WO2018147453A1

WO2018147453A1 - Scanning optical system and laser radar device

Info

Publication number: WO2018147453A1
Application number: PCT/JP2018/004754
Authority: WO
Inventors: 菖蒲鷹彦; 石川亮太; 井手義憲; 長澤光; 影山将史
Original assignee: コニカミノルタ株式会社
Priority date: 2017-02-09
Filing date: 2018-02-09
Publication date: 2018-08-16
Also published as: JP7157385B2; JPWO2018147453A1

Abstract

A scanning optical system 101 is equipped with: a light projection system 10 which is provided with a plurality of light sources 11a, 11b and a collimator unit 18 into which light from each of the light sources 11a, 11b is made to enter; a scanning mirror 31 which reflects the light from the light projection system 10 as a laser beam L1 to serve as a projection beam, and scans the laser beam in a main scanning direction; a light receiving lens 22 upon which returning light L2 from the scanning mirror 31 is incident; and a light receiving element 24 upon which returning light L2 that has passed through the light receiving lens 22 is incident. The plurality of light sources 11a, 11b are disposed in positions that differ in a direction corresponding to an auxiliary scanning direction, which is orthogonal to the main scanning direction. The light receiving element 24 is disposed so as to be capable of detecting returning light L2 corresponding to the plurality of light sources 11a, 11b and is provided with at least two pixels in a direction corresponding to the auxiliary scanning direction. The laser beam L1 is emitted such that the positions in the auxiliary scanning direction of the light projection fields from the light sources 11a, 11b are different. The light sources 11a, 11b corresponding to adjacent light projection fields from among the light projection fields emit light at different timings.

Description

Scanning optical system and laser radar device

The present invention relates to a scanning optical system for detecting return light from an object while scanning a projection beam, and a laser radar apparatus incorporating the scanning optical system.

2. Description of the Related Art A distance measuring device that detects a distance to an object by irradiating laser light while scanning in two dimensions and detecting reflected light returned from an object existing within the scanning range is known (for example, , See Patent Document 1). In the distance measuring device described in Patent Document 1, high power is obtained by collecting laser outputs from a plurality of light sources at one point.

However, in the apparatus of Patent Document 1, the light emission timing of the light source is unknown, and since a plurality of light sources are connected in series, each light source can only emit light simultaneously. For this reason, if there is an overlapping portion in the projection visual field corresponding to each light source, the energy density of the overlapping portion becomes high, which may cause a problem that the eye safe of Class 1 is not satisfied. When the return light is simultaneously received by the entire light receiving element, if the return light beam protrudes from the corresponding light detection area and enters the light detection area, erroneous detection may occur in the light detection area adjacent to the light receiving element due to crosstalk.

JP 2005-292156 A

The present invention has been made in view of the above-mentioned problems of the background art, and provides a scanning optical system and a laser radar device that can detect at a long distance while solving problems relating to eye-safety and the like. Objective.

In order to achieve at least one of the above objects, a scanning optical system reflecting one aspect of the present invention includes a plurality of light sources and a collimator unit that each receives light from the light sources. System, a scanning mirror that reflects the light from the light projecting system as a light projection beam and scans in the main scanning direction, a light receiving lens to which the return light from the scanning mirror is incident, and a return light that has passed through the light receiving lens is incident A plurality of light sources arranged at different positions in a direction corresponding to the sub-scanning direction orthogonal to the main scanning direction, and the light receiving elements arranged to detect return light corresponding to the plurality of light sources. And having two or more pixels in the direction corresponding to the sub-scanning direction, and the light projecting beams are emitted so that the positions of the light projecting fields of the light sources in the sub-scanning direction are different from each other. The light source corresponding to the field of view is different. It emits light at the timing. Here, the light projection field is a range on the scanning region of the beam emitted from the light source. When a plurality of light sources emit light, the range of the beam corresponding to each light source is defined as a group of light projection fields.

In order to achieve at least one of the above objects, a laser radar device reflecting one aspect of the present invention includes the above-described scanning optical system and detects an object based on return light.

It is the schematic explaining the structure of the laser radar apparatus which concerns on 1st Embodiment of this invention. 2A and 2B are a side view and a plan view for explaining the structure of the scanning optical system. It is a conceptual diagram explaining an interface circuit and its periphery among the laser radar apparatuses of FIG. 4A and 4B correspond to FIGS. 2A and 2B, and are a side view and a plan view in which the light projecting system and the light receiving system are enlarged. 5A to 5C are a front view, a side view, and a plan view around the light emitting surface of the first light source, and FIGS. 5D to 5F are a front view, a side view, and a plan view around the light emitting surface of the second light source. FIG. FIG. 6A is a diagram for explaining a projection state of the projection beam to a distant place, and FIG. 6B is a conceptual diagram for explaining a path such as intersection of the projection beam and vertical inversion. It is a figure explaining the state of a light receiving element. FIG. 8A is a diagram for explaining the first light emission timing of the light source, and FIG. 8B is a diagram for explaining the second light emission timing of the light source. It is a figure explaining the light emission timing of the light source of the laser radar apparatus in 2nd Embodiment. FIG. 10A is a diagram for explaining the projection pattern of the light source of the laser radar device according to the third embodiment, and FIG. 10B is a diagram for explaining the light emission timing of the light source. 11A to 11C are diagrams for explaining the projection field of view and the light emission timing of the light source of the laser radar device of FIG. 10A. 12A and 12B are a side view and a plan view illustrating the structure of the scanning optical system in the fourth embodiment. 13A and 13B are a side view and a plan view for explaining the structure of a scanning optical system in the fifth embodiment. It is the schematic explaining the laser radar apparatus which concerns on 6th Embodiment.

[First Embodiment]
Hereinafter, the scanning optical system according to the first embodiment and a laser radar device incorporating the same will be described with reference to FIG. 1 and the like.

A laser radar device 100 shown in FIG. 1 is an object detection device for indoor / outdoor monitoring or in-vehicle use, for example, and detects the presence of a detection target and the distance to the detection target. The laser radar device 100 includes a light projecting system 10, a light receiving system 20, a rotary reflection unit 30, a drive control unit 40, a main control unit 50, and an exterior component 60. Among these, the light projecting system 10, the light receiving system 20, and the rotary reflection unit 30 constitute a scanning optical system 101.

Of the laser radar device 100 or the scanning optical system 101, the light projecting system 10 projects the laser light L1 that is the source of the light projecting beam onto the scanning mirror 31 of the rotary reflector 30 described later. The detailed structure of the light projecting system 10 will be described later.

The light receiving system 20 receives the return light L2 reflected from the detection target OB incident through the optical window 63 of the exterior component 60, that is, the return light L2, and reflected by the scanning mirror 31 of the rotary reflection unit 30. To do. More specifically, when there is a detection target OB such as an object in the detection region, the laser light (projection beam) L1 emitted from the laser radar device 100 is reflected by the detection target OB and reflected by the detection target OB. Part of the emitted light enters the light receiving system 20 through the scanning mirror 31 in the laser radar device 100 as return light L2. The detailed structure of the light receiving system 20 will be described later.

The rotation reflection unit 30 includes a scanning mirror 31 and a rotation drive unit 32. The scanning mirror 31 is a double-reflection polygon mirror, and includes a first reflecting portion 31a and a second reflecting portion 31b for bending an optical path. The first and second reflecting

portions

31a and 31b are respectively arranged up and down along a rotation axis RX extending in parallel with the Z direction. The first and second reflecting

portions

31a and 31b have a pyramid shape (specifically, see FIG. 2A and the like). The inclination angles of the reflecting surfaces of the first and second reflecting

portions

31a and 31b gradually change with the rotation position of the scanning mirror 31 (in the illustrated example, the position facing four directions in units of 90 °). (For the specific shapes of the first and second reflecting

portions

31a and 31b, see International Publication No. 2014/168137). That is, in the scanning mirror 31, the mirror surfaces of the first and second reflecting

portions

31a and 31b are inclined with respect to the Z-axis, and a plurality of combinations of the first and second reflecting

portions

31a and 31b forming a pair are used. The crossing angles are different from each other. As a result, the scanning range in the ± Z direction (sub scanning direction described later) parallel to the rotation axis RX is widened. The reflecting surface of the first reflecting portion 31a reflects the laser light (projected beam) L1 incident from the + X direction, which is the left direction on the paper surface, in a direction substantially orthogonal to the second reflecting portion 31b upward on the paper surface. Lead to the mirror surface. The mirror surface of the second reflecting portion 31b reflects the laser light L1 incident from the −Z direction, which is the downward direction on the paper surface, in a substantially orthogonal direction and guides it to the detection target OB side in the left direction on the paper surface. A part of the return light L2 reflected by the detection target OB follows a path opposite to the path of the laser light L1, and is detected by the light receiving system 20. In other words, the scanning mirror 31 reflects the return light L2 reflected by the detection target OB again by the mirror surface of the second reflection unit 31b and guides it to the mirror surface of the first reflection unit 31a. Subsequently, the return light L2 is reflected again by the mirror surface of the first reflecting portion 31a and guided to the light receiving system 20 side. When the scanning mirror 31 rotates, the traveling direction of the laser light L1 changes in a plane orthogonal to the Z-axis direction (that is, the XY plane). That is, the laser beam L1 is scanned around the Z axis or along the Y axis direction as the scanning mirror 31 rotates. An angle area scanned by the laser beam L1 is a detection area. The range of the tilt angle with respect to the + X-axis direction, which is the traveling direction of the projecting laser beam L1, is the projecting angle, and the traveling direction of the laser beam L1 at the scanning start point and the traveling direction of the laser beam L1 at the scanning end point. Is an irradiation angle. A projection visual field is formed by the projection angle and the irradiation angle. In the above, the direction in which the laser beam (projected beam) L1 scans (in this embodiment, the ± Y direction perpendicular to the rotation axis RX) is the main scanning direction, the direction in which the laser beam (projected beam) L1 scans, and the laser beam. The direction orthogonal to the traveling direction of the (projection beam) L1 (in this embodiment, the ± Z direction parallel to the rotation axis RX) is referred to as a sub-scanning direction. As described above, the center angle of the projection beam in the vertical direction or the Z direction of the projection field gradually changes according to the rotation position of the scanning mirror 31, and makes one rotation (360 °) of the scanning mirror 31. Sub-scan that moves, for example, in four stages with rotation) is achieved.

The drive control unit 40 includes a light emission timing control unit 41 and a light reception timing control unit 42. The light emission timing control unit 41 controls operations of a plurality of

light sources

11 a and 11 b described later in the light projecting system 10. The light emission timing control unit 41 has a drive circuit including a DSP, a power supply, and the like. The plurality of

light sources

11a and 11b are driven and controlled to emit light at preset light emission timings. The light receiving timing control unit 42 controls the operation of the light receiving element 24 described later in the light receiving system 20. As illustrated in FIG. 3, the light reception timing control unit 42 includes an interface circuit 45 including a plurality of switching units 43, a plurality of processing circuits 44, and the like. The former switching unit 43 is provided between the light receiving element 24 and the processing circuit 44. Thereby, since the number of parts is reduced and the parts are shared, the cost can be reduced. Further, the optical system 101 can be miniaturized by reducing the circuit scale. The switching unit 43 is connected so as to correspond to the plurality of pixels 24p (see FIG. 7) constituting the light detection surface 24a of the light receiving element 24, and the light detection areas DA1 and DA2 can be switched or selected. Yes. Specifically, as shown in FIG. 7, when the light receiving element 24 has six pixels 24 p and the light detection area is divided into two in the vertical direction of the drawing, that is, in the Z direction, three switching units 43 are provided across the vertical direction. The upper three pixels 24p and the lower three pixels 24p are switched at a predetermined light receiving timing. The light detected in the upper or lower light detection areas DA2 and DA1 (that is, the three pixels 24p) is subjected to signal processing by a processing circuit 44 provided on the output side of each switching unit 43. The processing circuit 44 includes a DSP and an A / D conversion unit, and performs signal processing of light detected by the light receiving element 24. The interface circuit 45 may be provided with an amplifier. In this case, the amplifier is provided between the light receiving element 24 and the switching unit 43, or between the switching unit 43 and the processing circuit 44, for example.

The main control unit 50 controls the operations of the

light sources

11a and 11b of the light projecting system 10 (see FIG. 2A and the like), the light receiving element 24 of the light receiving system 20 (see FIG. 2A and the like), the rotational drive unit 32 of the rotary reflecting unit 30, and the like. To do. Further, the main control unit 50 obtains the object information of the detection target OB from the electrical signal obtained by converting the return light L2 incident on the light receiving element 24 of the light receiving system 20. Specifically, when the output signal at the light receiving element 24 is equal to or greater than a predetermined threshold, the main control unit 50 determines that the light receiving element 24 has received the return light L2 from the detection target OB. In this case, the distance to the detection target OB is obtained from the difference between the light emission timings of the

light sources

11a and 11b and the light reception timing of the light receiving element 24. Further, based on the light receiving position of the return light L2 to the light receiving element 24 in the sub-scanning direction and the rotation angle corresponding to the main scanning direction of the scanning mirror 31, object information such as the position, size, and shape of the detection target OB is obtained. Can be sought.

The exterior component 60 is for covering and protecting the built-in component of the laser radar device 100. The exterior component 60 includes a lid-shaped main exterior portion 61 and a cylindrical container-shaped sub-exterior portion 62. The main exterior portion 61 and the sub exterior portion 62 are detachably fixed at their edges with fasteners such as bolts in a state in which confidentiality inside the exterior component 60 is maintained.

As shown in FIGS. 2A and 2B or FIGS. 4A and 4B, the light projecting system 10 includes a plurality of

light sources

11a and 11b and a plurality of collimator lenses that individually receive light SB1 and SB2 from the plurality of

light sources

11a and 11b. 12a and 12b, and a mirror 13 for optical path synthesis. One light source 11a and one collimator lens 12a constitute a first light source element 14a, and the other light source 11b and the other collimator lens 12b constitute a second light source element 14b. Further, a combination of the

collimator lenses

12 a and 12 b and the optical path combining mirror 13 is a collimator unit 18. The second light source element 14b and the mirror 13 are arranged above the first light source element 14a, that is, at a position shifted in the + Z direction.

The light emitting surface 16a of the first light source 11a and the light emitting surface 16b of the second light source 11b are longer in the direction corresponding to the sub-scanning direction than in the direction corresponding to the main scanning direction. That is, as conceptually shown in FIGS. 5A to 5C, the Z width which is the vertical dimension of the light emitting surface 16a of the first light source 11a is several times larger than the Y width which is the horizontal dimension of the light emitting surface 16a. Yes. Further, as conceptually shown in FIGS. 5D to 5F, the Z width which is the vertical dimension of the light emitting surface 16b of the second light source 11b is several times larger than the X width which is the horizontal dimension of the light emitting surface 16b. Yes. As described above, the

light emitting surfaces

16a and 16b of the plurality of

light sources

11a and 11b are longer in the direction corresponding to the sub-scanning direction than the direction corresponding to the main scanning direction, so that even a small number of

light sources

11a and 11b are projected. It becomes easy to widen the visual field in the sub-scanning direction.

4A and 4B, the light source optical axis SX1 (that is, the optical axis of the collimator lens 12a) that is the optical axis of the first light source element 14a extends in parallel to the X axis. On the other hand, the light source optical axis SX2 (that is, the optical axis of the collimator lens 12b), which is the optical axis of the second light source element 14b, extends in parallel to the Y axis in the upstream region A1 upstream of the mirror 13 and further than the mirror 13. It extends in parallel with the X axis in the downstream area A2 downstream of the optical path. That is, the light source optical axis SX1 on the first light source 11a side is orthogonal to the preceding area A1 of the light source optical axis SX2 on the second light source 11b side, and both areas A1 and A2 are set in different angular directions. Yes. Further, the light source optical axis SX1 on the collimator lens 12a side and the rear region A2 of the light source optical axis SX2 on the collimator lens 12b side are arranged adjacent to each other in parallel, and the

light sources

11a, 11a, It is about 11b wide. That is, the plurality of

light sources

11a and 11b are arranged at different positions in the Z direction corresponding to the sub-scanning direction, and appear to overlap with the same position in plan view on the rear side in the Y direction corresponding to the main scanning direction. Is arranged.

As shown in FIGS. 5A to 5C and the like, the light emitting surface 16a of the first light source 11a is arranged so as to be biased in the −Z direction corresponding to the sub scanning direction from the vicinity of the light source optical axis SX1. That is, the center C1 of the light emitting surface 16a is deviated in the −Z direction, and is arranged off-axis in the −Z direction corresponding to the sub-scanning direction with respect to the collimator lens 12a constituting the collimator unit 18. . Further, as shown in FIGS. 5D to 5F and the like, the light emitting surface 16b of the second light source 11b is arranged so as to be biased in the + Z direction corresponding to the sub-scanning direction from the vicinity of the light source optical axis SX2. That is, the center C2 of the light emitting surface 16b is deviated in the + Z direction, and is arranged off-axis with respect to the + Z direction corresponding to the sub-scanning direction with respect to the collimator lens 12b constituting the collimator unit 18.

As shown in FIGS. 4A and 4B, the emission optical axis AX1 of the light projecting system 10 is on the optical path from the light projecting system 10 to the scanning mirror 31, and the light source optical axis SX1 of the first light source element 14a and the first light axis SX1. The two light source elements 14b are arranged in the middle of the light source optical axis SX2 and the subsequent region A2. When the optical path is developed assuming that the optical path is not bent by the mirror 13, the first light source 11a and the second light source 11b are slightly displaced along the direction of the emission optical axis AX1, but with respect to the emission optical axis AX1. It can be said that they are arranged substantially symmetrically. The light SB1 emitted from the light emitting surface 16a of the light source 11a of the first light source element 14a exhibits a relatively wide divergence angle in the Y direction which is the horizontal direction and a relatively narrow divergence angle in the Z direction which is the vertical direction ( See FIGS. 5B and 5C). On the other hand, since the light emitting surface 16a of the light source 11a is long in the vertical direction, the divergence angle of the light SB1 is initially wide in the horizontal Y direction, but on the downstream side of the optical path of the first reflecting portion 31a (specifically, the light source 11a After a few hundred mm, that is, about 50 mm in front of the optical window 63), the aspect ratio of the aspect ratio becomes 1: 1, and then becomes wider in the vertical Z direction corresponding to the sub-scanning direction than in the horizontal Y direction. Similarly, the light SB2 emitted from the light emitting surface 16b of the light source 11b of the second light source element 14b exhibits a relatively wide divergence angle in the X direction which is the horizontal direction and a relatively narrow divergence angle in the Z direction which is the vertical direction. (See FIGS. 5E and 5F). On the other hand, since the light emitting surface 16b of the light source 11b is long in the vertical direction, the divergence angle of the light SB2 is initially wide in the horizontal X direction, but the vertical and horizontal aspect ratio is 1: on the downstream side of the optical path of the first reflecting portion 31a. After that, it becomes wider in the vertical Z direction corresponding to the sub-scanning direction than in the horizontal Y direction.

As shown in FIG. 6A, the light SB1 emitted from the light source 11a of the first light source element 14a disposed on the lower side is projected relatively lower in the distance through the scanning mirror 31, and the lower region is projected. The light SB2 that is illuminated and emitted from the light source 11b of the second light source element 14b disposed on the upper side in the sub-scanning direction is projected relatively upward in the distance through the scanning mirror 31 to illuminate the upper region.

As conceptually shown in FIG. 6B, the light paths SB1 and SB2 from the pair of

light sources

11a and 11b cross the optical axis AX1 with respect to the sub-scanning direction before and after entering the scanning mirror 31. Take. However, since the top and bottom are inverted by two inversions at the scanning mirror 31, the projected light SB1 and SB2 are subjected to upside down by the collimator unit 18 and upside down by the scanning mirror 31. As a result, the original vertical relationship is maintained as shown in FIG. 6A. By making the light beams SB1 and SB2 from the

light sources

11a and 11b intersect with each other in the vertical direction corresponding to the sub-scanning direction by the collimator unit 18, the light projecting system 10 can be made relatively small in the sub-scanning direction. it can.

As shown in FIG. 6A, as the scanning mirror 31 rotates, the scanning areas AR1 and AR2 formed by the pair of

light sources

11a and 11b form a locus in which the light SB1 and SB2 are moved in the Y direction, which is the main scanning direction. , And projected in the Y direction. More specifically, the laser beam (projection beam) L1 composed of the light beams SB1 and SB2 extends in the Z direction or the sub-scanning direction on the object side to cover the range of projection angles. Further, the laser light (projected beam) L1 composed of the light SB1 and SB2 moves in the Y direction or the main scanning direction within the range of the irradiation angle as the scanning mirror 31 rotates. The laser light (projection beam) L1 is emitted so that the positions of the projection fields of the

light sources

11a and 11b in the sub-scanning direction are different, and the

light sources

11a and 11b corresponding to the adjacent projection fields of the projection field are , Emit light at different timing (non-simultaneous light emission).

4A and 4B, the light receiving system 20 includes a perforated mirror 21, a light receiving lens 22, a mirror 23, and a light receiving element 24.

The perforated mirror 21 is an optical path bending mirror disposed on the optical path between the scanning mirror 31 and the light receiving lens 22. The opening 21a of the perforated mirror 21 is formed at an appropriate position in the center of the perforated mirror 21 or in the vicinity thereof. The emission optical axis AX1 and the incident optical axis AX2 are disposed substantially coincident with each other in the section adjacent to the scanning mirror 31. That is, the exit optical axis AX1 and the incident optical axis AX2 of the light projecting system 10 pass through the approximate center of the opening 21a, and the light from the

light sources

11a and 11b around the exit optical axis AX1 or the incident optical axis AX2 passing through the opening 21a. The lights SB1 and SB2 are narrowed in the upper and lower Z directions corresponding to the sub-scanning direction, and spread is suppressed by the

collimator lenses

12a and 12b in the left and right Y directions corresponding to the main scanning direction. As a result, the light SB1 and SB2 pass through the opening 21a without waste. By using the perforated mirror 21, the size of the light projecting system 10 and the light receiving system 20 can be reduced in the sub-scanning direction, and the amount of received light can be increased.

The return light L2 reflected by the first reflecting portion 31a through the second reflecting portion 31b of the scanning mirror 31 is reflected by the reflecting surface 21b of the perforated mirror (optical path folding mirror) 21 and bends the optical path in the orthogonal direction. It is done. At this time, a part of the return light L2 leaks out of the optical path through the opening 21a and is lost, but if the area ratio of the opening 21a to the first reflecting portion 31a is relatively small, the detection accuracy does not decrease.

The light receiving lens 22 has a role of narrowing the beam diameter of the return light L2, and the mirror 23 has a role of guiding the return light L2 having passed through the light receiving lens 22 to the light receiving element 24. Between the light receiving element 24 and the mirror 23, a band pass type filter 26 that blocks visible light other than the wavelength of the return light L2, that is, the laser light L1, is disposed. The light receiving lens 22 and the mirror 23 are arranged along the incident optical axis AX2.

The light receiving element 24 detects the return light L2 that has passed through the light receiving lens 22 and the mirror 23. The light receiving element 24 is, for example, a CMOS, CCD, or other semiconductor device, and detects the intensity of the return light L2, and has position resolution in the vertical Z direction corresponding to the sub-scanning direction. That is, the light receiving element 24 has two or more pixels in the sub-scanning direction. The light receiving element 24 receives the return light L2 in the light detection areas DA1 and DA2 corresponding to the divided projection fields, and the adjacent light detection areas DA1 and DA2 receive the return light L2 at different timings (non-simultaneous light reception). ).

A specific example of the light detection surface 24a of the light receiving element 24 will be described with reference to FIG. The longitudinal direction of the light detection surface 24a is the sub-scanning direction. The light detection surface 24a includes six pixels 24p, and the six pixels 24p are arranged in the upper and lower Z directions corresponding to the sub-scanning direction. That is, the light detection surface 24a has a configuration of 6 pixels with respect to the Z direction corresponding to the sub-scanning direction and a configuration of 1 pixel with respect to the left and right Y directions corresponding to the main scanning direction. The light detection surface 24a of the light receiving element 24 has a width capable of capturing the return light L2 reflected in the reverse direction by the detection target OB within the projection angle range of the laser light L1 with respect to the vertical Z direction and the horizontal Y direction. Have. For reference, the detection light L21 due to the light SB1 from the light source 11a and the detection light L22 due to the light SB2 from the light source 11b in the return light L2 are conceptually shown on the light detection surface 24a.

The outline of the operation of the laser radar device 100 or the scanning optical system 101 will be described. The pair of

light sources

11a and 11b of the light receiving system 20 are periodically caused to emit light under the control of the main control unit 50. The laser beam (projection beam) L1 synthesized by the meter unit 18 passes through the opening 21a of the perforated mirror (optical path bending mirror) 21 and passes through the scanning mirror 31, and the laser beam L1 that is long in the upper and lower sub-scanning directions is The main scanning is performed in the horizontal main scanning direction. By operating the light receiving element 24 of the light receiving system 20 in synchronism with this, it is possible to detect the return light L2 from the detection target OB and measure the distance, arrangement, etc. to the detection target OB.

As described above, the

light sources

11a and 11b corresponding to the adjacent light projection fields emit light at different timings (specifically, the first light emission timing and the second light emission timing). As shown in FIG. 8A, at the first light emission timing, the main control unit 50 operates the light emission timing control unit 41 to cause only the light source 11b to emit light among the plurality of 11a and 11b. At this time, the main control unit 50 operates the light reception timing control unit 42 to detect the detection light detected in the upper light detection area DA2 (that is, the three pixels 24p) by the switching unit 43 in the light receiving element 24 on the light receiving side. L22 is signal-processed by the processing circuit 44. Therefore, as shown in the drawing, even if the return light L2 enters the lower light detection area DA1, light is not detected on the lower side. Further, as shown in FIG. 8B, at a second light emission timing different from the first light emission timing, the main control unit 50 operates the light emission timing control unit 41 to emit only the light source 11a among the plurality of 11a and 11b. . At this time, the main control unit 50 operates the light reception timing control unit 42, and in the light receiving element 24 on the light receiving side, detection detected in the lower light detection area DA1 (that is, the three pixels 24p) by the switching unit 43. The light L21 is signal-processed by the processing circuit 44. Therefore, as shown in the drawing, even if the return light L2 enters the upper light detection area DA2, light is not detected on the upper side.

In the scanning optical system described above, the laser light (projection beam) L1 from the plurality of

light sources

11a and 11b is emitted so that the positions of the projection fields in the sub-scanning direction are different, and corresponds to the adjacent projection fields. The

light sources

11a and 11b are caused to emit light at different timings. Thereby, since the energy density in a long distance increases, it is possible to detect the detection target OB that is a longer distance object. Here, at a long distance, the relationship between the size of the

light sources

11a and 11b and the focal length of the optical system 101 has a dominant influence on the beam diameter emitted from the

light sources

11a and 11b. On the other hand, since the energy density at a short distance decreases, it is possible to improve the eye safety. Here, at a short distance, the spread of the beams from the

light sources

11a and 11b and the focal length of the optical system 101 have a dominant influence on the beam diameter. In addition, by causing the

light sources

11a and 11b corresponding to the adjacent light projection fields to emit light at different timings, the adjacent light projection fields do not overlap with each other, so that it is possible to satisfy the relatively safe Class 1 eye safe. In addition, by receiving light at different timings in the adjacent light detection areas DA1 and DA2, that is, by switching the detectable light detection areas DA1 and DA2, the beam of the return light L2 protrudes slightly from the corresponding light detection areas DA1 and DA2. Even in this case, erroneous detection due to crosstalk can be prevented, and there is no need to increase the accuracy of alignment, thereby reducing the cost.

[Second Embodiment]
Hereinafter, a scanning optical system according to the second embodiment and a laser radar device incorporating the same will be described. Note that the scanning optical system and the like according to the second embodiment are obtained by partially changing the scanning optical system and the like of the first embodiment, and items that are not particularly described are the same as those of the first embodiment. .

Referring to FIG. 9, in the case of the present embodiment,

light sources

11a and 11b each have a structure stacked in a direction corresponding to the main scanning direction (the horizontal direction in the drawing). The adjacent

light sources

11a and 11b emit light at a timing at which the light emission timing of each layer of the stack structure is shifted. The width W of the

light sources

11a and 11b is obtained by combining the width d1 of the light emission area of each stack element SC and the width d2 between the light emission areas by the number of stacks X. Here, the total width (d1 + d2) of the width d1 and the width d2 is a spatial period of light projection. Further, the width W is adjusted so as to achieve a combined spatial period for each of the

light sources

11a and 11b. By causing the

light sources

11a and 11b to emit light at a timing shifted by a time corresponding to the width d1 of the light emitting area, it is possible to detect the detection target OB that is an object without leakage and without a gap. In the example of FIG. 9, each of the

light sources

11a and 11b is composed of three stack elements SC. In the drawing, the upper and

lower light sources

11a and 11b are displayed while being shifted in the horizontal direction, but are actually arranged spatially in the horizontal direction, and the horizontal direction is also generated in the projection space by causing a shift in the light emission timing. There is a gap. The light source 11a emitted at the second light emission timing (light emission 2 in the drawing) is shifted by the time corresponding to the width d1 of the light emitting area with respect to the light source 11b emitted at the first light emission timing (light emission 1 in the drawing). I am letting. During the operation of the laser radar device 100, the

light sources

11a and 11b repeat these light emission timings. In the example of FIG. 9, at the next first light emission timing (light emission 3 in the figure), the light source 11b emits light with respect to the light source 11a emitted at the immediately preceding second light emission timing (light emission 2 in the figure). The light is emitted while being shifted by a time corresponding to the width d1. Further, at the next second light emission timing (light emission 4 in the figure), the light source 11a corresponds to the width d1 of the light emission area with respect to the light source 11b emitted at the immediately preceding first light emission timing (light emission 3 in the figure). Turn on the light by shifting the time.

[Third Embodiment]
Hereinafter, a scanning optical system according to the third embodiment and a laser radar device incorporating the same will be described. It should be noted that the scanning optical system according to the third embodiment is a part of the scanning optical system according to the first embodiment, etc., and items not specifically described are the same as those of the first embodiment. It is.

In the present embodiment, the light emission period of the M light sources sequentially enables M lighting, and the light source is switched between the n-th rotation of the scanning mirror 31 and the n + 1-th rotation of the scanning mirror 31. In addition, the light emission timing is shifted by one pixel ΔP. Here, the value M is a natural number of 2 or more, and the value n is a natural number of 1 or more. Thereby, the pixel shift in the sub-scanning direction, that is, the vertical direction is reduced while shifting the light emission timing, and the shape of the detection target OB that is the target can be accurately recognized. In the example of FIG. 10A, the light source is configured by three light sources LD1, LD2, and LD3. As shown in FIG. 10B, each of the light sources LD1, LD2, and LD3 emits light at intervals of the light emission period T, and each light source LD1. , LD2 and LD3 have different first to third light emission timings at intervals of T / M (in this case, M = 3). The arrangement of the light sources LD1, LD2, and LD3 shown in FIG. 10A is a virtual arrangement that eliminates the bending of the optical path and the like for convenience of explanation. FIGS. 11A, 11B, and 11C show the projection state or projection field of the first rotation, the second rotation, and the third rotation, respectively, as an example. As described above, in the case of the scanning mirror 31 shown in FIG. 2A and the like, the laser light L1 is sub-scanned in four stages in the vertical direction, and FIGS. 11A to 11C show the projected field of view during the one-stage scanning. Some specific planes QA are shown. The upper part of each figure shows a projection pattern P1 composed of an image Q1 of the light source LD1, the middle part shows a projection pattern P2 composed of an image Q2 of the light source LD2, and the lower part shows a projection pattern P2 composed of an image Q3 of the light source LD3. In FIGS. 11A to 11C, the light emission period T of the three light sources LD1, LD2, and LD3 sequentially enables three lighting (intervals corresponding to individual light emission periods or spatial periods T1 to T3 (the light emission period T). Equivalent)). Further, when the scanning mirror 31 is switched between the first rotation and the second rotation and between the second rotation and the third rotation, the light sources LD1, LD2, and LD3 have intervals or spatial periods corresponding to the light emission period. The light emission timings of T1 to T3 are shifted by T / 3 corresponding to one pixel ΔP. The laser radar device 100 is also operated at the same light emission timing after the fourth rotation. Note that the spatial period obtained by integrating the light projections for three rotations of the scanning mirror 31 is T / 3.

[Fourth Embodiment]
Hereinafter, a scanning optical system according to the fourth embodiment and a laser radar device incorporating the same will be described. It should be noted that the scanning optical system according to the fourth embodiment is a partial modification of the scanning optical system according to the first embodiment, and the matters not specifically described are the same as those of the first embodiment. It is.

As shown in FIGS. 12A and 12B, in the case of the fourth embodiment, the light projecting system 10 and the light receiving system 20 are simply separated, and the light projecting system 10 and the light receiving system 20 are related to the sub-scanning direction or the Z direction. They are located at different positions. That is, the emission optical axis AX1 and the incident optical axis AX2 of the light projecting system 10 are arranged adjacent to each other in parallel in the section between the mirror 23 and the scanning mirror 31, and are in the Z direction or the sub scanning direction. Are separated. That is, at the position adjacent to the scanning mirror 31, the exit optical axis AX1 and the incident optical axis AX2 are arranged at different positions in the Z direction corresponding to the sub-scanning direction, and the Y direction corresponding to the main scanning direction. Are arranged so as to overlap each other in plan view. In the present embodiment, the light projecting system 10 and the light receiving system 20 are simply separated.

The light receiving system 20 includes a light receiving lens 22, a mirror 23, and a light receiving element 24. In this case, since the emission optical axis AX1 and the incident optical axis AX2 are arranged so as to be displaced with respect to the sub-scanning direction, a perforated mirror is unnecessary. Unlike the first embodiment, the light detection surface 24a of the light receiving element 24 extends in the X direction due to the optical path bending by the mirror 23, but the X direction corresponds to the sub-scanning direction.

[Fifth Embodiment]
Hereinafter, a scanning optical system according to a fifth embodiment and a laser radar device incorporating the same will be described. Note that the scanning optical system and the like according to the fifth embodiment are obtained by partially changing the scanning optical system and the like according to the first embodiment, and items not specifically described are the same as those of the first embodiment and the like. It is.

As shown in FIGS. 13A and 13B, in the case of the fifth embodiment, in the light projecting system 10, the first light source element 14a and the second light source element 14b are mirror images arranged in the vertical sub-scanning direction across the emission optical axis AX1. Has been. That is, the first light source 11a and the second light source 11b are disposed strictly symmetrically with respect to the emission optical axis AX1. In this case, a combination of the pair of

collimator lenses

12a and 12b is a collimator unit 18, and a mirror for synthesizing the optical path is not necessary. In the first light source element 14a, the light source 11a is arranged off-axis so as to be asymmetric in the sub-scanning direction with respect to the collimator lens 12a constituting the collimator unit 18, and the first light source element 14b. The light source 11b is arranged off-axis so as to be asymmetric in the sub-scanning direction with respect to the collimator lens 12b constituting the collimator unit 18.

In the example shown in FIGS. 13A and 13B, the light receiving system 20 is the same as that shown in the first embodiment, but the light receiving system 20 is the same as that shown in the fourth embodiment. It is also possible to completely separate the optical path.

[Sixth Embodiment]
Hereinafter, a scanning optical system according to a sixth embodiment and a laser radar apparatus incorporating the same will be described. Note that the scanning optical system according to the sixth embodiment is a partial modification of the scanning optical system according to the first embodiment, and the items not specifically described are the same as those of the first embodiment. It is.

As shown in FIG. 14, the laser radar device 100 includes a light projecting system 10, a light receiving system 20, a rotary reflection unit 30, a main control unit 50, and an exterior component 60, as in the first embodiment. . The scanning mirror 31 of the rotary reflection unit 30 of this embodiment is a one-time reflection type polygon mirror, and includes only the first reflection unit 31a for bending the optical path. In the scanning mirror 31, the mirror surface of the first reflecting portion 31 a is inclined with respect to the Z axis, and reflects the laser beam L 1 incident from the −Z direction, which is the downward direction on the paper surface, in a direction substantially orthogonal to the scanning mirror 31. It is guided to the left side to be detected OB on the paper surface. A part of the return light L2 reflected by the detection target OB follows a path opposite to the path of the laser light L1, and is detected by the light receiving system 20. In this case, unlike the case of FIG. 1, the left and right X directions perpendicular to the rotation axis RX of the scanning mirror 31 are sub-scanning directions, and the Y direction perpendicular to the rotation axis RX is the main scanning direction. It has become.

As mentioned above, although this invention was demonstrated according to embodiment, this invention is not limited to the said embodiment etc. For example, the number of pixels 24p constituting the light detection surface 24a of the light receiving element 24 is not limited to six, and can be an appropriate number according to the detection resolution.

In addition, the optical elements constituting the light projecting system 10 and the light receiving system 20 are not limited to those illustrated in FIG. 2A and the like, and by increasing the number of mirrors for bending the optical path, increasing the number of lenses, etc. Various changes are possible.

In the above-described embodiment, the light receiving element 24 receives the return light L2 at different timings in the adjacent light detection areas DA1 and DA2, but the light detection corresponding to the light projection field divided by the return light L2 by a filter or the like. The return light L2 may be received at the same timing as long as it is limited to be incident on the areas DA1 and DA2 almost accurately.

Claims

A light projecting system having a plurality of light sources and a collimator unit for making light from each of the light sources incident;
A scanning mirror that reflects light from the light projecting system as a light projecting beam and scans in the main scanning direction;
A light receiving lens on which return light from the scanning mirror is incident;
A light receiving element on which the return light passing through the light receiving lens is incident;
With
The plurality of light sources are arranged at different positions in a direction corresponding to a sub-scanning direction orthogonal to the main scanning direction,
The light receiving element is arranged to detect the return light corresponding to the plurality of light sources, and has two or more pixels in a direction corresponding to the sub-scanning direction,
The projection beam is emitted so that the position of the projection field of each light source in the sub-scanning direction is different,
A scanning optical system in which the light sources corresponding to adjacent ones of the projection fields emit light at different timings.
The light receiving element receives the return light in a light detection region corresponding to a light projection field of each light source,
The scanning optical system according to claim 1, wherein the adjacent light detection regions receive the return light at different timings.
3. The scanning optical system according to claim 1, wherein light emitting surfaces of the plurality of light sources are longer in a direction corresponding to the sub-scanning direction than in a direction corresponding to the main scanning direction.
Further comprising a processing circuit for signal processing the return light detected by the light receiving element;
4. The scanning optical system according to claim 1, further comprising a switching unit that selects a light detection region of the light receiving element between the light receiving element and the processing circuit. 5.
5. The light source according to claim 1, wherein the light source has a stack structure in a direction corresponding to the main scanning direction, and causes the adjacent light source to emit light at a timing at which the light emission timing of each layer of the stack structure is shifted. A scanning optical system according to claim 1.
The light emission periods of the M light sources enable M lights to be turned on sequentially,
The light source shifts the light emission timing by one pixel when switching between the nth rotation of the scanning mirror and the n + 1th rotation of the scanning mirror,
6. The scanning optical system according to claim 1, wherein the value M is a natural number of 2 or more and the value n is a natural number of 1 or more.
The exit optical axis from the light projecting system toward the scanning mirror and the incident optical axis from the scanning mirror toward the light receiving lens are disposed substantially coincident in a section adjacent to the scanning mirror,
The scanning according to any one of claims 1 to 6, further comprising an optical path bending mirror disposed on an optical path between the scanning mirror and the light receiving lens and having an opening through which the emission optical axis passes. Mold optics.
A laser radar device comprising the scanning optical system according to any one of claims 1 to 7 and detecting an object based on the return light.