JP2017138298A - Optical scanner type object detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical scanner type object detection device that has, for example, a broad detection area exceeding 180 degrees even with a comparatively simple configuration and low costs, and can effectively detect an object intruding into such the detection area.SOLUTION: An optical scanner type object detection device includes: one mirror that rotates around a rotary axis line; and a plurality of projection/light reception units that is equipped with a light source and a light reception unit, respectively. A light flux emitted from the light source of each projection/light reception unit is scanned and projected by rotation of the mirror after reflected by the mirror, and a part of the light flux scattered by an object of the scanned and projected light flux is configured to be received by the light reception unit of the corresponding projection/light reception unit after the part thereof is reflected by the mirror.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical scanning type object detection apparatus capable of detecting an object or the like that has entered a detection area.

  In recent years, with the growing awareness of crime prevention, there is an increasing demand for a monitoring system that can accurately detect an object that has entered a detection area. As a method for detecting such an object, a radio wave radar that transmits a radio wave and detects a reflected wave has been proposed, but there is a problem that it is difficult to accurately grasp the position of a distant object from the viewpoint of resolution. .

  On the other hand, the object detection apparatus which employ | adopted the TOF (Time of Flight) system has already been developed. In the TOF method, the distance to the object can be measured by measuring the time until the pulsed laser light hits the object and returns. However, the object detection device adopting the TOF method generally uses an amplification such as an APD (avalanche photodiode) in order to detect the weak reflected light generated when a laser beam is irradiated to a distant object. A light receiving element with a high rate is used. In order to increase the resolution of an object to be detected, a plurality of light receiving elements that receive reflected light are arranged to ensure high resolution.

  Patent Document 1 discloses a rotating mirror unit having a first mirror surface and a second mirror surface that are inclined with respect to a rotation axis, and at least one that emits a light beam toward an object through the mirror unit. A light projection system including a light source, and the light beam emitted from the light source is reflected by the first mirror surface of the mirror unit and then travels toward the second mirror surface, and further the second A radar device is disclosed that is reflected by a mirror surface and projected while being scanned with respect to the object in accordance with the rotation of the mirror unit. When such a mirror unit is used, the luminous flux emitted from the light projecting system is reflected by the rotating first mirror surface and the second mirror surface, and then is irradiated toward the object. Since the light is incident on the light receiving system after being reflected by the first mirror surface and the second mirror surface, in principle, only the reflected light of the projected light is incident on the light receiving system. It has the advantage of having a resolution and a wider field of view.

Japanese Patent Laying-Open No. 2015-180956 US Pat. No. 7,969,558

  Here, Patent Document 1 discloses that the number of scanning lines can be increased without deteriorating longitudinal distortion by using a plurality of light sources. However, the configuration disclosed in Patent Document 1 has a problem that the detection range around the rotation axis of the mirror unit is limited.

  In contrast, Patent Document 2 corresponds to reflected light from an object of laser light emitted from a light source by rotating a unit in which a large number of light sources and light receiving elements are two-dimensionally arranged. An optical measuring device capable of receiving light by a light receiving element one by one is disclosed. According to such an optical measurement device, it is possible to detect an object within a range of 360 degrees.

  However, the optical measurement device of Patent Document 2 has a problem of how to provide power and control of the light source and the light receiving element from the outside in addition to enormous cost by providing a large number of light sources and light receiving elements. . For example, if you use a contact-type rotary connector to supply power and control communication to a large number of light sources and light-receiving elements from the outside, there is a problem that the configuration will increase in size, as well as the occurrence of noise and difficulty in handling. There is a problem. On the other hand, in recent years, a non-contact type connector that can perform wireless power feeding using electromagnetic induction by a coil or wireless communication using infrared rays or light has been developed. However, in any case, it may increase the cost and complicate the configuration.

  The present invention has been made in view of the above circumstances, and has a relatively simple configuration and low cost, and has a wide detection area, for example, exceeding 180 degrees, and can effectively detect an object that has entered the detection area. An object is to provide an optical scanning type object detection device.

In order to solve the above-described problem, an optical scanning type object detection device of the present invention includes:
One mirror rotating around the axis of rotation;
A plurality of light emitting and receiving units each having a light source and a light receiving unit,
A light beam emitted from the light source of each light projecting / receiving unit is reflected by the mirror, then scanned and projected by the rotation of the mirror, and a part of the light beam scattered by the object among the projected light beams However, after being reflected by the mirror, the light receiving unit of the corresponding light projecting / receiving unit is configured to receive light.

  According to the present invention, an optical scanning type object detection device having a wide detection area of, for example, 180 degrees and capable of effectively detecting an object that has entered the detection area, while having a relatively simple configuration and low cost. Can be provided.

It is sectional drawing of the laser radar LR as an optical scanning type target object detection apparatus concerning 1st Embodiment. It is a perspective view of the principal part of the laser radar LR concerning this Embodiment. (A) is a schematic diagram which shows the 2nd reflection member which comprises a mirror unit seeing in the direction along the rotation axis, (b) is the 1st reflection member which comprises a mirror unit along the rotation axis. FIG. It is a figure which shows the scanning range seen in the rotating shaft direction of laser radar LR. It is a perspective view which shows typically the range which can detect an object by laser radar LR. It is a development view showing a scanning range of spot light SB emitted from laser radar LR. It is a figure similar to FIG. 3 concerning the modification of this Embodiment. It is a figure similar to FIG. 4 concerning the modification of this Embodiment. 7 is a side view of Example 1 showing only a mirror unit MU, a semiconductor laser LD1, and a collimating lens CL1 corresponding to the embodiment of FIGS. It is the figure which cut | disconnected the structure of FIG. 9 by the XX line and looked at the arrow direction. 9 is a side view of Example 2 showing only a mirror unit MU corresponding to the embodiment of FIGS. 7 and 8, a semiconductor laser LD1, and a collimating lens CL1. FIG. It is the figure which cut | disconnected the structure of FIG. 11 by the XII-XII line | wire, and looked at the arrow direction. It is a perspective view which shows the various examples of semiconductor laser LD1 and collimating lens CL1 which can be used for embodiment mentioned above. It is a perspective view of laser radar LR as an optical scanning type target object detection device concerning a 2nd embodiment. It is a perspective view shown in the state where a cover was removed in laser radar LR. It is a schematic diagram of the cross section of the laser radar LR concerning this Embodiment. It is a perspective view which shows the principal part except the housing | casing of the scanning unit SU concerning this Embodiment. It is the figure which looked at the scanning unit SU in the direction of rotation axis RO1. It is a figure which shows the unit rotation scanning range AR which can be scanned with the emitted light beam from two light projection / reception apparatus OPD, while the mirror unit MU carries out 1 rotation. It is the figure which looked at the unit rotation scanning range AR which is displaced while overlapping partially as the scanning unit SU rotates and displaces around the rotation axis RO2 in the equator direction (α direction) of the celestial sphere. It is a figure which expands and shows the site | part XXI in FIG. It is a figure which shows typically the 360-degree all-sky CSP which can detect an object with the laser radar LR. It is a figure which shows the principal part of the scanning unit SU concerning another embodiment. It is a perspective view of the laser radar LR concerning another embodiment. It is the figure which looked at the scanning unit SU concerning another embodiment in the direction of rotation axis RO1. In another embodiment, it is a diagram showing a unit rotation scanning range AR that can be scanned with light beams emitted from two light projecting and receiving devices OPD while the mirror unit MU rotates once. It is a figure which shows typically the 360-degree all-sky CSP which can detect a target object with the laser radar LR in another embodiment.

(First embodiment)
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view of a laser radar LR as an optical scanning type object detection device according to the first embodiment. FIG. 2 is a perspective view of the main part of the laser radar LR according to the present embodiment. The laser beam (solid line) directed to the object and the reflected light (dashed line) from the object only show the optical axes. ing. FIG. 3A is a schematic diagram showing the second reflecting member constituting the mirror unit as viewed in the direction along the rotation axis, and FIG. 3B is a diagram illustrating the rotating first reflecting member constituting the mirror unit. It is a figure seen from the direction along an axis, and the inclination-angle of the reflective surface with respect to a rotating shaft is attached | subjected for every reflective surface.

  In FIG. 1, the laser radar LR includes a first light projecting / receiving device (projecting / receiving unit) OPD1, a second light projecting / receiving device (projecting / receiving unit) OPD2, and a rotating mirror unit (mirror) MU. It is held in the casing CS (see FIG. 4). The first light projecting / receiving device OPD1 includes a pulsed semiconductor laser (light source) LD1 that emits a laser beam LB1, a collimator lens CL1 that transmits the laser beam LB1 emitted from the semiconductor laser LD1, and reflected light RB1 from the object. And a photodiode (light receiving unit) PD1 that receives the collected reflected light RB1. The second light projecting / receiving device OPD2 includes a pulsed semiconductor laser (light source) LD2 that emits a laser beam LB2, a collimator lens CL2 that transmits the laser beam LB2 emitted from the semiconductor laser LD2, and a reflection from an object. It has a lens LS2 that collects the light RB2, and a photodiode (light receiving unit) PD2 that receives the collected reflected light RB2.

  The mirror unit MU reflects the laser light beam LB1 emitted through the collimator lens CL1 of the first light projecting / receiving device OPD1 and applies an object to the object through a transparent plate (not shown) of the housing CS according to the rotation. The reflected light RB1 returned from the object through the transparent plate is reflected and incident on the lens LS1 of the first light projecting / receiving device OPD1, and further via the collimating lens CL2 of the second light projecting / receiving device OPD2. While reflecting the laser beam LB2 emitted in this manner, the object is scanned through a transparent plate (not shown) of the housing CS according to the rotation, and the reflection is returned from the object through the transparent plate. It has a function of reflecting the light RB2 and making it incident on the lens LS2 of the second light projecting / receiving device OPD2. Although not shown, it is preferable that the transparent plate is attached to the window portion of the housing CS and is inclined with respect to the emitted light. Although details will be described later, the light beams emitted from the semiconductor lasers LD1 and LD2 are longer in the sub-scanning angle direction (scanning orthogonal direction) than the scanning angle direction (scanning direction) when projected onto the object. preferable. The photodiodes PD1 and PD2 preferably have a plurality of light receiving areas arranged in the direction perpendicular to the scanning direction, but the light receiving areas may be two-dimensionally arranged.

  The optical axes of the first light projecting and receiving device OPD1 and the second light projecting and receiving device OPD2 (here, the center of the cross section of the laser light beams LB1 and LB2) are orthogonal to the rotation axis RX of the mirror unit MU. However, the optical axes of the first light projecting / receiving device OPD1 and the second light projecting / receiving device OPD2 may be slightly inclined from the direction orthogonal to the rotation axis depending on the size, shape, arrangement of optical elements, and the like. In addition, it is preferable that the optical axes of the first light projecting / receiving device OPD1 and the second light projecting / receiving device OPD2 are arranged approximately 180 ° apart about the rotation axis RX. Here, substantially 180 ° is assumed to be 180 ° ± 5 °.

  The mirror unit MU is held by a casing CS (see FIG. 4) so as to be rotatable about a rotation axis RX that is an axis, and as shown in FIGS. 2 and 3, the first reflecting member RF1 and the second reflecting member. It is formed in combination with RF2. As shown in FIG. 3B, the first reflecting member RF1 made of resin and having an equal thickness cup shape has an equilateral triangular joining surface RF1a centered on the rotation axis RX on the outer surface, and a joining surface. It has three substantially fan-shaped reflecting surfaces (first mirror surfaces) RF1c, RF1d, and RF1e that intersect each side of RF1a, and a cylindrical outer peripheral surface RF1f (FIG. 2) that contacts each reflecting surface. A central opening RF1g is formed at the center of the bonding surface RF1a.

  Similar to the first reflecting member RF1, the second reflecting member RF2 made of resin and having an equal thickness cup shape has an equilateral triangular shape centered on the rotation axis RX on the outer surface with reference to FIG. Bonding surface RF2a, three substantially fan-shaped reflection surfaces (second mirror surfaces) RF2c, RF2d, and RF2e intersecting each side of the bonding surface RF2a, and a cylindrical outer peripheral surface RF2f in contact with each reflection surface (FIG. 3) And have. A central opening RF2g is formed at the center of the bonding surface RF2a.

  Here, the inclination angle of the reflection surface RF1c with respect to the rotation axis RX is 44 °, the inclination angle of the reflection surface RF1d with respect to the rotation axis RX is 45 °, and the inclination angle of the reflection surface RF1e with respect to the rotation axis RX is 46 °. On the other hand, the inclination angle of the reflection surface RF2c with respect to the rotation axis RX is 44 °, the inclination angle of the reflection surface RF2d with respect to the rotation axis RX is 45 °, and the inclination angle of the reflection surface RF2e with respect to the rotation axis RX is 46 °.

  The first reflecting member RF1 and the second reflecting member RF2 are formed by injection molding, and a reflecting surface can be obtained by forming a film by vapor deposition of aluminum, gold, silver or the like on the surface thereof. As described above, when the inclination angle of each reflection surface with respect to the rotation axis RX is individually changed, there is an advantage that the accuracy of each reflection surface can be easily obtained by forming by injection molding.

  As shown in FIG. 1, the first reflecting member RF1 and the second reflecting member RF2 are configured such that the joint surfaces RF1a and RF2a are opposed to each other, a triangular plate-shaped spacer with a hole SP is interposed therebetween, and a cylindrical stepped shaft is provided. The CY is assembled by inserting and fitting the CY through the central openings RF1g and RF2g, respectively, and fixing them using bolts BT. A motor MT that rotationally drives the shaft CY is fixed to the casing CS.

  As described above, since the first reflecting member RF1 and the second reflecting member RF2 can be accurately formed by molding, the first reflecting member RF1 and the second reflecting member RF2 can be assembled so that their axes coincide with each other by the guide of the axis CY inserted through the central openings RF1g and RF2g. it can. At the time of assembly, the reflecting surface RF1c is opposed to be paired with the reflecting surface RF2c, the reflecting surface RF1d is opposed to be paired with the reflecting surface RF2d, and the reflecting surface RF1e is opposed to be paired with the reflecting surface RF2e. It is assumed that the phase in the rotational direction is set. Regardless of the manufacturing method described above, the first reflecting member RF1 and the second reflecting member RF2 may be integrally formed.

  Next, the distance measuring operation of the laser radar LR will be described. FIG. 4 is a diagram showing a scanning range viewed in the direction of the rotation axis of the laser radar LR. The mirror unit MU is shown only in the lower half, and the light projecting / receiving devices OPD1 and OPD2 are simply shown. Further, the range (G1, G2) in which the object can be detected is schematically shown by hatching, but the actual detectable limit is larger than that shown in the figure with respect to the size of the casing CS of the laser radar LR. FIG. 5 is a perspective view schematically showing a range in which an object can be detected by the laser radar LR. FIG. 6 is a development view showing the scanning range of the spot light SB emitted from the laser radar LR, which is shown together with an object such as a building. In FIG. 2, the laser beam emitted intermittently in pulses from the semiconductor laser LD1 of the first light projecting / receiving device OPD1 in a state where the mirror unit MU rotates at a constant speed by driving from a driving source (not shown) The light enters the point P1 of the reflection surface RF1c of the first reflection member RF1, is reflected here, travels along the rotation axis RX, or advances at a predetermined angle from the rotation axis RX, and further reflects the reflection surface RF2c of the second reflection member RF2. Is reflected at the point P2 and scanned and projected to the object side. At this time, the points P1 and P2 move in the circumferential direction on the reflecting surface according to the rotation of the mirror unit MU. Then, the mirror unit MU rotates relative to the reflecting surfaces RF1d and RF2d, and the mirror unit MU rotates further to the reflecting surfaces RF1e and RF2e.

  Similarly, the laser beam emitted intermittently in a pulse form from the semiconductor laser LD2 of the second light projecting / receiving device OPD2 is incident on the reflecting surface of the first reflecting member RF1 that is directly opposed according to the rotation of the mirror unit MU, The light is reflected here, travels along the rotational axis RX, or travels at a predetermined angle from the rotational axis RX, and is further reflected by the reflecting surface of the second reflecting member RF2 and scanned and projected to the object side.

  In FIG. 6, the spot light irradiated on the object by the laser beam LB1 is SB1, and the spot light irradiated on the object by the laser beam LB2 is SB2. The spot lights SB1 and SB2 are scanned in the horizontal direction on the detection range G of the laser radar LR according to the rotation of the mirror unit MU. The spot light SB1 is scanned over a first range G1 of 0 ° to 180 ° in the detection range G, and the spot light SB2 is scanned over a second range G2 of 180 ° to 360 ° in the detection range G.

  Here, as described above, the reflection surfaces of the mirror units MU have different inclination angles with respect to the rotation axis RX. Therefore, the spot light SB1, which is the laser light emitted from the first light projecting / receiving device OPD1 and reflected by the pair of reflecting surfaces RF1c, RF2c, is the first in the first range G1 according to the rotation of the mirror unit MU. The upper region Ln11 is scanned in the horizontal direction from left to right. Next, the spot light SB1, which is the laser light reflected by the pair of reflecting surfaces RF1d and RF2d, moves horizontally in the second region Ln12 from the top of the first range G according to the rotation of the mirror unit MU. Scanned from left to right. Next, the spot light SB1, which is the laser light reflected by the pair of reflecting surfaces RF1e and RF2e, moves horizontally in the third region Ln13 from the top of the first range G according to the rotation of the mirror unit MU. Scanned from left to right.

  Although the scanning timing is different from the above, the spot light SB2, which is laser light emitted from the second light projecting / receiving device OPD2 and reflected by the pair of reflecting surfaces RF1c, RF2c, corresponds to the rotation of the mirror unit MU. Thus, the uppermost region Ln21 of the second range G2 is scanned in the horizontal direction from left to right. Next, the spot light SB2 that is the laser light reflected by the pair of reflecting surfaces RF1d and RF2d moves in the horizontal direction in the second region Ln22 from the second range G2 in accordance with the rotation of the mirror unit MU. Scanned from left to right. Next, the spot light SB2, which is the laser light reflected by the pair of reflecting surfaces RF1e, RF2e, moves in the horizontal direction in the third region Ln23 from the second range G2 according to the rotation of the mirror unit MU. Scanned from left to right.

  That is, the scanning of the entire detection range G is completed when the mirror unit MU rotates once. Thereafter, if the paired reflecting surfaces RF1c and RF2c return, scanning from the top of the detection range G is repeated again. If one of the semiconductor lasers LD1 and LD2 that emit light in a pulsed manner is caused to emit light, the other light emission can be stopped to avoid the influence of stray light.

  3 and 4, the laser beam LB1 emitted from the first light projecting / receiving device OPD1 is emitted from the second light projecting / receiving device OPD2 when entering the center of the reflecting surface RF1c. The laser beam LB2 thus made starts to enter the reflecting surface RF1e. That is, the laser beams LB1 and LB2 are emitted from the mirror unit MU while being shifted by 90 ° from each other when viewed in the rotation axis direction (see FIG. 5).

  In FIG. 2, a part of the scattered light reflected from the object irradiated with the spot light SB1 becomes reflected light RB1, again enters the reflecting surface RF2c of the second reflecting member RF2, etc., is reflected here, and is rotated by the rotation axis RX. Or is inclined at a predetermined angle from the rotation axis RX, further reflected by the reflecting surface RF1c of the first reflecting member RF1, etc., collected by the lens LS1, and detected by the light receiving surface of the photodiode PD1. It becomes. On the other hand, a part of the scattered light reflected from the object irradiated with the spot light SB2 becomes reflected light RB2, and is incident again on the reflecting surface RF2c of the second reflecting member RF2, and is reflected here, along the rotation axis RX. Or is inclined at a predetermined angle from the rotation axis RX, further reflected by the reflecting surface RF1c of the first reflecting member RF1, etc., collected by the lens LS2, and detected by the light receiving surface of the photodiode PD2. . Thereby, as shown in FIGS. 4 to 6, the object can be detected over a range of 360 degrees around the laser radar LR. At this time, the rotation angle of the mirror unit MU is known based on the emission times of the laser beams LB1 and LB2, and the emission time of the laser beams LB1 and LB2 and the reception times of the reflected lights RB1 and RB2 reflected from the object are determined. Since the distance to the object can be known from the difference, the position of the object can be accurately determined based on the laser radar LR.

  By the way, when a laser beam is incident on three rotating reflecting surfaces, the scanning angle of the laser beam scanned from one reflecting surface is theoretically 240 °. However, in order to increase the detection efficiency, it is necessary to give the laser beams LB1 and LB2 incident on the reflection surface of the mirror unit MU to have a certain width, but this causes a problem that the scanning angle cannot be secured at 240 ° full. There is. More specifically, for example, as shown by a dotted line in FIG. 3, when the laser beam LB1 is irradiated so as to straddle the circumferential edge of the reflection surface RF1c, one laser beam LB1 is reflected on the reflection surface RF1c. Although reflected, the remaining laser beam LB1 is reflected by the reflection surface RF1d or RF1e adjacent thereto.

  In such a case, the reflected light from the object by the laser beam LB1 reflected by the reflecting surface RF1c is appropriately received by the photodiode PD1, but is reflected from the object by the laser beam LB1 reflected from other than the reflecting surface RF1c. The light cannot be received by the photodiode PD1, and may be detected by the photodiode PD2 of the second light projecting / receiving device OPD2 in some cases, which may lead to erroneous detection. Similar problems can occur with other reflective surfaces.

  In order to avoid such erroneous detection, a control unit (not shown) that controls the semiconductor laser LD1 detects the rotation angle of the mirror unit MU before the laser beam LB1 is applied to the circumferential edge of each reflecting surface. The emission of the semiconductor laser LD1 is stopped. Similar control is performed in the semiconductor laser LD2. However, if the emission control of the semiconductor laser is performed in this way, the scanning angle of the laser beam cannot be fully used. According to a study conducted by the present inventors, when a laser beam is incident on three rotating reflecting surfaces, the scanning angle of the laser beam scanned from one reflecting surface is at least 180 °. I found out that Therefore, by using two light projecting / receiving devices for the mirror unit MU having three reflecting surfaces arranged in the circumferential direction, the object can be detected over the entire 360 ° circumference. Examples thereof will be described later.

  FIG. 7 is a view similar to FIG. 3 according to a modification of the present embodiment, and FIG. 8 is a view similar to FIG. 4 according to a modification of the present embodiment. Differences from the above-described embodiment are mainly described. The laser radar LR of this modification has three light projecting / receiving devices OPD1, OPD2, OPD3 and one mirror unit MU. Each of the light projecting / receiving devices OPD1, OPD2, and OPD3 has the same configuration as that of the above-described embodiment, but as shown in FIG. 8, it is arranged at intervals of about 120 ° around the rotation axis RX. Here, approximately 120 ° is assumed to be 120 ° ± 5 °.

  On the other hand, the mirror unit MU of this modification has four pairs of reflecting surfaces. Specifically, with reference to FIG. 7B, the first reflecting member RF1 has four reflecting surfaces (first mirror surfaces) RF1c, RF1d, RF1e, and RF1h arranged in the circumferential direction. Further, referring to FIG. 7A, the second reflecting member RF2 has four reflecting surfaces (second mirror surfaces) RF2c, RF2d, RF2e, and RF2h arranged in the circumferential direction so as to face each other. doing.

  Here, the inclination angle of the reflection surface RF1c with respect to the rotation axis RX is 44 °, the inclination angle of the reflection surface RF1d with respect to the rotation axis RX is 45 °, the inclination angle of the reflection surface RF1e with respect to the rotation axis RX is 46 °, and the reflection surface The inclination angle of RF1h with respect to the rotation axis RX is 47 °. On the other hand, the inclination angle of the reflection surface RF2c with respect to the rotation axis RX is 44 °, the inclination angle of the reflection surface RF2d with respect to the rotation axis RX is 45 °, the inclination angle of the reflection surface RF2e with respect to the rotation axis RX is 46 °, and the reflection surface RF2h. The inclination angle with respect to the rotation axis RX is 47 °.

  Also in this modification, the reflection surfaces of the mirror unit MU have different inclination angles with respect to the rotation axis RX. Therefore, spot light (not shown), which is laser light emitted from the light projecting / receiving devices OPD1 to OPD3 and reflected by the pair of reflecting surfaces RF1c and RF2c, varies according to the rotation of the mirror unit MU. The top region of G3 in the vertical direction (the vertical direction in FIG. 8) is scanned from left to right in the horizontal direction. Next, the spot light, which is the laser light reflected by the paired reflecting surfaces RF1d and RF2d, passes through the second region from the top in the vertical direction of each of the ranges G1 to G3 according to the rotation of the mirror unit MU in the horizontal direction. Scanned from left to right. Next, the spot light SB1, which is the laser light reflected by the pair of reflecting surfaces RF1e and RF2e, horizontally moves the third region from the top in the vertical direction of each range G1 to G3 according to the rotation of the mirror unit MU. Scanned in the direction from left to right. Next, the spot light, which is the laser light reflected by the pair of reflecting surfaces RF1h and RF2h, moves in the horizontal direction in the fourth region from the top in the vertical direction of each range G1 to G3 according to the rotation of the mirror unit MU. Scanned from left to right. As described above, the object can be detected over a range of 360 degrees around the laser radar LR.

  Here, when a laser beam is incident on four rotating reflecting surfaces, the scanning angle of the laser beam scanned from one reflecting surface is theoretically 180 °. The scanning angle cannot be secured at 180 ° full. According to a study conducted by the present inventors, when a laser beam is incident on four rotating reflecting surfaces, the scanning angle of the laser beam scanned from one reflecting surface is at least 90 °. I found out that Therefore, the object detection can be performed over the entire 360 ° circumference by using three light projecting / receiving devices for the mirror unit MU having four reflecting surfaces arranged in the circumferential direction. Examples thereof will be described later.

(Example 1)
9 is a side view of Example 1 showing only a mirror unit MU corresponding to the embodiment of FIGS. 1 to 6, a semiconductor laser LD1, and a collimating lens CL1, and FIG. 10 shows the configuration of FIG. It is the figure which cut | disconnected and looked at the arrow direction. Incidentally, the mirror unit MU is mainly omitted except for the reflecting surface.

  In Example 1, the beam divergence angle of the laser beam LB1 emitted from the semiconductor laser LD1 is 28 ° (full width at half maximum), and is transmitted through the collimator lens CL1 having a focal length f = 6 mm, so that the beam diameter φ = The reflective surface of the mirror unit MU is converted into substantially parallel light of 5.5 mm (diameter at which the intensity is 95% when the intensity at the center is 100%) and along the direction orthogonal to the rotation axis RX. It is incident on RF1c. The incident position at this time is the rotational position of the mirror unit MU (see FIG. 10) where the virtual plane formed by the rotational axis RX and the center line of the reflecting surface RF1c overlaps the optical axis OA1 of the laser beam LB1, and the optical axis OA1 The distance Δ1 between the intersection point CP1 with the reflection surface RF1c and the rotation axis RX is set to 8 mm.

  When the mirror unit MU is rotated around the rotation axis RX, the intersection CP1 moves on the reflection surface in the circumferential direction as indicated by the dotted line, but the laser beam LB1 reflected in the reflection surface RF1c is reflected. The range that can be used effectively is the range of the maximum allowable angle θ1 (between the positions indicated by the dotted line) that does not reach the circumferential edge EG of the reflecting surface RF1c. According to the first embodiment related to the above specification, the allowable angle θ1 = 100 °. Therefore, since the fluctuation width of the laser beam LB1 is 100 ° × 2 = 200 °, by providing two light projecting / receiving devices, a total object detection range of 400 ° can be covered. In this case, a surplus exceeding the entire circumference (400 ° -360 °) = 40 ° can be used as a margin of the detection range, so that redundancy during manufacturing is increased.

(Example 2)
FIG. 11 is a side view of Example 2 showing only the mirror unit MU corresponding to the embodiment of FIGS. 7 and 8, the semiconductor laser LD1, and the collimating lens CL1, and FIG. 12 shows the configuration of FIG. It is the figure which cut | disconnected by the XII line and looked at the arrow direction. Incidentally, the mirror unit MU is mainly omitted except for the reflecting surface.

  In Example 2, the beam divergence angle of the laser beam LB1 emitted from the semiconductor laser LD1 is 28 ° (full width at half maximum), and is transmitted through the collimator lens CL1 having a focal length f = 6 mm, so that the beam diameter φ = The reflective surface of the mirror unit MU is converted into substantially parallel light of 5.5 mm (diameter at which the intensity is 95% when the intensity at the center is 100%) and along the direction orthogonal to the rotation axis RX. It is incident on RF1c. The incident position at this time is the rotational position of the mirror unit MU (see FIG. 10) where the virtual plane formed by the rotational axis RX and the center line of the reflecting surface RF1c overlaps the optical axis OA1 of the laser beam LB1, and the optical axis OA1 The distance Δ2 between the intersection CP2 with the reflection surface RF1c and the rotation axis RX is 8 mm.

  When the mirror unit MU is rotated about the rotation axis RX, the intersection point CP2 moves on the reflection surface in the circumferential direction as indicated by the dotted line according to the rotation angle, but the laser beam LB1 reflected in the reflection surface RF1c is reflected. The range of the maximum allowable angle θ2 (between the positions indicated by the dotted lines) that does not reach the circumferential edge EG of the reflecting surface RF1c can be used effectively. According to the second embodiment related to the above specification, the allowable angle θ2 = 70 °. Therefore, since the fluctuation width of the laser beam LB1 is 70 ° × 2 = 140 °, by providing three light projecting / receiving devices, a total object detection range of 420 ° can be covered. In this case, a surplus exceeding the entire circumference (420 ° -360 °) = 60 ° can be used as a margin of the detection range, so that redundancy at the time of manufacture is increased.

  FIG. 13 is a perspective view showing various examples of the semiconductor laser LD1 and the collimating lens CL1 that can be used in the above-described embodiment, and shows a cross section of the emitted laser light by hatching. In the figure, the Z direction is the optical axis direction, the Y direction is the direction corresponding to the scanning direction, and the X direction is the direction corresponding to the scanning orthogonal direction. In the example shown in FIG. 13A, a laser beam LB1 having a substantially circular cross section is emitted from the light emitting portion LP of the semiconductor laser LD1. This laser beam LB1 is shaped through a cylindrical lens CL1, and is irradiated to a mirror unit MU (not shown). The cylindrical lens CL1 shapes the cross section of the transmitted laser beam LB1 so as to extend the dimension in the X direction without changing the dimension in the Y direction. Thereby, in the cross-sectional shape of the laser beam LB1 that is projected and projected toward the object, the dimension in the scanning orthogonal direction becomes larger than the dimension in the scanning direction.

  In the example shown in FIG. 13B, a laser beam LB1 having a substantially elliptical cross section with the Y direction as the short axis and the X direction as the long axis is emitted from the light emitting portion LP of the semiconductor laser LD1. This laser beam LB1 is converted into a substantially parallel beam through the collimator lens CL1, and is irradiated to a mirror unit MU (not shown). Accordingly, in the cross-sectional shape of the laser beam LB1 that is scanned and projected toward the object, the dimension in the scanning orthogonal direction is larger than the dimension in the scanning direction.

  In the example shown in FIG. 13C, three light emitting portions LP are arranged in the X direction on the semiconductor laser LD1, and a laser beam LB1 having a substantially circular cross section is emitted from each light emitting portion LP. The three laser light beams LB1 are converted into substantially parallel light beams via the collimating lens CL1, and are irradiated to a mirror unit MU (not shown) in a state of being in contact with each other without a gap. When the laser beam LB1 aligned in the X direction without a gap is scanned and projected toward the object, the dimension in the scanning orthogonal direction is larger than the dimension in the scanning direction. Note that the same semiconductor laser LD2 and collimator lens CL2 can be used.

(Second Embodiment)
FIG. 14 is a perspective view of a laser radar LR as an optical scanning type object detection device according to the present embodiment. FIG. 15 is a perspective view showing the laser radar LR with the cover removed. FIG. 16 is a schematic cross-sectional view of the laser radar LR according to the present embodiment, and FIG. 17 is a perspective view showing a main part excluding the casing of the scanning unit SU according to the present embodiment. The shape and length of the elements may differ from the actual ones.

  As shown in FIGS. 14 and 15, the laser radar LR includes a base BS and a scanning unit SU that can rotate with respect to the base BS. In FIG. 16, the main body BD of the housing CS is connected to a rotary connector RC fixed to the base BS via a shaft SH2. The rotary connector RC enables contactless data transfer by GiGE communication between the light source and light receiving unit of the rotating scanning unit SU and a fixed external control device (not shown), and also provides an external power supply. The power supply from the (not shown) to the scanning unit SU is possible without contact.

  The shaft SH2 is connected to the first gear GR1, and the first gear GR1 meshes with the second gear GR2 connected to the rotation shaft of the base motor MT2 fixed to the base BS. Here, it is assumed that the rotation axis (second rotation axis) RO2 of the axis SH2 extends in the vertical direction. The rotational force of the base motor MT2 is transmitted to the shaft SH2 via the second gear GR2 and the first gear GR1, and rotates the casing CS of the scanning unit SU at a predetermined speed. The base motor MT2, the second gear GR2, the first gear GR1, and the shaft SH2 constitute a rotation unit.

  As shown in FIG. 16, the casing CS has a hollow box shape in which a main body BD and a cover CV are combined. A window WS capable of entering and exiting a light beam is formed on the side of the cover CV, and a curved transparent plate TR made of glass or resin is fitted into the window WS. The main part of the scanning unit SU is accommodated in the housing CS.

  As shown in FIGS. 15 and 17, the scanning unit SU has two light projecting / receiving devices (light projecting / receiving units) OPD. 16 and 17, a light projecting / receiving device OPD includes, for example, a pulsed semiconductor laser (light source) LD that emits a laser beam, and a collimating lens that narrows the divergence angle of the divergent light from the semiconductor laser LD and converts it into substantially parallel light. A mirror unit (which projects CL and laser light substantially parallel by the collimator lens CL toward the object side by a rotating mirror surface and reflects scattered light from the object that has been scanned and projected) A mirror) MU, a lens LS for collecting scattered light from the object reflected by the mirror unit MU, and a photodiode (light receiving unit) PD for receiving the light collected by the lens LS. The photodiode PD is a light receiving element having a high amplification factor, such as an APD (avalanche photodiode), and a plurality of (six in this case) elements in a direction (scanning orthogonal direction) along the rotation axis RO1 of the mirror unit MU. A line sensor arranged side by side is preferable because it has high resolution.

  The semiconductor laser LD and the collimating lens CL constitute a light projecting system LPS, and the lens LS and the photodiode PD constitute a light receiving system RPS. The optical axes of the light projecting system LPS and the light receiving system RPS are substantially orthogonal to the rotation axis RO1 of the mirror unit MU.

  As shown in FIG. 16, the mirror unit MU has a shape in which two quadrangular pyramids are joined together in opposite directions, that is, four pairs of mirror surfaces M1 and M2 that are inclined in a direction facing each other. doing. The crossing angles of each pair of mirror surfaces M1 and M2 are different. The mirror surfaces M1 and M2 inclined with respect to the rotation axis RO1 are preferably formed by depositing a reflective film on the surface of a resin material (for example, PC) in the shape of a mirror unit. The mirror surfaces M1 and M2 may be provided in 3 pairs or 5 pairs or more.

  As shown in FIG. 15, the mirror unit MU is connected to the shaft SH1 of the mirror motor MT1 fixed to the casing CS, and is driven to rotate at a predetermined speed. Here, the rotation axis (first rotation axis) RO1 of the axis SH1 is assumed to extend in the horizontal direction.

  Next, the object detection operation of the laser radar LR will be described. 15 and 16, the divergent light intermittently emitted from the semiconductor laser LD in a pulse shape is converted into a substantially parallel light beam by the collimator lens CL, and is incident on the first mirror surface M1 of the rotating mirror unit MU. As a laser spot light having a rectangular cross section that is vertically long (here, longer in the horizontal direction than in the vertical direction) on the external object side after passing through the transparent plate TR after being reflected by the second mirror surface M2. Scanned light is emitted. That is, at least the cross section of the emitted light beam that has been projected and projected when entering the object is longer in the scanning orthogonal direction (α direction described later) than in the scanning direction (θ direction described later). Here, the emitted light beam from the collimating lens CL is scanned by the rotating mirror unit MU. This scanning direction is defined as the θ direction.

  FIG. 17 is a diagram when the scanning unit SU is viewed in the direction of the rotation axis RO1. In FIG. 17, VL is a vertical line, and the mirror unit MU indicated by the dotted line is at a rotation angle position at which the optical axis of one light projecting system LPS intersects the angle. Here, the light beam emitted from the semiconductor laser LD through the collimator lens CL is reflected by the rotating mirror unit MU, but theoretically, it is used from end to end in the rotation direction of the mirror surfaces M1 and M2. Can be said to have a scan angle β of 180 °. However, since the shape and size of the mirror unit MU are actually limited, the effective scanning angle β ′ is approximately 100 °.

  Therefore, in the present embodiment, two light projecting / receiving devices OPD are provided, and an intersection angle γ (in the α direction) of the two light projecting systems LPS is set to 90 ° so that a part of the scanning range overlaps. As a result, as shown in FIG. 19, it is possible to detect an object without leakage in the meridian direction of the celestial sphere. Even when the base BS is installed on a tower or the like, the emitted light beam reaches an angle below the horizontal direction of the laser radar LR, so that an object approaching from the ground can be detected. Furthermore, by operating the two light projecting / receiving devices OPD in parallel, the entire sky can be scanned twice by one rotation of the scanning unit SU, so that the scanning efficiency is improved. AR shown in FIG. 19 indicates a unit rotation scanning range in which scanning can be performed with the light beams emitted from the two light projecting / receiving devices OPD while the mirror unit MU rotates once.

  Furthermore, since the scanning unit SU rotates around the rotation axis RO2 with respect to the base BS, the unit rotation scanning range AR is displaced around the rotation axis RO2 in the equator direction of the celestial sphere. This displacement direction is defined as α direction (see FIG. 20).

  The base motor MT2 and the mirror motor MT1 are preferably stepping motors capable of precisely controlling the speed.

  FIG. 20 is a diagram in which the unit rotation scanning range AR that is displaced while overlapping partially as the scanning unit SU is rotationally displaced about the rotation axis RO2 in the equator direction (α direction) of the celestial sphere is seen in the horizontal direction. FIG. 21 is an enlarged view of a part XXI in FIG. As described above, the crossing angles are different in the combination of the first mirror surface M1 and the second mirror surface M2 of the mirror unit MU. The outgoing light beam SB from one light projecting / receiving device OPD is sequentially reflected by the rotating first mirror surface M1 and second mirror surface M2. First, the outgoing light beam SB reflected by the first pair of the first mirror surface M1 and the second mirror surface M2 moves from top to bottom along the rightmost scanning line Ln1 in FIG. 21 according to the rotation of the mirror unit MU. Scanned towards. Here, scanning by the pair of mirror surfaces M1 and M2 is defined as one scanning.

  Next, the outgoing light beam SB reflected by the second pair of the first mirror surface M1 and the second mirror surface M2 rises along the second scanning line Ln2 from the right in FIG. 21 according to the rotation of the mirror unit MU. However, since the scanning unit SU itself rotates about the rotation axis RO2, when the position in the θ direction is the same, scanning along the scanning line Ln2 (following The emitted light beam SB to be scanned is shifted by a predetermined amount in the α direction with respect to the emitted light beam SB scanned (scanned in advance) along the scanning line Ln1. As a result, as shown in FIG. 22, it is possible to detect the object without missing using the 360-degree all-sky CSP as the detection area.

Here, as shown in FIG. 21, the spread angle in the α direction of the emitted light beam SB to be projected and projected (the angle formed by two lines from the rotation axis RO2 toward both ends in the α direction of the emitted light beam SB) is dα. The overlapping angle of the outgoing light beam SB scanned and projected by the first scanning and the outgoing light beam SB scanned and projected by the second scanning (from the rotation axis RO2 in the α direction at the portion where the outgoing light beams SB overlap each other) Equation (1) is satisfied, where d is an angle formed by two lines toward both ends.
0 <d <dα / 2 (1)

  When the overlap angle d exceeds the lower limit of the expression (1), there is no gap between the outgoing light beam SB scanned and projected by the first scan and the outgoing light beam SB scanned and projected by the second scan. , Leakage of object detection can be suppressed. On the other hand, when the overlap angle d is less than the upper limit of the expression (1), the overlap amount of the emitted light beams can be suppressed and the scanning efficiency can be improved.

  Next, the outgoing light beam SB reflected by the third pair of the first mirror surface M1 and the second mirror surface M2 rises along the third scanning line Ln3 from the right in FIG. 21 according to the rotation of the mirror unit MU. Is scanned downward. The relationship between the outgoing light beam SB scanned and projected by the second scan and the outgoing light beam SB scanned and projected by the third scan also satisfies the equation (1).

  Next, the outgoing light beam SB reflected by the fourth pair of the first mirror surface M1 and the second mirror surface moves from top to bottom along the leftmost scanning line Ln4 in FIG. 21 according to the rotation of the mirror unit MU. Scanned towards. The relationship between the emitted light beam SB scanned and projected by the third scan and the emitted light beam SB scanned and projected by the fourth scan also satisfies the expression (1). Thus, the scanning by one rotation of the mirror unit MU is completed. Then, after the mirror unit MU makes one rotation, if the first pair of the first mirror surface M1 and the second mirror surface M2 return to the position where the outgoing light beam SB is incident, the scanning along the scanning line Ln1 is repeated again. . At this time, the relationship between the outgoing light beam SB scanned and projected by the new first scan and the outgoing light beam SB scanned and projected by the preceding fourth scan also satisfies the equation (1).

  Further, in FIG. 16, when the scanned light beam hits the object, a part of the scattered light scattered there passes again through the transparent plate TR and the second mirror surface of the mirror unit MU in the housing CS. The light is incident on M2, reflected here, and further reflected by the first mirror surface M1, and then collected by the lens LS and detected by the light receiving surface of the photodiode PD. By obtaining a time difference between when the semiconductor laser LD is emitted and when the photodiode PD is detected by a circuit (not shown), the distance to the object can be obtained.

  However, even if the scattered light from the object is reflected by the entire surfaces of the second mirror surface M2 and the first mirror surface M1, the lens LS functioning as an aperture stop (here, circular, but limited to a circular shape). Therefore, a part of the light finally enters the photodiode PD. That is, light other than the scattered light shown by hatching in FIG. 16 does not enter the photodiode PD and is not used for light reception. Here, assuming that the light beam condensed by the lens LS is a received light beam RB, the received light beam having a predetermined cross section via the second mirror surface M2 and the first mirror surface M1, as shown by a one-dot chain line in FIG. RB enters the lens LS. In this embodiment, since the photodiode PD is a line sensor in which six elements are arranged side by side, the received light beam RB from the object in one scan is divided into six and received, and the object is detected with high resolution. can do. In the other light projecting / receiving apparatus OPD, the same operation is performed in parallel on the opposite side of the rotation axis RO2.

  According to the present embodiment, by using an emitted light beam having a wide width in the α direction and the photodiode PD as a line sensor in which a plurality of elements are arranged in a direction corresponding to the α direction, the α direction can be obtained in one scan. Since a wide range of detection is possible, the scanning efficiency can be improved. Further, by rotating the mirror unit MU, it is possible to scan in the θ direction, and it is possible to perform scanning limited to a necessary range. In particular, as compared with a case where the θ direction is scanned over 360 ° with a single mirror surface, an unnecessary space (here, below the horizon) can be distributed in the θ direction. Multiple (here, 4) scans in the direction are possible. As described above, a 360-degree all-sky detection area can be scanned at high speed without any gap, and an object that enters from all directions can be detected. Further, the three-dimensional polar coordinates of the detected object can be obtained, and the three-dimensional polar coordinates of the same object detected with a predetermined time can be obtained to calculate the speed.

  Furthermore, according to the present embodiment, since the mirror unit MU in which the second mirror surface M2 is disposed facing the first mirror surface M1 is used, the emitted laser light is emitted from the rotating mirror unit MU. The light enters the first mirror surface M1, is reflected here, travels along the rotation axis, is further reflected by the second mirror surface M2, and is scanned and projected onto the object. With this configuration, it is possible to suppress the vertical distortion and the rotation of the spot light irradiated to the object, and to suppress a change in resolution while having a wide visual field range.

  FIG. 23 is a diagram illustrating a main part of a scanning unit SU according to another embodiment. In this embodiment, a fiber laser is used as the light source instead of the semiconductor laser. A fiber laser is one in which excitation light is put into a special optical fiber with a rare earth added to the core, only light of a specific wavelength is confined and amplified in the core, and then emitted as high-intensity laser light. By propagating in the cable, there is a feature that the light emitting points can be arranged at arbitrary positions.

  Therefore, in the present embodiment, after extending the fiber cable FC from the single fiber laser unit FU, the fiber cable FC is branched at the branch point DP, and further the fibers from the first light emitting unit RP1 and the second light emitting unit RP2. The cable FC is extended. The high-intensity laser light emitted from the fiber laser unit FU propagates in the fiber cable FC, is branched at the branch point DP, and further, the first light emitting unit RP1 and the second light emitting unit RP2 via the fiber cable FC. Thus, the light is emitted from here toward the collimating lens CL. Since other configurations are the same as those of the above-described embodiment, the description thereof is omitted.

  FIG. 24 is a perspective view of a laser radar LR according to still another embodiment. In the present embodiment, the casing CS of the scanning unit SU has a triangular cylindrical shape, and the two transparent plates TR fitted into the window portion WS have a flat plate shape. In this way, by tilting the transparent plate TR, which is a light transmissive member, from the horizontal plane, dust and water droplets are less likely to adhere, and maintenance such as cleaning can be simplified. Note that it is optional to provide a wiper device on the transparent plate TR.

  FIG. 25 is a diagram of the scanning unit SU according to the present embodiment as viewed in the direction of the rotation axis RO1. In FIG. 25, VL is a vertical line, and the mirror unit MU indicated by the dotted line is at a rotation angle position where the optical axis of one light projecting system LPS intersects the angle. In the present embodiment, since the intersection angle γ of the two light projecting systems LPS is 110 °, as shown in FIG. 26, the unit rotation defined by the emitted light beams emitted from the two light projecting systems LPS The scanning ranges AR do not overlap. Since this is the boundary between the two transparent plates TR, it is possible to prevent the outgoing light flux emitted through the transparent plate TR from being affected. When the scanning unit SU is rotated in such a state, as shown in FIG. 27, an area IM incapable of detecting an object is generated near the zenith of the celestial sphere CSP. However, there is a low possibility that an object enters from the vicinity of the zenith of the celestial sphere CSP, and there are often no particular problems even if an area IM where the object cannot be detected is provided. Further, as shown in FIG. 25, by increasing the crossing angle γ of the two light projecting systems LPS, the ground-side scanning range is expanded, so that the base BS can be installed in a higher tower or the like. This also has the effect of making it easier to detect an object by avoiding the obstacle.

Hereinafter, the results of studies conducted by the present inventors will be described. As a specification of the laser radar, a scanning time t for 360 ° in all directions is set to 1.25 seconds. Further, the mirror unit MU is rotated at a rotation speed of 10 sec ⁻¹ . Therefore, the rotational speed rθ in the θ direction of the mirror is 40 sec ⁻¹ . Here, in order to satisfy the above-described formula (1), it is preferable to set the spread angle dα of the emitted light beam in the α direction within a range represented by the following formula.
180 / (rθ × t) <dα <360 / (rθ × t) (2)

  When a numerical value is substituted into the equation (2), 3.6 <dα <7.2. Here, the collimating lens CL is adjusted so that the spread angle dα in the α direction of the emitted light beam is 3.75 ° and the spread angle dθ in the θ direction of the emitted light beam is 0.12 °. It was made to emit.

  The scanning by the pair of mirror surfaces M1 and M2 in the mirror unit MU is 100 ° in the θ direction, and four scans are performed in the θ direction every rotation, so the scanning range is θ per light emitting / receiving device OPD. It becomes 100 ° in the direction and 14.55 ° in the α direction (= 3.75 ° pitch × 4 lines−0.15 ° × 3). However, the spread angle dα of the emitted light beam is 3.75 °, and the overlap angle d of the emitted light beam is 0.15 °. By arranging the two light projecting / receiving devices OPD so that the ends of the scanning range coincide with each other at the zenith of the celestial sphere, it becomes possible to scan in the range of 200 ° in the θ direction and 14.55 ° in the α direction.

Here, when scanning 360 degrees in all directions with the laser radar LR in 1.25 seconds, the two projectors and receivers OPD can share them, so that half of the 180 degrees is scanned in 1.25 seconds. That's fine. The rotation speed rα of the scanning unit SU was set to 0.4 sec ⁻¹ (2.5 seconds / rotation).

  When the above-mentioned conditions are applied to the laser radar LR of the embodiment shown in FIGS. 14 to 22 using a semiconductor laser having a light source wavelength of 870 nm, detection is performed on any object on the ground or in the air. It was found that detection was possible at a position 100 m away for a vehicle, 50 m for a person, and 35 m away for a drone with a maximum size of 30 cm.

  Note that the above examination is an example, and the spatial resolution can be improved by changing the intensity of the emitted light beam, the spread angle of the emitted light beam, the number of light receiving elements of the photodiode PD, the surface angle of the mirror unit, and the like depending on the size of the detection target. Adjustment is possible.

Further, as the laser radar LR of the embodiment shown in FIG. 21, a fiber laser capable of emitting a light beam with a wavelength of 1550 nm as a light source and a sensor sensitive to a wavelength of 1550 nm as a light receiving unit, for example, an InGaAs APD sensor, are studied. went. Laser light having a wavelength of 1550 nm is particularly suitable for detecting distant objects because the sensitivity of the human retina is low and the amount of light can be increased while satisfying laser class 1 because of so-called eye-safe characteristics. . The scanning unit SU has a omnidirectional 360 ° scanning time of 1.25 seconds and the mirror unit MU is rotated at a rotational speed of 10 sec ⁻¹ .

  With the above configuration, it was confirmed that an object having a maximum dimension of 30 cm can be detected and tracked at a position 200 m away. In such a case, for example, assuming that a drone of the same size approaches the laser radar LR from outside the detection range (radius 200 m) of the laser radar LR of this embodiment, it is 1.25 seconds between successive scans. In addition to not reaching the laser radar LR in the meantime, it takes some time to consider how to deal with the intruded drone after detection. Since a general drone can fly at a speed of 50 km / h (about 14 m / s), the maximum distance that a drone can approach without being detected is 14 × 1.25 = 17.5 m. In other words, the drone that has entered from the position 182.5m away from the laser radar LR can be detected at an early stage, and the time for studying how to deal with the drone that has entered after detection can be sufficiently secured. LR was found to be effective.

  The present invention is not limited to the embodiments described in the specification, and other embodiments and modifications are apparent to those skilled in the art from the embodiments and ideas described in the present specification. It is. The description and examples are for illustrative purposes only, and the scope of the invention is indicated by the following claims. For example, the number of the light projecting / receiving device OPD may be one. Further, instead of the mirror unit MU, one mirror may be rotated to scan the emitted light beam. Furthermore, the crossing angle γ of the light projecting system LPS can be set arbitrarily.

AR unit rotation scanning range BD Main body BS Base CL, CL1, CL2 Collimating lens CS Housing CV Cover DP Branch point FC Fiber cable FU Fiber laser unit GR1 First gear GR2 Second gear IM Undetectable area LD, LD1, LD2 Semiconductor lasers Ln1 to Ln4 Scan line Ln11 to Ln13 Scan line Ln21 to Ln23 Scan line LPS Projection system LR Laser radar LS Lens M1 First mirror surface M2 Second mirror surface MT1 Mirror motor MT2 Base motor MU Mirror unit OPD, OPD1, OPD2, OPD3 Projector / receiver PD, PD1, PD2 Photodiode RB Received light beam RB1, RB2 Reflected light beam RC Rotary connector RF1 First reflecting member RF2 Second reflecting member RO1 First rotation axis RO2 2 the axis of rotation RP1 first light emitting portion RP2 second light emitting portion RPS receiving system SB emitted light beam SB1, SB2 spotlight SH1 shaft SH2 axis SU scanning unit TR transparent plate WS window

Claims (12)

One mirror rotating around the axis of rotation;
A plurality of light emitting and receiving units each having a light source and a light receiving unit,
A light beam emitted from the light source of each light projecting / receiving unit is reflected by the mirror, then scanned and projected by the rotation of the mirror, and a part of the light beam scattered by the object among the projected light beams After being reflected by the mirror, the optical scanning type object detection device is configured to receive light by the light receiving unit of the corresponding light projecting / receiving unit.   The mirror has a first mirror surface and a second mirror surface that are inclined in a direction intersecting the rotation axis and face each other at a predetermined angle, and a light beam emitted from the light source of each light projecting / receiving unit is the first mirror surface. After being reflected by the mirror surface, a part of the light beam that is reflected by the second mirror surface and scanned and projected by the rotation of the mirror is scattered by the object out of the scanned and projected light beam. 2. The optical scanning type object detection device according to claim 1, wherein the optical scanning type object detection device is configured to be reflected by the first mirror surface and received by the light receiving unit of the corresponding light projecting / receiving unit after being reflected by the two mirror surfaces. .   The optical scanning type according to claim 2, wherein the mirror has a plurality of pairs of the first mirror surface and the second mirror surface, and the crossing angles of the first mirror surface and the second mirror surface are different from each other. Object detection device.   There are two light projecting / receiving units, and the mirror has three pairs of the first mirror surface and the second mirror surface, and when viewed in the rotation axis direction of the mirror, The optical scanning type object detection device according to claim 3, wherein the optical axes are separated by approximately 180 °.   The number of the light projecting / receiving units is three, and the mirror has four pairs of the first mirror surface and the second mirror surface, and when viewed in the rotation axis direction of the mirror, The optical scanning type object detection device according to claim 3, wherein the optical axes are arranged at approximately 120 ° intervals.   The optical scanning type object detection device according to claim 1, wherein a cross-sectional shape of a light beam projected and projected toward the object has a dimension in a scanning orthogonal direction larger than a dimension in a scanning direction.   The optical scanning type object detection device according to claim 1, wherein the light receiving unit includes a plurality of light receiving regions arranged in a direction corresponding to the scanning orthogonal direction of a light beam incident on the light receiving unit. When the mirror rotates in the θ direction around the first rotation axis, the mirror and the light projecting / receiving unit are integrally rotated in the α direction around a second rotation axis different from the first rotation axis. A rotating unit is provided,
At least the cross-sectional shape of the scanned and projected light beam when entering the object has a dimension in the θ direction that is shorter than a dimension in the α direction.
The luminous flux scanned and projected by the preceding scanning and the luminous flux scanned and projected by the subsequent scanning partially overlap in the α direction,
The spread angle in the α direction of the light beam projected is dα, and the overlap angle between the light beam scanned and projected by the preceding scan and the light beam scanned and projected by the subsequent scan is d. When it does, the optical scanning type target object detection apparatus in any one of Claims 1-7 which satisfy | fill Formula (1).
0 <d <dα / 2 (1)   The optical scanning type object detection device according to claim 8, wherein positions of optical axes of the light sources of the light projecting and receiving units are different from each other in the α direction.   10. The optical scanning type object detection device according to claim 8, wherein the light source of the light projecting / receiving unit includes a plurality of ends that diverge and emit light emitted from a single light emitter through a branch path. 11.   The optical scanning type object detection device according to claim 8, wherein the first rotation axis is along a horizontal direction and the second rotation axis is along a vertical direction.   The mirror and the plurality of light projecting and receiving units are housed in a housing, and a light beam is scanned and projected onto the object through a window formed in the housing, and the light from the object is The optical scanning type object detection according to any one of claims 1 to 11, wherein the light transmissive member configured to receive scattered light is inclined with respect to a horizontal direction. apparatus.