JP2021028597A - Light emission device, and range finder - Google Patents

Abstract

To provide a light emission device having a rotating element with a rotary-type light reflection body and being capable of emitting light in a desired direction over a wide range, and a range finder including the light emission device.SOLUTION: The light emission device comprises: a light source emitting light; and a rotating element 12 having a rotary body 12B which rotates around a first rotary axis AX and has at least one light reflection surface for reflecting light and also provided with a reflection-type diffraction grating 20 for diffracting light to any light reflection surface of the at least one light reflection surface so that diffraction light of a specific dimension is a main component.SELECTED DRAWING: Figure 2

Description

The present invention relates to a light emitting device that emits light and a ranging device that performs optical ranging.

Conventionally, a distance measuring device has been known that measures a distance to an object by emitting light toward the object and detecting the light reflected by the object. Further, there is known an optical scanning type distance measuring device that can perform optical scanning of an object and obtain information on the shape and orientation of the object in addition to the distance to the object. For example, Patent Document 1 includes a mirror unit having a first mirror surface and a second mirror surface inclined with respect to a rotation axis, and at least one light source that emits a luminous flux toward the first mirror surface. A scanning optical system comprising a system is disclosed.

International Publication No. 2016/056545

The scanning type ranging device has, for example, a light emitting unit that emits pulsed light toward a scanning region. Then, the ranging device uses each irradiated area of the pulsed light as seen from the light emitting portion as a ranging point, and receives light from each of the focusing points to obtain scanning information in the scanning region. For example, Patent Document 1 discloses an optical system in which light is incident on a rotary mirror provided with a plurality of light reflecting surfaces inclined with respect to a rotation axis from a plurality of positions. As a result, the emission region of the pulsed light can be expanded along the axial direction of the rotation shaft, and scanning can be performed over a wide range.

Further, in order to perform a wide range of scanning, as another example, a method of incidenting pulsed light on a rotating mirror having a plurality of light reflecting surfaces having different inclination angles with respect to the rotating shaft, or at least one time. Examples thereof include a method in which pulsed light is incident on a mirror that reciprocates around a moving axis.

In either case, considering that the scanning area is efficiently scanned and scanning information that is advantageous for handling is acquired, it is preferable that the elevation / depression angle of the scanning locus is maintained as constant as possible in the scanning area.

However, in the rotary mirror, the light reflection is caused by the fact that the direction of the normal vector of the light reflecting surface of the mirror changes with respect to the optical axis of the pulsed light incident from the light emitting portion during its operation. The elevation / depression angle of the scanning locus of the light reflected by the surface changes. This tendency becomes more remarkable as the swing angle of the mirror increases. In other words, it was difficult to widen the scanning area while maintaining the elevation / depression angle of the scanning locus constant.

The present invention has been made in view of the above points, and is a light emitting device having a rotating element having a rotating light reflector and capable of emitting light in a desired direction over a wide range. And one of the objects is to provide a distance measuring device including the light emitting device.

The invention according to claim 1 comprises a light source that emits light and a rotating body having at least one light reflecting surface that rotates around a first rotation axis and reflects light, and at least one. It is characterized by having a rotating element provided with a reflection type diffraction grating that diffracts light so that diffracted light of a specific order is the main component on any of the light reflecting surfaces. To do.

The invention according to claim 11 is the light emitting device according to claim 1 and a light receiving element that is projected through a rotating element, reflected by an object, and receives light that has passed through the rotating element. It is characterized by having a distance measuring unit that measures the distance to an object based on the result of receiving light that has passed through the rotating element by the light receiving element.

The invention according to claim 12 is a light source that emits light, and a prismatic shape, a grating shape, or a grating shape that rotates around a rotation shaft and has an axial direction of the rotation shaft as a height direction. It has a rotating element having the rotating body, and a reflection type diffraction grating provided on at least one side surface of the rotating body, and at least one of the plurality of side surfaces of the rotating body. The side surface and the other side surface are characterized in that the light emitted from the light source is reflected in directions in which the angles formed by the plane perpendicular to the rotation axis are different from each other.

It is a figure which shows the whole structure of the distance measuring apparatus which concerns on Example 1. FIG. It is a perspective view of the rotating element of the distance measuring device which concerns on Example 1. FIG. It is a side view of the rotating element of the distance measuring device which concerns on Example 1. FIG. It is a figure which shows the light reflection mode by the rotating element of the distance measuring device which concerns on Example 1. FIG. It is a side view of the rotating element of the distance measuring device which concerns on a comparative example. It is a figure which shows the elevation-depression angle of the distance measuring device which concerns on Example 1 and the distance measuring device by the conventional mirror surface. It is a figure which shows the scanning area of the distance measuring apparatus which concerns on Example 1. FIG. It is a figure which shows the arrangement example of the light source of the distance measuring device which concerns on Example 1. FIG. It is a figure which shows the whole structure of the distance measuring apparatus which concerns on Example 2. FIG. It is a perspective view of the rotating element of the distance measuring device which concerns on Example 2. FIG. It is a side view of the rotating element of the distance measuring device which concerns on Example 2. FIG. It is a figure which shows the light reflection mode by the rotating element of the distance measuring device which concerns on Example 2. FIG. It is a side view of the rotating element of the distance measuring device which concerns on Example 2. FIG. It is a figure which shows the light reflection mode by the rotating element of the distance measuring device which concerns on Example 2. FIG. It is a figure which shows the light reflection mode by the rotating element of the distance measuring device which concerns on Example 2. FIG. It is a figure which shows the scanning area of the distance measuring apparatus which concerns on Example 2. FIG. It is a figure which shows the whole structure of the distance measuring apparatus which concerns on Example 3. FIG. It is a perspective view of the rotating element of the distance measuring device which concerns on Example 3. FIG. It is a side view of the rotating element of the distance measuring device which concerns on Example 3. FIG. It is a side view of the rotating element of the distance measuring device which concerns on Example 3. FIG. It is a figure which shows the light reflection mode by the rotating element of the distance measuring device which concerns on Example 3. FIG. It is a figure which shows the light reflection mode by the rotating element of the distance measuring device which concerns on Example 3. FIG. It is a figure which shows the light reflection mode by the rotating element of the distance measuring device which concerns on Example 3. FIG. It is a figure which shows the scanning area of the distance measuring apparatus which concerns on Example 3. FIG. It is a figure which shows the arrangement example of the light source of the distance measuring device which concerns on Example 3. FIG.

Examples of the present invention will be described in detail below.

FIG. 1 is a schematic layout diagram of the distance measuring device 10 according to the first embodiment. In this embodiment, the distance measuring device 10 performs optical scanning of a predetermined area (hereinafter referred to as a scanning area) R0, and measures the distance to the object OB existing in the scanning area R0. It is a distance device. The configuration of the ranging device 10 will be described with reference to FIG. Note that FIG. 1 schematically shows the scanning region R0 and the object OB.

The distance measuring device 10 has, for example, a light source 11 that generates and emits pulsed light as emitted light L1. In this embodiment, the light source 11 generates a laser beam having a peak wavelength in the infrared region as the emitted light L1 and emits the laser beam intermittently.

The ranging device 10 rotates around rotation axes (second and first rotation axes) AX and AY that are orthogonal to each other, and reflects the emitted light L1 emitted from the light source 11 toward the scanning region R0. It has a rotating element 12 to be made to move. In this embodiment, the rotating element 12 functions as a deflecting element that deflects the emitted light L1 in a variable direction. The rotating element 12 emits the reflected emitted light L1 as scanning light L2.

In this embodiment, the rotating element 12 is a rotating mirror having one light reflecting surface 12S that rotates around the rotating shafts AX and AY. Further, the light reflecting surface 12S of the rotating element 12 has at least reflectivity with respect to the emitted light L1.

The rotating element 12 is configured such that the light reflecting surface 12S rotates periodically. Therefore, the emission direction of the scanning light L2 emitted from the rotating element 12 changes periodically. The region where the scanning light L2 is irradiated within the change cycle of the scanning light L2 in the emission direction is the scanning region R0. The scanning area R0 is a virtual three-dimensional space from which the scanning light L2 is emitted. In FIG. 1, the outer edge of the scanning region R0 is schematically shown by a broken line.

For example, the scanning region R0 has a height range along the height direction D1 corresponding to the axial direction of the rotation axis AY, a width direction range along the width direction D2 corresponding to the rotation axis AX, and non-rotation. It can be defined as a cone-shaped space having a depth direction range along the depth direction corresponding to the axial direction of the optical axis of the scanning light L2 reflected by the light reflecting surface 12S of time.

For example, the normal vector of the light reflecting surface 12S of the rotating element 12 changes periodically according to the rotation of the rotating element 12. Further, in this embodiment, the light source 11 emits the emitted light L1 toward the rotating element 12 so that the emitted light L1 is incident on the light reflecting surface 12S of the rotating element 12.

Therefore, for example, the height range of the scanning region R0 is determined by the axial direction of the optical axis of the emitted light L1 and the normal vector of the light reflecting surface 12S of the rotating element 12 when the emitted light L1 is incident. Corresponds to the range of change of the axial component of the rotation axis AY in the axial direction of the optical axis. Further, the width direction range of the scanning region R0 corresponds to the change range of the axial component of the rotation axis AX in the axial direction of the scanning light L2. Further, the depth direction range of the scanning area R0 corresponds to a range of distances at which the scanning light L2 can maintain a predetermined intensity (intensity that can be detected by the distance measuring device 10).

Further, when a virtual plane separated from the rotating element 12 in the scanning region R0 by a predetermined distance is defined as the scanning surface R1, the scanning surface R1 is two-dimensionally extending along the height direction D1 and the width direction D2. It can be defined as an area. The scanning light L2 is emitted toward the scanning region R0 so as to scan the scanning surface R1.

Further, as shown in FIG. 1, when an object OB (that is, an object or substance having reflection or scattering property with respect to the scanning light L2) exists in the scanning region R0, the scanning light L2 is reflected by the object OB. Or scattered. A part of the scanning light L2 reflected by the object OB travels in the same optical path as the scanning light L2 as the reflected light L3 in the direction opposite to the scanning light L2, and returns to the rotating element 12. Come.

The distance measuring device 10 includes a separation element 13 provided on the optical path of the emitted light L1 to separate the emitted light L1 and the reflected light L3, and a light receiving element 14 for receiving the separated reflected light L3. The separation element 13 is, for example, a beam splitter that reflects the emitted light L1 and transmits the reflected light L3.

In this embodiment, the light receiving element 14 receives the reflected light L3 which is the light projected through the rotating element 12, reflected by the object OB, and passed through the rotating element 12. Further, the light receiving element 14 has at least one detecting element that detects the reflected light L3 and generates an electric signal indicating the detection result of the reflected light L3, for example, the intensity value of the reflected light L3. The distance measuring device 10 generates the electric signal generated by the light receiving element 14 as a scanning result of the scanning region R0.

Although not shown, the distance measuring device 10 has, for example, an optical system provided on the optical path of the emitted light L1 between the light source 11 and the rotating element 12 to shape the emitted light L1. May be good. Further, the distance measuring device 10 may have an optical system provided on the optical path of the reflected light L3 between the separating element 13 and the light receiving element 14 to collect the reflected light L3. These optics may include, for example, at least one lens and may include a filter.

The distance measuring device 10 has a control unit 15 that drives and controls the light source 11, the rotating element 12, and the light receiving element 14. The control unit 15 includes a light source control unit 15A that drives and controls the light source 11, a rotating element control unit 15A that drives and controls the rotating element 12, and a light receiving element control unit that drives and controls the light receiving element 14. It has 15C and.

Further, the control unit 15 has a distance measuring unit 15D that measures the distance to the object OB based on the light receiving result of the reflected light L3 by the light receiving element 14. In this embodiment, the ranging unit 15D detects a pulse indicating the reflected light L3 from the electric signal generated by the light receiving element 14. Further, the distance measuring unit 15D determines the distance to the object OB (or a part of the surface region thereof) by the time-of-flight method based on the time difference between the emission timing of the scanning light L2 and the reception timing of the reflected light L3. Measure. Further, the distance measuring unit 15D generates data (distance measuring data) indicating the measured distance information.

Further, in the present embodiment, the distance measuring unit 15D distinguishes the scanning area R0 (scanning surface R1) into a plurality of distance measuring points (scanning points), and the distance measurement results (distance) of each of the plurality of distance measuring points. An image (distance measuring image) of the scanning region R0 showing the value) as a pixel is generated. In this embodiment, the distance measuring unit 15D associates the distance measuring point with the information indicating the displacement of the light reflecting surface 12S of the rotating element 12, and an image showing a two-dimensional map or a three-dimensional map of the scanning region R0. Generate data.

Further, the ranging unit 15D sets, for example, a scanning cycle which is a cycle of scanning the scanning region R0 as a change cycle of the scanning light L2 in the emission direction, and generates one ranging image for each scanning cycle. The distance measuring unit 15D may be connected to a display unit (not shown) that displays the distance measuring image, or may be configured to transmit the distance measuring image to the display unit.

FIG. 2 is a schematic perspective view of the rotating element 12. In this embodiment, the rotating element 12 is a MEMS (Micro Electro Mechanical System) mirror configured so that the light reflecting surface 12S rotates around the rotating shafts AX and AY.

First, in this embodiment, the rotating element 12 has a support 12A and a rotating body 12B that is supported by the support 12A and rotates around the rotating shafts AX and AY. For example, the support 12A is an annular frame.

Further, for example, the rotating body 12B has a rotating frame 12BA supported by the supporting body 12A so as to be rotatable around the rotating shaft AX at the inner peripheral portion of the supporting body 12A. For example, the rotating frame 12BA extends along the rotating shaft AX and is supported by the support 12A by a pair of torsion bars having elasticity in the circumferential direction of the rotating shaft AX. The rotating frame 12BA is, for example, an annular frame provided inside the support 12A.

Further, the rotating body 12B has a rotating plate 12BB supported by the rotating frame 12BA so as to be rotatable around the rotating shaft AY inside the rotating frame 12BA. For example, the rotating plate 12BB is supported by the rotating frame 12BA by a pair of torsion bars extending along the rotating shaft AY and having elasticity in the circumferential direction of the rotating shaft AY. The rotating plate 12BB is, for example, a disk-shaped plate provided inside the rotating frame 12BA.

The rotating frame 12BA rotates around the rotating shaft AX by twisting the torsion bar between the support 12A and the rotating frame 12BA. Further, the rotating plate 12BB rotates around the rotating shaft AY by twisting the torsion bar between the rotating frame 12BA and the rotating plate 12BB.

In this way, the rotating plate 12BB rotates around the rotating shafts AX and AY. In other words, the rotating body 12B is a movable body supported by the supporting body 12A and having a rotating plate 12BB which is rotatable around the rotating shaft AX and AY.

Further, the rotating plate 12BB has a reflectivity with respect to the emitted light L1. The surface of the rotating plate 12BB functions as a light reflecting surface 12S in the rotating body 12B. A metal reflective film, a dielectric multilayer film, or the like may be provided on the surface of the rotating plate 12BB. These films can be designed to maintain high reflectance against changes in the incident angle and wavelength of the emitted light L1. As a result, the light reflection characteristics (reflectance, etc.) of the rotating plate 12BB can be stabilized.

Further, a wavelength-selective reflective film that selectively reflects the emitted light L1 may be provided on the surface of the rotating plate 12BB. In this case, the surface of the rotating plate 12BB functions as a reflective bandpass filter. As a result, it is possible to prevent light having an unnecessary wavelength, such as ambient light, other than the emitted light L1 from being mixed with the reflected light L3 and incident on the light receiving element 14.

Further, for example, the rotating element 12 is provided on the support 12A and the rotating body 12B, is connected to the control unit 15, and generates a driving force (driving force) for rotating the rotating body 12B (shown in the figure). Do not have). For example, the driving force generation unit generates pressure power or electromagnetic force as the driving force by the driving signal supplied from the control unit 15.

Next, the distance measuring device 10 has a reflection type diffraction grating 20 provided on the light reflecting surface 12S of the rotating body 12B in the rotating element 12. That is, in this embodiment, the light reflecting surface 12S of the rotating body 12B functions as a diffraction reflecting surface that diffracts and reflects the emitted light L1.

In this embodiment, the diffraction grating 20 has a plurality of grating grooves 21 arranged along the light reflecting surface 12S. Further, in this embodiment, each of the lattice grooves 21 of the diffraction grating 20 is the first rotation of the rotation shaft AX and AY on the light reflecting surface 12S of the rotating body 12B. It extends along a direction perpendicular to the axial direction of the axis AY. Further, these plurality of lattice grooves 21 are arranged along the axial direction of the rotation axis AY, which is the one rotation axis.

FIG. 3 is a schematic side view of the rotating body 12B when the rotating plate 12BB is viewed along the axial direction of the rotating shaft AX. The configuration of the diffraction grating 20 will be described with reference to FIG. In this embodiment, the diffraction grating 20 is a blazed diffraction grating having a wave number vector in one direction DY1 in the axial direction of the rotation axis AY and having a blaze angle of θ _b.

More specifically, the diffraction grating 20 has a lattice surface (a surface defined by the top of the lattice groove 21 and a diffraction grating surface) DP1 parallel to the light reflecting surface 12S of the rotating body 12B, and from the lattice surface DP1 to the direction DY1. It has a blaze surface 21A that is inclined by an angle (blaze angle) θ _b and is arranged at a pitch (distance between adjacent lattice grooves 21) d.

FIG. 4 is a diagram schematically showing the incident direction of the emitted light L1 and the emitted direction of the scanning light L2 with respect to the rotating body 12B (rotating plate 12BB) of the rotating element 12. The incident mode of the emitted light L1 and the emitted mode of the scanning light L2 with respect to the light reflecting surface 12S will be described with reference to FIG.

In FIG. 4, for ease of understanding, the optical axis is inclined by an _{angle (incident angle) θ 1} from the normal of the light reflecting surface 12S to the direction DY1 with respect to the light reflecting surface 12S when not rotating. The case where the emitted light L1 is incident will be described as an example. In this embodiment, the emitted light L1 is incident on the lattice surface DP1 at an incident angle θ ₁ (= 2 θ _b ), is diffracted and reflected by the blazed grating, and is scanned light L2 in the normal direction of the lattice surface DP1. Is emitted as.

More specifically, a blazed grating is a diffraction grating configured to maximize the diffraction efficiency of a predetermined diffraction order and wavelength and minimize the diffraction efficiency of other diffraction orders and wavelengths. Therefore, the light diffracted by the blazed diffraction grating is the light whose main component is diffracted light of a specific order. Further, in this embodiment, the emission direction of the diffracted light of the order which is the main component depends on the blaze angle θ _b , the pitch d of the lattice groove 21, the wavelength of the emitted light L1, and the incident angle θ _{1 of the} emitted light L1. It is decided.

_{That is, by setting the blaze angle θ b} of the blazed diffraction grating and the pitch d of the lattice groove 21 according to the wavelength of the emitted light L1, the emitted light L1 incident on the lattice surface DP1 of the blazed diffraction grating at the incident angle θ ₁ Can be reflected at a desired angle as scanning light L2.

In other words, the scanning light L2 is emitted toward an angle different from the angle at which the emitted light L1 is specularly reflected on the light reflecting surface 12S in the axial direction of the rotation axis AY. Further, the component along the axial direction of the rotation axis AY in the emission direction of the scanning light L2 hardly changes even when the light reflecting surface 12S rotates around the rotation axis AY.

With reference to FIGS. 5A and 5B, the emission directions of the scanning light L2 with and without the diffraction grating 20 will be described. FIG. 5A is a schematic side view of the rotating element 101 of the distance measuring device 100 according to the comparative example. Further, FIG. 5B is a diagram showing changes in the emission angle of the scanning light L2 emitted from each of the rotating element 12 (this embodiment) and the rotating element 101 (comparative example).

First, as shown in FIG. 5A, the distance measuring device 100 according to the comparative example has the same configuration as the distance measuring device 100 except that it has a rotating element 101. Further, the rotating element 101 has the same configuration as the rotating element 12 except that it has a rotating body 101B having a mirror surface 101S which is a light reflecting surface having no diffraction grating.

Further, FIG. 5B is emitted from the light reflecting surface 12S of the rotating body 12B and the mirror surface 101S of the rotating body 101B when the normal line of the light reflecting surface 12S of the rotating body 12B at the time of non-rotation is used as a reference (0 degree). Changes in the emission angle (elevation angle of the optical axis of the scanning light L2) in the height direction D1 and the change in the emission angle (left-right angle of the optical axis of the scanning light L2) in the width direction D2 of each of the scanning light L2. It is a figure which shows.

As shown in FIG. 5A, the mirror surface 101S of the rotating body 101B rotates around a rotating shaft tilted by _{θ 1/2 with respect to the rotating shaft AY.} That is, the rotation shaft AYH of the rotating body 101B is tilted by _{θ 1/2 with respect to the rotating shaft AY of the rotating body 12B.}

Further, also in the distance measuring device 100, the light source 11 is such that the emitted light L1 is incident on the mirror surface 101S along a direction inclined by an angle θ1 with respect to a plane perpendicular to the rotation axis AY (indicated by a broken line). It is arranged.

As shown in FIG. 5B, the scanning light L2 emitted from the rotating element 101 of the distance measuring device 100 suddenly has an elevation / depression angle when the normal of the mirror surface 101S rotates from the non-rotating state to the left and right exceeding 20 °. Changes. On the other hand, the elevation / depression angle of the scanning light L2 emitted from the rotating element 12 of the distance measuring device 10 does not change even if the light reflecting surface 12S rotates.

FIG. 6 is a diagram schematically showing an irradiated position of the scanning light L2 on the scanning surface R1. In FIG. 6, the scanning locus of the scanning light L2 on the scanning surface R1 is shown by a broken line. In the present embodiment, the ranging device 10 sequentially emits the scanning light L2 along the width direction D2 on the scanning surface R1 while deflecting the scanning light L2, and this is performed a plurality of times along the height direction D1.

More specifically, for example, in this embodiment, the control unit 15 rotates the light reflecting surface 12S of the rotating body 12B at a high speed in the width direction D2 corresponding to the axial direction of the rotating shaft AX. It rotates at a low speed in the height direction D1 corresponding to the axial direction of the rotation shaft AY. The scanning light L2 emitted from the rotating body 12B is deflected at a high speed in the width direction D2 and at a low speed in the height direction D1.

In other words, the distance measuring device 10 sets a scanning line in the height direction D1 along the width direction D2 corresponding to the direction perpendicular to the rotation axis AY of the rotating body 12B in the rotating element 12 with respect to the scanning region R0. Raster scanning is performed so as to obtain a plurality of lines along the line. Further, the distance measuring device 10 performs an operation such as periodically performing the raster scanning.

At this time, since the diffraction grating 20 is provided on the light reflecting surface 12S like the rotating body 12B, the rotating body 12B is rotated (reciprocated) once along the width direction D2 (that is, the resonance direction). The component of the scanning light L2 in the height direction D1 hardly changes. Therefore, for example, even at the end of the scanning region R0, the elevation / depression angle of the scanning locus of the scanning light L2 hardly changes. As a result, the component in the height direction D1 in the emission direction of the scanning light L2 is stabilized over a wide range.

As described above, in this embodiment, the rotating element 12 provided with the blazed diffraction grating as the diffraction grating 20 is rotated on the light reflecting surface 12S of the rotating body 12B, and the emitted light L1 is reflected by the rotating element 12. As a result, the scanning light L2 is emitted toward the scanning region R0.

Therefore, for example, a change in the elevation / depression angle of the scanning light L2 (pulse light) scanning locus to the scanning region R0 is suppressed. Therefore, it is possible to efficiently scan a wide range of scanning areas R0 and obtain scanning results and ranging results that are advantageous for handling.

Further, by combining the rotating element 12 and the diffraction grating 20, the emission direction of the scanning light L2 is stabilized even when the emission light L1 is incident from various directions, for example. Therefore, the degree of freedom in arranging other optical elements such as the light source 11 is greatly improved.

FIG. 7 is a diagram schematically showing an arrangement example of the light source 11 and the rotating element 12. As shown in FIG. 7, the light source 11 causes the emitted light L1 to be incident on the light reflecting surface 12S of the rotating element 12 along the direction intersecting the plane PL1 perpendicular to the rotation axis AY. Can be configured and arranged.

As a result, the emitted light L1 is incident on the rotating element 12 on the optical axis along the direction having the axial component of the rotating shaft AY. In this case, as shown in FIG. 7, the solid angle of the light reflecting surface 12S of the rotating element 12 as seen from the point of the object OB during rotation is maximized.

Specifically, the light reflecting surface 12S of the rotating element 12 needs to be arranged so that the emitted light L1 is incident and the reflected light L3 is incident at the same time in a wide rotation range. Further, the reflected light L3 is usually light scattered by the object OB, and is light having a very weak intensity. Therefore, when the reflected light L3 is received through the rotating element 12 as in this embodiment, the light reflecting surface 12S is larger when viewed from the object OB in order to improve the light receiving accuracy of the light receiving element 14. It is preferable to have a solid angle.

If the diffraction grating 20 is not provided, it is difficult to arrange the rotating body 12B so that the light reflecting surface 12S faces the front with respect to the emitted light L1, and the rotating body 12B also faces the scanning region R0. Difficult to arrange so that it faces. Therefore, when the diffraction grating 20 is not provided, the light reflecting surface 12S of the rotating body 12B always has an angle with respect to the optical axis of the emitted light L1 when its normal direction is rotating, and the reflected light L3 ( It must be arranged so as to have an angle with respect to the optical axis of the scanning light L2).

On the other hand, in this embodiment, by providing the diffraction grating 20 and adjusting the diffraction conditions thereof, for example, even when the emitted light L1 is incident on the optical axis inclined from the normal line of the light reflecting surface 12S. , The scanning light L can be emitted along the normal direction of the light reflecting surface 12S.

Therefore, the arrangement of the rotating body 12B can be adjusted so as to increase the solid angle of the light reflecting surface 12S as seen from the object OB, for example, so as to face the front with respect to the scanning region R0. Therefore, it is possible to suppress a decrease in the amount of reflected light L3 incident on the light receiving element 14. Therefore, the light receiving accuracy of the reflected light L3, as well as the scanning accuracy and the distance measurement accuracy are improved.

In this embodiment, a case where the diffraction grating 20 is a blazed diffraction grating having a wave vector in the axial direction of the rotation axis AY has been described. However, the configuration of the diffraction grating 20 is not limited to this.

For example, the diffraction grating 20 may be a diffraction grating that diffracts the emitted light L1 so that the specific diffracted light is the main component. Further, for example, the diffraction gratings 20 extend along the direction perpendicular to the axial direction of one rotation axis (rotation axis AX or AY), and are arranged along the axial direction of the one rotation axis. It suffices to have a plurality of lattice grooves 21.

Further, in this embodiment, the case where the rotating body 12B has a light reflecting surface 12S that rotates around the rotating shafts AX and AY, which are two rotating shafts, has been described. However, the rotating body 12B may be configured to rotate around only one rotating shaft, for example, only the rotating shaft AY. Even in this case, the scanning light L2 can be stably emitted in a desired direction.

In this way, the ranging device 10 rotates around, for example, a light source 11 that emits light (emitted light L1) and at least one rotation axis (for example, rotation axes AX and AY) and emits the light. A rotating element 12 having a rotating body 12B having a light reflecting surface 12S to be reflected, and provided with a diffraction grid 20 on the light reflecting surface 12S so that the light is diffracted so that diffracted light of a specific order is the main component. Light receiving element 14 that is projected through the rotating element 12, reflected by the object OB, and receives the light (reflected light L3) that has passed through the rotating element 12, and the light that has passed through the rotating element 12 by the light receiving element 14. It has a ranging unit 15D that measures the distance to the object OB based on the light receiving result of the above. Therefore, there is provided a distance measuring device 10 having a rotating element 12 having a rotating light reflector and capable of performing high quality distance measurement by emitting light in a desired direction over a wide range. can do.

FIG. 8 is a schematic layout diagram of the distance measuring device 30 according to the second embodiment. The distance measuring device 30 includes a light source 31, a rotating element 32, a separating element 33, and a light receiving element 34. Further, the distance measuring device 30 has a control unit 35 that controls a light source 31, a rotating element 32, and a light receiving element 34.

The light source 31, the separation element 33, the light receiving element 34, and the control unit 35 have the same configurations as the light source 11, the separation element 13, the light receiving element 14, and the control unit 15 of the distance measuring device 10, respectively. On the other hand, in this embodiment, the distance measuring device 30 has a plurality of side surfaces 32S, each of which functions as a light reflecting surface, and has a rotating element 32 that rotates around the rotating shaft AY.

Specifically, the distance measuring device 10 of the first embodiment includes a rotating mirror as a rotating element 12, which rotates around rotating axes AX and AY orthogonal to each other and has one light reflecting surface 12S. I explained the case of. On the other hand, the rotating element 32 of the distance measuring device 30 of this embodiment is a rotating mirror that rotates around one rotating shaft AY and has a light reflecting surface provided on each of the plurality of side surfaces 32S. ..

In this embodiment, the rotating element 32 is a polygon mirror having a pyramid-shaped (polygonal frustum-shaped) shape, each having a plurality of side surfaces 32S inclined with respect to the rotation axis AY. Each of the side surfaces 32S of the rotating element 32 is reflective to the emitted light L1 and is arranged on the optical axis of the emitted light L1.

The scanning light L2 emitted from the rotating element 32 periodically changes in its emitting direction. The region where the scanning light L2 is irradiated within one change cycle of the scanning light L2 in the emission direction (within a period during which the rotating element 12A rotates once) is the scanning region R0. The scanning area R0 is a virtual three-dimensional space from which the scanning light L2 is emitted. In FIG. 8, the outer edge of the scanning region R0 is schematically shown by a broken line.

For example, in this embodiment, the scanning region R0 is in the height direction range along the height direction D1 corresponding to the axial direction of the rotation axis AY and in the width direction D2 corresponding to the direction perpendicular to the rotation axis AY. It can be defined as a cone-shaped space having a width direction range along the width direction and a depth direction range along the depth direction corresponding to the axial direction of the optical axis of the scanning light L2.

For example, the normal vector of the side surface 32S of the rotating element 32 changes periodically according to the rotation of the rotating element 32. Further, in the present embodiment, the light source 31 emits the emitted light L1 toward the rotating element 32 so that the emitted light L1 is incident on any of the side surfaces 32S of the rotating element 32.

Therefore, for example, in the present embodiment, the height range of the scanning region R0 is determined by the axial direction of the optical axis of the emitted light L1 and the normal vector of the side surface 32S of the rotating element 32 on which the emitted light L1 is incident. Corresponds to the range of change of the axial component of the rotation axis AY in the axial direction of the optical axis of the determined scanning light L2. Further, the width direction range of the scanning region R0 corresponds to the change range of the component in the direction perpendicular to the rotation axis AY in the axial direction of the scanning light L2. Further, the depth direction range of the scanning area R0 corresponds to a range of distances at which the scanning light L2 can maintain a predetermined intensity (intensity that can be detected by the distance measuring device 30).

Further, when a virtual plane separated from the rotating element 32 in the scanning region R0 by a predetermined distance is defined as the scanning surface R1, the scanning surface R1 is two-dimensionally extending along the height direction D1 and the width direction D2. It can be defined as an area. The scanning light L2 is emitted toward the scanning region R0 so as to scan the scanning surface R1.

FIG. 9 is a perspective view of the rotating element 32. In this embodiment, the rotating element 32 includes a support 32A and a rotating body 32B supported by the support 32A so as to be rotatable around the rotating shaft AY. That is, in this embodiment, the rotating element 32 is a polygon mirror having a rotating body 32B.

In this embodiment, the rotating body 32B of the rotating element 32 has a regular polygonal pyramid shape with the axial direction of the rotating shaft AY as the height direction. In this embodiment, the rotating body 32B has a regular triangular pyramid shape having three side surfaces 32SA, 32SB and 32SC as the side surface 32S. In the following, the side surface 32S of the rotating body 32B may be referred to as a first side surface, and similarly, the side surfaces 32SB and 32SC may be referred to as a second and third side surfaces, respectively.

In this embodiment, each of the side surfaces 32SA, 32SB and 32SC of the rotating body 32B is a part of a plane inclined with respect to the axial direction of the rotating shaft AY. Further, the side surfaces 32SA, 32SB and 32SC of the rotating body 32B are arranged so as to surround the rotating shaft AY at a position separated from the rotating shaft AY when viewed from a direction along the axial direction of the rotating shaft AY. There is.

In the present specification, the fact that the rotating body 32B has a pyramid-shaped shape means that, for example, the rotating body 32B has an outer shape portion forming a pyramid or a side surface of the pyramid. For example, the rotating body 32B may have a portion having another shape in addition to the pyramid trapezoidal portion. Further, the rotating body 32B may have irregularities or through holes on the side surface 32S, the upper surface or the bottom surface.

For example, the rotating body 32B of the rotating element 32 has a pyramid-shaped main body portion and a convex portion protruding from the bottom surface of the main body portion along the axial direction of the rotating shaft AY. The convex portion is rotatably coupled to the support 32A at its end. For example, the convex portion is a part of a shaft penetrating between the bottom surface and the upper surface of the main body portion.

Further, for example, the rotating element 32 is provided in the support 32A, is connected to the control unit 35, and has a driving force generating unit (not shown) that generates a force (driving force) for rotating the rotating body 32B. Have. For example, the driving force generating unit is a motor that rotates by a driving signal supplied from the control unit 35. Further, for example, the driving force generated by the driving force transmitting unit is transmitted to the rotating body 32B by a transmitting unit (not shown) such as a bearing.

Next, the distance measuring device 30 has a reflection type diffraction grating 40 provided on at least one of the side surfaces 32S of the rotating body 32B of the rotating element 32. In this embodiment, the diffraction grating 40 has reflective first and second diffraction gratings 41 and 42 provided on the first and second side surfaces 32SA and 32SB, respectively. The first and second diffraction gratings 41 and 42 have a plurality of grating grooves 41A and 42A arranged along the first and second side surfaces 32SA and 32SB, respectively.

In this embodiment, each of the first diffraction gratings 41 extends along the direction perpendicular to the rotation axis AY on the first side surface 32SA of the rotation body 32B, and along the axial direction of the rotation axis AY. It has a plurality of arranged lattice grooves 41A. Further, the second diffraction gratings 42 extend along the direction perpendicular to the axial direction of the rotating shaft AY on the second side surface 32SB of the rotating body 32B, and are arranged along the axial direction of the rotating shaft AY. It has a plurality of lattice grooves 42A.

Further, in this embodiment, the diffraction grating 40 is not provided on the third side surface 32SC of the rotating body 32B. In this embodiment, the third side surface 32SC is a side surface portion of the rotating body 32B having specular reflection with respect to the emitted light L1. That is, in this embodiment, the first and second side surfaces 32SA and 32SB function as diffractive reflection surfaces for diffracting and reflecting the emitted light L1, and the third side surface 32SC functions as a reflecting surface for reflecting the emitted light L1. ..

FIG. 10 is a schematic side view of the rotating body 32B when the rotating body 32B is viewed in a direction perpendicular to the rotating shaft AY and in a direction parallel to the first side surface 32SA of the rotating body 32B. is there. In FIG. 10, only a part of the rotating body 32B is shown. The configuration of the diffraction grating 40 will be described with reference to FIG.

In this embodiment, the first diffraction grating 41 is in the direction from the bottom surface to the top surface of the rotating body 32B along the first side surface 32SA, has a wave number vector in the upward direction DY3 in the figure, and has a blazed angle. Is a blazed diffraction grating with _{θ b1.} Further, the first diffraction grating 41 is composed of a lattice plane (a surface defined by the top of the lattice groove 41A, a first diffraction grating surface) 41SA parallel to the first side surface 32SA of the rotating body 32B and a lattice surface 41SA. It has a blaze plane (first blaze plane) 41SB that is inclined by an angle (first blaze angle) θ _b1 toward the direction DY3 and is arranged at a pitch (distance between adjacent lattice grooves 41A) d _1. .. As shown in FIG. 10, the angle θ _b1 is an angle formed by the normal of the lattice surface 41SA and the normal of the blaze surface 41SB.

FIG. 11 is a diagram schematically showing the incident direction of the emitted light L1 and the emitted direction of the scanning light L2 with respect to the first side surface 32SA of the rotating body 32B. The incident mode of the emitted light L1 and the emitted mode of the scanning light L2 with respect to the first side surface 32SA will be described with reference to FIG.

First, in the present embodiment, the light source 31 incidents the emitted light L1 on the first to third side surfaces 32SA to 32SC along the direction intersecting the plane PL1 perpendicular to the rotation axis AY of the rotating body 32B. It is configured and arranged to allow. In this embodiment, the light source 31 is configured and arranged so that the emitted light L1 is incident on the first to third side surfaces 32SA to 32SC on an optical axis inclined in the direction DY3 with respect to the plane PL1. ..

Next, as shown in FIG. 11, during the period during which the rotating body 32B is rotating so that the emitted light L1 is incident on the first side surface 32SA, the emitted light (hereinafter referred to as the first emitted light). L11 is incident on the first diffraction grating 41. Then, the first emitted light L11 is diffracted and reflected by the first diffraction grating 41. Further, the first emitted light L11 diffracted and reflected by the first diffraction grating 41 is emitted as scanning light (hereinafter referred to as first scanning light) L21.

Here, in this embodiment, the first diffraction grating 41 is a blazed diffraction grating, and more specifically, the blazed diffraction grating maximizes the diffraction efficiency of a predetermined diffraction order and wavelength, and other diffractions. A diffraction grating configured to minimize the order and wavelength diffraction efficiencies. Therefore, the light diffracted by the blazed diffraction grating is the light whose main component is diffracted light of a specific order.

Further, in this embodiment, the emission directions of the diffracted light of the order of the main component are the blaze angle θ _{b1 , the pitch d 1} of the lattice groove 41A, the wavelength of the emitted light L1, and the incident angle θ _{11 of the emitted light L1.} Determined by. _{That is, by setting the blaze angle θ b1} of the blazed diffraction grating and the pitch d ₁ of the lattice groove 41A according to the wavelength of the emitted light L1, the first first incident on the lattice surface 41SA of the blazed diffraction grating at the incident angle θ _11. The emitted light L11 can be reflected at a desired angle as the first scanning light L21.

In the present embodiment, as a result of the first outgoing light L11 is diffracted and reflected by the first diffraction grating 41, the scanning light L21 is, theta ₁₁ with respect to the normal direction of the grating surface 41SA -2 (θ _b1) It is emitted along an optical axis inclined in the direction opposite to the direction DY3.

In other words, the first scanning light L21 is emitted toward an angle different from the angle at which the first emitted light L11 is specularly reflected on the first side surface 32SA in the axial direction of the rotation axis AY. Further, the component along the axial direction of the rotation axis AY in the emission direction of the first scanning light L21 hardly changes even when the first side surface 32SA rotates around the rotation axis AY.

FIG. 12 is a schematic side view of the rotating body 32B when the rotating body 32B is viewed in a direction perpendicular to the rotating shaft AY and in a direction parallel to the second side surface 32SB of the rotating body 32B. is there. In this embodiment, the second side surface 32SB is provided with the second diffraction grating 42. Further, it is a blazed diffraction grating that is in the direction from the bottom surface to the top surface of the rotating body 32B along the second diffraction grating 42, has a wave number vector in the upward direction DY3 in the figure, and has a blaze angle of θ _b2.

The second diffraction grating 42 includes a lattice plane (a surface defined by the top of the lattice groove 42A, a second diffraction grating surface) 42SA parallel to the second side surface 32SB of the rotating body 32B, and a direction DY3 from the lattice surface 42SA. It has a blaze surface (second blaze surface) 42SB which is inclined by an angle (second blaze angle) θ _b2 and arranged at a pitch (distance between adjacent lattice grooves 42A) d _2. As shown in FIG. 12, the angle θ _b2 is an angle formed by the normal of the lattice surface 42SA and the normal of the blaze surface 42SB.

Further, in the present embodiment, the pitch d _{2 of the lattice groove 42A is equal to the pitch d 1} of the lattice groove 41A, and the angle θ _{b2 which} is the second blaze angle is larger than the _{angle θ b1} which is the first blaze angle. small. That is, the inclination angle of the blaze surface 42SB of the second diffraction grating 42 with respect to the lattice surface 42SA is smaller than the inclination angle of the blaze surface 41SB of the first diffraction grating 41 with respect to the lattice surface 41SA.

FIG. 13 shows the incident direction of the emitted light (hereinafter referred to as the second emitted light L12) and the emitted direction of the scanning light (hereinafter referred to as the second scanning light) L22 with respect to the second side surface 32SB of the rotating body 32B. It is a figure which shows typically.

As shown in FIG. 13, the second emitted light L12 incident on the second side surface 32SB is incident on the second diffraction grating 42 and diffracted. Further, the second emitted light L12 diffracted by the second diffraction grating 42 is emitted as the second scanning light L21.

Further, in the present embodiment, the second diffraction grating 42 is a blazed diffraction grating having a wave number vector in the direction DY3 and having a blaze angle θ _{b2 smaller than the first blaze angle θ b1.} Accordingly, in the present embodiment, as a result of the second outgoing light L12 is diffracted and reflected by the second diffraction grating 42, the scanning light L22 is, theta ₁₁ with respect to the normal direction of the grating surface 42SA -2 (θ _{Only b2} ) is emitted along the optical axis inclined in the direction opposite to the direction DY3. For example, as shown in FIG. 13, the second scanning light L22 is emitted from the second diffraction grating 42 along an optical axis substantially parallel to the plane PL1 perpendicular to the rotation axis AY.

In other words, in this embodiment, as shown in FIGS. 10 and 12, the diffraction grating 40 is the first diffraction grating 41 provided on the first side surface 32SA of the rotating body 32B, and the first side surface. It includes a second diffraction grating 42 provided on a second side surface 32SB different from the 32SA.

Further, each of the first and second diffraction gratings 41 and 42 extends along the direction perpendicular to the axial direction of the rotation axis AY, and rotates within the first and second side surfaces 32SA and 32SB. It has a plurality of grating grooves 41A and 42A arranged along the axial direction of the axis AY. Further, in this embodiment, the first and second diffraction gratings 41 and 42 are blazed diffraction gratings having different characteristics from each other.

FIG. 14 shows the incident direction of the emitted light (hereinafter referred to as the third emitted light L13) and the emitted direction of the scanning light (hereinafter referred to as the third scanning light) L23 with respect to the third side surface 32SC of the rotating body 32B. It is a figure which shows typically.

In this embodiment, the diffraction grating 40 is not provided on the third side surface 32SC of the rotating body 32B. Therefore, the third emitted light L13 is specularly reflected by the third side surface 32SC. Therefore, the emission direction of the third scanning light L23 is a direction corresponding to the reflection condition on the third side surface 32SC of the third emission light L13. That is, as a result of the third emitted light L13 being specularly reflected by the third side surface 32SC, the third scanning light L23 is on the side opposite to the direction DY3 by θ _{11 with respect to the normal direction of the third side surface 32SC.} It is emitted along the optical axis inclined to.

As described above, the scanning light L2 rotates the rotating body 32B so that the axial components of the rotating shaft AY differ among the first, second and third side surfaces 32SA, 32SB and 32SC of the rotating body 32B. The components are sequentially emitted while changing the components in the direction perpendicular to the rotation axis AY according to the above. In other words, the scanning light L2 is reflected between the first, second and third side surfaces 32SA, 32SB and 32SC in a plurality of directions in which the angles formed with the plane PL1 are different from each other.

FIG. 15 is a diagram schematically showing an irradiated position of the scanning light L2 on the scanning surface R1. In FIG. 15, the scanning locus of the scanning light L2 on the scanning surface R1 is shown by a broken line. In this embodiment, the scanning light L2 is emitted so as to draw three trajectories TR1, TR2, and TR3 along the width direction D2 so that the positions in the height direction D1 are different.

In other words, the distance measuring device 30 sets the scanning line along the width direction D2 corresponding to the direction perpendicular to the rotation axis AY of the rotating body 32B in the rotating element 32 to the height direction D1 with respect to the scanning region R0. Raster scanning is performed so as to obtain a plurality of lines along the line. Further, the distance measuring device 30 performs an operation such that the raster scanning is periodically performed. Further, a portion of the scanning surface R1 where the scanning light L2 is almost completely irradiated along the width direction D2A, for example, a central portion of the scanning surface R1 becomes an effective scanning region R11.

As described above, in the present embodiment, a blazed diffraction grating is provided as a diffraction grating 40 on at least one side surface 32S of the rotating element 32 having the pyramid trapezoidal rotating body 32B, and the rotating element 32 is rotated. The scanning light L2 is emitted toward the scanning region R0A by reflecting the emitted light L1.

Therefore, for example, it is selected whether or not the diffraction grating 40 is provided for each side surface 32S, and the diffraction conditions of the diffraction grating 40 provided for each side surface 32S (the tilt direction of the blaze surface, the pitch of the lattice grooves, etc.) are changed. As a result, it is possible to perform optical scanning in a wide range using a polygon mirror having a simple shape. For example, even if the blaze angles of the first and second diffraction gratings 41 and 42 and the pitch of the grating grooves are the same, if they have wave vector in the same different directions, they have different diffraction conditions. Can be regarded. As a result, for example, it is not necessary to prepare a plurality of light sources or use a polygon mirror having a complicated shape in order to widen the scanning area in the axial direction of the rotation axis AY.

Further, since the rotating body 32B has a shape rotationally symmetric with respect to the rotating shaft AY, it can be easily manufactured. Further, since the center of gravity of the rotating body 32B is arranged on the rotating shaft AY, it is possible to secure high rotational stability. Therefore, rattling during rotation of the rotating body 32B is unlikely to occur, and the unstable emission direction of the scanning light L2 due to this is also suppressed. That is, it is possible to suppress a change in the elevation / depression angle of the scanning locus of the scanning light L2. Therefore, it is possible to obtain highly accurate and even scanning results and distance measurement results for a wide range of scanning areas R0.

Further, by combining the rotating element 32 and the diffraction grating 40, for example, even when the emitted light L1 is incident from various directions, the scanning light L2 can be directed in a desired direction by adjusting the configuration of the diffraction grating 40. It can be emitted. For example, the rotating body 32B has a pyramidal grating shape in which the inclinations of the first to third side surfaces 32SA to 32SC with respect to the rotation axis AY are at least partially different, and any one side surface of the first to third side surfaces 32SA to 32SC. Even when the diffraction grating 40 is arranged in, the scanning light L2 can be emitted in a desired direction. Therefore, the degree of freedom in arranging other optical elements such as the light source 31 is greatly improved.

Further, in this embodiment, a case where the diffraction grating 40 is not provided on the third side surface 32SC of the rotating body 32B but a reflection surface having specular reflectivity is provided has been described. However, for example, a blazed diffraction grating may be provided as the diffraction grating 40 on the third side surface 32SC. That is, all the side surfaces 32SA to 32SC of the rotating body 32B may be provided with diffraction gratings 40 having different diffraction conditions between the side surfaces.

Also in this case, by changing the diffraction conditions of the diffraction grating 40 provided for each side surface 32S (the tilt direction of the blaze surface, the pitch of the lattice groove, etc.), the scanning light L2 reflected by each of the side surface 32S is at a desired angle. Can be reflected in.

Further, when all the scanning lights L2 are generated by diffraction, even if the emitted light L1 is incident on the side surface 32S at a large incident angle, the change in the elevation / depression angle of the scanning locus of the scanning light L2 due to each of the side surfaces 32S is suppressed. Can be done. Therefore, the light source 31 and the light receiving element 34 can be arranged so that the incident angle of the emitted light L1 on the side surface 32S becomes large, and the size of the housing accommodating the light source 31, the rotating element 32, and the light receiving element 34 can be increased. In particular, the size of the scanning light L2 in the optical axis direction can be significantly reduced.

In this embodiment, as the diffraction grating 30, a blazed diffraction grating in which the normal of the blaze surface is inclined in a direction (for example, direction DY3) along the axial direction of the rotation axis AY in each side surface of the rotating body 32B is used. The case of using it has been described. However, the configuration of the diffraction grating 40 is not limited to this. For example, the first and second diffraction gratings 41 and 42 may be diffraction gratings that diffract the emitted light L1 so that the specific diffracted light is the main component. Further, for example, the first and second diffraction gratings 41 and 42 each extend along the direction perpendicular to the axial direction of the rotation axis AY in each side surface 32S, and the rotation axis AY in each side surface 32S. It suffices to have a plurality of lattice grooves 41A and 42A arranged along the axial direction of.

Further, in this embodiment, the case where the diffraction grating 40 has the first and second diffraction gratings 41 and 42 under different diffraction conditions has been described. However, the diffraction grating 40 may be provided on at least one side surface 32S. For example, the diffraction grating 40 may be composed of only the first diffraction grating 41 provided only on the first side surface 32SA. Further, the first and second diffraction gratings 41 and 42 may have the same diffraction conditions.

Further, in this embodiment, the case where the rotating body 32B has a pyramid trapezoidal shape has been described. However, the rotating body 32B is not limited to having a pyramid trapezoidal shape, and may have a pyramid shape having a top.

Further, in this embodiment, the case where the rotating body 32B has a pyramid trapezoidal shape having three side surfaces has been described. However, the number of side surfaces of the rotating body 32B is not limited to three, and may have three or more side surfaces.

As described above, in the present embodiment, the ranging device 10A rotates around the rotation axis AY and rotates in the axial direction of the rotation axis AY, for example, with the light source 31 that emits light (emission light L1). It has a rotating body 32B having a prismatic shape or a grating trapezoidal shape in the height direction, and light is applied to at least one side surface of the plurality of side surfaces 32SA of the rotating body 32B so that the reflected light of a specific order is the main component. A rotating element 32 provided with a reflective diffraction grating 40 to be diffracted, and light projected through the rotating element 32, reflected by the object OB, and received light (reflected light L3) passing through the rotating element 32. It has a light receiving element 34 and a ranging unit 35D that measures the distance to the object OB based on the light receiving result of the light passing through the rotating element 32 by the light receiving element 34. Therefore, it is possible to provide the distance measuring device 30 which has a simple structure or a high degree of freedom of arrangement and can perform high quality distance measurement by emitting light in a desired direction over a wide range.

FIG. 16 is a schematic layout diagram of the distance measuring device 50 according to the third embodiment. The distance measuring device 50 includes a light source 51, a rotating element 52, a separating element 53, and a light receiving element 54. Further, the distance measuring device 50 includes a control unit 55 that controls a light source 51, a rotating element 52, and a light receiving element 54.

The light source 51, the separation element 53, the light receiving element 54, and the control unit 55 have the same configurations as the light source 31, the separation element 33, the light receiving element 34, and the control unit 35 of the distance measuring device 30, respectively. On the other hand, in this embodiment, the rotating element 52 of the distance measuring device 50 has a plurality of side surfaces 52S, each of which functions as a light reflecting surface, and has a prismatic shape that rotates around the rotating shaft AY. It has a moving element 52.

More specifically, in the distance measuring device 30 of the second embodiment, the case where the rotating element 32 is a polygon mirror having a pyramid-shaped (polygonal frustum) shape has been described. On the other hand, in this embodiment, the rotating element 52 is a polygon mirror having a prismatic shape (polygonal column shape).

In this embodiment, the emission direction of the scanning light L2 emitted from the rotating element 52 changes periodically. The region where the scanning light L2 is irradiated within one change cycle in the emission direction of the scanning light L2 is the scanning region R0. The scanning area R0 is a virtual three-dimensional space from which the scanning light L2 is emitted. In FIG. 16, the outer edge of the scanning region R0 is schematically shown by a broken line.

For example, the scanning region R0 is a height range along the height direction D1 corresponding to the axial direction of the rotation axis AY, and a width direction range along the width direction D2 corresponding to the direction perpendicular to the rotation axis AY. And can be defined as a cone-shaped space having a depth direction range along the depth direction corresponding to the axial direction of the optical axis of the scanning light L2.

For example, the normal vector of the side surface 52S of the rotating element 52 changes periodically according to the rotation of the rotating element 52. Further, in the present embodiment, the light source 51 emits the emitted light L1 toward the rotating element 52 so that the emitted light L1 is incident on any of the side surfaces 52S of the rotating element 52.

Therefore, for example, the height range of the scanning region R0 is the light of the scanning light L2 determined by the axial direction of the optical axis of the emitted light L1 and the normal vector of the side surface 52S of the rotating element 52 on which the emitted light L1 is incident. Corresponds to the range of change of the axial component of the rotating shaft AY in the axial direction of the shaft. Further, the width direction range of the scanning region R0 corresponds to the change range of the component in the direction perpendicular to the rotation axis AY in the axial direction of the scanning light L2. Further, the depth direction range of the scanning area R0 corresponds to a range of distances at which the scanning light L2 can maintain a predetermined intensity (intensity that can be detected by the distance measuring device 50).

Further, when a virtual plane separated from the rotating element 52 in the scanning region R0 by a predetermined distance is defined as the scanning surface R1, the scanning surface R1 is two-dimensionally extending along the height direction D1 and the width direction D2. It can be defined as an area. The scanning light L2 is emitted toward the scanning region R0 so as to scan the scanning surface R1.

FIG. 17 is a perspective view of the rotating element 52. In this embodiment, the rotating element 52 includes a support 52A and a rotating body 52B supported by the support 52A so as to be rotatable around the rotation shaft AY with respect to the support 52A. .. That is, in this embodiment, the rotating element 52 is a polygon mirror having a rotating body 52B.

In this embodiment, the rotating body 52B of the rotating element 52 has a right-angled pillar shape with the axial direction of the rotating shaft AY as the height direction. In this embodiment, the rotating body 52B has a regular triangular prism shape having three side surfaces 52SA, 52SB and 52SC as the side surface 52S. In the following, the side surface 52SA of the rotating body 52B may be referred to as a first side surface, and similarly, the side surfaces 52SB and 52SC may be referred to as second and third side surfaces, respectively.

In this embodiment, each of the side surfaces 52SA, 52SB and 52SC of the rotating body 52B is a part of a plane parallel to the axial direction of the rotating shaft AY. The side surfaces 52SA, 52SB and 52SC of the rotating body 52B are arranged so as to surround the rotating shaft AY at a position separated from the rotating shaft AY when viewed from a direction along the axial direction of the rotating shaft AY.

In the present specification, the term "rotating body 52B" having a prismatic shape means, for example, that the rotating body 52B has an outer shape portion forming a side surface of the prism. For example, the rotating body 52B may have a portion having another shape in addition to the prismatic portion. Further, the rotating body 52B may have irregularities or through holes on the side surface 52S, the upper surface or the bottom surface.

For example, the rotating body 52B of the rotating element 52 has a prismatic main body portion and a convex portion protruding from the bottom surface of the main body portion along the axial direction of the rotating shaft AY. The convex portion is rotatably coupled to the support 52A at its end. For example, the convex portion is a part of a shaft penetrating between the bottom surface and the upper surface of the main body portion.

Next, the distance measuring device 50 has a reflection type diffraction grating 60 provided on at least one of the side surfaces 52S of the rotating body 52B of the rotating element 52. In this embodiment, the diffraction grating 60 has reflective first and second diffraction gratings 61 and 62 provided on the side surfaces 52SA and 52SB, respectively. The first and second diffraction gratings 61 and 62 have a plurality of grating grooves 61A and 62A arranged along the side surfaces 52SA and 52SB, respectively.

In this embodiment, the first diffraction gratings 61 extend along the direction perpendicular to the rotation axis AY on the side surface 52SA of the rotation body 52B, and are arranged along the axial direction of the rotation axis AY. It has a plurality of grating grooves 61A. Further, a plurality of second diffraction gratings 62 extend along the direction perpendicular to the extension direction of the rotation axis AY on the side surface 52SB of the rotation body 52B, and are arranged along the axial direction of the rotation axis AY. Has a grating groove 62A of.

Further, in this embodiment, the diffraction grating 60 is not provided on the third side surface 52SC of the rotating body 52B. In this embodiment, the third side surface 52SC is a plane that is parallel to the axial direction of the rotation axis AY and has reflectivity with respect to the emitted light L1. That is, in this embodiment, the first and second side surfaces 52SA and 52SB function as diffracted and reflecting surfaces that diffract and reflect the emitted light L1, and the third side surface 52SC functions as a reflecting surface that reflects the emitted light L1. To do.

FIG. 18A is a schematic side view of the rotating body 52B when the rotating body 52B is viewed in a direction perpendicular to the rotating shaft AY and in a direction parallel to the first side surface 52SA of the rotating body 52B. is there. Further, FIG. 18B shows a schematic side surface of the rotating body 52B when the rotating body 52B is viewed in a direction perpendicular to the rotating shaft AY and in a direction parallel to the second side surface 52SB of the rotating body 52B. It is a figure. In FIGS. 18A and 18B, only a part of the side surface of the rotating body 52B is shown. The configuration of the diffraction grating 60 will be described with reference to FIGS. 18A and 18B.

In this embodiment, the first diffraction grating 61 is the first direction in the axial direction of the rotating shaft AY (the direction from the support 52A to the rotating body 52B in the axial direction of the rotating shaft AY, and is shown in the figure. (Upward) A blazed diffraction grating having a wave vector in DY4.

Further, the first diffraction grating 61 includes a lattice surface (a surface defined by the top of the lattice groove 61A, a first diffraction grating surface) DP1 parallel to the side surface 52SA of the rotating body 52B, and the lattice surfaces DP1 to the first. It has a blaze plane (first blaze plane) 61AS that is inclined by an angle (first blaze angle) θ _b3 toward the direction DY4 and is arranged at a pitch (distance between adjacent lattice grooves 61A) d _3. .. As shown in FIG. 18A, the angle formed by the normal of the lattice surface DP1 and the normal of the blaze surface 61AS is the angle θ _b3 .

Further, the second diffraction grating 62 is in a second direction opposite to the first direction DY4 in the axial direction of the rotation axis AY (direction from the rotating body 52B to the support 52A in the axial direction of the rotation axis AY). , Downward in the figure) A blazed diffraction grating having a wave vector on DY5.

Further, the second diffraction grating 62 includes a lattice surface (a surface defined by the top of the lattice groove 62A, a second diffraction grating surface) DP2 parallel to the side surface 52SB of the rotating body 52B, and the lattice surfaces DP2 to the second. It has a blaze plane (second blaze plane) 62AS that is inclined by an angle (second blaze angle) θ _b4 toward the direction DY 5 and is arranged at a pitch (distance between adjacent lattice grooves 62A) d _4. .. As shown in FIG. 18B, the angle formed by the normal of the lattice surface DP2 and the normal of the blaze surface 62AS is the angle θ _b4 .

In other words, in this embodiment, the diffraction grating 60 is formed on a first diffraction grating 61 provided on the first side surface 52SA of the rotating body 52B and a second side surface 52SB different from the first side surface 52SA. Includes a second diffraction grating 62 provided. Further, each of the first and second diffraction gratings 61 and 62 extends along the direction perpendicular to the axial direction of the rotation axis AY, and is arranged along the axial direction of the rotation axis AY. Has lattice grooves 61A and 62A. Further, in this embodiment, the first and second diffraction gratings 61 and 62 are blazed diffraction gratings having different characteristics from each other.

19A, 19B, and 19C are diagrams schematically showing the incident direction of the emitted light L1 and the emitted direction of the scanning light L2 with respect to the rotating body 52B of the rotating element 52. The incident mode of the emitted light L1 and the emitted mode of the scanning light L2 will be described with reference to FIGS. 19A to 19C.

In FIGS. 19A to 19C, the axial direction of the rotation shaft AY is referred to as the y direction for the sake of clarity of explanation. Further, in FIGS. 19A to 19C, there is an example in which the emitted light L1 is incident on the rotating body 52B along the direction perpendicular to the y direction, and the pitch d ₄ of the lattice groove 62A is equal to _{the pitch d 3} of the lattice groove 61A. Explain to. The axial direction of the optical axis of the emitted light L1 when it is incident on the rotating body 52B is referred to as the z direction. Further, a direction orthogonal to both the y direction and the z direction is referred to as an x direction.

For example, in this embodiment, each of the side surfaces 52S of the rotating body 52B is a plane extending along the axial direction of the rotating shaft AY. Therefore, each normal vector of the side surface 52S of the rotating body 52B has no component in the y direction. Further, in the rotating body 52B, the components in the x-direction and the z-direction in the normal vectors of the side surfaces 52S and the lattice planes DP1 and DP2 of the first and second diffraction gratings 61 and 62 change periodically. To rotate.

FIG. 19A shows the emitted light L1 (first emitted light L11) and the scanning light L2 (first scanning light) during the first period P1 in which the emitted light L1 is incident on the first side surface 52SA of the rotating body 52B. It is a figure which shows the aspect of L21) schematically.

In the first period P1, the first emitted light L11 is diffracted and reflected by the first diffraction grating 61. Further, the first emitted light L11 diffracted and reflected by the first diffraction grating 61 is emitted as scanning light L21.

Here, in this embodiment, the first diffraction grating 61 is a blazed diffraction grating. A blazed grating is a diffraction grating configured to maximize the diffraction efficiency of a predetermined diffraction order and wavelength and minimize the diffraction efficiency of other diffraction orders and wavelengths. Therefore, the light diffracted by the blazed diffraction grating is the light whose main component is diffracted light of a specific order.

Further, in this embodiment, the emission direction of the diffracted light of the order which is the main component is determined by the blaze angle θ _{b3 , the pitch d 3} of the lattice groove 61A, the wavelength of the emission light L1, and the incident angle of the emission light L1. .. _{That is, by setting the blaze angle θ b3} of the blazed diffraction grating and the pitch d ₃ of the lattice groove 61A according to the wavelength of the emitted light L1, the first emitted light L11 incident on the lattice surface DP1 of the blazed diffraction grating is generated. The first scanning light L21 can be reflected at a desired angle.

In this embodiment, the emitted light L11 is incident on the first diffraction grating 21B from the direction perpendicular to the y direction, and the normal of the blaze surface 61AS of the first diffraction grating 61 is from the first side surface 52SA. It is tilted by an _{angle θ b3} in the first direction DY4 in the y direction. Therefore, in the y direction, the first scanning light L21 is diffracted and reflected by the first diffraction grating 61 toward the first direction DY4.

As described above, in the first period P1, the first scanning light L21 is emitted in the y direction in a direction different from the direction in which the first emitted light L11 is specularly reflected on the first side surface 52SA. In the example shown in FIG. 19A, the first emitted light L11 has no component in the y direction, but the first scanning light L21 has a component in the y direction. Further, the y-direction component of the first scanning light L21 hardly changes during the first period P1.

Next, FIG. 19B shows the emitted light L1 (second emitted light L12) and the scanning light L2 (second emitted light L12) during the second period P2 in which the emitted light L1 is incident on the second side surface 52SB of the rotating body 52B. It is a figure which shows typically the aspect of the scanning light L22). In the second period P2B, the emitted light L1 is diffracted and reflected by the second diffraction grating 62.

In this embodiment, the second diffraction grating 62 is different from the first diffraction grating 61 in which the normal of the blazed surface 62AS is inclined in the second direction DY5 opposite to the first direction DY4 in the y direction. It is a blazed diffraction grating with different characteristics.

Therefore, in the y direction, the second emitted light L12 is diffracted and reflected by the second diffraction grating 62 as scanning light L22 in a direction different from the second direction DY5, that is, the first direction DY4. Further, the second scanning light L22 is emitted in a direction different from that of the first scanning light L21 in the y direction. Further, the y-direction component of the second scanning light L22 hardly changes during the second period P2.

FIG. 19C shows the emitted light L1 (third emitted light L13) and the scanning light L2 (third scanning light) during the third period P3B in which the emitted light L1 is incident on the third side surface 52SC of the rotating body 52B. It is a figure which shows the aspect of L23) schematically.

In this embodiment, the third side surface 52SC is not provided with a diffraction grating. Therefore, in the third period P3, the emitted light L1 is reflected by the third side surface 52SC. Therefore, the emission direction of the third scanning light L23 is a direction corresponding to the reflection condition on the third side surface 52SC of the third emission light L13 in all of the x direction, the y direction, and the z direction. For example, in the example shown in FIG. 19C, both the third emitted light L13 and the third scanning light L23 have no component in the y direction.

As described above, the scanning light L2 is in the x direction according to the rotation of the rotating body 52B so that the components in the y direction are different between the first, second and third side surfaces 52SA, 52SB and 52SC of the rotating body 12BB. And, it is emitted while changing the component in the z direction. In other words, when the plane PL1 is a plane that passes through the incident position of the emitted light L1 on the rotating body 52B and is perpendicular to the rotating axis AY, the scanning light L2 is the first, second, and third side surfaces 52SA. The angles formed by the plane PL1 are reflected between the 52SB and 52SC in a plurality of directions different from each other.

FIG. 20 is a diagram schematically showing an irradiated position of the scanning light L2 on the scanning surface R1. In FIG. 20, the scanning locus of the scanning light L2 on the scanning surface R1 is shown by a broken line. In this embodiment, the scanning light L2 is used in the first period P1 (first side surface 52SA), the second period P2 (second side surface 52SB), and the third period P3 (third side surface 52SC). , Are sequentially emitted so as to draw trajectories TR1, TR2, and TR3 along the width direction D2, respectively.

In other words, the distance measuring device 50 sets the scanning line along the width direction D2 corresponding to the direction perpendicular to the rotation axis AY of the rotating body 52B in the rotating element 52 to the height direction D1 with respect to the scanning region R0. Raster scanning is performed so as to obtain a plurality of lines along the line. Further, the distance measuring device 50 performs an operation such as periodically performing the raster scanning.

As described above, in the present embodiment, a blazed diffraction grating is provided as a diffraction grating 60 on at least one side surface 52S of the rotating element 52 having the prismatic rotating body 52B, and the rotating element 52 is rotated. By reflecting the emitted light L1, the scanning light L2 is emitted toward the scanning region R0.

Therefore, for example, it is selected whether or not to provide the diffraction grating 60 for each side surface 52S, and the diffraction conditions of the diffraction grating 60 provided for each side surface 52S (the tilt direction of the blaze surface, the pitch of the lattice grooves, etc.) are changed. As a result, it is possible to perform optical scanning in a wide range using a simple prismatic polygon mirror. For example, even if the blaze angles of the first and second diffraction gratings 61 and 62 and the pitch of the grating grooves are the same, if they have wave vector in the same different directions, they have different diffraction conditions. Can be regarded. As a result, for example, it is not necessary to prepare a plurality of light sources or use a polygon mirror having a complicated shape in order to widen the scanning area in the axial direction of the rotation axis AY.

For example, the fluctuation of the elevation / depression angle of light when the light is specularly reflected by the side surface inclined with respect to the rotation axis AY, and the non-uniformity of the irradiation density of the scanning light L2 (pulse light) to the scanning region R0 due to this. (The portion where the distance between the irradiation positions of the adjacent scanning light L2 is large and the portion where the distance is small is formed) does not occur. Further, since the rotating body 52B has a simple prismatic shape, it can be easily manufactured, and since high rotation accuracy can be maintained, the emission direction of the scanning light L2 may become unstable. It is suppressed. Therefore, it is possible to obtain highly accurate and even scanning results and distance measurement results for a wide range of scanning areas R0.

Further, by combining the rotating element 52 and the diffraction grating 60, the emission direction of the scanning light L2 is stabilized even when the emission light L1 is incident from various directions, for example. Therefore, the degree of freedom in arranging other optical elements such as the light source 51 is greatly improved.

FIG. 21 is a diagram schematically showing an arrangement example of the light source 51 and the rotating element 52. As shown in FIG. 21, the light source 51 causes the emitted light L1 to be incident on each of the side surfaces 52S of the rotating element 52 along the direction intersecting the plane PL1 perpendicular to the rotation axis AY. Can be configured and arranged. That is, the emitted light L1 may be configured to enter the rotating element 52 from a direction having a component in the y direction.

Even in this case, the components in the y-direction in the emission direction of the scanning light L2, for example, the emission direction of the scanning light L2 are stable depending on the blaze condition of the diffraction grating 60. Thereby, for example, the distance measuring device 50 can be miniaturized without sacrificing the scanning accuracy and the distance measuring accuracy.

In this embodiment, the case where the first and second diffraction gratings 61 and 62 are blazed diffraction gratings having a wave vector in the axial direction (that is, the y direction) of the rotation axis AY has been described. However, the configurations of the first and second diffraction gratings 61 and 62 are not limited to this.

For example, the first and second diffraction gratings 61 and 62 may be diffraction gratings that diffract the emitted light L1 so that the specific diffracted light is the main component. Further, for example, a plurality of first and second diffraction gratings 61 and 62 each extend along the direction perpendicular to the axial direction of the rotation axis AY and are arranged along the axial direction of the rotation axis AY. It suffices to have the lattice grooves 61A and 62A of.

Further, even when the first and second diffraction gratings 61 and 62 are blazed diffraction gratings, the case is not limited to the case where the first and second diffraction gratings 61 and 62 have wave number vectors in different directions. For example, the first and second diffraction gratings 61 and 62 have wave vector in the same direction (for example, the first direction DY4) and have different blazing angles (the angles θ _b3 and θ _b4 are different). It may be a blazed diffraction grating. Even in this case, for example, in the y direction, the first and second scanning lights L21 and 22 are emitted from the first and second diffraction gratings 21B and 22B toward different positions, respectively.

Further, in this embodiment, the case where the diffraction grating 60 has the first and second diffraction gratings 61 and 62 under different diffraction conditions has been described. However, the diffraction grating 60 may be provided on at least one side surface 52S. For example, the diffraction grating 60 may be provided only on the first side surface 52SA. Further, the first and second diffraction gratings 61 and 62 may have the same diffraction conditions.

Further, in this embodiment, the case where the rotating body 52B has a triangular prism shape has been described. However, the number of side surfaces of the rotating body 52B is not limited to three, and may have three or more side surfaces.

As described above, the distance measuring device 50 includes, for example, a light source 51 that emits light (emitted light L1) and a prism that rotates around the rotating shaft AY and has the axial direction of the rotating shaft AY as the height direction. It has a rotating body 52B having a shape, and light is applied to at least one side surface (first and second side surfaces 52SA and 52SB) of a plurality of side surfaces 52S of the rotating body 52B, and the main component is diffracted light of a specific order. Light projected through a rotating element 52 provided with a reflective diffraction grating 60 and the rotating element 52, reflected by an object OB, and passed through the rotating element 52 (reflected light L3). It has a light receiving element 54 that receives light, and a ranging unit 55D that measures the distance to the object OB based on the result of receiving light that has passed through the rotating element 52 by the light receiving element 54. Therefore, there is provided a distance measuring device 50 which has a rotating element 52 having a rotating light reflector and can perform high quality distance measuring by emitting light in a desired direction over a wide range. can do.

In Examples 2 and 3 described above, the case where each of the side surface 32S of the rotating body 32B and the side surface 52S of the rotating body 52 functions as a light reflecting surface for reflecting (and diffracting) the emitted light L1 has been described. However, the light reflecting surface may be any of the side surfaces 32S of the rotating body 32, and may be any of the side surfaces 52S of the rotating body 52.

In other words, like the rotating bodies 32 and 52, a pyramid shape in which the rotating body rotates around the rotating shaft AY (first rotating shaft) and the axial direction of the rotating shaft is the height direction. In the case of having a pyramid trapezoidal shape or a prismatic shape, at least one light reflecting surface for reflecting the emitted light L1 may be provided on at least one side surface of the plurality of side surfaces of the rotating body.

Further, the scanning light L2 in the present invention can be used for applications other than ranging, for example, scanning applications and simple lighting applications. In this case, for example, the distance measuring device 10 may not have the light receiving element 14 and the distance measuring unit 15D. In this case, for example, the light source 11, the rotating element 12, and the diffraction grating 20 function as a light emitting device that emits scanning light L2. Even in this case, since the change in the elevation / depression angle of the scanning light L2 is suppressed, stable scanning information and light distribution can be obtained.

In other words, for example, the light emitting device according to the present invention includes a light source that emits light and at least one that rotates around at least one rotation axis (first rotation axis) and reflects the light. A rotating body (rotating body 12B, 32B or 52B) having the above light reflecting surface (light reflecting surface 12S, side surface 32S or 52S), and any one of the at least one light reflecting surface ( A reflection type diffraction grid (diffraction lattice 20, 40 or 60) for diffracting the light so that the diffracted light of a specific order is the main component is provided on the light reflecting surface 12S, the side surface 32SA, 32SB, 52SA or 52SB). It has a rotating element (rotating element 12, 32 or 52). This makes it possible to provide a light emitting device capable of emitting light in a desired direction over a wide range.

10, 30, 50 Distance measuring device 11, 31, 51 Light source 12, 32, 52 Rotating element 12B, 32B, 52B Rotating body 20, 40, 60 Diffraction grating

Claims (12)

A light source that emits light and
A rotating body having at least one light reflecting surface that rotates around a first rotating shaft and reflects the light, and the light reflecting surface on any one of the at least one light reflecting surfaces. A light emitting device comprising: a rotating element provided with a reflection type diffraction grating that diffracts light so that diffracted light of a specific order is a main component. Each of the diffraction gratings has a plurality of grating grooves extending along a direction perpendicular to the axial direction of the first rotation axis and arranged along the axial direction of the first rotation axis. The light emitting device according to claim 1. The light emitting device according to claim 1 or 2, wherein the diffraction grating is a blazed diffraction grating. The light source is characterized in that light is incident on each of the at least one light reflecting surface of the rotating body along a direction intersecting a plane perpendicular to the first rotation axis. The light emitting device according to any one of 1 to 3. The rotating body has a pyramid shape, a frustum shape, or a prism shape that rotates around the first rotation shaft and has the axial direction of the first rotation shaft as the height direction.
The light emitting device according to any one of claims 1 to 4, wherein the at least one light reflecting surface is provided on at least one side surface of the plurality of side surfaces of the rotating body. .. The diffraction grating is different from the first diffraction grating provided on the first side surface of the plurality of side surfaces of the rotating body and the first side surface of the plurality of side surfaces of the rotating body. Including a second diffraction grating provided on the second side surface,
Each of the first and second diffraction gratings extends along a direction perpendicular to the axial direction of the first rotation axis, and the rotation within each of the first and second side surfaces. The light emitting device according to claim 5, further comprising a plurality of grating grooves arranged in a direction along the axial direction of the shaft. The light emitting device according to claim 6, wherein the first and second diffraction gratings are blazed diffraction gratings having different characteristics. The first diffraction grating is a blazed diffraction grating having a wave vector in the first direction in the axial direction of the first rotation axis.
6. The second diffraction grating is a blazed diffraction grating having a wave vector in a second direction opposite to the first direction in the axial direction of the first rotation axis. Or the light emitting device according to 7. The rotating body of the rotating element is characterized in that it rotates around the first rotating shaft and rotates around a second rotating shaft different from the first rotating shaft. The light emitting device according to any one of claims 1 to 4. The light emitting device according to claim 5, wherein the rotating body of the rotating element has a regular polygonal pyramid shape. The light emitting device according to any one of claims 1 to 10.
A light receiving element that is projected through the rotating element, reflected by an object, and receives light that has passed through the rotating element.
A distance measuring device including a distance measuring unit that measures a distance to an object based on the result of receiving light from the rotating element by the light receiving element. A light source that emits light and
A rotating element having a pyramid-shaped, frustum-shaped, or prismatic-shaped rotating body that rotates around a rotating shaft and whose height direction is the axial direction of the rotating shaft
It has a reflection type diffraction grating provided on at least one side surface of the plurality of side surfaces of the rotating body.
The at least one side surface and the other side surface of the plurality of side surfaces of the rotating body reflect the light emitted from the light source in directions in which the angles formed by the plane perpendicular to the rotation axis are different from each other. A light emitting device characterized by allowing the light to be emitted.

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