Beam scanning system

Abstract

To provide a new configuration for maintaining a beam image emitted to an object to be linear perpendicular to a scan range.SOLUTION: A beam scan system comprises: a light source emitting a beam including a linear image along a first direction; an irradiation mirror reflecting the beam emitted from the light source in a second direction perpendicular to the first direction and irradiating the object with the beam; an image rotation element arranged on a path of the beam from the light source to the irradiation mirror, and rotating the image of the beam emitted from the light source about an optical axis of the beam; a light receiving sensor receiving the beam reflected from the object; first rotation means for rotating the irradiation mirror about an axis along the first direction; and second rotation means for rotating the image rotation element about an axis along the first direction in matching with the rotation of the irradiation mirror.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The technology disclosed in the present specification relates to a beam scanning system that scans a beam.

Background Art

[0002] Patent Document 1 discloses a system including a light source that emits a beam, a mirror that reflects the beam emitted from the light source toward an object, a motor that rotates the mirror, and a light receiving system that receives the beam reflected from the object. The system scans the beam over a range having a predetermined angle (hereinafter referred to as "scanning range"). The system is used for measuring the distance to the object.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0004] In recent years, there has been a demand for three-dimensionally measuring the distance to an object. For example, the distance to the object can be three-dimensionally measured by forming the image of the beam applied to the object into a line shape orthogonal to the scanning range.

[0005] The present specification discloses a novel configuration for maintaining the image of the beam applied to an object in a line shape orthogonal to the scanning range.

Means for Solving the Problems

[0006] The beam scanning system disclosed herein comprises: a light source that emits a beam having a linear image along a first direction; an illumination mirror that reflects the beam emitted from the light source in a second direction perpendicular to the first direction to illuminate an object with the beam; an image rotation element positioned on the path of the beam from the light source to the illumination mirror and rotating the image of the beam emitted from the light source around the optical axis of the beam; a light receiving sensor that receives the beam reflected from the object; a first rotation means for rotating the illumination mirror around an axis along the first direction; and a second rotation means for rotating the image rotation element around an axis along the first direction in conjunction with the rotation of the illumination mirror, wherein the beam emitted from the light source passes through the image rotation element rotated by the second rotation means and is reflected by the illumination mirror rotated by the first rotation means, so that the image of the beam illuminating the object is maintained in the linear shape perpendicular to the second direction.

[0007] The beam is scanned across the scanning range by rotating the illumination mirror using the first rotation means. The scanning range is parallel to the second direction. For example, a comparative example can be considered that does not include an image rotation element and a second rotation means. In this comparative example, a beam having a line-shaped image, emitted from a light source, is reflected by the illumination mirror and illuminated onto the object. However, depending on the rotation position of the illumination mirror, the image of the beam illuminated on the object may not be perpendicular to the scanning range, making it impossible to measure the distance to the object in three dimensions.

[0008] According to the above configuration, the image of the beam irradiated from the light source is rotated around the optical axis by the image rotation element. Furthermore, by rotating the image rotation element in accordance with the rotation of the irradiation mirror, the image of the beam irradiated onto the object is maintained in a linear shape perpendicular to the scanning range. By providing an image rotation element and a second rotation means, the image of the beam irradiated onto the object can be maintained in a linear shape perpendicular to the scanning range.

[0009] The image rotation element is a dove prism, and the first speed at which the illumination mirror rotates by the first rotation means may be twice the second speed at which the image rotation element rotates by the second rotation means.

[0010] The dove prism may be positioned such that the beam is incident along the long axis of the dove prism.

[0011] The beam scanning system further comprises a first housing supporting the light source, the light receiving sensor, the first rotating means, and the second rotating means, wherein the second rotating means for rotating the image rotation element is fixed to a first beam extending inside the first housing, the light source is fixed to a first wall of the first housing facing the beam, the first rotating means for rotating the illumination mirror is fixed to a second wall of the first housing located on the opposite side of the first wall across the beam, the rotation axis of the illumination mirror and the rotation axis of the image rotation element are aligned linearly along a first direction, and the beam irradiated from the light source may pass around the image rotation element and the first rotating means fixed to the first beam before entering the illumination mirror.

[0012] According to the above configuration, an image rotation element that rotates along the beam path from the light source to the illumination mirror can be realized by utilizing the first wall that fixes the light source and the first beam that fixes the second rotation means.

[0013] The dove prism may be positioned such that the beam is incident on it along a direction perpendicular to the longitudinal plane of the dove prism.

[0014] The beam scanning system further comprises a second housing supporting the light source, the light receiving sensor, the first rotating means, and the second rotating means, wherein the light source is fixed to a second beam extending inside the second housing, the first rotating means for rotating the illumination mirror is fixed to a third wall of the second housing facing the second beam, and the second rotating means for rotating the image rotation element is fixed to a fourth wall of the second housing located on the opposite side of the third wall across the second beam, the rotation axis of the illumination mirror and the rotation axis of the image rotation element are aligned linearly along the first direction, and the beam irradiated from the light source may pass around the image rotation element and the light source fixed to the second beam before entering the illumination mirror.

[0015] According to the above configuration, an image rotation element that rotates along the beam path from the light source to the illumination mirror can be realized by utilizing the second beam that fixes the light source and the fourth wall that fixes the second rotation means.

[0016] The image rotation element comprises a first mirror that reflects the beam irradiated from the light source in a third direction intersecting the first direction, a second mirror that reflects the beam reflected by the first mirror in a fourth direction intersecting the third direction, and a third mirror that reflects the beam reflected by the second mirror in the first direction, wherein the first speed at which the irradiation mirror rotates by the first rotation means may be twice the second speed at which the image rotation element rotates by the second rotation means.

[0017] The first rotating means may be a first actuator, and the second rotating means may be a second actuator different from the first actuator.

[0018] The beam scanning system further includes an adjustment unit that adjusts at least one of the rotation state of the first actuator and the rotation state of the second actuator when the output image output by the light receiving sensor satisfies predetermined conditions, and the predetermined conditions for the output image may be that the output image has a shape different from a line, or that the output image is another line image tilted at a specific angle from a predetermined line image.

[0019] When the rotation state of the illumination mirror and the rotation state of the image rotation element are maintained in their design state, the output image of the light receiving sensor is a predetermined line image. However, if the output image of the light receiving sensor is not a predetermined line image, that is, when the above predetermined conditions are met, it is possible that at least one of the rotation state of the illumination mirror and the rotation state of the image rotation element is deviating from the design state. According to the above configuration, when at least one of the rotation state of the illumination mirror and the rotation state of the image rotation element is deviating from the design state, at least one of the rotation state of the first actuator and the rotation state of the second actuator is adjusted. This makes it possible to maintain the image of the beam irradiated onto the object in the shape of a line perpendicular to the second direction.

[0020] The beam scanning system may further include a specific actuator, wherein the first rotating means is a first gear that transmits the torque of the specific actuator to the rotation axis of the illumination mirror, and the second rotating means is a second gear that transmits the torque of the specific actuator to the rotation axis of the image rotation element. [Brief explanation of the drawing]

[0021] [Figure 1] This is a conceptual diagram of the beam scanning system of the first embodiment. [Figure 2] This figure shows a perspective view of the image rotation element and a diagram illustrating the first mode of use. [Figure 3] This is a conceptual diagram of a comparative example beam scanning system. [Figure 4]This is a modified example of the image rotation element. [Figure 5] This is a conceptual diagram of the beam scanning system of the second embodiment. [Figure 6] This is a conceptual diagram of the beam scanning system of the third embodiment. [Figure 7] This is a perspective view of the image rotation element and a diagram showing the second usage mode. [Figure 8] This is a perspective view showing the structure of the beam. [Figure 9] This is a conceptual diagram of the beam scanning system of the fourth embodiment. [Figure 10] This is a conceptual diagram of the beam scanning system of the fifth embodiment. [Figure 11] This is a conceptual diagram of the beam scanning system of the sixth embodiment. [Figure 12] This is a specific case where an abnormality has occurred in the rotation state. [Figure 13] This is a conceptual diagram of the beam scanning system of the eighth embodiment. [Figure 14] This is a diagram showing the characteristics of the conical mirror. [Figure 15] This is a perspective view of the polygonal pyramidal mirror. [Figure 16] This is a conceptual diagram of the beam scanning system of the ninth embodiment. [Figure 17] This is a conceptual diagram of the beam scanning system of the tenth embodiment. [Figure 18] This is a conceptual diagram of the beam scanning system of the eleventh embodiment. [Figure 19] This is a conceptual diagram of the beam scanning system of the twelfth embodiment. [Figure 20] This is a conceptual diagram of the beam scanning system of the thirteenth embodiment. [Figure 21] This is a conceptual diagram of the beam scanning system of the fourteenth embodiment. [Figure 22] This is a specific case where an abnormality has occurred in the rotation state. [Figure 23] This is a specific case where an abnormality has occurred in the rotation state. [Figure 24] This is a conceptual diagram of the beam scanning system of the sixteenth embodiment. [Modes for carrying out the invention]

[0022] (First embodiment) (Configuration of beam scanning system 1; Figures 1 and 2) Beam scanning system 1 is a system included in 3DLiDAR. 3DLiDAR, short for light detection and ranging, is a device that measures the distance to surrounding objects in three dimensions. A laser emitted from the 3DLiDAR reaches surrounding objects (e.g., people). The reflected light from the laser that reaches the object is received by the 3DLiDAR. The 3DLiDAR calculates the distance between the 3DLiDAR and the object by using the time from when the laser is emitted onto the object to when the reflected light of the laser is received.

[0023] The beam scanning system 1 comprises a light source 20, a half mirror 22, a light receiving sensor 24, an image rotation element 26, an actuator 28, an illumination mirror 30, an actuator 32, and a control device 34 for controlling actuators 28 and 32. The dashed-dotted arrows in Figure 1 indicate the beam path. The dashed-dotted arrows also indicate the optical axis of the beam. An XYZ coordinate system is also defined in the figure.

[0024] The light source 20 emits a beam in the negative Y-axis direction. The beam emitted by the light source 20 has an image B0. Image B0 is linear. In other words, image B0 is an elongated rectangle with a predetermined width.

[0025] The light source 20, half mirror 22, image rotation element 26, and illumination mirror 30 are arranged along the Y-axis. The half mirror 22 is tilted at 45 degrees with respect to the Y-axis. The beam emitted from the light source 20 passes through the half mirror 22 and is incident on the image rotation element 26.

[0026] The image rotation element 26 rotates the image B0 of the beam irradiated by the light source 20 around the optical axis of the beam. The image rotation element 26 is, for example, a dove prism as shown in Figure 2.

[0027] The dove prism has the shape of a rectangular prism. As shown in Figure 2, the base 40 of the prism is a polygon having two parallel sides 42a and 42b and two hypotenuses 44a and 44b. The base 40 is, for example, a trapezoid. The dove prism has a longitudinal shape along an axis (hereinafter referred to as the "major axis 46") parallel to the sides 42a and 42b.

[0028] As shown in Figure 2, the beam incident on the dove prism along the major axis 46 is refracted by the inclined plane 48a having the hypotenuse 44a and reflected inward by the side having the longitudinal side 42b (hereinafter referred to as the "longitudinal plane 50"). The beam reflected by the longitudinal plane 50 is refracted by the inclined plane 48b having the hypotenuse 44b and propagates out of the dove prism. Note that in Figure 1 and other figures (for example, Figures 5 and 13), the dove prism is depicted in a simplified manner, and in these figures, the optical axis of the beam passing through the image rotation element 26 is simplified and depicted as a straight line.

[0029] As shown in Figure 2, a beam incident on the dove prism along the major axis 46 propagates out of the dove prism along the major axis 46. As shown in Figure 2, the beam image B12 is inverted around the optical axis of the beam as it passes through the dove prism. Here, if the dove prism is rotated around the major axis 46, the image B12 also rotates. The rotation angle of the image B12 is twice the rotation angle θ of the dove prism.

[0030] In this embodiment, the long axis 46 of the image rotation element 26 coincides with the Y-axis direction. The beam propagating outward from the image rotation element 26 is incident on the irradiation mirror 30. The irradiation mirror 30 is tilted at 45 degrees with respect to the Y-axis. Therefore, the laser incident on the irradiation mirror 30 is reflected in the X-axis direction and incident on an object located outside the 3DLiDAR.

[0031] The beam incident on the object is reflected by the object. The reflected light from the object is reflected by the illumination mirror 30, passes through the image rotation element 26, and is reflected by the half mirror 22. The reflected light reflected by the half mirror 22 is incident on the light receiving sensor 24. The light receiving sensor 24 is an image sensor, such as a SPAD (Single Photon Avalanche Diode) sensor.

[0032] Actuator 28 rotates the image rotation element 26 around an axis along the Y-axis. For example, the torque of actuator 28 is transmitted to the image rotation element 26 via a power transmission mechanism such as a gear or belt. Actuator 32 rotates the illumination mirror 30 around an axis along the Y-axis. The shaft of actuator 32 is connected to the illumination mirror 30. In a modified example, the torque of actuator 32 may be transmitted to the image rotation element 26 via a power transmission mechanism. The control device 34 controls actuators 28 and 32 so that the speed at which the illumination mirror 30 rotates due to actuator 32 is twice the angular velocity ω at which the image rotation element 26 rotates due to actuator 28.

[0033] The irradiation mirror 30 is rotated by the actuator 32, causing the beam to be scanned over a range having a predetermined angle (hereinafter referred to as the "scanning range"). The scanning range is parallel to the X-axis direction, and the predetermined angle is, for example, 180 degrees or 360 degrees. Here, by making the image of the beam irradiated onto the object a line perpendicular to the scanning range, the distance to the object can be measured in three dimensions. In this embodiment, a beam having a line-shaped image B0 is generated by the light source 20.

[0034] (Effects of this embodiment) Figure 3 shows a comparative example without the image rotation element 26 and actuator 28. In this comparative example as well, the beam is scanned across the scanning range by the rotation of the illumination mirror 30. For example, at a rotation position where the direction in which the illumination mirror 30 tilts (hereinafter referred to as the "tilting direction") coincides with the direction in which the line of image B0 extends, the image B6 of the beam irradiated onto the object is perpendicular to the scanning range. However, at a rotation position where the tilt direction of the illumination mirror 30 intersects with the direction in which the line of image B0 extends, the images B4, B5, and B7 of the beam irradiated onto the object are not perpendicular to the scanning range. In other words, the image of the beam irradiated onto the object rotates around the optical axis, and the direction in which the image extends is not maintained to be perpendicular to the scanning range. In this state, it is not possible to achieve three-dimensional measurement of the distance to the object.

[0035] In this embodiment, the image B0 of the beam irradiated from the light source 20 is rotated around the optical axis by the image rotation element 26. Furthermore, the irradiation mirror 30 is rotated by the actuator 32, and the image rotation element 26 is also rotated by the actuator 28. Here, by setting the angular velocity of the irradiation mirror 30 to twice the angular velocity ω of the image rotation element 26, the direction in which the line of the beam image incident from the image rotation element 26 extends coincides with the tilt direction of the irradiation mirror 30, regardless of the rotation position of the irradiation mirror 30. As a result, as shown in images B1 to B3 in Figure 1, the image of the beam irradiated onto the object is maintained in a line shape perpendicular to the scanning range. By providing the image rotation element 26 and actuator 28, the image of the beam irradiated onto the object can be maintained in a line shape perpendicular to the scanning range.

[0036] In this embodiment, reflected light from the object also passes through the image rotation element 26. Therefore, the direction in which the line of image B9 incident on the light receiving sensor 24 extends is constant. In this embodiment, a one-dimensional image sensor is used as the light receiving sensor 24. In a modified example, a two-dimensional image sensor may be used as the light receiving sensor 24.

[0037] (Modified image rotation element 26; Figure 4) Similar properties to a dove prism can also be achieved with a combination of three mirrors. The image rotation element 26a in Figure 4 comprises a first mirror 52, a second mirror 54, and a third mirror 56. The first mirror 52 reflects the beam irradiated from the light source 20 in a first intersecting direction 52a that intersects with the Y-axis direction. The second mirror 54 reflects the beam reflected by the first mirror 52 in a second intersecting direction 54a that intersects with the first intersecting direction 52a. The third mirror 56 reflects the beam reflected by the second mirror 54 in the Y-axis direction.

[0038] Even if the image rotation element 26a shown in Figure 4 is used instead of the image rotation element 26 of the first embodiment, the image of the beam irradiated onto the object can be maintained in a line shape perpendicular to the scanning range. In this modified example as well, the angular velocity of the irradiation mirror 30 is twice the angular velocity ω of the image rotation element 26.

[0039] (Correspondence) The beam scanning system 1, light source 20, and illumination mirror 30 are examples of the "beam scanning system," "light source," and "illumination mirror," respectively. The image rotation element 26 and light receiving sensor 24 are examples of the "image rotation element" and "light receiving sensor," respectively. The actuator 32 and actuator 28 are examples of the "first rotation means (and first actuator)" and "second rotation means (and second actuator)," respectively. The Y-axis direction and X-axis direction are examples of the "first direction" and "second direction," respectively. The long axis 46 is an example of the "long axis." The first mirror 52, second mirror 54, and third mirror 56 are examples of the "first mirror," "second mirror," and "third mirror," respectively. The first intersecting direction 52a and second intersecting direction 54a are examples of the "third direction" and "fourth direction," respectively.

[0040] (Second example) (Configuration of beam scanning system 2; Figure 3) The beam scanning system 2 of this embodiment is the same as the first embodiment, except that a reflective mirror 122 is provided instead of a half mirror 22, and the position of the light receiving sensor 24 is different. The reflective mirror 122 is positioned at a location different from the beam path from the light source 20 to the illumination mirror 30. For example, the reflective mirror 122 is positioned on the opposite side of the illumination mirror 30 from the light source 20.

[0041] In this embodiment, the light receiving sensor 24 is positioned on the path of the reflected light reflected by the reflective mirror 122.

[0042] In this embodiment, the beam path from the light source 20 to the object is the same as in the first embodiment, except that it does not pass through the half mirror 22. On the other hand, in this embodiment, the path of the reflected light is different from that of the first embodiment. As shown in Figure 2, the reflected light is reflected by the reflective mirror 122 and incident on the light receiving sensor 24.

[0043] In this embodiment, reflected light from the object does not pass through the image rotation element 26. Therefore, the image of the reflected light incident on the light receiving sensor 24 rotates around the optical axis of the reflected light. Here, the direction in which the line of the image of the reflected light incident on the light receiving sensor 24 extends is uniquely determined according to the rotation angle of the irradiation mirror 30. In this embodiment, a two-dimensional image sensor is used as the light receiving sensor 24. The two-dimensional image sensor comprises a plurality of elements (e.g., photodiodes) arranged in a matrix. The beam scanning system 2 of this embodiment determines, based on the rotation angle of the irradiation mirror 30, the element that should detect reflected light from among the plurality of elements constituting the two-dimensional image sensor.

[0044] (Third embodiment) (Configuration of beam scanning system 3; Figures 6, 7, and 8) In the beam scanning system 3 of this embodiment, the light source 20, light receiving sensor 24, actuator 28, and actuator 32 are supported by the housing 202. Furthermore, in this embodiment, the method of using the image rotation element 26, which is a dove prism, differs from that of the first and second embodiments.

[0045] In this embodiment, as shown in Figure 7, the beam enters the dove prism from a point on the longitudinal surface 50 facing the inclined surface 48a, along a direction perpendicular to the longitudinal surface 50. The beam that enters the dove prism along a direction perpendicular to the longitudinal surface 50 is reflected on the inside of the inclined surface 48a and enters the inclined surface 48b. The beam that enters the inclined surface 48b is reflected on the inside of the inclined surface 48b and propagates from the longitudinal surface 50 out of the dove prism.

[0046] As shown in Figure 7, even when the beam is incident on the dove prism along a direction perpendicular to the longitudinal plane 50, the image B12 of the beam that has passed through the dove prism is inverted around the optical axis of the beam. Here, if the dove prism is rotated around the optical axis of the beam incident on the longitudinal plane 50 facing the inclined surface 48a, the image B12 also rotates. The rotation angle of the image B12 is twice the rotation angle θ of the dove prism.

[0047] As shown in Figure 6, the actuator 28 is fixed to the inside of the upper wall 202a of the housing 202. The shaft of the actuator 28 is connected to the image rotation element 26. The image rotation element 26 is positioned such that its rotation axis passes through the point where it faces the inclined surface 48a of the longitudinal surface 50.

[0048] The light source 20 and the light receiving sensor 24 are fixed to a beam 204 that spans the inside of the housing 202. The upper surface of the beam 204 faces the upper wall 202a of the housing 202. The light source 20 is exposed on the upper surface of the beam 204 and faces the image rotation element 26. The optical axis of the laser emitted from the light source 20 coincides with the rotation axis of the image rotation element 26.

[0049] Furthermore, the underside of the beam 204 faces the lower wall 202b of the housing 202. The light receiving sensor 24 is exposed on the underside of the beam 204.

[0050] An actuator 32 is fixed to the inside of the lower wall 202b. The shaft of the actuator 32 is connected to the illumination mirror 30. The rotation axis of the illumination mirror 30 and the rotation axis of the image rotation element 26 are aligned in a straight line along the Y-axis. The illumination mirror 30 faces the light receiving sensor 24 which is exposed from the lower surface of the beam 204.

[0051] In this embodiment as well, the control device 34 controls actuators 28 and 32 such that the speed at which the illumination mirror 30 rotates due to actuator 32 is twice the angular velocity ω at which the image rotation element 26 rotates due to actuator 28.

[0052] As shown in Figure 8, the beam 204 is placed inside a circular hole 208 formed in the support plate 206. The light source 20 is positioned in the center of the circular hole 208. That is, a semicircular hole exists around the light source 20. By fixing the support plate 206 inside the housing 202, the beam 204 is placed inside the housing 202.

[0053] As shown in Figure 6, the light source 20 emits a laser in the positive Y-axis direction. The laser emitted from the light source 20 is reflected within the image rotation element 26 and propagates outward in the negative Y-axis direction from the image rotation element 26. The optical axis of the laser propagating outward from the image rotation element 26 is offset from the optical axis of the laser emitted from the light source 20. The laser propagating outward from the image rotation element 26 passes through the holes 208 around the light source 20 and enters the irradiation mirror 30. As a result, the laser is irradiated onto the object.

[0054] Furthermore, the reflected light from the object is reflected by the illumination mirror 30 and incident on the light receiving sensor 24. In this embodiment, the reflected light does not pass through the image rotation element 26. In this embodiment, as in the second embodiment, a two-dimensional image sensor is used as the light receiving sensor 24.

[0055] (Effects of this embodiment) The beam scanning system 3 of this embodiment also includes an image rotation element 26 and an actuator 28, which allows the image of the beam irradiating the object to be maintained in a linear shape perpendicular to the scanning range. In particular, in this embodiment, the actuator 28 is fixed to the upper wall 202a of the housing 202. Therefore, it is not necessary to place a mechanism for rotating the image rotation element 26 in the hollow of the housing 202.

[0056] As described above, a semicircular hole exists around the light source 20. Therefore, in this embodiment, the scanning range is 180 degrees or less. For example, if the beam 204 is made of a transparent material or a mesh-like material, the laser can pass through the inside of the beam 204. In this modified example, the scanning range can be extended up to 360 degrees.

[0057] (Correspondence) The beam scanning system 3 and the longitudinal surface 50 are examples of the "beam scanning system" and "longitudinal surface," respectively. The housing 202, beam 204, lower wall 202b, and upper wall 202a are examples of the "second housing," "second beam," "third wall," and "fourth wall," respectively.

[0058] (Fourth embodiment) (Configuration of beam scanning system 4; Figure 9) The beam scanning system 4 of this embodiment is the same as the beam scanning system 3 of the third embodiment, except that the path of the reflected light is different and the arrangement of the light receiving sensor 24 is different.

[0059] In this embodiment, the light receiving sensor 24 is exposed on the upper surface of the beam 204, similar to the light source 20. The light receiving sensor 24 faces the image rotation element 26. For example, the light source 20 and the light receiving sensor 24 are aligned parallel to each other along the X-axis.

[0060] In this embodiment, the laser path from the light source 20 to the object is the same as in the third embodiment. However, in this embodiment, the reflected light from the object is reflected by the irradiation mirror 30, passes through the hole 208 in the beam 204, and enters the image rotation element 26. The reflected light that enters the image rotation element 26 is reflected in the reverse order of the order shown in Figure 7 and propagates outward from the image rotation element 26 in the negative Y-axis direction. The laser that propagates outward from the image rotation element 26 enters the light receiving sensor 24.

[0061] In this embodiment, reflected light from the object passes through the image rotation element 26. Therefore, the direction in which the image line incident on the light receiving sensor 24 extends is constant. In this embodiment, either a one-dimensional image sensor or a two-dimensional image sensor can be used as the light receiving sensor 24. The same effects as in the third embodiment can be obtained in this embodiment as well.

[0062] (Fifth example) (Configuration of beam scanning system 5; Figure 10) In the beam scanning system 5 of this embodiment, the light source 20, light receiving sensor 24, actuator 28, and actuator 32 are supported by the housing 212. The image rotation element 26 of this embodiment is a prism that has an image rotation effect equivalent to that of a dove prism, and its shape is similar to that of the dove prism in Figure 2, having a longitudinal surface 50, a transverse surface 51 facing the longitudinal surface 50, and two inclined surfaces 48a and 48b. The method of using the image rotation element 26 of this embodiment is the same as in the first embodiment (see Figure 2).

[0063] As shown in Figure 10, multiple columns 212c extend from the upper wall 212a of the housing 212 to the inside of the housing 212. An upper beam 213 and a lower beam 214 are connected to the multiple columns 212c. The light source 20 is fixed to the upper beam 213 and is exposed from the lower surface of the upper beam 213. In other words, the light source 20 is fixed to the upper wall 212a via the upper beam 213 and the multiple columns 212c. In a modified example, the light source 20 may be directly fixed to the upper wall 212a.

[0064] Furthermore, an actuator 28 is fixed to the upper surface of the lower beam 214. The shaft of the actuator 28 is connected to the image rotation element 26. The rotation axis of the actuator 28 coincides with the optical axis of the laser emitted from the light source 20. The lower beam 214 is placed within a circular hole 208 formed in the support plate 206, as in Figure 8. That is, a semicircular hole exists around the actuator 28.

[0065] As shown in Figure 10, the image rotation element 26 is positioned such that its major axis 46 coincides with the Y-axis direction. In particular, the light source 20, whose short side 51 facing the longitudinal side 50 is located outward in the radial direction around the optical axis of the laser, and whose longitudinal side 50 is located inward in the same radial direction, is positioned biased toward the side where the longitudinal side 50 is located and faces the inclined surface 48a. In this case, as shown in Figure 10, the laser emitted from the light source 20 propagates outward from the inclined surface 48b at a position shifted in the X-axis direction from the position where it was incident on the inclined surface 48a. The inclined surface 48b faces the semicircular hole around the actuator 28. As a result, the laser passes through the hole around the actuator 28. Note that in the image rotation element 26 of this embodiment, a part of the inclined surface 48b is cut off.

[0066] The light receiving sensor 24 is exposed on the lower surface of the beam 214. The actuator 32 is fixed to the inside of the lower wall 212b of the housing 212. The positional relationship between the light receiving sensor 24, the actuator 32, and the illumination mirror 30 is the same as in the third embodiment (see Figure 6). In this embodiment as well, the rotation axis of the illumination mirror 30 and the rotation axis of the image rotation element 26 are aligned in a straight line along the Y-axis direction.

[0067] (Effects of this embodiment) The beam scanning system 5 of this embodiment also includes an image rotation element 26 and an actuator 28, which allows the image of the beam irradiated onto the object to be maintained in a linear shape perpendicular to the scanning range.

[0068] (Correspondence) The enclosure 212, beam 214, upper wall 212a, and lower wall 212b are examples of the "first enclosure," "first beam," "first wall," and "second wall," respectively.

[0069] (Sixth embodiment) (Configuration of beam scanning system 6; Figure 11) The beam scanning system 6 in this embodiment is the same as in the fifth embodiment, except that the orientation of the image rotation element 26 is different.

[0070] As shown in Figure 11, the longitudinal surface 50 is located outward in the radial direction around the optical axis of the laser, and the transverse surface 51 is located inward in the same radial direction. Here, the light source 20 is biased toward the side where the transverse surface 51 is located and faces the inclined surface 48b. In this case, as shown in Figure 11, the laser irradiated from the light source 20 propagates outward from the inclined surface 48a at a position shifted in the X-axis direction from the position where it was incident on the inclined surface 48b. The inclined surface 48a faces the semicircular hole around the actuator 28. As a result, the laser passes through the hole around the actuator 28. This embodiment can also obtain the same effects as the fifth embodiment.

[0071] (Seventh Example) (Adjusting the rotation state; Figure 12) This embodiment is the same as the first embodiment, except that the control device 34 performs a process to adjust the rotation state of either the actuator 28 or 32.

[0072] The rotation angle of the laser image is determined by the relative angle of the image rotation element 26 with respect to the light source 20. Furthermore, in order to maintain the laser image emitted from the 3DLiDAR in a line perpendicular to the scanning range, the angular velocity of the irradiation mirror 30 is maintained at twice the angular velocity ω of the image rotation element 26. Here, the above relative angle and angular velocity together are referred to as the "rotation state."

[0073] If any abnormality occurs in the mechanism that rotates the irradiation mirror 30 and the image rotation element 26, the rotation state may change from the state specified in the design. If an abnormality occurs in the rotation state, it may not be possible to maintain the image of the laser emitted from the 3DLiDAR in a line perpendicular to the scanning range.

[0074] In this embodiment, the control device 34 analyzes the output image output by the light receiving sensor 24 to detect when the rotation state has changed from the design state. Case C1 in Figure 12 is a case in which an abnormality occurs in the ratio of the angular velocity of the illumination mirror 30 to the angular velocity of the image rotation element 26. When the ratio of the angular velocity of the illumination mirror 30 to the angular velocity of the image rotation element 26 is 2:1, which is normal, the output image is a line-shaped image. However, when an abnormality occurs in this ratio, the output image changes to a fan-shaped image in which multiple line-shaped images overlap. When the control device 34 detects that the output image of the light receiving sensor 24 is a fan-shaped image, it adjusts the angular velocity of at least one of the actuators 28 and 32 so that the output image of the light receiving sensor 24 returns to a line-shaped image.

[0075] Furthermore, Case C2 in Figure 12 is a case in which an abnormality occurs in the relative angle of the image rotation element 26 with respect to the light source 20. When the relative angle is normal and matches the relative angle at the time of design, the output image is a line-shaped image IM1 extending in a certain direction. However, when an abnormality occurs in the relative angle, the output image changes from image IM1 to a line-shaped image IM2 tilted at a specific angle α. When the control device 34 detects that the output image of the light receiving sensor 24 is image IM2, it adjusts the rotation angle of the actuator 28 to adjust the relative angle so that the output image of the light receiving sensor 24 returns to image IM1. Here, the control device 34 analyzes the output image and calculates the angle α. The control device 34 uses the calculated angle α to determine the direction in which to adjust the rotation angle of the actuator 28.

[0076] According to the configuration of this embodiment, the control device 34 adjusts at least one of the rotational states of actuator 28 and actuator 32 when an abnormality occurs in the rotational state of the irradiation mirror 30 and the image rotation element 26. This resolves the abnormality in the rotational state of the irradiation mirror 30 and the image rotation element 26. Even if an abnormality occurs in the rotational state of the irradiation mirror 30 and the image rotation element 26, the image of the laser emitted from the 3DLiDAR can be maintained in a line shape perpendicular to the scanning range.

[0077] (Correspondence) The control device 34 is an example of an "adjustment unit". The fan-shaped image of case C1 and the image IM2 of case C2 are examples of "different shapes" and "other line images," respectively.

[0078] (Eighth example) (Configuration of beam scanning system 8; Figure 13) The beam scanning system 8 of this embodiment includes a fixed conical mirror 330 instead of the irradiation mirror 30 and actuator 32. The positional relationship between the light source 20, half mirror 22, light receiving sensor 24, image rotation element 26, and actuator 28 is the same as in the first embodiment. The image rotation element 26 in this embodiment may be a dove prism as shown in Figure 2, or a modified example as shown in Figure 4.

[0079] The conical mirror 330 is a cone-shaped mirror with height in the Y-axis direction. The side surface of the conical mirror 330 is a reflective surface 330a that reflects the laser. The reflective surface 330a is a surface inclined at 45 degrees from the Y-axis direction. In other words, the reflective surface 330a is the side surface of a body of revolution obtained by rotating a right-angled isosceles triangle, which has sides inclined at 45 degrees from the Y-axis direction, around an axis along the Y-axis direction. In a modified example, the beam scanning system 8 may be equipped with a frustoconical mirror with height in the Y-axis direction instead of the conical mirror 330. Generally speaking, the beam scanning system 8 can be equipped with a mirror in the shape of a body of revolution obtained by rotating a planar figure, which has sides inclined at 45 degrees from the Y-axis direction, around an axis along the Y-axis direction.

[0080] The conical mirror 330 faces the image rotation element 26. The reflective surface 330a exists continuously around an axis along the Y-axis. The image rotation element 26 is rotated around an axis along the Y-axis by the actuator 28. By aligning the axis of rotation of the image rotation element 26 with the axis of the conical mirror 330, the direction in which the image line of the beam incident on the reflective surface 330a extends coincides with the inclination direction of the reflective surface 330a, regardless of the position where the beam is incident on the reflective surface 330a. As a result, the image of the beam reflected by the reflective surface 330a is maintained as a line perpendicular to the scanning range.

[0081] As shown in Figure 13, the optical axis of the image B0 of the beam incident on the conical mirror 330 is located on the reflective surface 330a. The position where image B0 is projected onto the reflective surface 330a is offset radially outward with respect to the axis of the conical mirror 330. For example, by adjusting the incident position of the beam on the image rotation element 26, as in Figure 10, the incident position of image B0 can be offset radially outward with respect to the axis of the conical mirror 330.

[0082] (Effects of this embodiment) In this embodiment, the image B0 of the beam irradiated from the light source 20 is rotated around the optical axis by the image rotation element 26. Furthermore, by rotating the image rotation element 26 to match the shape of the reflective surface 330a, the image of the beam reflected by the reflective surface 330a is maintained in a line perpendicular to the scanning range, regardless of the position where the beam enters the reflective surface 330a. The image rotation element 26, actuator 28, and fixed conical mirror 330 make it possible to maintain the images B1 to B3 of the beam irradiated onto the object in a line perpendicular to the scanning range.

[0083] Furthermore, in this embodiment, a fixed conical mirror 330 is used. The rotation mechanism can be simplified compared to the first embodiment, in which not only the image rotation element 26 but also the illumination mirror 30 is rotated. In addition, the control device 34 only needs to control the actuator 28. The program within the control device 34 can also be simplified.

[0084] Furthermore, in this embodiment, the reflected light from the object is reflected by the conical mirror 330 and passes through the image rotation element 26. Therefore, the direction in which the line of image B9 incident on the light receiving sensor 24 extends is constant. In this embodiment, either a one-dimensional image sensor or a two-dimensional image sensor can be used as the light receiving sensor 24.

[0085] (Characteristics of the conical mirror 330; Figure 14) In a cone, the radius of curvature increases from the apex to the base. Here, the image B0 is projected onto the reflective surface 330a along the line segment from the apex P0 to a point P1 at the base. As a result, the image B10 of the beam reflected by the reflective surface 330a expands on the side closer to the apex P0 than on the side closer to the point P1 at the base. The shape of the image B10 is a trapezoid or triangle that widens from the side of the apex P0 to the side of the point P1 at the base. In this embodiment, although the image of the beam irradiated onto the object can be maintained in a manner orthogonal to the scanning range, the image of the beam irradiated onto the object may be deformed into a shape different from a line.

[0086] (Modified version of the 8th embodiment) (Configuration of the polygonal pyramidal mirror 340; Figure 15) This modification uses a polygonal pyramidal mirror 340 instead of a conical mirror 330. The polygonal pyramidal mirror 340 is a polygonal pyramidal mirror with height in the Y-axis direction. The sides of the polygonal pyramid are flat. Unlike a cone, the radius of curvature of a polygonal pyramid does not change from the top to the bottom. In this modification, it is possible to suppress the change in shape of the beam image projected onto the object from a linear shape.

[0087] (9th example) (Configuration of beam scanning system 9; Figure 16) The beam scanning system 9 in this embodiment is the same as in the eighth embodiment, except that an image conversion lens 350 is added.

[0088] The image conversion lens 350 is a lens that converts a linear image B0 into a trapezoidal image B20. The image conversion lens 350 is positioned on the beam path from the image rotation element 26 to the conical mirror 330.

[0089] As explained in Figure 14, the image B10 of the beam reflected by the reflective surface 330a of the conical mirror 330 is trapezoidal. In this embodiment, the beam incident on the reflective surface 330a passes through the image conversion lens 350 before it enters the reflective surface 330a. The shape of the image B20 of the beam incident on the reflective surface 330a is pre-deformed into a trapezoid or triangle that is vertically inverted from the image B10. The image of the laser reflected by the reflective surface 330a is deformed by the reflective surface 330a from a vertically inverted trapezoid or triangle into a linear shape. As a result, it is possible to suppress the change in the shape of the beam image irradiated onto the object from a linear shape.

[0090] (Tenth example) (Configuration of beam scanning system 10; Figure 17) The beam scanning system 10 in this embodiment is the same as in the eighth embodiment, except that an inversion prism 360 is added.

[0091] The inversion prism 360 is a prism with a shape that is the inverted cone shape of the conical mirror 330. The inversion prism 360 is positioned on the beam path from the image rotation element 26 to the conical mirror 330.

[0092] The inversion prism 360 also has the characteristic of deforming the shape of the beam's image from a linear shape to a trapezoid or triangle that is vertically inverted from the image B10. By having the beam pass through the inversion prism 360 beforehand, the effect of the radius of curvature of the conical mirror 330 can be canceled. In this modified example as well, it is possible to suppress the change in the shape of the beam's image irradiated onto the object from a linear shape.

[0093] (11th example) (Configuration of beam scanning system 10; Figure 18) The beam scanning system 11 of this embodiment is the same as that of the eighth embodiment, except that it includes a frustum mirror 370 and a frustum prism 372 instead of a conical mirror 330.

[0094] The frustum-shaped mirror 370 is a frustum-shaped mirror with height in the Y-axis direction. The frustum-shaped prism 372 is a frustum-shaped prism formed to surround the side surface of the frustum-shaped mirror 370. The side surfaces of the frustum-shaped mirror 370 and the frustum-shaped prism 372 are parallel.

[0095] The frustum prism 372 has the characteristic of canceling the effect of the radius of curvature of the frustum mirror 370. The laser propagating outward from the image rotation element 26 passes through the upper surface 372a of the frustum prism 372 and is incident on the frustum mirror 370. In the path from the upper surface 372a to the frustum mirror 370, the beam image is not deformed. The shape of the beam image reflected by the frustum mirror 370 is deformed into a trapezoid or triangle, as shown in Figure 14. However, as the beam passes from the side of the frustum mirror 370 to the side of the frustum prism 372, the deformation into a trapezoid or triangle is canceled, and the beam image returns to a linear shape. In this modified example as well, it is possible to suppress the change in the shape of the beam image irradiated onto the object from a linear shape.

[0096] (Twelfth Example) (Configuration of beam scanning system 12; Figure 19)

[0097] In the eighth embodiment, the optical axis of the image B0 of the beam incident on the conical mirror 330 is located on the reflective surface 330a. In contrast, in this embodiment, the optical axis of the image B0 of the beam incident on the conical mirror 330 passes through the apex of the conical mirror 330. That is, the shape of the reflective surface 330a of the conical mirror 330 is a cone that is symmetrical with respect to the optical axis of the image B0 of the beam incident on the conical mirror 330 as its central axis. As a result, the beam incident on the reflective surface 330a is divided into two directions, the positive X-axis direction and the negative X-axis direction, with respect to the symmetrical central axis of the conical mirror 330. The image B30 of the beam divided in the positive X-axis direction and the image B32 of the beam divided in the negative X-axis direction each have a line shape that is half the size of image B0. It is possible to simultaneously irradiate in two directions with beams that have line-shaped images perpendicular to the scanning range. Compared to the eighth embodiment, the angle at which the image rotation element 26 is rotated can be halved.

[0098] (13th example) (Configuration of beam scanning system 13; Figure 20) The beam scanning system 13 of this embodiment is the same as the beam scanning system 4 of the fourth embodiment, but uses a conical mirror 330 instead of the irradiation mirror 30 and actuator 32. The conical mirror 330 is fixed to the lower wall 202b of the housing 202. In this embodiment, the rotation mechanism including the actuator 32 does not need to be provided on the lower wall 202b. This modified example allows for a simpler rotation mechanism than the eighth embodiment.

[0099] (14th example) (Configuration of beam scanning system 14; Figure 21) The beam scanning system 14 of this embodiment includes a light source 420, an actuator 422, a rotating unit 430, an image rotation element 440, an actuator 442, a light receiving sensor 444, and a control device 424 that controls actuators 422 and 442.

[0100] The rotating unit 430 comprises a mirror 432, a cylindrical lens 434, and a reflective mirror 436. The mirror 432 and the cylindrical lens 434 are housed within the rotating unit 430. The reflective mirror 436 is exposed on the surface of the rotating unit 430.

[0101] The light source 420 emits a beam with a point-like image in the Y-axis direction. The laser emitted from the light source 420 propagates inside the rotating unit 430 and is incident on the mirror 432. The mirror 432 is tilted at 45 degrees with respect to the Y-axis direction. The laser incident on the mirror 432 is reflected in the X-axis direction and passes through the cylindrical lens 434. As a result, the image of the beam is transformed from a point-like image to a line-like image B40. The beam with image B40 is incident on an object located outside the 3DLiDAR along the X-axis direction.

[0102] Furthermore, the actuator 422 rotates the rotating unit 430 around an axis along the Y-axis. As the rotating unit 430 rotates due to the actuator 422, the beam having image B40 is scanned over the scanning range. The actuator 422 has a hollow structure, and the laser passes through the hollow structure and is incident on the mirror 432. The hollow structure is, for example, a hollow shaft.

[0103] The beam incident on the object is reflected by the object. The reflected light from the object is incident on the reflective mirror 436 of the rotating unit 430. The reflective mirror 436 is tilted at 45 degrees with respect to the Y-axis. The reflected light reflected by the reflective mirror 436 propagates along the Y-axis.

[0104] The reflective mirror 436 faces the image rotation element 440 along the Y-axis. The reflected light reflected by the reflective mirror 436 is incident on the image rotation element 440.

[0105] The image rotation element 440 faces the light receiving sensor 444 along the Y-axis. The beam propagating outward from the image rotation element 440 is incident on the light receiving sensor 444.

[0106] The image rotation element 440 is a dove prism, with its major axis 46 coinciding with the Y-axis direction. The actuator 442 rotates the image rotation element 440 around an axis along the Y-axis direction. The image rotation element 440 may also be the modified form shown in Figure 4.

[0107] The control device 424 controls actuators 422 and 442 such that the speed at which the rotation unit 430 is rotated by actuator 422 is twice the angular velocity ω at which the image rotation element 440 is rotated by actuator 442.

[0108] (Effects of this embodiment) For example, a comparative example can be considered that does not include the image rotation element 440 and the actuator 442. In this comparative example, the image of the reflected light incident on the light receiving sensor 444 rotates around the optical axis due to the rotation of the rotation unit 430. Here, the direction in which the line of the image of the reflected light incident on the light receiving sensor 444 extends is uniquely determined according to the rotation angle of the rotation unit 430. For example, in this modified example, if a two-dimensional image sensor is used as the light receiving sensor 444, detection of reflected light can be achieved. However, in this case, the system of the comparative example needs to perform a decision process to determine which element should detect the reflected light from among the multiple elements constituting the two-dimensional image sensor, based on the rotation angle of the rotation unit 430.

[0109] In this embodiment, the image B42 of the reflected light reflected by the reflective mirror 436 is rotated around the optical axis by the image rotation element 440. Furthermore, the image rotation element 440 is rotated by the actuator 442, and the reflective mirror 436 is rotated by the actuator 422. Here, by setting the angular velocity of the reflective mirror 436 to twice the angular velocity ω of the image rotation element 440, the image of the beam propagating outward from the image rotation element 440 is maintained as a line extending in a certain direction (for example, the X-axis direction), regardless of the rotation position of the reflective mirror 436. The image of the beam incident on the light receiving sensor 444 is also maintained as a line extending in a certain direction. By providing the image rotation element 440 and the actuator 442, the image of the reflected light can be maintained as a line extending in a certain direction. By maintaining the image of the reflected light as a line extending in a certain direction, the above determination process can be omitted. In this embodiment, either a one-dimensional image sensor or a two-dimensional image sensor can be used as the light receiving sensor 444.

[0110] (Example 15) (Adjusting the rotation state; Figures 22 and 23) This embodiment is the same as the 14th embodiment, except that the control device 34 performs a process to adjust the rotation state of at least one of the actuators 422 and 442. If any abnormality occurs in the mechanism that rotates the rotation unit 430 and the image rotation element 440, the rotation state may change from the state at the time of design. If an abnormality occurs in the rotation state, it may not be possible to maintain the image of the reflected light incident on the light receiving sensor 444 as a line extending in a certain direction.

[0111] In this embodiment, the light receiving sensor 444 is a one-dimensional image sensor. The image B50 shown by the dashed line in Figure 22 is the image incident on the light receiving sensor 444 in the normal case where the rotation state of the reflective mirror 436 and the rotation state of the image rotation element 440 are maintained in the design state. On the other hand, the image B52 shown by the solid line in Figure 22 is the image incident on the light receiving sensor 444 in the abnormal case where an abnormality occurs in the relative angle between the image rotation element 440 or the reflective mirror 436 and the light receiving sensor 444. Image B52 is tilted at an angle α with respect to image B50. That is, the image of the reflected light incident on the light receiving sensor 444 is not maintained as a line extending in a certain direction.

[0112] Under normal conditions, the beam image B50 is detected across the entire area of ​​the light receiving sensor 444. Under normal conditions, the light intensity of the image detected by the light receiving sensor 444 (hereinafter referred to as the "sensor image") is approximately constant across the entire area of ​​the sensor image. Here, "approximately constant" means that the light intensity is within a tolerance of plus or minus a few percent relative to the reference value.

[0113] In case C3 of Figure 22, where the relative angle is abnormal, the beam image B52 is detected in the central region of the light receiving sensor 444, but the beam image B52 is hardly detected in the regions at both ends of the light receiving sensor 444. Therefore, in case C3, as shown in gradient diagram F1 of Figure 22, the light intensity at both ends of the sensor image is weaker than the light intensity at the center of the sensor image.

[0114] Furthermore, in case C4 of Figure 23, where an abnormality occurs in the ratio of the angular velocity of the reflective mirror 436 to the angular velocity of the image rotation element 440, the angle of the image incident on the light receiving sensor 444 changes in the order of α, B50, B51, and B52, as shown in the upper part of Figure 23. As a result, the intensity of light in the center of the sensor image also gradually changes, as shown in the gradient diagrams F0 to F2 in the lower part of Figure 23.

[0115] In this embodiment, the control device 424 analyzes the intensity of light detected by the light receiving sensor 444. If the light intensity of the sensor image is not substantially constant across the entire sensor image, the control device 424 adjusts at least one of the rotation angles of actuator 422 and actuator 442 to adjust the relative angle so that the light intensity of the sensor image becomes substantially constant across the entire sensor image. This makes it possible to maintain the image of the reflected light incident on the light receiving sensor 444 as a line extending in a certain direction, even if an abnormality in the relative angle occurs.

[0116] Furthermore, when the intensity of light in the center of the sensor image gradually changes, the control device 424 adjusts at least one of the angular velocities of actuator 422 and actuator 442 to adjust the ratio of angular velocities. This ensures that even if an abnormality occurs in the ratio of angular velocities, the image of the reflected light incident on the light receiving sensor 444 can be maintained as a line extending in a certain direction.

[0117] (Example 16) (Configuration of beam scanning system 16; Figure 24) The beam scanning system 16 of this embodiment has a configuration that adds a half mirror 446 and a light receiving sensor 448 to the beam scanning system 14 of the 14th embodiment.

[0118] The half-mirror 446 is positioned on the path of reflected light from the image rotation element 440 to the light receiving sensor 444. The half-mirror 446 is tilted at 45 degrees with respect to the Y-axis. A portion of the beam propagating outward from the image rotation element 26 passes through the half-mirror 446 and is incident on the light receiving sensor 444. In addition, a portion of the beam propagating outward from the image rotation element 26 is reflected by the half-mirror 446 and is incident on the light receiving sensor 448.

[0119] The light-receiving sensor 448 is a two-dimensional image sensor. For example, if an anomaly occurs in the relative angle, as shown in case C2 of Figure 12, the output image output by the light-receiving sensor 448 changes from a line-shaped image IM1 extending in a certain direction to a line-shaped image IM2 tilted at a specific angle α. Also, for example, if an anomaly occurs in the ratio of angular velocities, as shown in case C1 of Figure 12, the output image output by the light-receiving sensor 448 changes to a fan-shaped image in which multiple line-shaped images overlap.

[0120] In this embodiment, the control device 424 analyzes the output image output by the light receiving sensor 448. When the output image changes from image IM1 to image IM2, as in case C2, the control device 424 adjusts at least one of the rotation angles of actuator 422 and actuator 442 to adjust the relative angle. Also, when the output image changes from image IM1 to a fan-shaped image, as in case C1, the control device 424 adjusts at least one of the angular velocity of actuator 422 and actuator 442 to adjust the ratio of angular velocities. In this embodiment as well, even if an abnormality occurs in the rotation state of the illumination mirror 30 and the image rotation element 26, the image of the reflected light incident on the light receiving sensor 444 can be maintained as a line extending in a certain direction.

[0121] The above describes specific examples of the technology disclosed herein, but these are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples described above. For example, the following modifications may be adopted.

[0122] (Modification 1) The "first rotating means" and the "second rotating means" are not limited to actuators 28 and 32. For example, in the first embodiment, the beam scanning system 1 may be equipped with a specific actuator, the torque of which is transmitted to the rotation axis of the illumination mirror 30 via a first gear, and the torque is further transmitted to the rotation axis of the image rotation element 26 via a second gear. The gear ratio of the first gear and the second gear may be designed such that the ratio of the angular velocity of the illumination mirror 30 to the angular velocity of the image rotation element 26 is 2:1. In this modification, the first gear and the second gear are examples of the "first rotating means" and the "second rotating means," respectively.

[0123] (Modification 2) The ratio of the angular velocity of the irradiation mirror 30 to the angular velocity of the image rotation element 26 is determined by the characteristics of the image rotation element 26. If the image of the beam irradiated onto the object is maintained in the shape of a line perpendicular to the scanning range, the ratio of the angular velocities is not limited to 2:1.

[0124] The technical elements described herein or in the drawings demonstrate technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated herein or in the drawings achieve multiple objectives simultaneously, and achieving even one of these objectives constitutes technical usefulness in itself. [Explanation of Symbols]

[0125] 1, 2, 3, 4, 5, 6, 8, 9, 10: Beam scanning systems 11, 12, 13, 14, 16: Beam scanning system 20:Light source 22: Half-mirror 24: Light receiving sensor 26: Image rotation element 26a: Image rotation element 28: Actuator 30: Illumination mirror 32: Actuator 34: Control device 40: Bottom 42a, 42b: sides 44a, 44b: hypotenuse 46:Long axis 48a, 48b: Slope 50:Longitudinal surface 51:Short side 52: First Mirror 52a: First intersecting direction 54: Second Mirror 54a: Second intersecting direction 56: Third Mirror 122: Reflective mirror 202: Enclosure 202a: Upper wall 202b: Lower wall 204: Beam 206: Support plate 208 :hole 212: Cabinet 212a: Upper wall 212b: Lower wall 212c:Column 213: Beam 214: Beam 330: Conical Mirror 330a: Reflective surface 340: Polygonal pyramidal mirror 350: Image conversion lens 360: Inverted Prism 370: Truncated cone mirror 372: Truncated cone prism 372a:Top surface 420 :Light source 422: Actuator 424: Control device 430: Rotating Unit 432: Miller 434: Cylindrical lens 436: Reflective mirror 440: Image rotation element 442: Actuator 444: Light receiving sensor 446: Half mirror 448: Light receiving sensor B0~B9: Statue B10, B12, B20, B30, B32, B40, B42, B50, B52: Statue F0~F2: Gradient diagram IM1, IM2: Images P0: Vertex P1: One point α :Angle θ: Rotation angle ω: Angular velocity

Claims

1. A light source that emits a beam having a linear image along a first direction, An illumination mirror that reflects the beam irradiated from the light source in a second direction perpendicular to the first direction, and irradiates the beam onto an object, An image rotation element is positioned on the beam path from the light source to the irradiation mirror, and rotates the image of the beam irradiated from the light source around the optical axis of the beam. A light receiving sensor that receives the beam reflected from the object, A first rotating means for rotating the illumination mirror about an axis along the first direction, A second rotation means for rotating the image rotation element around an axis along the first direction in accordance with the rotation of the illumination mirror, A first housing supporting the light source, the light receiving sensor, the first rotating means, and the second rotating means, Equipped with, The second rotating means for rotating the image rotation element is fixed to a first beam that extends inside the first housing, The light source is fixed to the first wall of the first housing facing the first beam, The first rotating means for rotating the illumination mirror is fixed to the second wall of the first housing, which is located on the opposite side of the first wall across the first beam. The rotation axis of the illumination mirror, the rotation axis of the image rotation element, and the rotation axis of the second rotation means are aligned in a straight line along the first direction. The first beam has a hole provided around the second rotating means, The aforementioned image rotation element is A longitudinal surface which is a side surface that extends in the first direction and has a longitudinal edge, A first hypotenuse facing the light source and inclined with respect to the longitudinal surface, A second hypotenuse facing the hole around the second rotating means and inclined with respect to the longitudinal surface, It has, The beam irradiated from the light source passes through the image rotation element rotated by the second rotation means and is reflected by the irradiation mirror rotated by the first rotation means, so that the image of the beam irradiated onto the object is maintained in the line shape perpendicular to the second direction. The beam irradiated from the light source is refracted at the first hypotenuse, reflected by the longitudinal plane, refracted at the second hypotenuse, passes through the hole around the second rotating means, and enters the irradiation mirror. Beam scanning system.

2. The beam scanning system according to claim 1, wherein the first speed at which the irradiation mirror rotates by the first rotating means is twice the second speed at which the image rotation element rotates by the second rotating means.

3. The first rotating means is the first actuator, The beam scanning system according to claim 1 or 2, wherein the second rotating means is a second actuator different from the first actuator.

4. The beam scanning system further, The system includes an adjustment unit that adjusts at least one of the rotational state of the first actuator and the rotational state of the second actuator when the output image output by the light receiving sensor satisfies predetermined conditions. The output image satisfies the predetermined conditions. The output image has a shape different from a line shape, The output image is another line image tilted at a specific angle from a predetermined line image, The beam scanning system according to claim 3, which satisfies any of the following conditions.

5. The beam scanning system further comprises a specific actuator, The first rotating means is a first gear that transmits the torque of the specific actuator to the rotation axis of the illumination mirror, The beam scanning system according to claim 1 or 2, wherein the second rotating means is a second gear that transmits the torque of the specific actuator to the rotation axis of the image rotation element.

6. The beam scanning system according to claim 1 or 2, wherein the second hypotenuse is not in contact with the longitudinal surface.

Images