Optical scanner and object detection device

Abstract

To provide an object detection device for detecting reflected light of light irradiated to an object and optically detecting the object, in which the accuracy of detecting the object is improved while maintaining the intensity of an optical beam suppressed to a safe level.SOLUTION: An optical scanner according to the present invention and an object detection device including the same comprise: a spatial light modulator having a light emission unit whose emission direction of incident light is changeable by electrical control; a light source unit for enabling a first light beam to enter a first region and a second light beam to enter a second region different from the first region of the light emission unit; and a control unit for controlling the spatial light modulator so as to change an emission direction of light in the first region and an emission direction of light in the second region independently of each other. Meanwhile, the emission direction of the first light beam and the emission direction of the second light beam are changed with the passage of time, whereby optical scanning of a space is conducted.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to an object detection device that optically detects an object by irradiating light into space and detecting reflected light from the object, and an optical scanning device for realizing the same.

Background Art

[0002] As a technique for detecting the distance and position of an object, there is a technique of irradiating light onto the object, receiving the reflected light from the object, and optically measuring the distance to the object, the shape of the object, etc. based on the information of the reflected light. For example, a technique using laser light called LiDAR (Light Detection And Ranging) is an example of this. The LiDAR technique is expected to be applied to, for example, obstacle detection in automobiles and robot control.

[0003] For example, in the technique described in Patent Document 1, the laser light beam is scanned by changing the direction of the emitted light from the laser light source over time by a MEMS (Micro Electro Mechanical Systems; microelectromechanical system) phased array, and the light reflected from the object is received to detect the position to the object in a specific direction. Here, the MEMS phased array functions as a diffraction grating with an aggregate of a large number of arranged minute optical elements, and by individually driving each element and adjusting its position, the emission direction of the diffracted light can be electrically controlled.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The intensity of the scanning light beam reaching the object to be detected and the intensity of its reflected light decrease as the distance to the object increases. For this reason, it is inevitable that the detection accuracy of the distance, size, etc. of an object far away decreases. Also, when the object is composed of a material with a low reflectivity, the detection accuracy decreases because the intensity of the reflected light is low. To improve the detection accuracy, it is conceivable to increase the intensity of the scanning light beam, but for example, there are safety issues in scanning a space where there may be people with a high-intensity light beam. From this, it is desired to improve the detection accuracy of an object, particularly a distant object, while keeping the intensity of the light beam at a level without safety problems.

[0006] This invention has been made in view of the above problems, and in an object detection device that optically detects an object by detecting the reflected light of the light irradiated on the object and an optical scanning device applicable thereto, an object is to provide a technology capable of improving the detection accuracy of the object while keeping the intensity of the light beam at a safe level.

Means for Solving the Problems

[0007] One aspect of the optical scanning device according to this invention includes a spatial light modulator having a light emitting unit capable of changing the emission direction of the incident light by electrical control, a light source unit that makes a first light beam incident on a first region among the light emitting units and makes a second light beam incident on a second region different from the first region among the light emitting units, and a control unit that controls the spatial light modulator to independently change the emission direction of the light in the first region and the emission direction of the light in the second region. Here, the control unit realizes optical scanning of the space by changing the emission direction of the first light beam emitted from the first region and the emission direction of the second light beam emitted from the second region over time.

[0008] Also, one aspect of the object detection device according to the present invention includes the optical scanning device configured as described above and a light receiving unit that receives reflected light generated by the first light beam and the second light beam being reflected by an object in space. The control unit controls the optical element to emit the first light beam and the second light beam toward space to perform optical scanning, and detects the object based on information on the reflected light received by the light receiving unit.

[0009] In the optical scanning device configured as described above, it is possible to make a light beam enter different regions of the light emitting unit of the spatial light modulator and independently change their emission directions. Therefore, it is possible to irradiate a plurality of light beams in different directions to scan different spaces, or irradiate the same spatial region to increase the amount of light of the reflected light from the region.

[0010] By utilizing this function, it is possible to scan a wide area by emitting a plurality of light beams in different directions, or to selectively focus the light beams on a partial region by converging the emission directions of the light beams. As a result, for example, it is possible to selectively concentrate the light beams in a direction where a larger light intensity is required, such as when the distance to the object is large. Therefore, when detecting an object by receiving the reflected light of such a light beam, it is possible to enhance the effective beam light intensity only in the necessary direction and improve the detection accuracy of the object in that direction.

[0011] Also, in the object detection device including the optical scanning device configured as described above, for example, it is possible to use the light beams in different ways, such as usually making the emission directions of the respective light beams different to scan different ranges from each other, and concentrating the light beams in the vicinity of an object at a large distance for scanning. Therefore, it is possible to improve the detection accuracy of the object while keeping the intensity of each light beam low.

Effects of the Invention

[0012] As described above, according to the present invention, it is possible to selectively use the operation of scanning a space individually with a plurality of light beams and the operation of integrating these light beams to scan a specific region. Therefore, in the detection of an object using optical scanning, it is possible to improve the detection accuracy of the object while ensuring safety by keeping the intensity of each light beam low.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0014] FIG. 1 is a block diagram showing a schematic configuration of an embodiment of an object detection device according to the present invention. This object detection device 1 uses LiDAR (Light Detection And Ranging) technology to detect an object OB in a space, and is a device that measures at least one of the distance, size, and shape (hereinafter collectively referred to as "spatial features") from the object detection device 1 to the object OB, and is applicable to various measurement and control fields such as robot control and obstacle detection in vehicles.

[0015] In this object detection device 1, a MEMS (Micro Electro Mechanical Systems) phased array is used for beam steering to optically scan the space that may contain the object OB. Note that the operating principle and basic configuration of an object detection device using beam steering by a MEMS phased array are described in Patent Document 1, and the same concept can also be applied in this embodiment. Therefore, here, only a schematic explanation will be given for the detection principle and device configuration.

[0016] As already known, typical examples of object detection techniques using LiDAR include, for example, the ToF (Time of Flight) method and the FMCW (Frequency Modulated Continuous Wave) method. In the ToF method, pulsed laser light is used as the scanning light Ls, and the distance is calculated from the time difference until the scanning light is reflected by the object and received. Also, in the FMCW method, the wavelength of the continuously emitted laser light is changed over time, and distance information is obtained from the interference signal between the reflected light from the object and the reference light. Either of these methods can be applied to this embodiment.

[0017] The main components of the object detection device 1 include an optical scanning unit 10 that emits laser light as the scanning light Ls to scan the target space, a light receiving unit 20 that receives the reflected light Lr when the scanning light Ls is reflected by the object OB, and a control unit 30 that controls the operation of each part of the device and detects the presence or absence of the object OB and its spatial characteristics from the received reflected light Lr.

[0018] In the optical scanning unit 10, the emission direction of the laser light emitted from the laser light source 11 is temporally changed by the scanning unit 12, thereby realizing optical scanning directed at a predetermined scanning range in space. In the light receiving unit 20, the reflected light Lr from the object OB is incident on the photodetector 21 via a band-pass filter and an optical system (not shown). The photodetector 21 generates a signal including information representing the position, distance, etc. of the object OB from the received light and outputs it to the control unit 30.

[0019] Based on the signal input from the photodetector 21, the control unit 30 detects the object OB existing in the space within the scanning range. Specifically, the CPU (Central Processing Unit) 31 provided in the control unit 30 calculates the presence or absence of an object and its distance in each direction within the scanning range from the reflected light received in each direction. For this purpose, in addition to the CPU (Central Processing Unit) 31, the control unit 30 can include a memory (RAM) as the storage unit 32 and a storage, etc.

[0020] Further, the control unit 30 further includes a recognition unit 33 that executes a process of recognizing the spatial characteristics of the detected object for various operations described later, and a pattern generation unit 34 that generates an optical scanning pattern according to the processing result of the recognition unit 33. These may be realized software-wise by the CPU 31 executing a predetermined control program, or may be configured as dedicated hardware.

[0021] Next, the configuration and operation of the scanning unit 12 will be described. In this embodiment, an MEMS phased array capable of changing the emission direction of the laser light emitted from the laser light source 11 by electrical control is used for the steering technology that changes the emission direction of the laser light.

[0022] FIG. 2 schematically shows the structure of the MEMS phased array. FIG. 3 is a diagram for explaining the operation of the MEMS phased array. In this embodiment, the MEMS phased array is used as a programmable one-dimensional diffraction grating type optical element that diffracts incident light and emits it, and changes the emission direction over time. Hereinafter, the MEMS phased array may be referred to as a "diffractive optical element". As the diffractive optical element (Diffractive Optical Element; DOE) 120, for example, a GLV (Grating Light Valve; "GLV" is a registered trademark of the company) element of Silicon Light Machines can be preferably applied. With this element, high-speed switching, for example, at 100 kHz is possible.

[0023] FIG. 2(a) schematically shows the schematic configuration of the diffractive optical element 120. FIG. 2(b) shows the states that the diffractive optical element 120 can take. FIG. 2(c) shows the light emitting surface Se in the diffractive optical element 120. As shown in FIG. 2(a), the diffractive optical element 120 has a schematic configuration in which a plurality of movable ribbons 122 are arranged at regular intervals in a direction parallel to the surface of a flat bottom electrode 123 while facing the surface on the substrate 121. In the movable ribbon 122, the upper surface thereof is a reflective surface that reflects light, for example, by a metal coating. Each of the movable ribbons 122 is fixed at a certain interval with respect to the bottom electrode 123. That is, the distance between the movable ribbon 122 and the bottom electrode 123 is defined by a pair of post anchors 124 erected on the substrate 121 so as to sandwich the bottom electrode 123.

[0024] In order to uniformly indicate the directions in the following description, XYZ orthogonal coordinates are set as shown in FIG. 2(a). Among the directions along the surface of the substrate 121, the arrangement direction of the plurality of movable ribbons 122 is the X direction, and the longitudinal direction of each movable ribbon 122 is the Y direction. Further, the direction perpendicular to the surface of the substrate 121 is the Z direction. Also, the arrangement pitch of the movable ribbons 122 in the X direction is represented by the symbol d.

[0025] The movable ribbon 122 is displaceable with respect to the bottom electrode 123. Specifically, as shown in Fig. 2(b), when a control voltage V is applied between the movable ribbon 122 and the bottom electrode 123, the movable ribbon 122 deforms due to the electrostatic force and displaces in the approaching and separating direction with respect to the bottom electrode 123, that is, in the Z direction, as shown by the solid line and the dotted line. The displacement amount of the movable electrode 122 depends on the magnitude of the control voltage V. The control unit 30 is provided with a driving circuit (CMOS driver) not shown in the figure, and the control voltage V is applied to the movable ribbon 122 from the driving circuit.

[0026] The control voltage V supplied from the driving circuit can be set individually for each movable ribbon 122. Therefore, the height of the movable ribbon 122 in the Z direction can be individually controlled by the magnitude of the control voltage V. Accordingly, when the surfaces of the plurality of movable ribbons 122 are viewed macroscopically, various uneven patterns are realized due to the difference in the height of each movable ribbon 122.

[0027] For example, as shown in Fig. 3(a), when the surface heights of all the movable ribbons 122 are the same, the surfaces of those movable ribbons 122 constitute a plane mirror as a whole. That is, when light (solid line arrow) is incident on the surface of the movable ribbon 122, the specularly reflected light (dotted line arrow) is emitted from the surface of the movable ribbon 122. That is, the surface of the diffractive optical element 120, which is an aggregate of the movable ribbons 122, acts as a plane mirror.

[0028] On the other hand, as shown in Fig. 3(b), when a stepped uneven pattern is formed by making the surface heights slightly different between adjacent movable ribbons 122, the light reflected with a phase difference between the individual movable ribbons 122 interferes with each other and a diffraction phenomenon occurs. For this reason, only the diffracted light (indicated by the dotted line arrow) in a specific direction is emitted from the diffractive optical element 120.

[0029] The diffraction angle θ is defined by the wavelength of light (hereinafter represented by the symbol λ), the pitch p of the uneven pattern, and the height difference h. In the example of Fig. 3(b), a stepped repeating pattern with five movable ribbons 122 as one unit is formed, and the pitch p of the pattern is 5d. The diffraction angle θ at this time can be expressed by the following formula using the wavelength λ and the repeating pitch p: θ = λ / p = λ / (n·d) … (Equation 1) Here, n is the number of movable ribbons 122 that make up one unit of the repeating pattern, and the example of Fig. 3(b) corresponds to the case of n = 5.

[0030] These uneven patterns are variable by electrical control. By controlling the control voltage V applied to each movable ribbon 122 to form an uneven pattern that is periodically repeated, and changing the diffraction angle θ over time while forming a blazed pattern with a height difference h = (λ / 2) for the entire diffraction optical element 120, it is possible to continuously change the direction of the emitted light. Utilizing this, optical scanning can be realized.

[0031] In reality, by specifying the value of n corresponding to the direction in which light is desired to be emitted and controlling each movable ribbon 122 so that a blazed pattern corresponding to this is formed, desired optical scanning is possible. Note that the value of n is not limited to an integer and can take continuous real values. The blazed pattern corresponding to the case where the value of n is other than an integer can be realized by discretizing the number of ribbons forming the stepped pattern or setting the height difference h, that is, the displacement amount of the movable ribbon 122 hitting the end of each stepped pattern, to a value greater than 0 and less than (λ / 2).

[0032] Thus, in the diffraction optical element 120, the surfaces of the respective movable ribbons 122 arranged in a large number in the X direction each reflect the incident light, and by individually controlling their surface heights, the emission direction of the emitted light due to the diffraction phenomenon is defined. That is, as shown in Fig. 2(c), it can be said that the surfaces of the respective movable ribbons 122 function as a light emission surface Se capable of changing the emission direction of the incident light as a whole.

[0033] Regarding this light emitting surface Se, it can be operated so as to define one emission direction as a whole, and it is also possible to divide the light emitting surface Se into several regions in the ribbon array direction (X direction), and perform an operation such that the emission direction is defined for each of these regions. That is, for example, as shown in FIG. 3(c), several movable ribbons 122 arranged continuously are taken as one group, and by making the control mode different for each group, it is possible to make the emission direction of light different depending on the position.

[0034] In the example shown in FIG. 3(c), a region R1 in which a repeating pattern is formed with five movable ribbons 122 as a unit and a region R2 in which a repeating pattern is formed with four movable ribbons 122 as a unit are realized on the light irradiation surface Se of one diffractive optical element 120. Then, as is clear from (Equation 1), the diffraction angle θ1 in region R1 and the diffraction angle θ2 in region R2 will be different from each other. Moreover, since it is possible to independently change and control the repeating patterns between region R1 and region R2, it is possible to independently change the emission direction of the light incident on region R1 and the emission direction of region R2.

[0035] Here, the diffraction angles θ1 and θ2 are made different by varying the number n of movable ribbons 122 that are one unit of the repeating pattern between region R1 and region R2. However, as described above, the height difference h between the movable ribbons 122 can also be used as a control factor for the diffraction angle.

[0036] In the scanning unit 12 of the object detection device 1 of this embodiment, optical scanning is realized by utilizing the characteristics of the diffractive optical element 120 as described above. Hereinafter, the implementation mode of optical scanning in this embodiment will be described in more detail.

[0037] FIG. 4 is a diagram showing the concept of optical scanning in this embodiment. As shown in FIG. 4, in this embodiment, two laser light sources 111 and 112 that each emit a laser light beam are provided, and all of the laser light beams emitted by these laser light sources 111 and 112 are incident on one optical element 120 provided in the scanning unit 12.

[0038] More specifically, the diffractive optical element 120 is installed such that the arrangement direction of the movable ribbons 122 (the X direction in FIG. 2(a)) is horizontal, and two regions on the light emission surface Se (FIG. 2(c)) that are different in position in this direction are irradiated with the first incident light L11 incident from the first laser light source 111 and the second incident light L21 incident from the second laser light source 112, respectively.

[0039] The first emitted light L12 emitted from the diffractive optical element 120 corresponding to the first incident light L11 and the second emitted light L22 emitted from the diffractive optical element 120 corresponding to the second incident light L21 are irradiated into space through an appropriate diffusive optical element 129. The diffusive optical element 129 diffuses and shapes the beam spot of the incident light into a vertically long shape that spreads widely in the vertical direction and is narrow in the horizontal direction. As a result, the first emitted light L12 is irradiated into space as the first scanning light L13 that spreads in the vertical direction, and the second emitted light L22 is irradiated into space as the second scanning light L23 that spreads in the vertical direction.

[0040] By controlling the diffractive optical element 120 by the control unit 30, the directions of the emitted lights L12 and L22 from the diffractive optical element 120 change in the horizontal direction. Therefore, the emission directions of the scanning lights L13 and L23 also change in the horizontal direction. In this way, the scanning lights L13 and L23 with the spot shape widened in the vertical direction are irradiated onto the strip-shaped regions Rb1 and Rb2 within the scanning range Rs. In other words, the spread of the light beam of each of the scanning lights L13 and L23 determines the size of the scanning range Rs in the vertical direction. Then, by emitting the scanning lights L13 and L23 while changing the emission direction in the horizontal direction within a predetermined range over time, the strip-shaped regions Rb1 and Rb2 move, and optical scanning of a predetermined scanning range Rs in space is realized. That is, the amplitude of the scanning lights L13 and L23 in the horizontal direction determines the size of the scanning range Rs in the same direction.

[0041] Here, in order to show the correspondence between the direction of optical scanning and the direction in real space, the directions are defined for convenience by the vertical direction and the horizontal direction associated with the direction of gravity. However, in principle, the scanning direction is not restricted by the direction of gravity.

[0042] FIG. 5 is a diagram for explaining two operation modes in optical scanning. Here, the horizontal optical path of the scanning light when viewed from above is shown, and for the sake of clarity of the figure, the description of the diffractive optical element 129 that does not affect the horizontal optical path is omitted.

[0043] As shown in FIG. 5(a), in the first operation mode in which two scanning lights L13 and L23 are emitted so as not to intersect each other, different spatial ranges are scanned by the two scanning lights L13 and L23. Therefore, for example, if the required scanning range Rs in the space is divided into two, and they are individually scanned by the two scanning lights L13 and L23, the scanning range of each scanning light can be reduced. As a result, the scanning period can be shortened, so that, for example, it is possible to perform optical scanning at high speed over a wide scanning range Rs.

[0044] Also, in the second operation mode shown in FIG. 5(b), two scanning lights L13 and L23 are emitted so as to intersect in the space. By appropriately controlling the diffractive optical element 120, it is possible to realize horizontal scanning while maintaining the state in which the two scanning lights L13 and L23 intersect. In this way, since the light amount increases at the intersection of the two scanning lights L13 and L23, the signal-to-noise ratio (S / N ratio) in receiving the reflected light from an object near the intersection and detecting the object based thereon can be improved.

[0045] When the object is far away or the object itself is a substance with low reflectivity, the reflected light returning from the object is weak. The resulting decrease in the signal-to-noise ratio causes a decrease in the object detection accuracy at long distances in LiDAR technology. In particular, in this embodiment, since the light beam emitted from the laser light source 11 is expanded in the vertical direction, the amount of light of the scanning light itself decreases as the distance increases. In principle, it is possible to improve the signal-to-noise ratio by increasing the intensity of the scanning light. However, especially for a space where there may be people, from the perspective of safety to the human body (especially the eyes), it is not preferable to perform scanning with a high-intensity light beam.

[0046] In view of such problems, in this embodiment, object detection is performed while switching between the above two operation modes according to the purpose. Thereby, an improvement in detection accuracy when the distance to the object is large is achieved. Hereinafter, the details of the object detection process in this embodiment will be described with reference to FIGS. 6 to 9.

[0047] FIG. 6 is a diagram for explaining the principle of a process for accurately detecting a distant object. As shown in FIG. 6(a), there are two objects OB1 and OB2 within the scanning range Rs of the object detection device 1. It is assumed that the object OB1 is at a relatively close position and the other object OB2 is at a farther position as viewed from the object detection device 1. Also, for the sake of convenience of explanation, it is assumed that the object OB1 is on the (-) direction side and the object OB2 is on the (+) direction side with respect to the central direction of the scanning range Rs indicated by the dashed-dotted line.

[0048] First, in order to scan the scanning range Rs widely and at high speed, optical scanning is performed in a first operation mode in which the scanning lights do not intersect. That is, as shown in the left diagram of FIG. 6(a), a combination is made of the optical scanning of half of the scanning range Rs by the first scanning light L13 using the laser light source 111 as the light source and the optical scanning of the remaining half of the scanning range Rs by the second scanning light L23 using the laser light source 112 as the light source to scan the entire scanning range Rs.

[0049] FIG. 6(a) The right figure is a diagram schematically showing the intensity distribution of the reflected light received by the light receiving unit 20. As shown in this figure, on the (-) direction side, relatively strong reflected light from an object OB1 at a relatively close position reaches the light receiving unit 20. On the other hand, on the (+) direction side, the reflected light reaching from an object OB2 farther away is weaker. For this reason, the detection accuracy for the object OB2 is lower than that for the object OB1. Specifically, the existence of the object OB2 itself may not be detected, or the calculation results such as the distance and size may be significantly different from the actual values.

[0050] Here, only the reflected light intensity is focused on, but in the actual detection process, information representing the distance to the object, such as the flight time of light (in the case of the ToF method) and the wavelength at which the interference light is detected (in the case of the FMCW method), is also acquired. However, since these information cannot be acquired unless reflected light of sufficient intensity is obtained, it can be said that the reflected light intensity is one of the important parameters.

[0051] The obtained reflected light intensity distribution indicates that there may be some object on the (+) direction side, but it is uncertain. Therefore, as shown in FIG. 6(b) left figure, a second operation mode is executed in which the scanning lights intersect each other in the space centering on the region where the existence of the object is uncertain, and further optical scanning is performed. If the scanning lights L13 and L23 are made to intersect in the region where there may be an object, the amount of irradiation light for the object OB2 is enhanced. As a result, as shown in FIG. 6(b) right figure, the intensity of the reflected light from the object OB2 becomes higher. In this way, it becomes possible to reliably detect the distant object OB2.

[0052] Thus, in the optical scanning of this embodiment, for the purpose of scanning a relatively wide scanning range Rs at high speed, the first operation mode can be preferably applied. In this sense, the first operation mode can be said to be a wide-area or wide-angle scanning mode functionally. On the other hand, the second operation mode is suitable for the purpose of scanning a part of the scanning range Rs with higher-intensity scanning light. From this meaning, the second operation mode can be said to be a narrow-area scanning mode functionally.

[0053] When performing optical scanning with a single optical beam, in order to compensate for the decrease in detection accuracy for a distant object, for example, it is conceivable to perform optical scanning a plurality of times and statistically process the results. However, such processing takes time and the effect of improving accuracy is also limited. The diffractive optical element 120 of the present embodiment can cause a plurality of optical beams to be incident on different regions of its light emitting surface Se and can individually control the emission directions of the respective optical beams. For this reason, it is possible to scan different regions with a plurality of optical beams or increase the amount of light by synthesizing those optical beams in space.

[0054] In actual processing, the proper use of the first operation mode (hereinafter referred to as the "wide area mode") and the second operation mode (hereinafter referred to as the "narrow area mode") can be performed as follows. The basic idea is to normally perform periodic optical scanning of a wide scanning range Rs in the wide area mode and, when necessary, execute the narrow area mode only for the necessary region.

[0055] FIG. 7 is a diagram showing the concept of processing for the received light signal. FIG. 7(a) is a diagram showing the same reflected light intensity distribution as that shown in FIG. 6(a) and the result of binarization by applying a predetermined threshold value Vt1 thereto. Consider performing binarization of the reflected light intensity distribution acquired by the light receiving unit 20 with a predetermined threshold value Vt1, and determining that a region where the reflected light intensity is greater than the threshold value Vt1 is "with object" and a region smaller than this is "without object".

[0056] Then, on the (-) direction side where sufficient reflected light can be obtained from the object OB1, a region Ra where the reflected light intensity exceeds the threshold value Vt1 and is determined as "object present" appears continuously. In such a case, it can be said that there is a high probability that an optically dense object exists in this direction. On the other hand, on the (+) direction side where the reflected light from the object OB2 is weak, as a result, a region where the reflected light intensity exceeds the threshold value Vt1 appears only limitedly, and a region Rb where small regions determined as "object present" appear intermittently is detected. This state can be interpreted as an optically sparse object existing in the corresponding direction.

[0057] The "optically sparse object" mentioned here includes, in addition to physically sparse objects having many gaps and objects that are "optically sparse" because of their extremely low reflectivity, objects that can be regarded as "sparse" even if they are dense objects but are far away and only return sparse reflected light. Depending only on the detection results by scanning in the wide area mode, these may not be distinguishable.

[0058] If optical scanning in the narrow area mode is performed on the region where such an "optically sparse" object is detected, it is possible to distinguish them. Specifically, as shown in Fig. 7(b), when the reflected light intensity distribution obtained by optical scanning in the narrow area mode is binarized by the threshold value Vt1, if the region Rc determined as "object present" appears continuously, it can be determined that it is a dense but distant object or an object with a low reflectivity. The distinction between the two can be made based on the distance at which the object is detected.

[0059] On the other hand, when the region where it is still determined as "object present" is intermittent even though the reflected light intensity increases by optical scanning in the narrow area mode, there is a high probability that the object is actually physically sparse. Also in this case, it is possible to classify them more finely according to the detected distance.

[0060] From the above, when the presence of an object is detected by optical scanning in the wide-area mode, it is possible to adopt an algorithm that determines whether the object is a "dense object" or a "sparse object", and executes the narrow-area mode when a sparse object is detected. Whether the detected object is dense or sparse can be determined, for example, as follows.

[0061] When the points in the space determined as "object present" in the detection results of the object in each direction are represented as a point group in pixel units, it can be determined that the point group region where the filling rate of the points in the space is greater than a predetermined threshold Vt2 corresponds to a "dense object". The "filling rate" mentioned here is an index value representing the ratio occupied by the points determined as "object present" in the region of interest, and in that sense, it can be considered the same concept as the density of the points in the region. On the other hand, a point group region where the filling rate is less than the threshold Vt2 and greater than another threshold Vt3 (<Vt2) can be determined to correspond to a "sparse object".

[0062] Here, the threshold Vt3 is a value set to distinguish between the state of "the presence of some object" and the state of "nothing", and is chosen to be sufficiently smaller than the threshold Vt2 and large enough to avoid false detection due to the influence of noise, etc. Therefore, it can be determined that no object exists in the region where the filling rate of the point group is less than the threshold Vt3. These thresholds can be determined in advance, for example, by prior experiments.

[0063] The fact that an object is detected in the scanning range Rs means that, even if it is a sparse object, the direction and distance occupied by the object in the space are generally specified. Therefore, for the sparse object to be the target of optical scanning in the narrow-area mode, it is possible to set the emission directions of the respective scanning lights L13, L23 from the diffractive optical element 120 so that the two scanning lights intersect at the position where the object is detected. By doing so, the two scanning lights L13, L23 can be superimposed on the sparse object to enhance the light amount, and it becomes possible to obtain a reflected light with higher intensity.

[0064] Note that within the scanning range Rs, there may be a plurality of regions to which the narrow region mode is applied. That is, when a plurality of sparse objects are detected within the scanning range Rs, the narrow region mode can be applied to each of their neighboring regions. After optically scanning one neighboring region in the narrow region mode, to move the scanning lights L13 and L23 to other neighboring regions, it is only necessary to simply change the concavo-convex pattern in the diffractive optical element 120, so the time required for this movement is very short.

[0065] The concavo-convex pattern of the diffractive optical element 120 for emitting the scanning lights L13 and L23 in an arbitrary direction can be set as follows. The concavo-convex pattern for emitting the scanning lights L13 and L23 in various directions is defined in advance as the displacement amount of each movable ribbon 122 for realizing it and is stored in the storage unit 32. When it is necessary to emit the scanning lights L13 and L23 in a certain direction, the CPU 31 calls the one corresponding to the emission direction from the concavo-convex pattern stored in the storage unit 32, and controls the diffractive optical element 120 based on it, so that the scanning lights L13 and L23 can be emitted in the desired directions respectively.

[0066] FIG. 8 is a flowchart showing the object detection process in this embodiment. This process is realized by the CPU 31 of the control unit 80 executing a control program prepared in advance to cause each part to perform a predetermined operation. In this process, first, as "normal scanning", optical scanning in the wide region mode and object detection based on it are executed. That is, the concavo-convex pattern corresponding to the wide region mode is called from the storage unit 32 (step S101), and based on it, the wide region mode is executed, so that optical scanning in the normal scanning is performed (step S102). That is, the scanning light is sequentially irradiated in each direction of the space within the scanning range Rs. The CPU 31 attempts to detect an object in the space based on the signal output by the photodetector 21 of the light receiving unit 20 according to the received light amount.

[0067] If the detected object does not contain a "sparse object" (NO in step S103), the process proceeds to step S108, where the detected object is recognized. That is, the CPU 31 grasps the shape of the detected object, and the recognition unit 33 refers to the shape data stored in advance to determine whether the object corresponds to a registered type, thereby recognizing what the object is. For example, in an in-vehicle object detection device, it is possible to determine whether an object detected in front is a person or not.

[0068] Note that the object detection device of the present invention does not necessarily need to perform the recognition of the detected object in this way. That is, it is sufficient if at least one of the "spatial features" of the object described in this specification, that is, the distance to the object, the size of the object, and its shape, is obtained.

[0069] If YES in step S103, that is, if a sparse object is detected, then it is subsequently determined whether the position where the sparse object is detected is farther than a predetermined limit distance from the object detection device 1 (step S104). The processes of steps S105 to S107 are executed only when the detected sparse object is outside the range of the limit distance. That is, if the detected object is at a position closer than the limit distance (NO in step S104), steps S105 to S107 are skipped. The reason for this will be explained below.

[0070] For example, when optically scanning a space where there may be a person, it is an essential requirement that no safety problems occur even if the scanning light is irradiated on the human body. Specifically, it is necessary that no health effects occur even if the scanning light is irradiated on a person's eyes. In other words, in order to meet such conditions, an upper limit is set for the intensity of the scanning light. When use in a public space is assumed, this upper limit value may be determined by regulations, for example.

[0071] FIG. 9 is a diagram showing the relationship between the distance and the intensity of the scanning light. More specifically, as shown in FIG. 9(a), FIG. 9(b) shows the relationship between the distance D represented by the distance from the diffractive optical element 120 to the intersection of the scanning lights L13 and L23 and the intensity of the scanning light at the position of the distance D. Here, the "safety reference value" for the scanning light intensity is the above-mentioned upper limit value.

[0072] As shown in FIG. 9(b), as the distance D increases, the intensity of the scanning light decreases. However, since it is unknown at what distance a person is at the time of irradiation, it is necessary to ensure that the intensity of the scanning light does not exceed the safety reference value even when the distance D is the minimum. For this reason, the intensity of each of the scanning lights L13 and L23 is set to be equal to or lower than the safety reference value. Then, in the region where the distance D is large, the amount of light decreases and the reflected light also becomes weak.

[0073] In the narrow region mode of the present embodiment, the amount of light increases by synthesizing the two scanning lights L13 and L23 in space. As a result, at a short distance, the intensity of the synthesized light may exceed the safety reference value. This situation is of course not allowed. Therefore, a "limiting distance" Dr at which the intensity of the synthesized light decreases to the safety reference value is set in advance, and the scanning lights are made to intersect only in the region beyond this limiting distance Dr. By doing so, the intensity of the scanning light does not exceed the safety reference value in either the short distance region or the long distance region, and moreover, the S / N ratio can be improved by enhancing the amount of light of the scanning light in the long distance region.

[0074] In other words, since it is guaranteed that light synthesis is not performed in a situation where the intensity of the synthesized light exceeds the safety reference value, the intensity of each of the individual scanning lights L13 and L23 can be arbitrarily set as long as it does not exceed the safety reference value.

[0075] In this embodiment, the scanning lights L13 and L23 are light beams whose spot shapes are widened in the vertical direction by the diffusing optical element 129. Therefore, the decrease in intensity associated with the distance D is significant, and the limit distance Dr is relatively short. On the other hand, when the scanning light is emitted as a light beam with a small spot diameter, the attenuation due to distance is more negligible. For this reason, the limit distance Dr becomes longer, and in some cases, it may not be possible to execute the narrow region mode substantially.

[0076] Returning to FIG. 8, the description of the object detection process will be continued. Based on the above concept, only when a sparse object is detected (YES in step S103) and the object is at a position farther than the limit distance Dr (YES in step S104), the optical scanning in the narrow region mode where the two scanning lights intersect is executed. Here, a series of operations including the optical scanning in the narrow region mode and the object detection based on it will be referred to as "focus scan" because the two scanning lights are irradiated as if they converge on the object.

[0077] Specifically, the pattern generation unit 34 of the control unit 30 generates an emission pattern of the scanning light, that is, a "scanning pattern for focus scan", which intersects at a position corresponding to the object from the information on the direction and distance of the "sparse object" given from the recognition unit 33 and scans the object by moving the intersection point in the vicinity of the object (step S105).

[0078] At this time, the information stored in the storage unit 32 can be used in combination as necessary. Specifically, if information indicating the correspondence between the concavo-convex pattern by each movable ribbon 122 in the diffractive optical element 120 and the light emission direction at that time is stored in the storage unit 32 in advance, by calling and applying the concavo-convex pattern necessary for emitting the scanning light in the desired direction from the storage unit 32, it becomes possible to emit the scanning light in the intended direction.

[0079] The CPU 31 controls the scanning unit 12 based on the generated scanning pattern for focus scanning, and intensively optically scans the area where a sparse object has been detected in the narrow area mode. Then, based on the information on the amount of light received by the photodetector 21, an object is detected in the scanned area. As a result, it is determined whether an object actually exists in the area where the "sparse object" has been detected, and if so, its spatial characteristics are calculated (focus scanning; step S106).

[0080] The detection result by focus scanning is merged with the detection result in the normal scanning obtained previously (step S107). Specifically, among the detection results obtained by normal scanning, for the area where focus scanning has been executed, they are replaced with the detection results by focus scanning. By doing so, the overall detection result can be made more accurate.

[0081] By performing object recognition on the detection result thus merged (step S108), for both an object at a relatively short distance (for example, object OB1 in FIG. 6(a)) and an object at a farther distance (for example, object OB2 in FIG. 6(a)), the detection and recognition of the object can be performed accurately.

[0082] When a series of processes is completed, it returns to step S101 or S102, and by repeatedly executing normal scanning, object detection within the scanning range Rs can be continuously performed. And when a sparse object is detected, by executing focus scanning, the spatial characteristics of the object can be detected more reliably. By periodically executing object detection in this way, even if the distribution status of the objects within the scanning range Rs changes moment by moment, it can be detected reliably. Also, by comparing the detection results of multiple times, for example, when the detected object is moving, its direction and speed can be calculated.

[0083] As described above, in this embodiment, a diffractive optical element 120 that allows a plurality of light beams to be incident on the light emitting surface Se and independently controls the emission directions of these light beams is used to realize beam steering in the object detection device 1. That is, two laser light beams are incident on different positions of the light irradiation surface Se of the movable ribbon type diffractive optical element 120, and by individually controlling the emission directions of the respective light beams, it is possible to execute a plurality of operation modes with different applications. Specifically, for example, an operation mode in which two light beams scan different spatial regions and an operation mode in which two light beams intersect in space and scan the same spatial region can be realized.

[0084] Therefore, if the scanning range Rs is divided and each range is scanned with two light beams, it is possible to shorten the time required for scanning. On the other hand, by intersecting two light beams, the amount of irradiation light on the object can be increased. As a result, the amount of reflected light from a distant object can be increased, and the S / N ratio can be improved. Therefore, usually, a wide area mode in which two light beams scan different regions is executed to scan a wide scanning range at high speed. When there is an area where the detection result is unclear, the irradiation light amount on the object can be increased in a narrow area mode in which two light beams intersect in that area, thereby improving the detection accuracy at a long distance.

[0085] Whether or not scanning in the narrow area mode is necessary can be determined by whether the detected object is optically dense, that is, whether the light irradiated on the object is highly likely to be reflected and received, or optically sparse, that is, whether the reflected light from the object is received only sparsely. Technically, a determination based on the "filling rate" in the spatial region where the object is detected can be introduced. The filling rate is an index representing the ratio of the points determined to be "with object" occupying the region when a certain spatial region is regarded as a point cloud, and is, for example, a concept equivalent to the density of the point cloud in that region.

[0086] In a spatial region with a sufficiently high filling rate, it is possible to determine with high accuracy that there is an optically dense object. On the other hand, when the filling rate is zero or extremely low, it is possible to determine that there is no object in that region. When the filling rate is an intermediate value between them, it can be determined that there is an optically sparse object in that region, that is, an object with weak reflected light. These can be discriminated by appropriately setting threshold values for the filling rate values.

[0087] And for the region where a sparse object is detected, it is desirable to perform optical scanning in the narrow region mode and object detection based on the reflected light at that time. By doing so, it becomes possible to obtain more detailed spatial features (distance, size, shape, etc.) of the sparse object, thereby improving the detection accuracy. For example, in a case where the object is far away and sufficient reflected light cannot be obtained by optical scanning in the wide region mode, the amount of reflected light can be increased by concentrating two scanning lights on the object, and its detection accuracy can be improved.

[0088] Compared with the wide region mode, the narrow region mode takes a longer time to scan a wide area, but by performing this only for the region determined to be necessary, an increase in processing time can be suppressed. Also, if optical scanning is performed so that two light beams intersect in all spatial regions within the scanning range, the intensity of the combined light may exceed a level acceptable from the viewpoint of safety. In this embodiment, since the combined light is irradiated only in the direction in which an optically sparse object is detected, in other words, in the direction where there is no dense object in a closer position in that direction, such safety problems are avoided.

[0089] Furthermore, in this embodiment, as a measure to further enhance the safety for the human body, the intersection of the two scanning lights is allowed only at a position farther than the limit distance Dr where the intensity of the synthesized scanning light does not exceed the safety reference value determined in advance by laws and regulations or the like. Therefore, in all regions within the scanning range Rs, a situation where the intensity of the scanning light exceeds the safety reference value does not occur. For this reason, in this embodiment, it is possible to suppress the light intensity of each scanning light to avoid safety problems, and moreover, it is possible to detect a distant object with high detection accuracy.

[0090] As described above, in the object detection device 1 of this embodiment, the optical scanning unit 10 functions as the "optical scanning device" of the present invention, and the light receiving unit 20 functions as the "light receiving unit" of the present invention. Further, the control unit 30 has the function as the "control unit" of the present invention. Also, the laser light source 11 functions as the "light source unit" of the present invention, and the diffusing optical element 129 functions as the "beam expanding unit" of the present invention. Further, the storage unit 32 of the control unit 30 functions as the "storage unit" of the present invention.

[0091] Also, in the above embodiment, the scanning unit 12 functions as the "scanning unit" of the present invention, and the diffractive optical element 120 which is a MEMS phased array corresponds to the "spatial light modulator" of the present invention. And the reflecting surfaces of each of the movable ribbons 122 arranged on the diffractive optical element 120 together constitute a light emitting surface Se corresponding to the "light emitting unit" of the present invention.

[0092] Also, in the above embodiment, the laser beam L11 emitted from the first laser light source 111 corresponds to the "first light beam" of the present invention, and the laser beam L21 emitted from the second laser light source 112 corresponds to the "second light beam" of the present invention. And among the light emitting surfaces Se of the diffractive optical element 120, the region where the first light beam L11 is incident corresponds to the "first region" of the present invention, and the region where the second light beam L21 is incident corresponds to the "second region" of the present invention, respectively. Also, the "optically sparse object" in the above description has a concept corresponding to the "weakly reflecting object" in the present invention.

[0093] Note that the present invention is not limited to the above-described embodiments, and various modifications can be made other than those described above without departing from the spirit of the invention. For example, the above-described embodiment is one embodiment of the "object detection device" of the present invention, but its main feature lies in the optical scanning unit 10 which is one embodiment of the "optical scanning device". Therefore, the optical scanning unit 10 of the above-described embodiment can be implemented alone as the "optical scanning device" of the present invention. In this case, its application is not limited to the above-described object detection device. That is, it is possible to apply the "optical scanning device" of the present invention to various technical fields for detecting the presence, position, shape, surface state, etc. of an object by scanning a space with light, or as an illumination light source for imaging.

[0094] In the above-described embodiment, the two laser light beams incident on the diffractive optical element 120 are respectively emitted from different laser light sources. However, instead of this, for example, it may be configured to generate two laser light beams by branching from one laser light source.

[0095] As described above by exemplifying specific embodiments, in the optical scanning device according to the present invention, the control unit may be configured to execute, as a control mode for controlling the spatial light modulator, a mode in which a first light beam emitted from a first region and a second light beam emitted from a second region intersect in space, and a mode in which the first light beam and the second light beam do not intersect.

[0096] By emitting the two light beams in different directions respectively, it becomes possible to scan a wide range in the space evenly in a short time. Therefore, high-speed scanning is possible. On the other hand, when the two light beams are emitted so as to intersect, they are synthesized in the space and the light intensity is enhanced. Therefore, for example, even when irradiating far away, it is possible to suppress a decrease in the light amount.

[0097] For example, the spatial light modulator may have a one-dimensional optical diffraction grating that constitutes the light emitting unit. According to such a configuration, the emission direction of the light beam can be changed within the plane along the one-dimensional direction.

[0098] More specifically, this optical diffraction grating has, for example, a plurality of movable ribbons each provided with a reflecting surface for reflecting incident light and electrically driven independently of each other. Each of the movable ribbons is strip-shaped and extends in one direction, and the plurality of movable ribbons are arranged at regular intervals in an arrangement direction orthogonal to the one direction. The reflecting surfaces of each of the plurality of movable ribbons may be configured to integrally form the light emitting unit. Such an optical element is called a MEMS phased array, and by controlling the displacement amount of each movable ribbon, various blazed patterns can be realized, so that the emission direction of light can be controlled at high speed and precisely.

[0099] In this case, the first region and the second region where the light beams are incident can be set so that their positions are different from each other in the movable ribbon arrangement direction. In a MEMS phased array, by individually controlling the displacement amount of each movable ribbon, it is possible to realize a plurality of regions with different light emission directions within a single optical diffraction grating.

[0100] For example, a beam expander may be further provided that changes the emission directions of the first light beam and the second light beam from the spatial light modulator in one direction within the plane and expands the beam spots of the first light beam and the second light beam in the axial direction intersecting the one direction within the plane. According to such a configuration, two-dimensional scanning can be realized by scanning a beam having an elongated spot shape in a direction intersecting its longitudinal direction.

[0101] In addition, in an object detection device including such an optical scanning device, the control unit spatially differentiates the optical scanning range by the first light beam and the optical scanning range by the second light beam, and performs a wide-area mode in which optical scanning is performed for a relatively wide scanning range in the space, and a narrow-area mode in which optical scanning is performed for a scanning range narrower than the wide-area mode while spatially overlapping the first light beam and the second light beam. It may be configured to execute.

[0102] As described above, in the wide-area mode, since different ranges can be scanned for each light beam, it is possible to scan a wide scanning range in a short time. On the other hand, in the narrow-area mode, since the amount of light can be increased by overlapping the light beams, for example, even a distant object can be irradiated with a sufficient amount of light, improving the S / N ratio of the reflected light returned from the object and enhancing the detection accuracy of the object. can be improved.

[0103] In this case, the control unit may be configured to execute the narrow-area mode for a scanning range including the spatial range where the weak reflection object is detected when an object is detected in the space during the execution of the wide-area mode and the object is a weak reflection object whose reflected light intensity is smaller than a predetermined threshold value. By executing the narrow-area mode only for the region where there is a weak reflection object that cannot obtain a sufficient reflected light intensity, it is possible to improve the detection accuracy for such an object without causing an increase in processing time.

[0104] Also, for example, the control unit is preferably configured to control the spatial light modulator so that the first light beam and the second light beam intersect in the spatial region where the weak reflection object is detected in the narrow-area mode. In this way, if the detected weak reflection object is actually an optically dense object, the surface thereof will be irradiated with a light beam synthesized and enhanced in intensity, so that it is possible to detect a reflected light with sufficient intensity.

[0105] In this case, for example, the control unit may be configured to execute the narrow region mode when the distance to the weakly reflecting object is greater than a predetermined limit distance. As a result of the combination of the first light beam and the second light beam, the light intensity may exceed a safety reference value. In particular, when the distance from the optical scanning device to the intersection point of the light beams is small, the attenuation of each light beam is small, so the intensity of the combined light beam increases. On the other hand, in the combination at a far position, since each light beam has already been attenuated, the combined light intensity does not increase so much. From this, if the light beams are configured to intersect at a position farther than a certain limit distance, it is possible to avoid the combined light beam intensity causing safety problems.

[0106] Also, for example, the control unit may be configured to detect at least one of the size, distance, and shape of an object based on the detection result in the wide region mode and the detection result in the narrow region mode. When each object detected within the scanning range returns reflected light with a sufficient amount of light, it is possible to grasp the characteristics of each object only from the detection result in the wide region mode. On the other hand, when the detected objects include a weakly reflecting object, the characteristics of the object are unclear only from the detection result in the wide region mode. For such an object, by applying the detection result in the narrow region mode, it becomes possible to more reliably grasp the characteristics of the object.

[0107] Also, for example, it further includes a storage unit that stores information representing the relationship between the control signal given from the control unit to the spatial light modulator and the emission directions of the first light beam and the second light beam from the corresponding emission surface, and the control unit can control the spatial light modulator based on the information stored in the storage unit. That is, when it is desired to emit the first light beam and the second light beam in specific directions respectively, by calling the corresponding information and applying it to the control of the spatial light modulator, it becomes possible to immediately emit each light beam in the desired direction.

Industrial Applicability

[0108] This invention is suitable for various sensing technology fields, such as obstacle detection in the control of robots and vehicles, for example.

Explanation of Signs

[0109] 1 Object detection device 10 Optical scanning unit (optical scanning device) 11 Laser light source (light source unit) 12 Scanning unit 20 Light receiving unit (light receiving part) 30 Control unit (control part) 32 Storage unit 120 Diffractive optical element (spatial light modulator) 129 Diffusing optical element (beam expanding part) L11 First light beam L21 Second light beam Se Light emitting surface (light emitting part)

Claims

1. A spatial light modulator having a light emitting unit capable of electrically controlling the emission direction of incident light, A light source unit that emits a first light beam into a first region of the light emitting unit and emits a second light beam into a second region different from the first region of the light emitting unit, A control unit that controls the spatial light modulator to independently change the emission direction of light in the first region and the emission direction of light in the second region Comprising, A light scanning device that performs light scanning on a space by changing the emission direction of the first light beam emitted from the first region and the emission direction of the second light beam emitted from the second region over time.

2. As a control mode for controlling the spatial light modulator, the control unit A mode in which the first light beam emitted from the first region and the second light beam emitted from the second region intersect in space, A mode in which the first light beam and the second light beam do not intersect The light scanning device according to claim 1, which executes.

3. The spatial light modulator has a one-dimensional light diffraction grating that constitutes the light emitting unit, and the light scanning device according to claim 1 or 2.

4. The light diffraction grating has a plurality of movable ribbons provided with reflecting surfaces for reflecting the incident light, respectively, and electrically driven independently of each other, Each of the movable ribbons extends in a strip shape in one direction, and the plurality of movable ribbons are arranged at regular intervals in an arrangement direction orthogonal to the one direction, and the reflecting surfaces of each of the plurality of movable ribbons integrally constitute the light emitting unit. The light scanning device according to claim 3.

5. The first region and the second region are different from each other in the arrangement direction, and the light scanning device according to claim 4.

6. The control unit changes the emission directions of the first light beam and the second light beam from the spatial light modulator in a scanning direction within a plane, The light scanning device according to claim 1 or 2, further comprising a beam enlarging unit that enlarges the beam spots of the first light beam and the second light beam in an axial direction intersecting the scanning direction in the plane.

7. The light scanning device according to claim 1 or 2, A light receiving unit that receives reflected light generated when the first light beam and the second light beam are reflected by an object in space Comprising, The control unit controls the optical element to emit the first light beam and the second light beam toward space to perform optical scanning, and detects the object based on information on the reflected light received by the light receiving unit. An object detection device.

8. The control unit spatially differentiates the optical scanning range by the first light beam and the optical scanning range by the second light beam, and performs a wide-area mode in which the optical scanning is performed for a relatively wide scanning range in the space, a narrow-area mode in which the first light beam and the second light beam are spatially overlapped and the optical scanning is performed for a scanning range narrower than the wide-area mode The object detection device according to claim 7, which executes.

9. When the control unit detects the object in the space during execution of the wide-area mode, and the object is a weakly reflecting object whose intensity of the reflected light is smaller than a predetermined threshold value, the narrow-area mode is executed for the scanning range including the spatial range where the weakly reflecting object is detected. The object detection device according to claim 8.

10. In the narrow-area mode, the control unit controls the spatial light modulator so that the first light beam and the second light beam intersect in the spatial region where the weakly reflecting object is detected. The object detection device according to claim 7.

11. When the distance to the weakly reflecting object is greater than a predetermined limit distance, the control unit executes the narrow-area mode. The object detection device according to claim 10.

12. Based on the detection result in the wide-area mode and the detection result in the narrow-area mode, the control unit detects at least one of the size, distance, and shape of the object. The object detection device according to claim 8.

13. Further includes a storage unit that stores information representing the relationship between the control signal given from the control unit to the spatial light modulator and the emission directions of the first light beam and the second light beam from the emission surface corresponding thereto, The control unit controls the spatial light modulator based on the information stored in the storage unit. The object detection device according to claim 7.

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