212, and the amount of laser light that enters the photodetector 122 via the reflective surface 221 can be set by the reflectance of the reflective surfaces 211 and 212. The amount of light can be set by the reflectance of the reflective surfaces 221 and 212 and the transmittance of the ND filter 252. Also in this case, the amount of laser light that enters the photodetector 122 via the reflective surface 211 and the amount of laser light that enters the photodetector 122 via the reflective surface 221 are different by a predetermined difference. The reflectances of the reflective surfaces 211 and 221 and the reflectance of the ND filter 252 are set so as to. Note that also in this configuration, the reflectances of the reflective surfaces 211 and 221 may be different from each other or may be the same.

Furthermore, as shown in FIG. 18(b), the light shielding member 230 and ND filters 251 and 252 may be combined. In this case, the amount of laser light that enters the photodetector 122 via the reflective surface 211 can be set by the reflectance of the reflective surfaces 211 and 212, the transmittance of the ND filter 251, and the size of the aperture 231. The amount of laser light that enters the photodetector 122 via the filter 221 can be set by the reflectance of the reflective surfaces 221 and 212, the transmittance of the ND filter 252, and the size of the aperture 232. In this case as well, the reflectances of the reflective surfaces 211 and 221, the reflectances of the ND filters 251 and 252, and the sizes of the apertures 231 and 232 may be set so that these two amounts of light differ by a predetermined difference. Note that either one of the ND filters 251 and 252 may be omitted from the configuration of FIG. 18(b).

<Change example 3>
In the above embodiment, the light shielding member 230 is arranged on the Y-axis positive side of the reflective surfaces 211, 221, 212 so as to correspond to the reflective surfaces 211, 221, 212. The light shielding member 230 may be arranged so as to correspond to at least one or more reflecting surfaces, and the arrangement position of the light shielding member 230 is not limited to the Y-axis positive side of the reflecting surfaces 211, 221, and 212.

FIG. 19(a) is a diagram schematically showing the configuration of the guide section 200 when the light shielding member 230 is disposed only on the positive side of the Y-axis of the reflective surface 211. In this case, the laser beam directed toward the reflective surface 211 passes through the opening 234 provided in the light shielding member 230.

FIG. 19(b) is a diagram schematically showing the configuration of the guide section 200 when the light shielding member 230 is disposed only between the reflective surface 211 and the reflective surface 212. In this case, the laser light traveling from the reflective surface 211 to the reflective surface 212 passes through the opening 234 provided in the light shielding member 230.

FIG. 19(c) is a diagram schematically showing the configuration of the guide section 200 when the light shielding member 230 is disposed only in the region on the negative side of the X-axis among the regions on the positive side of the Y-axis of the reflective surface 212. In this case, the laser light that is directed from the reflective surface 211 to the reflective surface 212 and reflected by the reflective surface 212 passes through the opening 234 provided in the light shielding member 230 .

In any case of FIGS. 19A to 19C, the amount of laser light that enters the photodetector 122 via the reflective surfaces 211 and 212 can be adjusted by changing the size of the aperture 234.

Note that the light shielding member 230 may be disposed only on the Y-axis positive side of the reflective surface 221, or the light shielding member 230 may be disposed only between the reflective surface 221 and the reflective surface 212, and the light shielding member 230 may be disposed only on the Y-axis positive side of the reflective surface 212. The light shielding member 230 may be arranged only in the region on the positive side of the X-axis among the regions on the positive side. Further, the light shielding members 230 may be arranged at a plurality of the six arrangement positions of the light shielding members 230.

<Change example 4>
In the embodiment described above, the guiding section 200 has a configuration including the first reflecting member 210 and the second reflecting member 220, but the present invention is not limited to this, and other configurations may be used. For example, a prism 410 shown below may be used as the guide section 200.

FIG. 20(a) is a diagram schematically showing a configuration when a prism 410 is used.

The prism 410 guides the plurality of laser beams to the plurality of photodetectors 122. Prism 410 includes reflective surfaces 411 and 412 having a conical side surface shape. The shapes of the reflective surfaces 411 and 412 are similar to the reflective surfaces 211 and 212 of the above embodiment. The reflective surfaces 411 and 412 are formed to totally reflect the laser beam. In the configuration of FIG. 20(a), reflective surfaces having different reflectances are not provided, and substantially all of the laser light incident on the reflective surfaces 411 and 412 is reflected. The light shielding member 230 includes openings 231 and 233, and the openings 231 and 233 are positioned on the positive side of the Y-axis of the reflective surfaces 411 and 412, respectively.

Also in this modified example, the laser beam emitted from the light source 111 can be appropriately guided to the photodetector 122. Furthermore, the optical path lengths from the nine light sources 111 to the photodetector 122 via the prism 410 can be made substantially the same. Further, depending on the size of the aperture 231, the amount of laser light that enters the photodetector 122 via the prism 410 can be adjusted.

Furthermore, as shown in FIG. 20(b), the light shielding member 230 and the ND filter 251 may be combined. In this case, the amount of laser light that enters the photodetector 122 via the prism 410 can be adjusted by the transmittance of the ND filter 251 and the size of the aperture 231.

Note that in addition to the reflective surfaces 411 and 412 corresponding to the reflective surfaces 211 and 212 of the above embodiment, the prism 410 may include another reflective surface corresponding to the reflective surface 221 of the above embodiment. Thereby, laser light passing through the reflective surface 411 and laser light passing through other reflective surfaces can be guided to the photodetector 122.

Furthermore, the width of the opening 233 in the X-axis direction may be adjusted, and an ND filter may be placed at the position of the opening 233. Thereby, the amount of laser light incident on the photodetector 122 can be further adjusted.

In addition, when using prisms as shown in FIGS. 20(a) and 20(b), there is a set of a prism and a light shielding member having a reflective surface with a low reflectance, and a set of a prism and a light shielding member having a reflective surface with a high reflectance. By arranging them in the rotational direction, it is possible to perform highly accurate distance correction using reflected light of two types of intensities, as in the above embodiment.

<Change example 5>
An optical fiber 420 shown below may be used as the guide section 200.

FIG. 21 is a diagram schematically showing a configuration when an optical fiber 420 is used.

In the configuration of FIG. 21, a plurality of optical fibers 420 are arranged side by side in the Z-axis direction. More specifically, the input ends 420a of the nine optical fibers 420 are installed at the positions where the nine laser beams shown in FIG. 2 enter. The input ends 420a of the nine optical fibers 420 are arranged, for example, along an arc defining the reflective surface 211 in FIG. 13(a) and the reflective surface 221 in FIG. 14(a). The output ends 420b of the nine optical fibers 420 are installed so that the laser beams emitted from these output ends 420b are guided to the corresponding photodetectors 122 by the condenser lenses 121. The lengths of the nine optical fibers 420 are approximately the same. The lengths of these optical fibers 420 may be adjusted so that the optical path lengths of the laser beams from the light source 111 to the photodetector 122 via each optical fiber 420 are approximately the same.

Also in this modified example, the laser beam emitted from the light source 111 can be appropriately guided to the photodetector 122. Furthermore, the optical path lengths from the nine light sources 111 to the photodetector 122 via the optical fibers 420 can be made substantially the same.

Note that in FIG. 21, a light shielding member may be arranged on the Y-axis positive side of the optical fiber 420. In this case, for example, openings of the light shielding member are positioned corresponding to the input end 420a and the output end 420b of the optical fiber 420, respectively.

In addition, when using optical fibers as shown in Fig. 21, there is an optical fiber group in which an ND filter having a first transmittance is arranged at the entrance, and an ND filter having a second transmittance different from the first transmittance at the entrance. It is sufficient that the arranged optical fiber groups are arranged side by side in the rotation direction. Thereby, as in the above embodiment, highly accurate distance correction can be performed using reflected light of two types of intensities.

<Change example 6>
In the above embodiment, the openings 231 and 232 formed in the light shielding member 230 have a rectangular shape when viewed in a direction parallel to the YZ plane, but the shape is not limited to this. Any shape is sufficient as long as it is approximately the same regardless of the position through which it passes.

FIG. 22(a) is a diagram schematically showing the configuration of a light shielding member 230 according to modification example 5.

In this modified example, the optical axis of the central laser beam among the nine laser beams is positioned at the central position P11 in the length direction (Z-axis direction) of the apertures 231 and 232, and the optical axis of the laser beams at both ends is assumed to be positioned at an end position P12 in the length direction (Z-axis direction) of the openings 231 and 232. In this case, if the width of the apertures 231, 232 is constant, the amount of laser light passing through the apertures 231, 232 at the end position P12 is smaller than the amount of laser light passing through the apertures 231, 232 at the center position P11. turn into.

Therefore, in this modified example, the aperture 231, The shape of 232 is adjusted. That is, the width of the end portions of the openings 231 and 232 is set wider than the width of the central portion of the openings 231 and 232. For example, in the example of FIG. 22(a), the width of the openings 231 and 232 in the X-axis direction increases from the center position P11 to the end position P12. Moreover, in the example of FIG. 22(b), only a predetermined range of the end position P12 is gradually widened, and the width of the other ranges is constant.

The shapes of the apertures 231 and 232 are determined by taking into account the size of the laser light incident on the apertures 231 and 232, the deviation from both ends of the apertures 231 and 232, and the Gaussian distribution of the laser light intensity after passing through the aperture 231. The light intensity of the nine laser beams may be substantially the same, and the light intensity of the nine laser beams after passing through the aperture 232 may be set to be substantially the same. This makes it possible to suppress the difference in the amount of laser light passing through the center position P11 and the amount of laser light passing through the end position P12.

<Other change examples>
The configuration of the laser radar 1 can be modified in various ways in addition to the configurations shown in the above embodiments and modified examples.

In the above embodiment, nine light sources 111 are arranged in the projection optical system 110, but the number of light sources 111 arranged in the projection optical system 110 is not limited to nine. For example, the number of light sources 111 may be 2 to 8, or 10 or more. In these cases as well, the plurality of light sources 111 are arranged such that the angles formed by the emission direction of each laser beam and the rotation axis R10 differ by a predetermined angle.

In the above embodiment, a plurality of light sources 111 are arranged in the projection optical system 110 in order to generate a plurality of laser beams, but the present invention is not limited to this. One laser beam emitted from 111 may be divided.

FIG. 23 is a side view schematically showing the configuration of the projection optical system 110 when dividing one laser beam.

In the projection optical system 110 in this case, one light source 111 is arranged on the substrate 113, compared to the configuration in FIG. Furthermore, a diffraction element 114 is arranged on the downstream side of the collimator lens 112 in the laser beam emission direction. The diffraction element 114 splits one laser beam converted into parallel light by the collimator lens 112, and generates 0th-order diffraction light, +1st-order diffraction light, and +1st-order diffraction light. The diffraction element 114 is, for example, a step-type diffraction element.

In the configuration of FIG. 23 as well, similar to the embodiment described above, a plurality of laser beams whose angles with the rotation axis R10 differ by a predetermined angle are emitted from the projection optical system 110.

Note that in the example shown in FIG. 23, three laser beams are generated by the diffraction element 114, but the number of laser beams generated by the diffraction element 114 may be two or four or more.

In the above embodiment, the reflective surfaces 211 and 212 are configured such that the reflectance of the reflective surface 211 is lower than the reflectance of the reflective surface 212, but the present invention is not limited to this. The amount of laser light incident on the photodetector 122 and the amount of laser light incident on the photodetector 122 via the reflective surface 221 are set to have a predetermined difference so that the correction described with reference to FIG. 11 can be made. It is sufficient if they are set to be different. That is, as long as these amounts of light differ by a predetermined difference, the reflectances of the reflecting surfaces 211 and 221 may be higher or may be the same.

In the above embodiment, as shown in FIG. 3(b), nine photodetectors 122 are arranged on a substrate 123 parallel to the XZ plane, and the light receiving surfaces of the nine photodetectors 122 are , parallel to the XZ plane. However, the present invention is not limited to this, and the photodetectors 122 on the positive side of the Z-axis and the photodetectors on the negative side of the Z-axis are arranged so that the distances between the light receiving surfaces of the nine photodetectors 122 and the condensing lens 121 are approximately the same. The vessel 122 may be tilted with respect to the XZ plane and brought closer to the condenser lens 121.

In the above embodiment, as shown in FIGS. 15(a) and 15(b), the laser beam emitted from the light source 111 is reflected by the reflective surfaces 211 and 221 of the guide section 200, and then further reflected by the reflective surface 212. Although the laser beam is reflected and guided to the photodetector 122, the reflective surface 212 may be omitted and the laser beam may be directly guided to the photodetector 122 from the reflective surfaces 211 and 221. However, in this case, since the laser beam heads toward the photodetector 122 from an oblique direction, it is difficult to make the laser beam enter the photodetector 122 with a sufficient amount of light while avoiding collision with other members such as the collimator lens 112. Have difficulty. Therefore, in order to make the laser beam enter the photodetector 122 with a sufficient amount of light, as in the above embodiment, the reflective surface 212 is arranged to guide the laser beam from the front of the condensing lens 121 to the photodetector 122. It is preferable.

In the embodiments described above, the configurations of the projection optical system 110 and the light receiving optical system 120 are not limited to those described above. For example, the light receiving optical system 120 may include two or more condensing lenses.

In the above embodiment, the rotating direction of the rotating part 12 was clockwise when viewed in the negative direction of the Z-axis, but it may be rotated counterclockwise when viewed in the negative direction of the Z-axis.

In the above embodiment, one optical system 100 is installed in the laser radar 1, but a plurality of optical systems 100 may be installed along the circumferential direction of the rotation axis R10. In this case, the plurality of optical systems 100 can scan the scanning area with high frequency. In this case, the projection angles in the Z-axis direction of the projection lights emitted from the central light source 111 of the plurality of optical systems 100 may be different from each other. This makes it possible to detect objects located at different positions in the Z-axis direction.

Further, the configuration of the scanning unit 10 is not limited to the configuration shown in the above embodiment. For example, a plurality of laser beams emitted vertically upward from the fixed part 11 along the rotation axis R10 may be reflected by a mirror rotating about the rotation axis R10, and the plurality of laser beams may be rotated and scanned. good. In this case, a circular condenser lens 121 is arranged on the fixed part 11 side so that the optical axis 121a is aligned with the rotation axis R10. The reflected light of each laser beam from the scanning position is reflected by a mirror and then guided by a condenser lens 121 to a corresponding photodetector 122. A plurality of light sources 111 that emit a plurality of laser beams and a collimator lens 112 are embedded in the center of a condenser lens 121, for example.

Furthermore, it is also possible to apply the structure according to the present invention to a device that does not have a distance measurement function and only has a function of detecting whether or not an object exists in the projection direction based on a signal from the photodetector 122. Also in this case, according to the configuration of the above embodiment, the optical path length from the light source 111 to the photodetector 122 via the guide section 200 can be made substantially the same for a plurality of laser beams. When determining whether an abnormality has occurred in the light source 111 and the photodetector 122 based on the amount of received reflected light, the magnitude of the amount of light can be determined using a common threshold value.

In addition, the embodiments of the present invention can be appropriately modified in various ways within the scope of the technical idea shown in the claims.

(Additional note)
The following technology is disclosed by the description of the above embodiments.

(Technology 1)
a scanning unit that rotates and scans a plurality of laser beams whose angles with the rotation axis differ by a predetermined angle, and that individually receives reflected light from an object of the plurality of laser beams;
a guide section that guides the plurality of laser beams emitted from the scanning section to the plurality of photodetectors of the scanning section at a predetermined rotational position, respectively, with optical path lengths that are substantially the same as each other;
A laser radar characterized by:
According to this technique, a plurality of laser beams are guided to a photodetector by the guiding section with optical path lengths that are substantially the same. As a result, the processing for each laser beam can be shared, and the operation of the device can be monitored using simpler processing.

(Technology 2)
In the laser radar described in technology 1,
The guide section has a reflective surface on which the plurality of laser beams are incident at the predetermined rotational position,
When the reflective surface is cut along a plane that is parallel to the rotational axis and includes the optical axis of the laser beam incident on the reflective surface, the cross-sectional shape is concave in a circular arc shape in a direction away from the rotational axis. be,
A laser radar characterized by:
According to this technique, the optical path lengths of a plurality of laser beams to the reflecting surface can be made close to each other with a simple configuration.

(Technology 3)
In the laser radar described in technology 2,
The scanning unit includes:
a projection optical system that projects the plurality of laser beams;
a light receiving optical system that guides the plurality of reflected lights to the plurality of photodetectors,
The optical axis of the projection optical system and the optical axis of the light receiving optical system are separated from each other,
The reflective surface reflects the plurality of incident laser beams in a direction from the optical axis of the projection optical system toward the optical axis of the light receiving optical system,
The guiding section includes a second reflecting surface that reflects the plurality of laser beams reflected by the reflecting surface in a direction along the optical axis of the light receiving optical system and guides them to the plurality of photodetectors, respectively,
When the second reflective surface is cut along a plane that is parallel to the rotation axis and includes the optical axis of the laser beam reflected by the second reflection surface, the shape of the cross section is circular in the direction away from the rotation axis. It has an arcuate concave shape,
A laser radar characterized by:
According to this technique, at a predetermined rotational position where the projection optical system faces the guide section, a plurality of laser beams can be made to respectively enter the condenser lens in a direction along the optical axis of the condenser lens. Thereby, the photodetector can output a detection signal of sufficient magnitude, and the state of the device can be appropriately monitored. Furthermore, by curving the shape of the second reflective surface into an arc in the same direction as the reflective surface, the optical path lengths from the second reflective surface to the corresponding photodetectors for the plurality of laser beams can be made closer to each other. be able to.

(Technology 4)
In the laser radar described in technology 3,
The guide section includes a third reflective surface on which the plurality of laser beams are incident at a position shifted by a predetermined rotation angle from the predetermined rotation position,
When the third reflective surface is cut along a plane that is parallel to the rotation axis and includes the optical axis of the laser beam incident on the third reflection surface, the cross-sectional shape is a circular arc in the direction away from the rotation axis. having a concave shape and reflecting the plurality of incident laser beams toward the second reflective surface;
A laser radar characterized by:
According to this technology, for example, the amount of laser light that enters the photodetector via the reflective surface and the amount of laser light that enters the photodetector via the third reflective surface are set to be different from each other. By doing so, the distance to the object can be accurately corrected based on the detection signal of the laser beam that has passed through the reflective surface and the detection signal of the laser beam that has passed through the third reflective surface.

(Technique 5)
In the laser radar described in technology 4,
The reflective surface and the third reflective surface have different reflectances from each other,
A laser radar characterized by:
According to this technology, the amount of laser light that enters the photodetector via the reflective surface and the amount of laser light that enters the photodetector via the third reflective surface can be controlled with a simple configuration. They can be made different from each other.

(Technology 6)
In the laser radar according to any one of Techniques 1 to 5,
The guide section includes a prism that guides the plurality of laser beams to the plurality of photodetectors.
A laser radar characterized by:
According to this technique, a reflective surface can be arranged by installing a prism.

(Technology 7)
In the laser radar described in technology 1,
The guide section includes an optical fiber that guides the plurality of laser beams to the plurality of photodetectors.
A laser radar characterized by:
According to this technique, the guide path can be flexibly set while adjusting the optical path length.

(Technology 8)
In the laser radar according to any one of Techniques 1 to 7,
The guide section has a limiter for limiting the amount of the laser beam incident on the photodetector.
A laser radar characterized by:
According to this technique, the amount of laser light incident on the photodetector can be adjusted as appropriate using the limiter. Thereby, for example, it is possible to suppress the output of the photodetector from becoming saturated, and it is also possible to appropriately perform the distance correction described above by giving a difference in the amount of light received by the photodetector depending on the optical path.

(Technology 9)
In the laser radar described in technology 8,
The limiter is a light shielding member in which an opening is formed.
A laser radar characterized by:
According to this technique, the amount of laser light incident on the photodetector can be adjusted by changing the size of the aperture. Thereby, the waveform of the detection signal based on the laser beam can be adjusted to a desired waveform. Therefore, the distance correction described above can be performed appropriately.

(Technology 10)
In the laser radar described in technology 9,
The opening is a narrow slit in the rotation direction of the plurality of laser beams,
A laser radar characterized by:
According to this technique, for example, in the configuration of the above embodiment, the area of incidence of the laser beam on the reflective surface of the guiding section can be restricted, so the reflective surface can be made small and the guiding section can be made compact.

(Technology 11)
In the laser radar described in technology 10,
The aperture has a shape such that the amount of light of the plurality of laser beams transmitted therethrough is substantially the same regardless of the position through which the aperture is transmitted;
A laser radar characterized by:
According to this technique, since the light quantities of the plurality of laser beams after passing through the aperture are approximately the same, the light quantities of the laser beams incident on the plurality of photodetectors can be made close to each other. Therefore, common processing can be applied to each detection signal.

(Technology 12)
In the laser radar described in technology 8,
the restrictor is an ND filter;
A laser radar characterized by:
According to this technique, the amount of each laser beam incident on the photodetector can be adjusted using the ND filter.

1 Laser radar R10 Rotation axis 10 Scanning unit 110 Projection optical system 111 Light source 112a Optical axis 120 Light receiving optical system 121a Optical axis 122 Photodetector 200 Guide unit 211 Reflective surface 212 Reflective surface (second reflective surface)
212a, 212b reflective surface (second reflective surface)
221 Reflective surface (third reflective surface)
230 Light shielding member (limiting body)
231, 232, 233, 234 opening (slit)
251, 252 ND filter (restrictor)
410 Prism 411 Reflective surface 412 Reflective surface (second reflective surface)
420 optical fiber

Claims (12)

1. a scanning unit that rotates and scans a plurality of laser beams whose angles with the rotation axis differ by a predetermined angle, and that individually receives reflected light from an object of the plurality of laser beams;
   a guide section that guides the plurality of laser beams emitted from the scanning section to the plurality of photodetectors of the scanning section at a predetermined rotational position, respectively, with optical path lengths that are substantially the same as each other;
   A laser radar characterized by:
   
2. The laser radar according to claim 1,
   The guide section has a reflective surface on which the plurality of laser beams are incident at the predetermined rotational position,
   When the reflective surface is cut along a plane that is parallel to the rotational axis and includes the optical axis of the laser beam incident on the reflective surface, the cross-sectional shape is concave in the shape of an arc in a direction away from the rotational axis. be,
   A laser radar characterized by:
   
3. The laser radar according to claim 2,
   The scanning unit includes:
   a projection optical system that projects the plurality of laser beams;
   a light receiving optical system that guides the plurality of reflected lights to the plurality of photodetectors,
   The optical axis of the projection optical system and the optical axis of the light receiving optical system are separated from each other,
   The reflective surface reflects the plurality of incident laser beams in a direction from the optical axis of the projection optical system toward the optical axis of the light receiving optical system,
   The guiding section includes a second reflecting surface that reflects the plurality of laser beams reflected by the reflecting surface in a direction along the optical axis of the light receiving optical system and guides them to the plurality of photodetectors, respectively,
   When the second reflective surface is cut along a plane that is parallel to the rotation axis and includes the optical axis of the laser beam reflected by the second reflection surface, the shape of the cross section is circular in the direction away from the rotation axis. It has an arcuate concave shape,
   A laser radar characterized by:
   
4. The laser radar according to claim 3,
   The guide section includes a third reflective surface on which the plurality of laser beams are incident at a position shifted by a predetermined rotation angle from the predetermined rotation position,
   When the third reflective surface is cut along a plane that is parallel to the rotation axis and includes the optical axis of the laser beam incident on the third reflection surface, the cross-sectional shape is a circular arc in the direction away from the rotation axis. having a concave shape and reflecting the plurality of incident laser beams toward the second reflective surface;
   A laser radar characterized by:
   
5. The laser radar according to claim 4,
   The reflective surface and the third reflective surface have different reflectances from each other,
   A laser radar characterized by:
   
6. The laser radar according to claim 1,
   The guide section includes a prism that guides the plurality of laser beams to the plurality of photodetectors.
   A laser radar characterized by:
   
7. The laser radar according to claim 1,
   The guide section includes an optical fiber that guides the plurality of laser beams to the plurality of photodetectors.
   A laser radar characterized by:
   
8. The laser radar according to any one of claims 1 to 7,
   The guide section has a limiter for limiting the amount of the laser beam incident on the photodetector.
   A laser radar characterized by:
   
9. The laser radar according to claim 8,
   The limiter is a light shielding member in which an opening is formed.
   A laser radar characterized by:
   
10. The laser radar according to claim 9,
    The opening is a narrow slit in the rotation direction of the plurality of laser beams,
    A laser radar characterized by:
    
11. The laser radar according to claim 10,
    The aperture has a shape such that the amount of light of the plurality of laser beams transmitted therethrough is substantially the same regardless of the position through which the aperture is transmitted;
    A laser radar characterized by:
    
12. The laser radar according to claim 8,
    the restrictor is an ND filter;
    A laser radar characterized by:

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