Distance measuring device

Abstract

To provide a distance measuring device with which, when using a plurality of laser beams and sensors, it is possible to have an iFOI and an iFOV approximately matched.SOLUTION: A distance measuring device 10 comprises a scan unit for scanning laser light from an irradiation unit in a scan direction, and a light detection element for receiving a portion of the reflected light having reflected from an object scanned with the laser light. The irradiation unit includes: a lens element provided with an incidence part or an emission part having at least two lens optical axes perpendicular to the scan direction and including at least two refractive surfaces intersecting the lens optical axes, respectively; and a light source for supplying laser light to the two refractive surfaces and having two effective emission regions which are eccentric to a position getting closer to or away from each other between the lens optical axes and also eccentric in mutually opposite directions from a plane that includes the lens optical axes. The respective edges of the two effective emission regions are aligned on a plane that includes the lens optical axes, and the two effective emission regions extend in mutually opposite directions from the edges.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a distance measuring device. [Background technology]

[0002] Conventionally, for example, Patent Document 1 discloses an object detection device that, as a distance measuring device, calculates the time it takes for light to be emitted from a laser diode and for the reflected light from an object to be received by a photodiode, and detects the distance to the object based on that time (see paragraph 0030 of Patent Document 1).

[0003] In such an object detection device, laser light from two laser diode modules, each having four laser diodes, is projected onto the object in a planar manner as two upper and lower instantaneous irradiation fields (each of 4 x 4 arrays) through two corresponding upper and lower projector lenses, and the reflected light is received by 16 x 2 photodiodes (see paragraph 0055 of Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-077073 A Summary of the Invention [Problem to be solved by the invention]

[0005] Generally, the light projecting and receiving device in a conventional object detection device instantaneously projects individual laser beams onto an object to create an instantaneous field of illumination (hereinafter also referred to as iFOI). The light projecting and receiving device also detects light that enters an instantaneous field of view (hereinafter also referred to as iFOV), which is an area where light reflected by the object can be seen instantaneously. The light projecting and receiving device measures the distance to the object using the iFOI and iFOV. The iFOI is expressed as the area range onto which the emitter shape of the laser beam is projected by the projecting lens. The iFOV is expressed as the area range seen by the light receiving surface of the light receiving unit by the receiving lens.

[0006] Patent document 1 does not mention that even if the light projecting and receiving device in an object detection device is designed so that the shape of the iFOI and the shape of the iFOV match each other and the iFOI and iFOV overlap without any misalignment, in reality the shape of the iFOI will deform from the designed shape due to various factors such as the arrangement of optical elements in the optical system.

[0007] In recent years, the configuration of the light-projecting unit and the light-receiving unit in a distance measuring device and an imaging device using the same has been, for example, a configuration in which the light-projecting unit projects laser light in a long and narrow beam shape in a predetermined vertical direction so as to scan the target area, and the light-receiving unit receives the reflected light from the target with a plurality of light-receiving elements arranged in a row. However, it is difficult to design the light-projecting unit and the light-receiving unit so that the shape of the iFOI and the shape of the iFOV match each other and so that the iFOI and the iFOV overlap without being misaligned with each other.

[0008] The present invention has been made in consideration of the above-mentioned points, and one of its objectives is to provide a distance measuring device that can approximately match the iFOI and iFOV of each when using multiple laser lights and corresponding sensors. [Means for solving the problem]

[0009] The invention described in claim 1 includes: an irradiation unit that outputs laser light; A scanning unit that scans the laser light in a scanning direction; a light detection element that receives a portion of the reflected light reflected from an object scanned with the laser light; The irradiation unit includes: a lens element having an entrance portion or an exit portion having at least two lens optical axes perpendicular to the scanning direction and including at least two refracting surfaces each intersecting the lens optical axes; a light source that supplies the laser light to the two refracting surfaces, and has two effective light-emitting areas that are eccentrically disposed at positions approaching each other between the lens optical axis or at positions moving away from each other from the lens optical axis, and that are eccentrically disposed in opposite directions from each other from a plane that includes the lens optical axis; The ends of the two effective light-emitting regions are aligned on a plane including the lens optical axis, and the two effective light-emitting regions extend in opposite directions from the ends. The present invention relates to a distance measuring device. [Brief description of the drawings]

[0010] [Figure 1] 1 is a configuration diagram showing an overall configuration of a distance measuring device according to a first embodiment. [Diagram 2] 4 is a schematic perspective view conceptually showing the relationship between a scanning area formed by a trajectory of laser light from a laser element according to the first embodiment and a light-receiving line sensor that receives reflected light. FIG. [Diagram 3] 2 is a perspective view showing a pair of collimator lenses and a laser element in the distance measuring device according to the first embodiment. FIG. [Figure 4] FIG. 2 is a perspective view showing a laser element in the distance measuring device according to the first embodiment. [Diagram 5] 2 is a schematic front view of a pair of collimator lenses as viewed from an irradiation axis in the distance measuring device according to the first embodiment. FIG. [Figure 6] 2 is a schematic front view of two laser elements, partially seen through a pair of collimating lenses, as viewed from on the irradiation axis in the distance measuring device according to the first embodiment. FIG. [Figure 7]13 is a schematic front view of two laser elements, partially seen through a pair of collimating lenses, as viewed from on the irradiation axis in a distance measuring device as a modified example of the first embodiment. FIG. [Figure 8] 3A to 3C are schematic three-sided views showing the relationship between the effective light emission area of ​​a laser element, a collimator lens, and an iFOI in the distance measuring device of the first embodiment. [Figure 9] FIG. 11 is a configuration diagram showing the overall configuration of a distance measuring device according to a second embodiment. [Figure 10] 10 is a schematic perspective view conceptually showing the relationship between a scanning area formed by the trajectory of laser light from a laser element according to the second embodiment and a light-receiving line sensor that receives reflected light. FIG. [Figure 11] FIG. 11 is a perspective view showing a lens element and a laser element in a distance measuring device according to a second embodiment. [Figure 12] 11 is a schematic front view of two laser elements, partially seen through a lens element, as viewed from on the irradiation axis in a distance measuring device according to Example 2. FIG. [Figure 13] FIG. 1 is a schematic perspective view showing how input and output cylindrical lenses, each with its cylindrical axis perpendicular to each other, collimate divergent laser light. [Figure 14] 11A to 11C are schematic three-sided views showing the relationship between the effective light emitting area of ​​a laser element, a lens element, and an iFOI in a distance measuring device according to a second embodiment. [Figure 15] FIG. 11 is a perspective view showing a modified example of a lens element in the distance measuring device according to the second embodiment. [Figure 16] FIG. 11 is a perspective view showing another modified example of the lens element in the distance measuring device according to the second embodiment. [Figure 17] FIG. 11 is a perspective view showing an irradiation unit including two pairs of laser elements and lens elements in a distance measuring device according to a third embodiment. [Figure 18] FIG. 11 is a schematic perspective view showing how other entrance and exit cylindrical lenses, each having a cylindrical axis perpendicular to each other, collimate divergent laser light. [Figure 19] FIG. 11 is a perspective view showing a lens element and a laser element in a distance measuring device according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] A scanning type distance measuring device such as a LiDAR (Light Detection And Ranging) device according to an embodiment of the present invention will be described in detail below. Note that in the following description of the embodiment and the accompanying drawings, the Z direction is the reference light irradiation direction (also called the irradiation axis Z) in an XYZ orthogonal coordinate space, the X direction is the horizontal direction, and the Y direction is the vertical direction. Also, since substantially the same or equivalent components are given the same reference symbols, duplicated descriptions of those components will be omitted. EXAMPLES

[0012] FIG. 1 is a diagram showing the overall configuration of a distance measuring device 10 according to this embodiment.

[0013] The distance measuring device 10 of this embodiment is a uniaxial scanning type distance measuring device that performs scanning irradiation of two laser beams L1a and L1b in the horizontal direction (X direction), forms two rectangular scanning areas Ra and Rb overlapping in the vertical direction (Y direction), i.e., scanned surfaces, and measures the distance to an object Ob present in the scanning areas Ra and Rb. Note that the present invention is not limited to the uniaxial scanning type distance measuring device.

[0014] The distance measuring device 10 of this embodiment has, as a light projecting and receiving optical system, an irradiation unit SH including laser elements 11a, 11b and a lens element BS, a scanning unit SCN including a deflection element 16, an imaging optical system 17 that receives a part of the reflected light from an object Ob via the deflection element 16, and a light receiving unit LRV including light receiving line sensors 18a, 18b. Furthermore, the distance measuring device 10 has a control unit 20 that controls the light projecting and receiving optical system.

[0015] The distance measuring device 10 of this embodiment measures the distance to the object Ob (or a part of its surface area) based on a TOF (Time of Flight) method that measures the time difference between the timing of projecting the laser beams L1a, L1b from the laser elements 11a, 11b onto the object Ob and the timing of receiving the return beams L2a, L2b from the object Ob by the light receiving line sensors 18a, 18b. Note that in this embodiment, a case will be described in which the distance is measured within a wide area in the vertical direction by scanning and irradiating two laser beams L1a, L1b.

[0016] FIG. 2 is a schematic perspective view conceptually showing the relationship between scanning areas Ra, Rb formed by the trajectories of laser light L1a, L1b from laser elements 11a, 11b of the light source and light-receiving line sensors 18a, 18b that receive reflected light.

[0017] As shown in Fig. 2, in this embodiment, the laser elements 11a and 11b emit linear laser light having a rectangular cross-sectional shape with the Y direction as the longitudinal direction and the X direction as the transverse direction to the scanning regions Ra and Rb. That is, the irradiation unit SH irradiates the laser light L1a and L1b from the laser elements 11a and 11b as iFOIfpa and fpb in the scanning regions Ra and Rb via the scanning unit SCN by the lens element BS. When an object (not shown) exists in the two iFOIfpa and fpb, a part of the light reflected or scattered by the object from the iFOIfpa and fpb returns to the light receiving unit LRV as return light via the scanning unit SCN.

[0018] The light receiving unit LRV is configured so that the returning light from iFOIfpa, fpb is respectively directed by the imaging optical system 17 into iFOVvFPa, vFPb defined by light receiving line sensors 18a, 18b extending in the Y direction, and the returning light is detected by the light receiving line sensors 18a, 18b.

[0019] [Irradiation unit] FIG. 3 is a perspective view showing collimator lenses BS1 and BS2 and laser elements 11a and 11b of the lens element BS in the irradiation unit SH of the distance measuring device according to the first embodiment.

[0020] [light source] FIG. 4 is a perspective view showing one laser element in the distance measuring device according to the first embodiment.

[0021] Each of the laser elements 11a and 11b serving as the light source of the distance measuring device 10 is, for example, an edge-emitting laser element of a semiconductor laser. Each of the laser elements 11a and 11b generates a laser beam having a peak wavelength in the infrared region and emits the laser beam intermittently in a pulsed manner. An edge-emitting laser element generally emits a laser beam in an elliptical cone shape from a cleaved edge light-emitting portion of the element. The intensity distribution of the cross section of the emitted laser beam is called a far-field pattern.

[0022] Each of the laser elements 11a and 11b shown in Fig. 4 is arranged so that the vertical direction (Y direction) of the far-field pattern ffp of each light emission is larger than the horizontal direction (X direction) and the radiation directions are both parallel. Here, the area of ​​the intensity distribution pattern of the element that is used by the distance measuring device 10 is called the effective light-emitting area EFE. The center of the laser light emitted from each laser element parallel to the irradiation axis Z is also called the laser optical axis Ea. The laser optical axis Ea passes through the center of the effective light-emitting area EFE. The effective light-emitting area EFE has a rectangular shape with the Y direction as the long side and the X direction as the short side.

[0023] As the laser element of the light source, in addition to the edge-emitting laser element, a vertical cavity surface-emitting laser (VCSEL) in which a resonator is formed in the vertical direction of the active layer, that is, a surface-emitting laser element (not shown), can also be used. In the case of such a surface-emitting laser element, a plurality of them can be arranged in a planar array to form a laser unit, and the light emission pattern, that is, the effective light-emitting area EFE, can be formed in various shapes.

[0024] [Lens element] 3, the irradiation section SH of the distance measuring device 10 includes a pair of collimator lenses BS1 and BS2 that are translucent lens elements BS that convert the cross-sectional shapes of the light beams of the laser beams L1a and L1b passing therethrough from the laser elements 11a and 11b. Each of the two collimator lenses BS1 and BS2 of the lens element BS includes a curved surface that is rotationally symmetric about the lens optical axis Rsa, and both have convex curved surfaces (preferably aspheric refractive surfaces) with the same magnitude of curvature.

[0025] The collimating lenses BS1 and BS2 have convex refracting surfaces RFP1 and RFP2 (also called incident lens surfaces RFP1 and RFP2) at the incident portion, which face the laser elements 11a and 11b, respectively. The two incident lens surfaces of these refracting surfaces RFP1 and RFP2 each have a positive power. Furthermore, the lens element BS has exit lens surfaces RFP3 and RFP4 on the opposite side of the incident lens surfaces RFP1 and RFP2, which may have the same lens surface or plane as the incident lens surface.

[0026] Each of the collimating lenses BS1 and BS2 converts the rectangular cross-section laser beams of laser light L1a and L1b from the effective light-emitting areas EFE of the pair of laser elements 11a and 11b into rectangular light beams iFOIfpa and fpb having a length L and a width S that create the scanning areas Ra and Rb shown in Figure 1.

[0027] The collimating lenses BS1 and BS2 are disposed, for example, at an equal distance from the irradiation axis Z so that their lens optical axes Rsa are parallel to the irradiation axis Z. As long as the irradiation axis Z is positioned parallel to the middle of the two lens optical axes Rsa, there is no limitation as to whether the collimating lenses BS1 and BS2 are separate or integrated.

[0028] Fig. 5 is a schematic front view of a pair of collimating lenses BS1 and BS2 as viewed from the irradiation axis Z in the distance measuring device. Fig. 6 is a schematic front view of two laser elements 11a and 11b partially seen through the collimating lenses BS1 and BS2 as viewed from the irradiation axis Z (output side of the laser elements) in the distance measuring device. Fig. 7 is a schematic front view of two laser elements partially seen through the pair of collimating lenses as viewed from the irradiation axis in a distance measuring device as a modified example of this embodiment.

[0029] 6, the laser elements 11a and 11b are disposed such that their laser optical axes Ea are symmetrically arranged with respect to the irradiation axis Z, and are further displaced (D, Dy) in parallel with the lens optical axes Rsa of the collimating lenses BS1 and BS2 in the X and Y directions, and are disposed eccentrically at positions approaching each other by a distance D between the lens optical axes Rsa. Note that the distance D (X direction) between the laser elements 11a and 11b may be the same or different, but the distance Dy (Y direction) is the same.

[0030] As shown in FIG. 7, as a modified example of the arrangement of the laser elements 11a, 11b and the collimating lenses BS1, BS2, the laser elements 11a, 11b may be displaced (D, Dy) parallel to the X direction and the Y direction from the lens optical axis Rsa of the collimating lenses BS1, BS2 and disposed eccentrically at positions away from each other by a distance D from the lens optical axis Rsa.

[0031] [Scanning section] 1, the distance measuring device 10 has, as the scanning unit SCN, a uniaxial scanning deflection element 16 that variably deflects and projects the laser beams L1a and L1b in a direction. That is, the deflection element 16 variably deflects the laser beams L1a and L1b along the X direction. Thus, the distance measuring device 10 defines scanning regions Ra and Rb by changing and scanning the emission directions of the linear laser beams L1a and L1b extending in the Y direction along the X direction.

[0032] The deflection element 16 has, for example, at least one rotating mirror 16A such as a galvanometer mirror or a polygon mirror that rotates around a rotation axis aY (Y direction) and reflects the laser beams L1a and L1b. Note that the deflection element 16 may be, for example, a one-axis rotating MEMS (Micro Electro Mechanical System) mirror in addition to the rotating mirror.

[0033] The laser elements 11a and 11b emit laser beams L1a and L1b having a rectangular cross-sectional shape (rectangular effective light-emitting area of ​​the laser element) extending along the axial direction of the rotation axis aY of the rotating mirror 16A. The deflection element 16 periodically changes the deflection direction of the laser beams L1a and L1b. The deflection element 16 emits the laser beams L1a and L1b while bending the traveling direction of the laser beams L1a and L1b, and periodically changes the bending direction. The laser beams L1a and L1b deflected by the deflection element 16 are projected as scanning beams toward two scanning areas Ra and Rb, respectively.

[0034] Each of the two scanning regions Ra, Rb overlapped in the vertical direction is also a cone-shaped three-dimensional space having a virtual scanned surface consisting of a vertical range along the longitudinal direction of the cross section of the laser beams L1a, L1b and a horizontal range in the width direction of the same cross section along the scanning direction SL (X direction) corresponding to the variable range of the deflection direction of the laser beams L1a, L1b by the deflection element 16, and a depth range in the distance direction within which the laser beams L1a, L1b can maintain a predetermined intensity.

[0035] The two scanning regions Ra, Rb are continuous in the vertical direction according to the positional relationship of the laser beams L1a, L1b emitted from the laser elements 11a, 11b. In addition, the two scanning regions Ra, Rb are shifted in the horizontal direction according to the offset amount from the optical axis of each of the laser beams L1a, L1b.

[0036] 1, when an object Ob (i.e., an object or material having reflectivity or scattering properties with respect to the scanning laser light) is present in the two scanning regions Ra and Rb, the laser light L1a and L1b are reflected or scattered by the object Ob. Then, a part of the light reflected by the object Ob travels as return light L2a and L2b along substantially the same optical path as the laser light L1a and L1b in the opposite direction and returns to the deflection element 16.

[0037] [Light receiving section] As shown in FIG. 1, distance measuring device 10 has, as a light receiving section LRV of a light projecting and receiving optical system, a deflection element 16, a light separating element SP, an imaging optical system 17, and two rectangular light receiving line sensors 18a and 18b adjacent to each other at one end.

[0038] The light separating element SP is provided on an irradiation axis Z common to the laser beams L1a, L1b and the return beams L2a, L2b between the deflection element 16 and the lens element BS, and deflects only the return beams L2a, L2b to the imaging optical system 17. For example, the light separating element SP is a beam splitter that separates the laser beams L1a, L1b and the return beams L2a, L2b by transmitting the laser beams L1a, L1b and reflecting the return beams L2a, L2b.

[0039] The imaging optical system 17 receives the return light beams L2a and L2b deflected by the light separation element SP, and shapes the return light beams L2a and L2b while forming images on the light receiving surfaces of the two light receiving line sensors 18a and 18b, respectively.

[0040] Each of the two light receiving line sensors 18a, 18b has a linear light receiving surface on which a plurality of light receiving segments SG arranged in one or more rows in the Y direction, which is the same as the direction of the iFOIfpa, fpb of the laser light L1a, L1b in the scanning regions Ra, Rb, are arranged so as to detect the return light L2a, L2b. The light receiving surfaces of the photodetection elements of the two light receiving line sensors 18a, 18b are arranged, for example, on the imaging plane of the imaging optical system 17. The photodetection elements of each of the two light receiving line sensors 18a, 18b detect the imaged return light L2a, L2b, and generate electrical signals corresponding to the detection results (light receiving results) of the return light L2a, L2b. Each of the light receiving segments receives the reflected light (return light L2a, L2b) from the object Ob independently of each other, and detects the light receiving timing. An avalanche photodiode operating in Geiger mode is used as the light receiving segment of the light detecting element.

[0041] [Control Unit] 1, the distance measuring device 10 has a control unit 20 that drives and controls the laser elements 11a and 11b of the irradiation unit SH, the deflection element 16 of the scanning unit / light receiving unit, and the two light receiving line sensors 18. The control unit 20 can be realized by an integrated unit chip such as an LSI chip or a microprocessor, a logic device such as a field programmable gate array (FPGA), a combination of an integrated unit chip and a logic device, or the like, and control program software for controlling them.

[0042] The control unit 20 has a light source driving unit 21 that drives the laser elements 11a and 11b, a deflection element driving unit 22 that drives the deflection element 16, and a distance measuring unit 23 that calculates the distance to the object Ob. The control unit 20 also independently performs switching driving of each of the two light-receiving line sensors 18a and 18b.

[0043] The light source control unit 21 is an irradiation control unit that drives and controls each of the laser elements 11a and 11b independently. The light source driving unit 21 controls the emission timing and emission intensity of the laser elements 11a and 11b.

[0044] The deflection element driver 22 controls the movement (or deflection angle) of the deflection element 16 .

[0045] The distance measuring unit 23 measures the distance to the object Ob based on the results of receiving the return lights L2a, L2b by the two light receiving line sensors 18a, 18b. The distance measuring unit 23 detects pulses indicating the return lights L2a, L2b (parts of the reflected light of the laser lights L1a, L1b) from the electrical signal. The distance measuring unit 23 also measures the distance to the object Ob or a part of its surface area by a TOF method based on the time difference between the projection timing of the laser lights L1a, L1b and the reception timing (detection pulse) of the return lights L2a, L2b, and generates first and second distance measurement data indicating the distance corresponding to the laser lights L1a, L1b.

[0046] The distance measuring unit 23 also generates distance measurement images of the two scanning areas Ra and Rb based on the generated first and second distance measurement data and information indicating the displacement of the rotating mirror 16A. The distance measuring unit 23 associates the distance measurement data generated by the distance measuring unit 23 with information indicating the displacement of the rotating mirror 16A, and generates a distance measurement image, which is two-dimensional / three-dimensional image data of the entire scanning area including the two scanning areas Ra and Rb, showing the distance values ​​of the distance measurement data as pixels.

[0047] [Effective light-emitting area in optical system / iFOI / sensor light-receiving part] The distance measuring device 10 performs scanning irradiation (rectangular iFOI) in the horizontal direction (X direction) of the scanning areas Ra and Rb using two laser beams, one above and one below, emitted from a rectangular effective light-emitting area EFE, and detects the reflected light (return light) from the object Ob by two upper and lower light-receiving line sensors 18.

[0048] Generally, in the light-projecting and light-receiving optical system of a distance measuring device, it is difficult to make the shape (positional relationship) of the rectangular effective light-emitting area EFE of the laser element similar to the shape (positional relationship) of the corresponding light-receiving line sensor, but it is necessary to do so. This is because, in order to use a light-receiving line sensor (especially in the case of a Geiger mode APD (Avalanche PhotoDiode) line sensor), the following two conditions (1) and (2) must be similar to each other, and if they are not similar, the signal amplitude will be small and the iFOV will be small. (1) The shape of the rectangular effective light emission area EFE of the laser element is similar to the shape of the rectangular iFOI of the irradiated laser light, and (2) The shape of the rectangular iFOI is similar to the shape of the light receiving part of the light receiving line sensor.

[0049] Another difficult condition for achieving similarity is that even if actual edge-emitting laser elements or light-receiving line sensors are simply lined up in the vertical direction (Y direction), gaps will always be created (because there are structures such as the semiconductor part around the light-emitting part of the laser element and the frame around the light-receiving part of the sensor). Therefore, the edge-emitting laser elements or light-receiving line sensors must be shifted horizontally (X direction) to prevent gaps from being created. In this case, there are two parameters for the size in the horizontal direction (X direction): (3) and (4). (3) The width (X direction) of the effective light-emitting area / iFOI / light-receiving area, and (4) Distance between effective light-emitting area / iFOI / light-receiving unit (X direction).

[0050] Due to the limitations of these parameters, even if a beam diameter aspect ratio conversion expander is added to the light projection and receiving optical system, the above conditions (1) and (2) cannot be satisfied. For example, if the effective light emission area and the light receiving section are aligned using a beam diameter aspect ratio conversion expander, the shapes of the iFOI and the light receiving section cannot be made similar, and for example, the iFOI width becomes too narrow, making it impossible to obtain returned light that fills the horizontal width of the light receiving section, resulting in a small signal amplitude and a small iFOV.

[0051] Therefore, in this embodiment, lens elements BS of collimator lenses BS1 and BS2 that face each other for the effective light-emitting areas of laser elements 11a and 11b are used, and the relative position of the effective light-emitting area of ​​the laser element is changed, i.e., decentered, with respect to the lens optical axis of the two collimator lenses BS1 and BS2, making it possible to change the spacing between the two iFOIs of the irradiated laser light while maintaining the relative shape.

[0052] [Operation of the distance measuring device of this embodiment] Figure 8 is a schematic three-sided view showing the relationship between the effective light emitting area EFE of a pair of laser elements 11a, 11b in the distance measuring device of this embodiment, a pair of collimating lenses BS1, BS2 of the lens element, and iFOIfpa, fpba, and is a front view of the XY plane perpendicular to the light beam (Z direction) of the laser light (Figure 8(a)), a ZX plane view including the irradiation axis Z (Figure 8(b)), and a ZY side view including the irradiation axis Z (Figure 8(c)).

[0053] As shown in Fig. 8(a) and (b), the two collimating lenses BS1 and BS2 of the lens element BS transmit laser light to positions away from both lens optical axes Rsa by maintaining the relative shapes of the rectangular shapes iFOIfpa and fpba adjacent to each other in the width direction (X direction) parallel to each other. Note that in the modification of Fig. 7, the rectangular shapes iFOIfpa and fpba transmit laser light to positions approaching each other from both lens optical axes Rsa.

[0054] The laser elements 11a and 11b are arranged such that their effective light emitting areas EFE, whose longitudinal directions (Y direction) are parallel to each other, are offset from each other in their lateral directions (X direction) (FIG. 8(a)).

[0055] This prevents the occurrence of a gap (see FIG. 8(c)) between two scanning regions Ra and Rb that overlap in the vertical direction (Y direction) shown in FIG. 1. To ensure the gap, it is preferable that the rectangular effective light-emitting regions EFE of the laser elements 11a and 11b are arranged such that one ends of the effective light-emitting regions EFE that face each other in opposite directions in the length direction (Y direction) are aligned in a straight line (ZX plane) as shown in FIG. 8(a).

[0056] Thus, in this embodiment, the laser elements 11a and 11b are arranged so that their two effective light-emitting areas EFE are eccentric to positions between the lens optical axis Rsa where they approach each other (in the modified example of Figure 7, positions where they move away from the lens optical axis Rsa), and are eccentric in opposite directions from each other from a plane containing both lens optical axes Rsa, and so that each end of the effective light-emitting area EFE is aligned on a plane (ZX plane) containing the lens optical axis Rsa, and the effective light-emitting areas EFE extend in opposite directions from each other from the ends.

[0057] The effective light emitting areas EFE of the laser elements 11a and 11b are arranged offset by a distance D from the two lens optical axes Rsa with respect to the lens element BS, at a position closer to (FIG. 6) or farther away (FIG. 7) from the irradiation axis Z. By adjusting the distance D, it is possible to match the left-right deviation (X direction) of the light receiving line sensors 18a and 18b (see FIG. 2).

[0058] According to this embodiment, by arranging the laser elements 11a and 11b so that their rectangular effective light-emitting areas EFE are eccentric, it is possible to form the iFOIfpa and fpba of the laser light with different intervals (angles) on the left and right (X direction) while maintaining the vertical (Y direction) continuity of the two scanning areas Ra and Rb (see FIG. 1) that overlap in the vertical direction (Y direction). Since the relationship between the effective light-emitting area iFOI and the light-receiving part iFOV can be made similar, a distance measuring device that can suppress a decrease in the signal sensitivity of the light-receiving line sensor is achieved.

[0059] Furthermore, according to this embodiment, the collimator lenses BS1 and BS2 are preliminarily aligned with the laser elements 11a and 11b and assembled, so that the optical axis of each assembly can be adjusted. EXAMPLES

[0060] 9 is a diagram showing the overall configuration of a distance measuring device 10 according to this embodiment. The distance measuring device 10 of this embodiment has the same configuration as that of the first embodiment, except that, as the lens element of the irradiation section SH, instead of the collimator lenses BS1 and BS2, one lens element BS3 having cylindrical lens surfaces with cylindrical axes perpendicular to each other at the emission section and the incidence section is used. Therefore, the changed components will be mainly described.

[0061] In this embodiment, instead of two collimating lenses, a translucent optical element having optical power in only one axial direction and a pair of cylindrical lens surfaces (refractive surfaces) that do not affect light in the axial direction perpendicular to that direction is used as the lens element BS3.

[0062] Fig. 10 is a schematic perspective view conceptually showing the relationship between the scanning areas Ra, Rb formed by the trajectories of the laser beams L1a, L1b from the laser elements 11a, 11b of the light source and the light-receiving line sensors 18a, 18b that receive the reflected light. Fig. 11 is a perspective view showing the lens element BS3 and the laser elements 11a, 11b in the distance measuring device according to this embodiment.

[0063] As shown in Fig. 10 and Fig. 11, the lens element BS3 has, at the entrance portion, refracting surfaces RFPa, RFPb (also called entrance cylindrical lens surfaces RFPa, RFPb) which are convex cylindrical surfaces facing the laser elements 11a, 11b, respectively. As shown in Fig. 11, the two entrance cylindrical lens surfaces of the refracting surfaces RFPa, RFPb have a center of curvature CoC on a vertical axis Vta perpendicular to the scanning direction (X direction), i.e., on the cylindrical axis, and each has a positive power. In addition, the entrance cylindrical lens surfaces RFPa, RFPb have cylindrical surfaces with the same curvature as the entrance portion.

[0064] Furthermore, the lens element BS3 has a convex cylindrical refracting surface RFPc (also called the exit cylindrical lens surface RFPc) at the exit portion opposite the entrance cylindrical lens surfaces RFPa and RFPb. The exit cylindrical lens surface RFPc faces both the entrance cylindrical lens surfaces RFPa and RFPb. This exit cylindrical lens surface RFPc has a center of curvature CoC2 on a cylindrical axis PLa parallel to the scanning direction (X direction), and is a refracting surface with positive power. The cylindrical axis PLa of the exit cylindrical lens surface RFPc is perpendicular to each of the cylindrical axes Vta of the two entrance cylindrical lens surfaces RFPa and RFPb. Any of the entrance and exit cylindrical lens surfaces can be configured as aspherical surfaces as well as cylindrical surfaces.

[0065] The lens element BS3 has two parallel lens optical axes Rsa that are perpendicular to the cylindrical axis PLa of the exit cylindrical lens surface RFPc and perpendicular to the two cylindrical axes Vta of the entrance cylindrical lens surfaces RFPa and RFPb. The lens element BS3 is disposed in the distance measuring device 10 such that the irradiation axis Z is located parallel to the midpoint between the two lens optical axes Rsa (entrance cylindrical lens surfaces RFPa and RFPb).

[0066] The laser beams L1a and L1b from the laser elements 11a and 11b are not directly focused in the cylindrical axis direction Vta (Y direction in FIG. 11) of the entrance cylindrical lens surfaces RFPa and RFPb, respectively, but are focused only in the direction perpendicular to the cylindrical axis direction of the entrance cylindrical lens surfaces (X direction in FIG. 11) and are emitted through the exit cylindrical lens surface RFPc. The emitted laser beams L1a and L1b are not directly focused in the cylindrical axis direction Vtc (X direction in FIG. 11) of the exit cylindrical lens surface RFPc, but are focused only in the direction perpendicular to the cylindrical axis direction of the entrance and exit cylindrical lens surfaces (Y direction in FIG. 11).

[0067] Fig. 12 is a schematic front view of the two laser elements 11a and 11b, partially seen through the lens element BS3 in the distance measuring device 10, as viewed from the irradiation axis Z. As shown in Fig. 12, the lens element BS3 is disposed so that its two lens optical axes Rsa are both located on the XZ plane including the irradiation axis Z. Furthermore, the entrance cylindrical lens surfaces RFPa and RFPb of the lens element BS3 are disposed so that their two lens optical axes Rsa sandwich the effective light emission area EFE (laser optical axis Ea) of the two laser elements 11a and 11b. The two parallel lens optical axes Rsa of the lens element BS3 do not coincide with the laser optical axis Ea of the laser elements 11a and 11b. That is, the laser elements 11a and 11b and the lens element BS3 are arranged such that the effective light-emitting areas EFE of the laser elements 11a and 11b are offset in parallel by a distance D to a position approaching the two cylindrical axes Vta (or the lens optical axis Rsa) of the lens element BS3, the ends of the effective light-emitting areas EFE are aligned with a plane (XZ plane) including the lens optical axis Rsa, and the effective light-emitting areas EFE extend in opposite directions (perpendicular direction Y of the XZ plane). In this way, the rectangular effective light-emitting areas EFE (see FIG. 4) of the laser elements 11a and 11b face the two entrance cylindrical lens surfaces RFPa and RFPb while being offset from both laser optical axes Ea.

[0068] Although the lens optical axis Rsa of the lens element BS3 does not coincide with the laser optical axes Ea of the laser elements 11a and 11b, the lens element BS3 can collimate the incident laser light and emit it.

[0069] FIG. 13 is a schematic perspective view showing how divergent laser light is collimated by input and output cylindrical lenses whose cylindrical axes are perpendicular to each other.

[0070] In general, a pair of flat cylindrical lenses (exit cylindrical lens and entrance cylindrical lens) each having an exit cylindrical lens surface and an entrance cylindrical lens surface can collimate a divergent incident beam of laser light when their cylindrical axes (X direction, Y direction) are perpendicular to each other. In this case, if the entrance and exit cylindrical lens surfaces are used to process the light beams in the X direction and Y direction independently from a common lens optical axis that is orthogonal to each other, a collimated exit beam such as a perfect circle or ellipse can be obtained. The effective light emitting area of ​​the laser element is placed on the optical axis that is orthogonal to the cylindrical lines of both lens surfaces by adjusting the focal length ratio of the pair of entrance and exit cylindrical lens surfaces to the ratio of the beam divergence in the X direction and the Y direction, and the entrance and exit cylindrical lens surfaces are placed so that they are separated by the focal length difference (F2-F1) between the focal length of the pair of entrance cylindrical lens surfaces (F1) and the focal length of the exit cylindrical lens surface (F2), thereby designing a lens element with a desired exit beam cross section. Additionally, rays from eccentric points of the incident beam displaced from the lens optical axis also become components in the collimated beam.

[0071] If the shaping of the collimated beam is insufficient using only the lens element BS3, a beam diameter aspect ratio conversion expander or the like may be added to the light projecting / receiving optical system.

[0072] [Operation of the distance measuring device of this embodiment] Figure 14 is a schematic three-sided view showing the effective light emitting areas of a pair of laser elements 11a and 11b in the distance measuring device of this embodiment, and the relationship between the lens element BS3 and iFOIfpa and fpb, and is a front view of the XY plane perpendicular to the light beam (Z direction) of the laser light (Figure 14(a)), a ZX plane view including the irradiation axis Z (Figure 14(b)), and a ZY side view including the irradiation axis Z (Figure 14(c)).

[0073] As shown in Figures 14(a) and (b), the two entrance cylindrical lens surfaces RFPa, RFPb and the exit cylindrical lens surface RFPc of lens element BS3 maintain the relative shapes of adjacent rectangular shapes iFOIfpa, fpba in the width direction (X direction) parallel to each other, and send laser light to positions away from both lens optical axes Rsa.

[0074] The laser elements 11a and 11b are arranged such that their effective light emitting areas EFE, whose longitudinal directions (Y direction) are parallel to each other, are offset from each other in their lateral directions (X direction) (FIG. 14(a)).

[0075] This prevents the occurrence of a gap (see FIG. 14(c)) between two scanning regions Ra and Rb overlapping in the vertical direction (Y direction) shown in FIG. 9. To ensure the gap, it is preferable that the rectangular effective light-emitting regions EFE of the laser elements 11a and 11b are arranged such that one ends of the effective light-emitting regions EFE facing each other in opposite directions in the length direction (Y direction) are aligned in a straight line (ZX plane) as shown in FIG. 14(a).

[0076] Thus, in this embodiment, the laser elements 11a and 11b are arranged so that their two effective light-emitting areas EFE are eccentric to positions approaching each other between the lens optical axes Rsa, and are eccentric in opposite directions from the plane containing both lens optical axes Rsa, and so that each end of the effective light-emitting areas EFE is aligned on the plane (ZX plane) containing the lens optical axes Rsa, and the effective light-emitting areas EFE extend in opposite directions from the ends.

[0077] The effective light emitting areas EFE of the laser elements 11a, 11b can be positioned eccentrically from the two lens optical axes Rsa to a position closer to the irradiation axis Z (by a distance D in FIG. 12) or farther away (not shown) with respect to the lens element BS3, so that by adjusting the distance D, it is possible to match the left-right deviation (X direction) of the light receiving line sensors 18a, 18b (see FIG. 10).

[0078] According to this embodiment, by arranging the laser elements 11a and 11b so that their rectangular effective light-emitting areas EFE are eccentric, it is possible to form the iFOIfpa and fpba of the laser light with different intervals (angles) on the left and right (X direction) while maintaining the vertical (Y direction) continuity of the two scanning areas Ra and Rb (see FIG. 9) overlapping in the vertical direction (Y direction). Since the relationship between the iFOI of the effective light-emitting area and the iFOV of the light-receiving unit can be made similar, a distance measuring device that can suppress the decrease in signal sensitivity of the light-receiving line sensor is achieved. That is, in this embodiment, a lens element BS3 having a refracting surface on the light-receiving side facing each other is used for each effective light-emitting area of ​​the laser elements 11a and 11b, and the relative positions of the two refracting surfaces on the light-receiving side (lens optical axis) are changed, that is, eccentrically, so that the interval between the two iFOI of the irradiated laser light can be changed while maintaining the relative shape.

[0079] [Modification of lens element BS3] 15 and 16 are perspective views showing modified examples of lens element BS3. Lens element BS3 having entrance cylindrical lens surfaces RFPa, RFPb and exit cylindrical lens surface RFPc may be integrally formed or may be configured as an assembly made up of multiple parts.

[0080] 15, the lens element BS3 may be an assembled lens element that is divided into two partial lens elements BSa and BSb along the ZX plane including the irradiation axis Z of the device. The curvatures of the entrance cylindrical lens surfaces RFPa and RFPb and the exit cylindrical lens surface RFPc of the partial lens elements BSa and BSb are the same.

[0081] 16, lens element BS3 may be an assembled lens element divided into three parts: a partial lens element BSc (plano-convex cylindrical lens) including an exit cylindrical lens surface RFPc, bounded by an XY plane including the scanning direction (X direction) of the device, and partial lens elements BSe, BSd (plano-convex cylindrical lenses) each including an entrance cylindrical lens surface RFPa, RFPb, divided into two parts by a ZX plane including the irradiation axis Z of the device. The entrance cylindrical lens surfaces RFPa, RFPb of partial lens elements BSe, BSd have the same curvature.

[0082] According to these modified examples, each partial lens element including the incident cylindrical lens surfaces RFPa, RFPb is aligned with the laser elements 11a, 11b in advance and assembled, and the optical path of the laser light for each assembly can be adjusted. EXAMPLES

[0083] FIG. 17 is a perspective view showing an irradiation unit SH including two pairs of laser elements (11a, 11b) (11c, 11d) and a lens element BS3 of a distance measuring device 10 according to the third embodiment.

[0084] This embodiment has the same configuration as Example 2, except that in addition to the two laser elements (11a, 11b) of Example 2, additional laser elements (11c, 11d) arranged point-symmetrically with respect to the irradiation axis Z are used. Therefore, the modified components will be described.

[0085] The four laser elements (11c, 11a, 11b, 11d) are arranged facing the entrance cylindrical lens surfaces RFPa, RFPb of the lens element BS3 so that their rectangular effective light emitting areas EFE are offset alternately in the Y direction.

[0086] The additional laser elements (11c, 11d), like the laser elements 11a, 11b, have their effective light-emitting areas EFE (see FIG. 4) eccentrically disposed to face the two incident cylindrical lens surfaces RFPa, RFPb. That is, the additional laser elements 11c, 11d are disposed with their effective light-emitting areas EFE eccentrically disposed by a distance D at positions approaching the irradiation axis Z from the two cylindrical axes Vta (i.e., the two lens optical axes Rsa) of the lens element BS3.

[0087] As a result, the lens element BS3 emits the laser light of the rectangular-shaped light beams iFOIfpc, fpa, fpb, and fpd so as to be offset alternately in the length direction (Y direction) as shown in Fig. 17. According to this embodiment, although not shown in Fig. 1, two additional scanning areas resulting from additional laser elements (11c, 11d) are generated above and below the two scanning areas Ra, Rb that overlap in the vertical direction (Y direction).

[0088] According to this embodiment, when a set of cylindrical lenses is arranged for each laser element pair, by decentering the rectangular effective light emission area EFE of the laser element as shown in FIG. 17, it is possible to form an iFOI of laser light with different intervals (angles) on the left and right (X direction) while maintaining continuity in the vertical direction (Y direction), and to expand the scanning area in the vertical direction (Y direction).

[0089] [Other Examples] In the above-mentioned Examples 2 and 3, one lens element BS3 is used which has a cylindrical lens surface RFPc extending in the scanning direction and having a cylindrical axis parallel to the scanning direction at the exit portion, and two refracting surfaces each having cylindrical lens surfaces RFPa, RFPb having a cylindrical axis extending in a direction perpendicular to the scanning direction at the entrance portion.

[0090] Furthermore, generally, as shown in FIG. 18, the pair of orthogonal entrance / exit cylindrical lenses in FIG. 13 can be rotated 90 degrees around the lens optical axis, and the diverging laser light can also be collimated based on the principle of other orthogonal entrance / exit cylindrical lenses.

[0091] Therefore, by utilizing the above-mentioned second embodiment, it is possible to configure a distance measuring device of the fourth embodiment, in which a lens element BS4 is used, instead of the lens element BS3 shown in Fig. 11, in which an entrance portion has a scanning direction-extending cylindrical lens surface RFPc having a cylindrical axis PLa parallel to the scanning direction SL (X direction), and two refracting surfaces RFPa, RFPb of an exit portion each have a cylindrical lens surface having a cylindrical axis Vta extending in the vertical direction, as shown in Fig. 19. The lens element BS4 is disposed in the distance measuring device 10 so that the irradiation axis Z is located parallel to the middle of the two lens optical axes Rsa (exiting cylindrical lens surfaces RFPa, RFPb).

[0092] That is, the laser elements 11a and 11b are arranged such that their effective light-emitting areas EFE are parallel and decentered by a predetermined distance to a position approaching the two cylindrical axes Vta (or lens optical axis Rsa) of the emission cylindrical lens surfaces RFPa and RFPb of the lens element BS4, the ends of the effective light-emitting areas EFE are aligned with a plane (XZ plane) including the lens optical axis Rsa, and the effective light-emitting areas EFE extend in opposite directions (perpendicular direction Y of the XZ plane). The effective light-emitting areas EFE of the laser elements 11a and 11b each supply laser light to two refracting surfaces (emission cylindrical lens surfaces RFPa and RFPb) via the entrance cylindrical lens surface RFPc.

[0093] In the above embodiments 1 to 3, a light projecting and receiving optical system is described in which the light projection and receiving system including the light projection unit SH, scanning unit SCN, and light receiving unit LRV is a common light projection and receiving optical system. However, the present invention can also be used in a biaxial type distance measuring device in which the light receiving system that receives return light from the target object is a separate optical system from the light projection system. [Explanation of symbols]

[0094] 10 Ranging device 11a, 11b, 11c, 11d Laser elements 16 Deflection element 17 Light collecting optical system 18a, 18b Light receiving line sensor 20 Control section 21 Light source driver 22 Deflection element driver 23 Ranging section Ob Object BS1, BS2 collimating lenses BS, BS3, BS4 lens elements Rsa Lens Optical Axis Ea Laser optical axis Z irradiation axis SG Light receiving segment Ra, Rb scanning area

Claims

1. An irradiation unit that outputs laser light along two parallel laser optical axes; a scanning unit that scans the laser light in a scanning direction that is an in-plane direction of a plane including the laser optical axis; a light detection element that receives a portion of light reflected from an object scanned with the laser light; Including, The light detection element includes two light receiving line sensors adjacent to each other, each of which is adjacent to an end of the light detection element and extends in opposite directions from the end in a vertical direction perpendicular to the scanning direction, receives the reflected light, and is adjacent to each other; The irradiation unit includes: a lens element including an entrance portion and an exit portion having two adjacent lens optical axes parallel to the laser optical axis and including two refracting surfaces each intersecting the lens optical axes; a light source that supplies the laser light to the refracting surface, and includes two laser elements that are eccentrically disposed at positions approaching each other between the lens optical axes or at positions moving away from each other from the lens optical axes, and that are eccentrically disposed in opposite directions from each other from a plane that includes the lens optical axes, and each of the two laser elements has an effective light emitting area; Each end of the effective light-emitting area is aligned on a plane including the lens optical axis, and the effective light-emitting areas extend in opposite directions from each other from the ends; the laser elements are arranged so that an instantaneous irradiation field of light emitted from each of the effective light-emitting regions and an instantaneous field of view of the light-receiving line sensor are similar in shape to each other; the two laser elements are configured so that the eccentricity of the effective light emitting area from the lens optical axis can be adjusted in a plane including the lens optical axis, A distance measuring device, characterized in that each of said effective light emitting areas is adjusted while maintaining vertical continuity of two scanning areas formed by said lens elements.

2. 2. The distance measuring device according to claim 1, wherein the lens element is a collimating lens, the refracting surface of which includes a curved surface that is rotationally symmetric about the lens optical axis.

3. 2. The distance measuring device according to claim 1, wherein the lens element is a light-transmitting optical element configured to have cylindrical lens surfaces having cylindrical axes at the exit portion and the entrance portion that are perpendicular to each other.

4. 4. The distance measuring device according to claim 3, wherein the lens element is divided between the refracting surfaces in a direction perpendicular to a plane including the laser optical axis.

5. 5. The distance measuring device according to claim 3, wherein the lens element has a partial cylindrical lens divided into an exit side and an entrance side perpendicular to the lens optical axis.

6. A distance measuring device described in any one of claims 3 to 5, characterized in that multiple pairs of the two laser elements are arranged along the cylindrical lens surface.

7. 7. The distance measuring device according to claim 1, wherein the scanning unit has a deflection element that scans the laser light in the scanning direction.

8. 8. The distance measuring device according to claim 7, further comprising a distance measuring section for measuring a distance to the object based on a result of reception of the reflected light by the light receiving line sensor.

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