WO2020116078A1

WO2020116078A1 - Laser radar

Info

Publication number: WO2020116078A1
Application number: PCT/JP2019/043478
Authority: WO
Inventors: 英治武田; 野口　仁志; 公博村上
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2018-12-03
Filing date: 2019-11-06
Publication date: 2020-06-11
Also published as: JPWO2020116078A1

Abstract

A laser radar (10) comprising: a plurality of laser light sources (11a) arranged lined up in one direction; a plurality of collimator lenses (13a) that are arranged corresponding to each laser light source (11a) and collimate laser light emitted from each laser light source (11a) in a direction corresponding to the one direction; a condensing lens (14) having a condensing action in at least a direction corresponding to the one direction; and an optical deflector (15) having a mirror (15a) to which each laser light condensed by the condensing lens (14) is incident. The plurality of laser light sources (11a) are arranged so as to fulfil the condition P1 ≥ S1 + 2f1 × tan (θ1/2), when the arrangement interval between the laser light sources (11a) is P1, the width of the light-emission region for the laser light sources (11a) is S1, the full width of the laser light dispersion is θ1, and the focal distance for the collimator lenses (13a) is f1.

Description

Laser radar

The present invention relates to a laser radar that detects an object using laser light, and is suitable for being mounted on a moving body such as a passenger car, for example.

Conventionally, laser radars that detect objects using laser light have been developed in various fields. For example, in a vehicle-mounted laser radar, laser light is projected from the front of the vehicle, and it is determined whether or not an object such as a vehicle is present in front of the vehicle based on the presence or absence of reflected light. Further, the distance to the object is measured based on the projection timing of the laser light and the reception timing of the reflected light.

The following Patent Documents 1 and 2 disclose a device that scans a linear beam to detect an obstacle in front of the vehicle.

JP-A-5-205199 JP, 2017-150990, A

In the laser radar with the above configuration, when detecting an object at a longer distance and a wider angle, it is necessary to increase the light emission power of the light source. As a method for this, a method of arranging a plurality of laser light sources side by side can be used. However, according to this method, the beam size of the entire laser light incident on the mirror for scanning the beam becomes large, which causes a problem that the mirror becomes large. If the size of the mirror is increased, the response of the mirror is deteriorated and the scanning performance is deteriorated. There is also a problem that the device becomes larger as the mirror becomes larger.

In view of such a problem, an object of the present invention is to provide a laser radar capable of increasing the irradiation light amount of laser light while suppressing an increase in the size of a mirror for scanning laser light.

A laser radar according to a main aspect of the present invention, a plurality of laser light sources arranged side by side in one direction, arranged corresponding to each of the laser light sources, the laser light emitted from each laser light source in the one direction. A plurality of collimator lenses that make parallel light in corresponding directions and laser beams that have passed through the collimator lenses are incident side by side in a direction corresponding to the one direction, and a condensing action is performed at least in a direction corresponding to the one direction. And a light deflector for deflecting the laser light by changing the direction of the mirror. .. The arrangement interval of the laser light sources is P1, the width of the light emitting region of the laser light source in the direction parallel to the one direction is S1, the divergence angle of the laser light in the direction parallel to the one direction is θ1, and the focus of the collimator lens is When the distance is f1, the plurality of laser light sources are arranged so as to satisfy the condition of P1≧S1+2f×tan (θ1/2).

According to the laser radar of this aspect, since a plurality of laser light sources are used, it is possible to increase the irradiation light amount of the laser light on the target area. Moreover, since the laser light emitted from each laser light source is condensed on the mirror of the optical deflector by the condenser lens, the mirror of the optical deflector can be made small. Further, since the laser light source is arranged so as to satisfy the above condition, the laser light emitted from the laser light source can be properly incident on the corresponding collimator lens without protruding. Thus, the collimator lens can accurately collimate each laser beam, and as a result, the beam condensing size in the mirror can be narrowed to an extremely small size. Therefore, the mirror of the optical deflector can be significantly reduced.

As described above, according to the present invention, it is possible to provide a laser radar capable of increasing the irradiation light amount of laser light while suppressing an increase in the size of a mirror for scanning laser light.

The effect or significance of the present invention will be further clarified by the description of the embodiments below. However, the embodiment described below is merely an example for embodying the present invention, and the present invention is not limited to what is described in the embodiment below.

FIG. 1 is a diagram showing a configuration of an optical system and a circuit unit of the laser radar according to the embodiment. 2A and 2B are perspective views showing the configuration of the laser light source according to the embodiment, and FIG. 2C is a perspective view showing the configuration of the light source unit of the laser radar according to the embodiment. .. FIG. 3A is a perspective view schematically showing the configuration of a collimator lens that collimates laser light in the fast axis direction according to the embodiment. FIG. 3B is a perspective view schematically showing the configuration of the collimator lens array that collimates the laser light in the slow axis direction according to the embodiment. FIG. 4 is a diagram schematically showing a laser beam emission state of a laser radar and a line beam state in a target area according to the embodiment. FIG. 5A is a diagram schematically showing a condensed state of reflected light on the light receiving surface when the image sensor is used as the light receiving element according to the first embodiment. FIG. 5B is a diagram schematically showing the condensed state of the reflected light on the light receiving surface when the line sensor is used as the light receiving element according to the first embodiment. FIG. 6A is a diagram illustrating the relationship between the laser light source and the collimator lens that collimates the laser light in the slow axis direction according to the embodiment. FIG. 6B is a diagram illustrating the relationship between the condenser lens and the mirror of the optical deflector according to the embodiment. FIG. 7A is a diagram showing the configuration of the optical system of the laser radar according to the first modification. FIG. 7B is a diagram showing the configuration of the optical system of the laser radar according to the second modification. FIG. 8A is a diagram showing the configuration of the optical system of the laser radar according to the third modification. FIG. 8B is a diagram showing the configuration of the optical system of the laser radar according to the fourth modification.

However, the drawings are for explanation only and do not limit the scope of the present invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. For the sake of convenience, the X, Y, and Z axes that are orthogonal to each other are appropriately added to each drawing. The X-axis direction and the Y-axis direction are the long side direction and the short side direction of the line beam, respectively, and the Z-axis positive direction is the line beam projection direction.

FIG. 1 is a diagram showing a configuration of an optical system and a circuit unit of the laser radar 10.

The laser radar 10 includes a light source unit 11, a collimator lens 12, a collimator lens array 13, a condenser lens 14, an optical deflector 15, a light receiving lens 16, and a light receiving element 17 as an optical system configuration. Prepare An optical system on the outward path from the light source unit 11 to the optical deflector 15 generates a line beam B10 that is long in the Y-axis direction from the laser light emitted from the light source unit 11.

The light source unit 11 is configured by integrating a plurality of laser light sources 11a. The laser light 11a emits laser light having a predetermined wavelength. The laser light source 11a is a laser diode. In this embodiment, it is assumed that the laser radar 10 is mounted on a vehicle. Therefore, the emission wavelength of each laser light source 11a is set to the infrared wavelength band (for example, 905 nm). The emission wavelength of the laser light source 11a can be appropriately changed according to the usage mode of the laser radar 10.

2A and 2B are perspective views showing the configuration of the laser light source 11a, and FIG. 2C is a perspective view showing the configuration of the light source unit 11.

As shown in FIG. 2A, the laser light source 11a has a structure in which an active layer 111 is sandwiched between an N-type clad layer 112 and a P-type clad layer 113. The N-type clad layer 112 is laminated on the N-type substrate 114. Further, the contact layer 115 is laminated on the P-type cladding layer 113. By applying a current to the electrode 116, laser light is emitted from the light emitting region 117 in the Z axis positive direction. Generally, in the light emitting region 117, the width W1 in the direction parallel to the active layer 111 is larger than the width W2 in the direction perpendicular to the active layer 111.

The axis in the short side direction of the light emitting region 117, that is, the axis in the direction perpendicular to the active layer 111 (Y-axis direction) is called the fast axis, and the axis in the long side direction of the light emitting region 117, that is, the active layer 111. The axis in the parallel direction (Z-axis direction) is called the slow axis. In FIG. 2B, 118a indicates a fast axis and 118b indicates a slow axis. The laser beam emitted from the light emitting region 117 has a larger spread angle in the fast axis direction than in the slow axis direction. Therefore, the shape of the beam B20 is an elliptical shape that is long in the fast axis direction, as shown in FIG.

In this embodiment, a laser diode whose emission intensity distribution is a single mode on both the fast axis and the slow axis is used as the laser light source 11a.

As shown in FIG. 2C, a plurality of laser light sources 11a are installed on the base 119 so as to be lined up along the slow axis to configure the light source unit 11. Therefore, the light emitting regions 117 of each laser light source 11a are arranged in one line in the slow axis direction. Here, each laser light source 11a is arranged such that the fast axis 118a of the light emitting region 117 is parallel to the direction (Y-axis direction) corresponding to the short side direction of the line beam B10 shown in FIG. The plurality of laser light sources 11a forming the light source unit 11 all have the same emission characteristics.

Note that, in FIG. 2C, the light source unit 11 is configured by installing a plurality of laser light sources 11a adjacent to each other on the base 119, but a plurality of light emitting regions 117 are arranged in the slow axis direction. One formed semiconductor light emitting device may be installed on the base 119. In this case, in the semiconductor light emitting element, the structural portion that emits the laser light from each light emitting region 117 corresponds to the laser light source 11a.

Returning to FIG. 1, the collimator lens 12 converges the laser light emitted from each laser light source 11a of the light source unit 11 in the fast axis direction and adjusts the spread of the laser light in the fast axis direction to be substantially parallel. .. That is, the collimator lens 12 has a function of collimating the laser light emitted from each laser light source 11 a of the light source unit 11 only in the fast axis direction.

The collimator lens array 13 converges the laser light emitted from each laser light source 11a of the light source unit 11 in the slow axis direction and sets the spread of the laser light in the slow axis direction to be substantially parallel. That is, the collimator lens array 13 has a function of collimating the laser light emitted from each of the laser light sources 11a of the light source unit 11 only in the slow axis direction.

FIG. 3A is a perspective view schematically showing the configuration of the collimator lens 12, and FIG. 3B is a perspective view schematically showing the configuration of the collimator lens array 13.

As shown in FIG. 3A, the collimator lens 12 has a lens surface 12a that is curved only in a direction parallel to the XY plane. The collimator lens 12 is, for example, a cylindrical lens. The generatrix of the lens surface 12a is parallel to the Z axis. The fast axis of each laser beam incident on the collimator lens 12 is perpendicular to the generatrix of the lens surface 12a. The respective laser lights enter the collimator lens 12 side by side in the Z-axis direction. Each laser beam is converged by the lens surface 12a in the fast axis direction (Y axis direction), and is collimated in the fast axis direction.

As shown in FIG. 3B, the collimator lens array 13 has a plurality of collimator lenses 13a that are curved only in a direction parallel to the XZ plane. That is, on the emission surface of the collimator lens array 13, a plurality of collimator lenses 13a are integrally formed side by side in the Z-axis direction. The generatrix of each collimator lens 13a is parallel to the Y axis. The slow axis of each laser beam incident on the collimator lens array 13 is perpendicular to the generatrix of the collimator lens 13a.

Each laser beam is incident on one collimator lens 13a. Each laser light source 11a is arranged such that the emission optical axis of each laser light source 11a passes through the center of the collimator lens 13a in front of each laser light source 11a. Each laser beam is converged by the collimator lens 13a in the slow axis direction (Z axis direction), and is collimated in the slow axis direction.

In this way, the laser light emitted from each laser light source 11a of the light source unit 11 is adjusted by the collimator lens 12 and the collimator lens array 13 to have a substantially parallel spread over the entire circumference.

Returning to FIG. 1, the condenser lens 14 has an optical function of converging only in the direction in which the laser light sources 11a are arranged, that is, in the slow axis direction. The condenser lens 14 is, for example, a cylindrical lens. The generatrix of the lens surface of the condenser lens 14 is parallel to the Y-axis direction. Therefore, the beam formed by each laser beam after passing through the condenser lens 14 is converged only in the slow axis direction (Z axis direction). Therefore, the shape of the beam at the focal position of the condenser lens 14 is a linear shape that is long in the fast axis direction. The length of this linear shape is approximately the same as the width in the fast axis direction of each laser beam that is collimated by the collimator lens 12.

The beam condensed by the condenser lens 14 enters the mirror 15 a of the optical deflector 15. The optical deflector 15 is, for example, a MEMS (Micro Electro Mechanical Systems) mirror using a piezoelectric actuator, an electrostatic actuator, or the like. The mirror 15a is arranged at the position of the focal length of the condenser lens 14.

The beam is condensed only in the Z-axis direction by the condenser lens 14, so the beam after being reflected by the mirror 15a spreads only in the X-axis direction. Thus, the line beam B10 that spreads in the X-axis direction is generated.

The optical deflector 15 drives the mirror 15a by the drive signal from the mirror drive circuit 33, and scans the beam reflected from the mirror 15a in the Y-axis direction. As a result, the line beam B10 is scanned in the lateral direction (Y-axis direction).

FIG. 4 is a diagram schematically showing the emission state of the laser beam of the laser radar 10 and the state of the line beam B10 in the target area. In the upper part of FIG. 4, the cross-sectional shape of the line beam B10 when viewed in the projection direction (Z-axis positive direction) is schematically shown.

As shown in FIG. 4, in this embodiment, the laser radar 10 is mounted on the front side of the vehicle 200, and the line beam B10 is projected in front of the vehicle 200. The divergence angle θ11 in the long side direction of the line beam B10 is 120°, for example. The upper limit of the distance D11 at which the object can be detected is, for example, about 200 m. In FIG. 4, for the sake of convenience, the spread angle θ11 is expressed smaller than it actually is.

As shown in FIG. 1, since the plurality of laser light sources 11a are arranged side by side in one direction, the laser light emitted from each laser light source 11a is projected so as to be arranged along the line L1 in FIG. It In this way, the laser beams emitted from the respective laser light sources 11a are combined to form the line beam B10.

Returning to FIG. 1, the reflected light of the line beam B10 reflected from the target area is condensed by the light receiving lens 16 on the light receiving surface of the light receiving element 17. The light receiving element 17 is, for example, an image sensor. The light receiving element 17 has, for example, a rectangular light receiving surface, and is arranged such that the long side of the light receiving surface is parallel to the X axis. The long side direction of the light receiving surface of the light receiving element 17 corresponds to the long side direction of the line beam B10 in the target region. The reflected light of the line beam B10 is imaged on the light receiving surface of the light receiving element 17 by the light receiving lens 16 so as to extend along the long side direction of the light receiving surface.

Here, the pixel position in the X-axis direction on the light-receiving surface corresponds to the position in the X-axis direction in the target area. Therefore, it is possible to detect at which position in the X-axis direction of the target area the object is present based on the position of the pixel where the light reception signal is generated. As the light receiving element 17, a line sensor in which pixels are arranged in the X-axis direction may be used.

FIG. 5A is a diagram schematically showing a condensed state of the reflected light R10 on the light receiving surface 171a when the image sensor 171 is used as the light receiving element 17. Note that FIG. 5A shows a light receiving state of the reflected light R10 when all of the line beam B10 is reflected in the target area. Further, FIG. 5A schematically shows the arrangement of the pixels 171b, and actually, the pixels 171b, which are significantly larger than those in FIG. 5A, are arranged with high precision.

On the light receiving surface 171a of the image sensor 171, a large number of pixels 171b arranged vertically and horizontally are arranged. Each pixel 171b outputs a detection signal when light enters during the exposure period. In FIG. 4, when the line beam B10 is scanned in the Y axis direction (short side direction of the line beam B10), the reflected light R10 scans the light receiving surface 171a in the Y axis direction. The scanning range of the line beam B10 in the Y-axis direction corresponds to the scanning range of the reflected light R10 on the light receiving surface 171a. The scanning range of the reflected light R10 is set to be substantially equal to the width of the light receiving surface 171a in the Y axis direction. Accordingly, the position of the pixel 171b in the Y-axis direction corresponds to the scanning position of the line beam B10 in the Y-axis direction, and the position of the pixel 171b in the X-axis direction corresponds to the position of the line beam B10 in the X-axis direction. Therefore, it is possible to detect at which position in the X-axis direction of the target area the object is present based on the position of the pixel where the light reception signal is generated.

The image sensor 171 may be a CMOS image sensor or a CCD image sensor, or may be an APD array in which an avalanche photodiode is arranged in each pixel 171b. The avalanche photodiode has a function of multiplying electrons generated by photoelectric conversion. Therefore, the detection sensitivity of each pixel 171b can be increased, and the weak reflected light R10 from a long distance can be detected more accurately. In this case, the avalanche photodiode may be used in Geiger mode. Accordingly, when photons are incident on the avalanche photodiode of each pixel 171b, the amount of charge generated in the avalanche photodiode can be increased to the saturated charge amount and output. Therefore, the weak reflected light R10 can be detected with higher accuracy.

FIG. 5B is a diagram schematically showing a condensed state of the reflected light R10 on the light receiving surface 172a when the line sensor 172 is used as the light receiving element 17. Note that FIG. 5B also shows the light reception state of the reflected light R10 when the entire line beam B10 is reflected in the target area.

On the light receiving surface 172a of the line sensor 172, a plurality of rectangular optical sensors 172b extending in the Y-axis direction are arranged side by side in the X-axis direction. Each optical sensor 172b outputs a signal having a magnitude corresponding to the amount of received light. In FIG. 4, when the line beam B10 is scanned in the Y axis direction (short side direction of the line beam B10), the reflected light R10 scans the light receiving surface 172a in the Y axis direction. The scanning range of the line beam B10 in the Y-axis direction corresponds to the scanning range of the reflected light R10 on the light receiving surface 172a. The scanning range of the reflected light R10 is set to be substantially equal to the width of the light receiving surface 172a in the Y axis direction.

The position of each optical sensor 172b in the X-axis direction corresponds to the position of the line beam B10 in the X-axis direction. Therefore, the position of the object in the X-axis direction in the target area can be detected from the position of the optical sensor 172b where the received light signal is generated. The scanning position of the line beam B10 in the Y-axis direction can be grasped from the swing position of the mirror 15a in the optical deflector 15, for example. That is, when a light receiving signal is output from each optical sensor 172b at the timing when the mirror 15a is at each swing position, the light receiving signal can be associated with the scanning position of the line beam B10 corresponding to the swing angle. Therefore, by making this correspondence on the circuit unit side, it is possible to detect at which position in the Y-axis direction of the target area the object is present.

The number, length, and width of the optical sensors 172b are not limited to those shown in FIG. 5(b). In order to improve the resolution in the X-axis direction, the width of the optical sensors 172b is preferably as narrow as possible, and the number of optical sensors 172b is preferably as large as possible.

Returning to FIG. 1, the laser radar 10 includes a controller 31, a laser drive circuit 32, a mirror drive circuit 33, and a signal processing circuit 34 as a circuit configuration.

The controller 31 includes an arithmetic processing circuit such as a CPU (Central Processing Unit) and a storage medium such as a ROM (Read Only Memory) and a RAM (Random Access Memory), and controls each unit according to a preset program. The laser drive circuit 32 causes each of the laser light sources 11a of the light source unit 11 to emit a pulse under the control of the controller 31.

The mirror drive circuit 33 drives the optical deflector 15 under the control of the controller 31. The controller 31 controls the optical deflector 15 so that the line beam B10 is scanned in the short side direction of the line beam B10 in the target area.

The signal processing circuit 34 outputs the light receiving signal of each pixel of the light receiving element 17 to the controller 31. As described above, the controller 31 can detect at which position in the X-axis direction of the target area the object exists, based on the position of the pixel where the light reception signal has occurred. Further, the controller 31 uses the time difference between the timing at which the light source unit 11 emits pulsed light and the timing at which the light receiving element 17 receives the reflected light from the target area, that is, the timing at which the light receiving signal is received from the light receiving element 17. The distance to the object existing in the area is calculated.

In this way, the controller 31 detects the presence or absence of an object in the target area by causing the light deflector 15 to scan the line beam B10 while causing the light source unit 11 to emit light in pulses, and further detects the position of the object in the Y-axis direction and the object. Measure the distance to. These measurement results are transmitted to the control unit on the vehicle side at any time.

Next, a method of setting the optical system of the laser radar 10 will be described.

FIG. 6A is a diagram for explaining the relationship between the laser light source 11a and the collimator lens 13a that collimates the laser light in the slow axis direction. For convenience, the collimator lens 12 is omitted in FIG.

In FIG. 6A, P1 is the arrangement interval of the laser light sources 11a, S1 is the width of the light emitting region 117 of the laser light sources 11a in the arrangement direction of the laser light sources 11a (here, the slow axis direction), and θ1 is the arrangement of the laser light sources 11a. Direction (here, slow axis direction), the total divergence angle of the laser light, and f1 is the focal length of the collimator lens 13a. In this case, the laser light source 11a is arranged so as to satisfy the following equation.

P1≧S1+2f1×tan (θ1/2)…(1)

Here, the total divergence angle θ1 of the laser light is the total divergence angle of the laser light included in the region of 1/e ² or more of the peak intensity. The full divergence angle θ1 of the laser light may be the full divergence angle of the laser light included in the half-value width of the peak intensity.

When the laser light sources 11a are arranged in this way, the laser light emitted from each laser light source 11a properly enters the front collimator lens 13a without being caught by the adjacent collimator lens 13a. As a result, each laser beam is accurately collimated by the corresponding collimator lens 13a. As a result, the beam formed by integrating the laser beams can be converged by the condenser lens 14 into a substantially focused state. Therefore, the size of the beam condensed by the condenser lens 14 can be made extremely small.

FIG. 6B is a diagram illustrating the relationship between the condenser lens 14 and the mirror 15 a of the optical deflector 15.

In FIG. 6(b), D2 is the effective diameter of the condenser lens 14, f2 is the focal length of the condenser lens 14, and θ2 is the total angle of convergence of the beam with respect to the mirror 15a. In this case, the condenser lens 14 and the mirror 15a are arranged so as to satisfy the following equation.

θ2=2 tan ⁻¹ (D2/2f2) (2)

By arranging the condenser lens 14 and the mirror 15a in this way, the beam formed by integrating the laser beams is converged by the condenser lens 14 on the mirror 15a in a substantially focal line state. Therefore, the size of the mirror 15a can be made extremely small.

<Effects of the embodiment>
According to this embodiment, the following effects are exhibited.

Since a plurality of laser light sources 11a are used, it is possible to increase the irradiation light amount of the laser light to the target area. Further, since the laser light emitted from each laser light source 11a is condensed on the mirror 15a of the optical deflector 15 by the condenser lens 14, the mirror 15a of the optical deflector 15 can be made small. Further, since the laser light source 11a is arranged so as to satisfy the condition of the above expression (1), the laser light emitted from the laser light source 11a is properly incident on the corresponding collimator lens 13a without protruding. You can As a result, the collimator lens 13a can accurately collimate each laser beam, and as a result, the beam converging size at the mirror 15a can be narrowed to an extremely small size. Therefore, the mirror 15a of the optical deflector 15 can be significantly reduced.

Further, the plurality of laser light sources 11a are arranged such that the slow axis of each laser light source 11a is parallel to the arrangement direction of the laser light sources 11a, and each collimator lens 13a formed in the collimator lens array 13 has each laser light source 11a. The laser light from is collimated in the slow axis direction. As a result, since the laser light is incident on each collimator lens 13a with a small divergence angle, even if the collimator lens 13a is slightly displaced in the traveling direction of the laser light, it is difficult for the laser light to impinge on the adjacent collimator lens 13a. Therefore, each laser beam can be made into a parallel beam more accurately.

Further, since the condenser lens 14 and the mirror 15a are arranged so as to satisfy the condition of the above expression (2), the beam formed by integrating the laser light emitted from each laser light source 11a is a condenser lens. The light beam is focused on the mirror 15a by 14 in a substantially focused state. Therefore, the size of the mirror 15a of the optical deflector 15 can be made extremely small.

As described above, by making the mirror 15a of the optical deflector 15 extremely small, the optical system and the laser radar 10 can be downsized and the response performance of the mirror 15a can be improved. Therefore, the line beam B10 can be smoothly and accurately scanned in the target area.

Further, the laser light source 11a has a single-mode emission intensity distribution on both the fast axis 118a and the slow axis 118b. As a result, the laser light emitted from each laser light source 11a can be accurately collimated in the fast axis direction and the slow axis direction by the fast axis collimator lens 12 and the slow axis collimator lens 13a. Since the laser light can be collimated in the fast axis direction with high accuracy, the beam spread in the short side direction of the line beam B10 can be suppressed, and the line beam B10 can be irradiated further. Therefore, the detectable distance of the laser radar 10 can be widened. Further, since the laser light can be made parallel to the slow axis with high accuracy, the shape of the beam focused on the mirror 15a can be made closer to a linear shape. Therefore, the mirror 15a can be made smaller.

The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments, and various modifications can be made.

<Modification 1>
For example, as shown in FIG. 7A, a diffusing plate 18 to which the laser beams emitted from the plurality of laser light sources 11a respectively enter may be further arranged. FIG. 7A shows only the optical system of the laser radar 10.

In the above-described embodiment, since the laser light sources 11a are arranged side by side in a straight line, the line beam B10 is configured by arranging the laser light from each laser light source 11a in the long side direction. Therefore, the intensity distribution of the line beam B10 repeats high and low in the long side direction.

On the other hand, in Modification 1, the intensity distribution of the line beam B10 in the long side direction is made uniform by the diffuser plate 18. Thereby, the detectable distances of the object at the respective positions in the long side direction of the line beam B10 can be equal to each other. Therefore, at each position in the long side direction of the line beam B10, it is possible to uniformly and accurately measure the distance to the object. Note that the diffusion plate 18 may be arranged in the emission window of the laser radar 10, or the emission window itself may be the diffusion plate 18.

<Modification 2>
Further, as shown in FIG. 7B, a magnifying lens 19 for further widening the divergence angle of the line beam B10 in the long side direction may be provided. In FIG. 7B, only the optical system of the laser radar 10 is shown.

The magnifying lens 19 has a concave lens surface 19a curved only in a direction parallel to the XZ plane. The generatrix of the lens surface 19a is parallel to the Y axis. The concave lens surface 19a may be provided on the entrance surface of the magnifying lens 19 or may be provided on both the entrance surface and the exit surface.

By providing the magnifying lens 19 in this way, the range in which the distance measurement can be performed by the laser radar 10 can be expanded in the X-axis direction. Therefore, it is possible to measure the distance for an object existing in a wider range.

<Modification 3>
In the above embodiment, the condenser lens 14 has a converging action only in the direction in which the laser light sources 11a are arranged. However, the condensing lens 14 has a converging action to uniformly converge the light over the entire circumference. May be.

FIG. 8A is a diagram showing the configuration of the optical system in this case.

The condenser lens 14 has an optical function of converging parallel light incident in the optical axis direction into one point. In this case, the beam composed of the laser light emitted from each laser light source 11a is condensed by the condenser lens 14 on the mirror 15a of the optical deflector 15 as a substantially circular beam spot. After that, the beam spreads not only in the X-axis direction but also in the Y-axis direction.

Therefore, in this modified example, the collimator lens 20 for collimating the beam in the Y-axis direction is provided on the rear side of the optical deflector 15. The collimator lens 20 is, for example, a cylindrical lens. The exit surface of the collimator lens 20 is a lens surface 20a which is convexly curved only in the direction parallel to the YZ plane. The generatrix of the lens surface 20a is parallel to the X axis. By collimating the beam in the Y-axis direction by the collimator lens 20, a line beam B10 that spreads in the X-axis direction is generated.

According to the configuration of Modification 3, the collimator lens 13a is further required as compared with the above embodiment. However, according to the configuration of the third modification, the beam can be condensed into a substantially circular beam spot on the mirror 15a of the optical deflector 15. Therefore, the size of the beam on the mirror 15a can be further reduced as compared with the above embodiment. Therefore, the size of the mirror 15a can be further reduced.

<Modification 4>
In the above embodiment, the laser light sources 11a are arranged in the slow axis direction, but the laser light sources 11a may be arranged in the fast axis direction.

FIG. 8B is a diagram showing the configuration of the optical system in this case.

Here, a collimator lens array 21 that collimates the laser light emitted from each laser light source 11a in the fast axis direction and a collimator lens 22 that collimates the laser light emitted from each laser light source 11a in the slow axis direction. And are provided.

On the emission surface of the collimator lens array 21, a plurality of collimator lenses 21a on which the laser beams from the laser light sources 11a respectively enter are formed, as in FIG. 3B. The collimator lens 21a has a convex lens surface curved only in a direction parallel to the XZ plane. The generatrix of the collimator lens 21a is parallel to the Y-axis direction.

Further, the exit surface of the collimator lens 22 is formed with a lens surface 22a on which the laser light from each laser light source 11a enters, as in FIG. 3A. The lens surface 22a has a convex shape curved only in a direction parallel to the XZ plane. The generatrix of the lens surface 22a is parallel to the Z-axis direction. The collimator lens 22 is, for example, a cylindrical lens.

Also in the modification 4, the collimator lens 21a and the laser light source 11a are arranged so as to satisfy the condition of the above expression (1). In the configuration of Modification 4, P1 in the above formula (1) is the arrangement interval of the laser light sources 11a, S1 is the width of the light emitting region 117 of the laser light sources 11a in the arrangement direction of the laser light sources 11a (fast axis direction), and θ1 is the laser light source. The divergence full angle of the laser light in the arrangement direction of 11a (fast axis direction), and f1 is the focal length of the collimator lens 21a.

In the modified example 4, by arranging the collimator lens 21a and the laser light source 11a so as to satisfy the condition of the above formula (1), each laser beam can be accurately parallelized in the fast axis direction. As a result, the mirror The beam can be linearly focused on 15a. Therefore, the mirror 15a can be downsized and the response performance of the mirror 15a can be improved.

<Other changes>
In the above-described embodiment, the fast axis collimator lens 12 and the slow axis collimator lens array 13 are separate bodies, but they may be integrated. For example, an optical element in which one collimator lens (lens surface) for the fast axis is formed on the entrance surface and a plurality of collimator lenses for the slow axis is formed on the exit surface is formed by the light source unit 11 and the condenser lens 14. It may be arranged in between.

In the above embodiment, the slow axis collimator lens 13a is arrayed, but a plurality of collimator lenses corresponding to the laser light sources 11a may be arranged side by side. The same applies to the collimator lens 21a shown in the fourth modification.

Further, in the above embodiment, the optical system is configured such that the light source unit 11, the collimator lens 12, the collimator lens array 13, the condenser lens 14, and the optical deflector 15 are arranged in one direction, but the layout of the optical system is this. It is not limited to. For example, the optical system may be configured such that a mirror is arranged in the middle of the optical path and the optical path is bent.

Further, in the above embodiment, six laser light sources 11a are arranged, but the number of laser light sources 11a may be another number as long as it is plural. Further, the plurality of laser light sources 11a may not necessarily be unitized, and the plurality of laser light sources may be individually arranged. The laser light source 11a does not necessarily have to be a single mode in both the fast axis and the slow axis.

Further, in the above embodiment, the laser radar 10 is mounted on the vehicle 200, but the laser radar 10 may be mounted on another moving body. Further, the laser radar 10 may be mounted on equipment or equipment other than the moving body. Further, the laser radar 10 may have only the function of detecting an object.

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

10... Laser radar 11a...

Laser light source

12, 13a, 21a, 22... Collimator lens 14... Condensing lens 15... Optical deflector 15a... Mirror 16... Light receiving lens 17... Light receiving element 18... Diffusion plate 117... Light emitting area 118a Axis 118b... Slow axis 171... Image sensor 172... Line sensor

Claims

A plurality of laser light sources arranged side by side in one direction,
A plurality of collimator lenses arranged corresponding to each of the laser light sources, for collimating the laser light emitted from each of the laser light sources in a direction corresponding to the one direction,
Condensing lenses having respective laser beams passing through the collimator lenses incident side by side in a direction corresponding to the one direction, and having a condensing function in at least a direction corresponding to the one direction,
An optical deflector that has a mirror to which each of the laser beams condensed by the condenser lens is incident, and that deflects the laser beam by changing the direction of the mirror;
The arrangement interval of the laser light sources is P1, the width of the light emitting region of the laser light source in the direction parallel to the one direction is S1, the divergence full angle of the laser light in the direction parallel to the one direction is θ1, and the focus of the collimator lens is When the distance is f1,
P1≧S1+2f1×tan (θ1/2)
The plurality of laser light sources are arranged so as to satisfy the condition of
A laser radar characterized in that.
The laser radar according to claim 1,
The plurality of laser light sources are arranged so that the slow axis of each of the laser light sources is parallel to the one direction.
Each of the collimator lenses collimates the laser light from each of the laser light sources in the slow axis direction,
A laser radar characterized in that.
The laser radar according to claim 1 or 2,
When the effective diameter of the condensing lens is D2, the focal length of the condensing lens is f2, and the total condensing angle with respect to the mirror is θ2,
θ2=2 tan −1 (D2/2f2)
The condenser lens and the mirror are arranged so as to satisfy the condition of
A laser radar characterized in that.
The laser radar according to any one of claims 1 to 3,
A collimator lens for collimating the laser light from each light source in a direction perpendicular to the one direction,
Each laser beam that has passed through the collimator lens and the other collimator lens is incident on the condenser lens,
A laser radar characterized in that.
The laser radar according to any one of claims 1 to 4,
The laser light source has a single-mode emission intensity distribution on both the fast axis and the slow axis,
A laser radar characterized in that.
The laser radar according to any one of claims 1 to 5,
The optical deflector is a MEMS mirror,
A laser radar characterized in that.
The laser radar according to any one of claims 1 to 6,
The laser light emitted from the plurality of laser light sources is provided with a diffuser plate, respectively.
A laser radar characterized in that.
The laser radar according to any one of claims 1 to 7,
The laser light reflected by the mirror forms a line beam that spreads in a direction corresponding to the one direction,
A light receiving element for receiving the reflected light from the target area of the line beam,
A light receiving lens for condensing the reflected light on the light receiving element,
A laser radar characterized in that.
The laser radar according to claim 8,
The light receiving element is an image sensor,
A laser radar characterized in that.
The laser radar according to claim 9,
The image sensor is an APD array in which an avalanche photodiode is arranged in each pixel,
A laser radar characterized in that.
The laser radar according to claim 8,
The light receiving element is a line sensor,
A laser radar characterized in that.