Optical system and electromagnetic wave detection device

Abstract

This optical system includes an optical member and a detector. The optical member includes a first surface. The first surface has first and second regions. From the first region, electromagnetic waves emitted from an emission unit travel in a first direction. From the second region, reflected waves of the electromagnetic waves traveling in the first direction from an object travel in a second direction. The second direction is different from the first direction. The detector detects reflection waves traveling in the second direction.

Description

Optical System and Electromagnetic Wave Detection Device Cross - reference to Related Applications 【0001】 This application claims the priority of Japanese Patent Application No. 2024 - 218227 filed in Japan on December 12, 2024, and incorporates the entire disclosure of the prior application herein for reference purposes. 【0002】 The present invention relates to an optical system and an electromagnetic wave detection device. 【0003】 In a distance measurement device such as LiDAR, an optical member that reflects or transmits light is used. While the propagation axes of the radiation wave emitted from the radiation source and the reflected wave from the irradiation target coincide, the reflected wave transmitted through the optical member is detected by the detector (see Patent Document 1). 【0004】 Japanese Patent Application Laid - Open No. 2003 - 172612 【0005】 The optical system according to the first aspect includes: an optical member in which, in a first region and a second region on a first surface, from the first region, the electromagnetic wave emitted from the radiation part travels in a first direction, and from the second region, the reflected wave of the electromagnetic wave reflected by the object travels in a second direction different from the first direction; and a detection part that detects the reflected wave traveling in the second direction. 【0006】 The electromagnetic wave detection device according to the second aspect includes: the optical system according to the first aspect; and a scanning part that changes the radiation direction of the electromagnetic wave traveling in the first direction. 【0007】 It is a configuration diagram of an optical system and an electromagnetic wave detection device according to the first embodiment. It is a functional block diagram showing the schematic configuration of an electromagnetic wave detection device including the optical system of FIG. 1. It is a configuration diagram of an optical system and an electromagnetic wave detection device according to the second embodiment. It is a configuration diagram of an optical system and an electromagnetic wave detection device according to the third embodiment. 【0008】 Hereinafter, embodiments of an optical system and an electromagnetic wave detection device to which the present disclosure is applied will be described with reference to the drawings. 【0009】As shown in Figure 1, in this disclosure, the optical system 10 comprises an optical member 11 and a detection unit 12. The optical system 10 may further comprise a collimator lens 13 and a focusing lens 14. The optical system 10 may together with a scanning unit 21 to constitute an electromagnetic wave detection device 20. The electromagnetic wave detection device 20 may further comprise a radiating unit 22 and a control unit 23, as shown in Figure 2. 【0010】 In the drawings of this application, electromagnetic waves are depicted with dashed lines. In addition, in the drawings of this application, wireless or wired communication lines that transmit signals between functional blocks are depicted with solid lines. 【0011】 As shown in Figure 2, the electromagnetic wave em emitted by the radiating unit 22 is irradiated onto the object ob via the optical system 10. The reflected wave re of the electromagnetic wave em irradiated onto the object ob is incident on the optical system 10. The control unit 23 generates information about the object ob based on the electromagnetic wave em emitted by the radiating unit 22 and the reflected wave re detected by the detection unit 12 of the optical system 10. The components of the electromagnetic wave detection device 20 are described in detail below. 【0012】 In this specification, the reflection of any electromagnetic wave by any optical component may mean that the component reflects the electromagnetic wave with a reflectance of more than 50%. Furthermore, the reflectance of the optical component to the electromagnetic wave is preferably more than 70%, more preferably more than 80%, even more preferably more than 90%, and most preferably substantially 100%. 【0013】 In this specification, the transmission of any electromagnetic wave by any optical component may mean that the electromagnetic wave is transmitted with a transmittance of more than 50%. Furthermore, the transmittance of the optical component to the electromagnetic wave is preferably more than 70%, more preferably more than 80%, even more preferably more than 90%, and most preferably substantially 100%. 【0014】As shown in Figure 1, the radiating unit 22 may emit electromagnetic waves em. Electromagnetic waves em may include, for example, at least one of infrared rays, visible light, ultraviolet rays, and radio waves. Electromagnetic waves em may also be invisible light such as near-infrared rays. The radiating unit 22 may emit electromagnetic waves em in the form of a narrow beam, for example, 0.5°. Alternatively, the radiating unit 22 may emit electromagnetic waves em in a pulsed manner. The radiating unit 22 may switch between emitting and stopping electromagnetic waves em based on the control of the control unit 23. The radiating unit 22 may include, for example, a radiation source such as an LD (Laser Diode) and an LED (Light Emitting Diode). 【0015】 The collimator lens 13 may collimate the electromagnetic wave em emitted by the radiating part 22. 【0016】 The optical member 11 may be positioned in the radiation path of the electromagnetic wave em collimated by the collimator lens 13. For example, the optical member 11 may be positioned in the direction of radiation of the electromagnetic wave em via the collimator lens 13. Alternatively, the optical member 11 may be positioned in the direction in which the electromagnetic wave em collimated by the collimator lens 13 is deflected using at least one mirror. 【0017】 The optical member 11 has a first surface 11S1. The first surface 11S1 may be planar. The first surface 11S1 may have through holes in part, and in this disclosure, the portion that is hollow due to the through holes may also be included in the first surface. The optical member 11 may be arranged such that the first surface 11S1 is inclined with respect to the propagation axis of the electromagnetic wave em radiated from the radiating unit 22. The inclination angle of the propagation axis with respect to the first surface 11S1 may be 45°. The optical member 11 may be plate-shaped or triangular prism-shaped. In the following description, a plate-shaped optical member 11 will be described. In a configuration in which the optical member 11 is plate-shaped, the first surface 11S1 is the main surface of the plate-shaped member. The main surface means the surface having the largest area. 【0018】The first surface 11S1 has a first region 11R1 and a second region 11R2. From the first region 11R1, electromagnetic waves em radiated from the radiating portion 22 propagate in a first direction d1. Specifically, the first region 11R1 may allow electromagnetic waves propagating inside the optical member 11 to propagate in the first direction d1. Alternatively, the first region 11R1 may allow electromagnetic waves em incident from outside the optical member 11 to propagate in the first direction d1. From the second region 11R2, the reflected waves re of the electromagnetic waves em propagated in the first direction d1 at the object ob propagate in a second direction d2. Specifically, the second region 11R2 may allow electromagnetic waves propagating inside the optical member 11 to propagate in a second direction d2. The second region 11R2 may allow electromagnetic waves em incident from outside the optical member to propagate in a second direction d2. 【0019】 The reflected wave re may be an electromagnetic wave whose bandwidth overlaps with that of the electromagnetic wave em. The first direction d1 may coincide with the direction in which the electromagnetic wave em radiated from the radiating section 22 propagates. The second direction d2 is a different direction from the first direction d1. The second direction d2 may be a direction inclined with respect to the first direction d1. The second surface 11S2, which is the back surface of the first surface 11S1, may be planar. A more specific configuration will be described below. 【0020】 The first region 11R1 may be located near the center of the first surface 11S1. The first region 11R1 may be smaller than the second region 11R2. The first region 11R1 may be approximately the same size as the beam of electromagnetic waves em radiated from the radiating section 22 when viewed from the direction of incidence of the electromagnetic waves em onto the first surface 11S1. As described above, the optical member 11 is plate-shaped, and the first region 11R1 is elliptical. The first region 11R1 may be circular when viewed from the radiating section 22. If θ1 is the inclination angle of the propagation axis of the electromagnetic waves em radiated from the radiating section 22 with respect to the first surface 11S1, the ratio of the minor axis to the major axis may be 1:1 / cos(90°-θ1). The first region 11R1 may also be circular. 【0021】In the first embodiment, the first region 11R1 may transmit electromagnetic waves em. For example, the optical member 11 may be made entirely of a material that transmits electromagnetic waves em, and the first region 11R1 may not have a reflective member or the like. Furthermore, the portion of the optical member 11 that overlaps with the first region 11R1 as viewed from the direction of propagation of the electromagnetic wave em radiated from the radiating portion 22 does not have to have a reflective member that reflects electromagnetic waves em. Specifically, the portion of the second surface 11S2, which is the back surface of the first surface 11S1 of the plate-shaped optical member 11, that overlaps with the first region 11R1 as viewed from the direction of propagation of the electromagnetic wave em does not have to have a reflective member. The mounting position and orientation of the optical member 11 may be adjusted so that the bundle of electromagnetic waves em radiated from the radiating portion 22 overlaps with the first region 11R1. 【0022】 In the first embodiment, the second region 11R2 may reflect electromagnetic waves. Alternatively, the electromagnetic waves may be reflected on the back surface 11S2 of the second region 11R2 and propagated from the second region 11R2 in the second direction d2. More specifically, the second region 11R2 may reflect reflected waves re. The second region 11R2 of the optical member 11 may be provided with a reflective member that reflects reflected waves re. The reflective member may be an aluminum mirror or a gold mirror. 【0023】 The second region 11R2 may surround the first region 11R1. The second region 11R2 may be a region on the first surface 11S1 other than the first region 11R1. The second region 11R2 may be located only around the first region 11R1. The second region 11R2 may surround only a part of the outer perimeter of the first region 11R1. 【0024】 The optical element 11 may be something other than a half-mirror. 【0025】 The scanning unit 21 may be positioned on the first direction d1 side of the optical member 11. The scanning unit 21 may change the radiation direction of the electromagnetic wave em propagating from the optical member 11. The scanning unit 21 may further change the propagation direction of the reflected wave re, which is the electromagnetic wave em reflected by the object ob, so that it is directed towards the optical member 11. 【0026】The scanning unit 21 may, for example, radiate electromagnetic waves em in multiple different directions in space by reflecting them while changing their direction. The scanning unit 21 may change the direction in which it reflects electromagnetic waves em based on the control of the control unit 23. The scanning unit 21 may change the direction of reflection around two axes that intersect each other, with these two axes as axes of rotation. These two axes may be orthogonal. The two directions in which it swings around these two axes are called the first swing direction sd1 and the second swing direction sd2, respectively. The scanning unit 21 includes, for example, a MEMS (Micro Electro Mechanical Systems) mirror, a polygon mirror, and a galvanometer mirror. 【0027】 The condensing lens 14 may be located in a second direction d2 from the optical element 11. 【0028】 The detection unit 12 may be provided near the imaging position of the reflected wave re by the focusing lens 14. In a configuration in which the detection unit 12 does not include an element array, or in other words, is a single element, as will be described later, the detection unit 12 does not have to be provided near the imaging position of the reflected wave re. Specifically, the detection unit 12 may be located in a second direction d2 from the optical member 11. The detection unit 12 may be positioned relative to the optical member 11 such that the propagation axis of the reflected wave re propagating in the second direction d2 from the second region 11R2 of the optical member 11 is parallel to the detection axis of the detection unit 12. This propagation axis is the central axis of the reflected wave re propagating in the second direction d2 from the optical member 11. This detection axis passes through the center of the detection surface of the detection unit 12 and is perpendicular to the detection surface. 【0029】 The detection unit 12 detects the reflected wave re propagating from the optical member 11 in the second direction d2. The detection unit 12 may transmit detection information to the control unit 23 as a signal indicating that it has detected the reflected wave re from the object ob. 【0030】 The detection unit 12 more specifically includes elements that constitute a distance measuring sensor. For example, the detection unit 12 includes a single element such as an APD (Avalanche PhotoDiode), a PD (PhotoDiode), and a distance measuring image sensor. Alternatively, the detection unit 12 may include an array of elements such as an APD array, a PD array, a distance measuring imaging array, and a distance measuring image sensor. 【0031】 The control unit 23 includes one or more processors and memory. The processor may include at least one of a general-purpose processor that loads a specific program and executes a specific function, and a dedicated processor specialized for a specific process. The dedicated processor may include an Application Specific Integrated Circuit (ASIC). The processor may include a Programmable Logic Device (PLD). The PLD may include an FPGA (Field-Programmable Gate Array). The control unit 23 may include at least one of a System-on-a-Chip (SoC) and a System-In-a-Package (SiP) in which one or more processors cooperate. 【0032】 The control unit 23 may control the scanning unit 21 and the radiating unit 22. The control unit 23 may also generate three-dimensional position information of an arbitrary point on object ob based on the drive signal for controlling the scanning unit 21 and the information obtained from the detection unit 12. 【0033】 Specifically, the control unit 23 may acquire distance information for an arbitrary point on object ob by Time of Flight (ToF) based on the time when the radiating unit 22 emits pulsed electromagnetic waves em and the time when the detection unit 12 detects the reflected waves re after emission. 【0034】 Furthermore, the control unit 23 may calculate the deflection direction of the electromagnetic wave em and the reflected wave re based on the drive signal to the scanning unit 21. The deflection direction corresponds to the orientation of the reflective surface on which the scanning unit 21 changes the radiation direction of the electromagnetic wave em and the reflected wave re. The control unit 23 may calculate the deflection direction of the electromagnetic wave em as the direction of the first oscillation direction sd1 and the second oscillation direction sd2 components. 【0035】 The control unit 23 may output, for example, a sinusoidal drive signal that causes the scanning unit 21 to oscillate along a first oscillation direction sd1. The control unit 23 may output, for example, a sinusoidal drive signal that causes the scanning unit 21 to oscillate along a second oscillation direction sd2. 【0036】The control unit 23 may generate three-dimensional position information of the object ob based on the deflection direction and distance information to an arbitrary object point calculated as described above. 【0037】 Next, an optical system according to a second embodiment of this disclosure will be described. In the second embodiment, the structure of the optical members differs from that of the first embodiment. The second embodiment will be described below, focusing on the differences from the first embodiment. Note that the same reference numerals are used for parts having the same configuration in the first and second embodiments. 【0038】 As shown in Figure 3, the optical system 110 according to the second embodiment is configured similarly to the first embodiment, including an optical element 111 and a detection unit 12. The optical system 110 may further include a collimator lens 13 and a focusing lens 14, similarly to the first embodiment. The optical system 110 may together with the scanning unit 21 to constitute an electromagnetic wave detection device 120. The electromagnetic wave detection device 120 may further include a radiating unit 22 and a control unit 23, as shown in Figure 2. In the second embodiment, the configuration of the detection unit 12, collimator lens 13 and focusing lens 14, scanning unit 21, radiating unit 22, and control unit 23 is the same as in the first embodiment. 【0039】 The optical member 111 has a first surface 111S1. In the second embodiment, unlike the first embodiment, a through hole 111H is formed in the first surface 111S1 in a first region 111R1, which will be described later. As mentioned above, the portion that is empty due to the through hole 111H is also included in the first surface 111S1. 【0040】 The first surface 111S1 has a first region 111R1 and a second region 111R2. Similar to the first embodiment, the first region 111R1 propagates the electromagnetic wave em radiated from the radiating portion 22 in a first direction d1. Similar to the first embodiment, the second region 111R2 propagates the reflected wave re of the electromagnetic wave em propagated in the first direction d1 at the object ob in a second direction d2. In the second embodiment, the second direction d2 may be opposite to the first direction d1. Unlike the first embodiment, the first region 111R1 is circular from a manufacturing standpoint. The first region 111R1 may also be elliptical. 【0041】 The entire electromagnetic wave em radiated from the radiation unit 22 may pass through the through-hole 111H of the first region 111R1. Similar to the first embodiment, the optical member 111 may be adjusted in its mounting position and orientation such that the bundle of the electromagnetic wave em radiated from the radiation unit 22 and the through-hole 111H overlap. 【0042】 The through-hole 111H may include at least one of a cylindrical portion 111C and a tapered portion 111T. The cylindrical portion 111C may terminate at least at the first surface 111S1. The cylindrical portion 111C may define an inner peripheral surface with a constant inner diameter. The tapered portion 111T may terminate at least at the back surface 111S2 of the first surface 111S1. The tapered portion 111T may be connected to the second surface 111S2. In a plane passing through the central axis of the through-hole 111H, the inner peripheral surface of the tapered portion 111T may be inclined with respect to the central axis so as to increase in diameter toward the back surface 111S2. The tapered portion 111T may be formed so as to satisfy the following formula (1). θ2>90°-θ1 (1) Here, θ2 is an angle formed by the axis A of the through-hole 111H and the inner peripheral surface of the tapered portion 111T as viewed from a direction perpendicular to the traveling axis of the electromagnetic wave em and parallel to the first surface 111S1. 【0043】 The optical member 111 may further include an antireflection portion facing the radiation unit 22. The antireflection portion may be located on the inner peripheral surfaces of the tapered portion 111T and the cylindrical portion 111C. The antireflection portion may be located on the back surface 111S2. In the antireflection portion, reflection of the electromagnetic wave em is reduced at least more than the surrounding portions. The antireflection portion may be an absorption portion. The absorption portion absorbs the electromagnetic wave em. The absorption portion may be a black portion. The absorption portion may be composed of paint or a sheet. 【0044】 Next, an optical system according to the third embodiment of the present disclosure will be described. In the third embodiment, the structure of the optical member and the arrangement of the constituent elements are different from those of the first embodiment. Hereinafter, the third embodiment will be described focusing on the differences from the first embodiment. Note that the same reference numerals are given to the portions having the same configuration in the first embodiment and the third embodiment. 【0045】As shown in FIG. 4, the optical system 210 according to the third embodiment is configured to include an optical member 211 and a detection unit 12, similar to the first embodiment. The optical system 210 may further include a collimator lens 13 and a condenser lens 14, similar to the first embodiment. The optical system 210 may form an electromagnetic wave detection device 220 together with the scanning unit 21. The electromagnetic wave detection device 220 may further include a radiation unit 22 and a control unit 23 as shown in FIG. 2. In the third embodiment, the configurations of the detection unit 12, the collimator lens 13, the condenser lens 14, the scanning unit 21, the radiation unit 22, and the control unit 23 are the same as those in the first embodiment. 【0046】 In the third embodiment, different from the first and second embodiments, the first region 211R1 may reflect the electromagnetic wave em. Alternatively, the electromagnetic wave em may be reflected in the region corresponding to the first region 211R1 on the second surface 211S2 and advanced from the first region 211R1 in the second direction d2. A reflecting member for reflecting the electromagnetic wave em may be provided in a portion of the optical member 211 that overlaps the first region 211R1 as viewed from the traveling direction of the traveling path of the electromagnetic wave em. The reflecting member may be an aluminum mirror or a gold mirror. The mounting position and orientation of the optical member 211 may be adjusted so that the bundle of electromagnetic waves em radiated from the radiation unit 22 overlaps the first region 211R1. 【0047】 In the third embodiment, different from the first and second embodiments, the second region 211R2 may transmit the electromagnetic wave em. For example, the optical member 211 may be formed of a material that transmits the reflected wave re as a whole. Further, a reflecting member for reflecting the electromagnetic wave em may not be provided in a portion of the optical member 211 that overlaps the second region 211R2 as viewed from the traveling direction of the traveling path of the electromagnetic wave em radiated from the radiation unit 22. 【0048】In the third embodiment, the larger the diameter (size) of the first region 211R1, the larger the amount (width) of electromagnetic waves em incident on the first region 211R1 and reflected in the direction of the scanning unit 21. Therefore, the light intensity efficiency of the irradiation from the radiating unit 22 to the object ob (the ratio of the amount of light emitted by the radiating unit 22 to the amount of light irradiated to the object ob, and is called the irradiation efficiency) increases. On the other hand, the larger the diameter of the first region 211R1, the larger the amount (width) of reflected waves re incident on the first region 211R1 and shielded. Therefore, the light intensity efficiency of the light received from the object ob to the detection unit 12 (the ratio of the amount of light reflected by the object ob to the amount of light received by the detection unit 12, and is called the light reception efficiency) decreases. The diameter of the first region 211R1 may be designed to maximize the product of the irradiation efficiency and the light reception efficiency (called the illumination-reception efficiency). When the illumination efficiency is maximized, the maximum measurable distance or accuracy of the electromagnetic wave detection device may be maximized. Irradiation efficiency and light reception efficiency vary depending on the spread angle of the electromagnetic wave em emitted by the radiating unit 22 (the angle formed by the two outermost rays of the electromagnetic wave em), the focal length of the collimator lens 13, and the size of the scanning unit 21, etc. In the first or second embodiment described above, the diameter of the first region 11R1 or 111R1 may be designed similarly. 【0049】 Furthermore, the spread angle of the electromagnetic wave em emitted by the radiating unit 22 and the focal length of the collimator lens 13 affect the resolution of the Lidar. The size of the scanning unit 21 affects the swing angle of the MEMS mirror (angles of the first oscillation direction sd1 and the second oscillation direction sd2), and the resonant frequency, etc. 【0050】 In one embodiment, (1) the optical system comprises an optical member in which, in a first region and a second region on a first surface, electromagnetic waves emitted from a radiating unit propagate in a first direction from the first region, and reflected waves from the second region, which are the electromagnetic waves reflected by an object, propagate in a second direction different from the first direction, and a detection unit for detecting the reflected waves propagating in the second direction. 【0051】 (2) In the optical system of (1) above, the area in the first region irradiated with the electromagnetic wave is smaller than the area in the second region irradiated with the reflected wave. 【0052】(3) In the optical system of (1) or (2) above, the first region transmits the electromagnetic wave, and the second region reflects the reflected wave. 【0053】 (4) In the optical system of (1) or (2) above, the first region is a through hole through which the electromagnetic wave passes, and the second region reflects the reflected wave. 【0054】 (5) In the optical system of (4) above, the through hole includes a tapered portion on the radiating portion side that widens toward the radiating portion in the axial direction of the through hole, and the angle between the axis of the through hole and the tapered portion is greater than the angle obtained by subtracting the inclination angle of the propagation axis of the electromagnetic wave radiated from the radiating portion with respect to the first plane from 90°. 【0055】 (6) In the optical system of (4) or (5) above, the optical member further includes an absorbing portion on the inner circumferential surface of the through hole. 【0056】 (7) In the optical system of (1) or (2) above, the first region reflects the electromagnetic wave, and the second region transmits the reflected wave. 【0057】 (8) In any of the optical systems described in (1) to (7) above, the first region is located near the center of the optical member, and the second region is located around the first region. 【0058】 (9) In any optical system described in (1) to (8) above, the electromagnetic wave radiated from the radiating portion is propagated in the first direction from the first region of the first surface, and the reflected wave whose bandwidth overlaps with the electromagnetic wave incident on the second region of the first surface from the opposite direction to the first direction is propagated in the second direction different from the first direction. 【0059】 (10) In any of the optical systems described in (1) to (9) above, the electromagnetic waves emitted from the radiating unit are propagated from the first region at a rate exceeding 50% of the light intensity, or the reflected waves reflected by the object are propagated from the second region at a rate exceeding 50% of the light intensity. 【0060】(11) In any of the optical systems described in (1) to (10) above, the propagation axis of the reflected wave traveling in the second direction is parallel to the detection axis of the detection unit. 【0061】 In one embodiment, the electromagnetic wave detection device (12) comprises an optical system of any of (1) to (11) above, and a scanning unit that changes the radiation direction of the electromagnetic wave traveling in the first direction. 【0062】 The optical systems 10, 110, and 210, having the configuration described above, include an optical member 11 such that, in the first regions 11R1, 111R1, and 211R1 and the second regions 11R2, 111R2, and 211R2 on the first surfaces 11S1, 111S1, and 211S1, electromagnetic waves em radiated from the radiating unit 22 propagate in a first direction d1 from the first regions 11R1, 111R1, and 11R2, 111R2, and 211R2, and reflected waves re, obtained by reflecting the electromagnetic waves em off an object ob, propagate in a second direction d2 different from the first direction d1 from the second regions 11R2, 111R2, and 211R2. In an optical system, as described in Patent Document 1, in which the propagation axes of electromagnetic waves incident from a radiating unit and reflected waves obtained by reflecting said electromagnetic waves off an object are aligned by a half-mirror, a portion of the electromagnetic waves is lost when the electromagnetic waves from the radiating unit are reflected by a reflective surface located inside the half-mirror. Furthermore, when the reflected wave from the object is transmitted to the half-mirror, a portion of the reflected wave is lost. Therefore, the measurement sensitivity was reduced with the optical system described above. On the other hand, in the optical systems 10, 110 and 210 having the above configuration, the loss of electromagnetic waves em can be reduced when the electromagnetic waves em radiated from the radiating unit 22 are propagated in the first direction d1 by the first regions 11R1, 111R1 and 211R1, for example, on the surface of the optical members 11, 111 and 211. Also, when the reflected waves re, which are reflected by the electromagnetic waves em from the object ob, are propagated in the second direction d2 by the second regions 11R2, 111R2 and 211R2, the loss of reflected waves re can be reduced when the reflected waves re are propagated in the second direction d2 by the electromagnetic waves em from the object ob. 【0063】Furthermore, in optical systems 10, 110, and 210, the area irradiated by electromagnetic waves em in the first regions 11R1, 111R1, and 211R1 is smaller than the area irradiated by reflected waves re in the second regions 11R2, 111R2, and 211R2. With this configuration, the area of ​​the first regions 11R1, 111R1, and 211R1 irradiated by electromagnetic waves em is reduced. Therefore, when the electromagnetic waves em radiated from the radiating unit 22 are propagated in the first direction d1 from the first regions 11R1, 111R1, and 211R1, the loss of electromagnetic waves em can be further reduced. 【0064】 Furthermore, in the optical system 110, the first region 110R1 is a through-hole 111H through which the electromagnetic wave em passes, and the second region 111R2 reflects the reflected wave re. With this configuration, when the electromagnetic wave em passes through the first region 110R1, the attenuation of the electromagnetic wave em can be reduced compared to a configuration in which the electromagnetic wave em is transmitted through the first region 111R1. 【0065】 Furthermore, in the optical system 110, the through-hole 111H includes a tapered portion 111T on the radiating portion 22 side that widens toward the radiating portion 22 in the axial direction of the through-hole 111H, and the angle between the axis A of the through-hole 111H and the tapered portion 111T is greater than the angle obtained by subtracting the inclination angle of the propagation axis of the electromagnetic wave em radiated from the radiating portion 22 with respect to the first surface 111S1 from 90°. With this configuration, the irradiation of the tapered portion 111T by the electromagnetic wave em can be reduced. Therefore, the scattering of the electromagnetic wave em can be reduced. Consequently, the noise of the reflected wave re due to the scattered electromagnetic wave em can be reduced. 【0066】 Furthermore, in the optical system 110, the optical member 111 further includes an absorption portion around the through hole 111H. With this configuration, the absorption portion can absorb electromagnetic waves em. Therefore, noise in the reflected wave re due to electromagnetic waves em can be further reduced. 【0067】Furthermore, in optical systems 10, 110, and 210, the first regions 11R1, 111R1, and 211R1 are located near the center of the optical member 11, while the second regions 11R2, 111R2, and 211R2 are located around the first regions 11R1, 111R1, and 211R1. With this configuration, for example, the propagation axis of the electromagnetic wave em irradiated onto the first regions 11R1, 111R1, and 211R1 can be parallel to the propagation axis of the reflected wave re irradiated onto the second regions 11R2, 111R2, and 211R2. Therefore, the optical element that irradiates the object ob with the electromagnetic wave em and the optical element that images the reflected wave re from the object ob onto the detection unit 12 can be shared at least partially. For example, as shown in Figure 1, the scanning unit 21 can change the radiation direction of electromagnetic waves em transmitted through the optical members 11, 111 and 211 toward the object ob, and can also change the radiation direction of reflected waves re reflected by the object ob toward the second regions 11R2, 111R2 and 211R2. 【0068】 Furthermore, in optical systems 10, 110, and 210, the electromagnetic wave em radiated from the radiating unit 22 is propagated in the first regions 11R1, 111R1, and 211R1 at a rate exceeding 50% of the light intensity, or the reflected wave re reflected by the object ob is propagated in the second region 11R2 at a rate exceeding 50% of the light intensity. With this configuration, the loss of the electromagnetic wave em or the reflected wave re can be reduced. 【0069】 The embodiments of optical systems 10, 110, and 210 have been described above, but the figures illustrating the embodiments of this disclosure are schematic. The dimensional ratios and other details in the drawings do not necessarily correspond to those of reality. 【0070】 While embodiments relating to this disclosure have been described based on the drawings and examples, it should be noted that those skilled in the art can make various modifications or alterations based on this disclosure. Therefore, it should be noted that these modifications or alterations are within the scope of this disclosure. For example, the functions included in each component can be rearranged in a logically consistent manner, and multiple components can be combined into one or separated. 【0071】For example, in the above embodiment, a portion of the reflected wave re, which is reflected by the electromagnetic wave em from the object ob, will be blocked by the optical member 11, which may affect the accuracy of the distance information when the control unit 23 acquires distance information for an arbitrary point on the object ob. Therefore, for example, when the control unit 23 acquires distance information for an arbitrary point on the object ob, it may predict the intensity of the reflected wave re, which is reflected by the electromagnetic wave em from the object ob, based on a Gaussian distribution or the like, and acquire distance information for the arbitrary point from the predicted intensity of the reflected wave re. 【0072】 All of the constituent elements described in this disclosure, and / or all of the methods or steps of the processes disclosed, can be combined in any combination, except for any combination in which these features are mutually exclusive. Furthermore, each of the features described in this disclosure can be replaced by an alternative feature that works for the same, equivalent, or similar purposes, unless expressly disregarded. Thus, unless expressly disregarded, each of the disclosed features is merely one example of a comprehensive set of identical or equivalent features. 【0073】 Furthermore, the embodiments relating to this disclosure are not limited to any specific configuration of the embodiments described above. The embodiments relating to this disclosure can be extended to all novel features or combinations thereof described herein, or all novel methods or processing steps or combinations thereof described herein. 【0074】 In this disclosure, the designations "First," "Second," etc., are identifiers used to distinguish the configurations. Configurations distinguished by the designations "First," "Second," etc., in this disclosure may have their numbers swapped. The identification swaps are performed simultaneously. The configurations remain distinguishable even after the identification swaps. Identifiers may be deleted. Configurations from which identifiers have been deleted are distinguished by codes. The designations "First," "Second," etc., in this disclosure should not be used alone to interpret the order of the configurations or to justify the existence of smaller numbered identifiers. 【0075】10, 110, 210 Optical system 11, 111, 211 Optical components 11S1, 111S1, 211S1 First surface 11S2, 111S2, 211S2 Second surface 11R1, 111R1, 211R1 First region 11R2, 111R2, 211R2 Second region 111S2 Back surface 111H Through hole 111C Cylindrical part 111T Tapered part 12 Detection unit 13 Collimator lens 14 Focusing lens 20, 120, 220 Electromagnetic wave detection device 21 Scanning unit 22 Radiation unit 23 Control unit d1 First direction d2 Second direction em Electromagnetic wave re Reflected wave ob Object sd1 First oscillation direction sd2 Second oscillation direction θ1 Angle of inclination of the electromagnetic wave propagation axis with respect to the first plane θ2 Angle between the first plane and the inner circumferential surface of the tapered portion A Axis of the through hole of the optical member

Claims

1. An optical system comprising: an optical member in which, in a first region and a second region on a first surface, electromagnetic waves radiated from a radiating unit propagate in a first direction from the first region, and reflected waves from the second region, which are the electromagnetic waves reflected by an object, propagate in a second direction different from the first direction; and a detection unit for detecting the reflected waves propagating in the second direction.

2. An optical system according to claim 1, wherein the area irradiated by the electromagnetic wave in the first region is smaller than the area irradiated by the reflected wave in the second region.

3. An optical system according to claim 1 or 2, wherein the first region transmits the electromagnetic wave and the second region reflects the reflected wave.

4. An optical system according to claim 1 or 2, wherein the first region is a through-hole through which the electromagnetic wave passes, and the second region reflects the reflected wave.

5. The optical system according to claim 4, wherein the through hole includes a tapered portion on the radiating portion side that widens toward the radiating portion in the axial direction of the through hole, and the angle between the axis of the through hole and the tapered portion is greater than the angle obtained by subtracting the inclination angle of the propagation axis of the electromagnetic waves radiated from the radiating portion with respect to the first plane from 90°.

6. An optical system according to claim 4 or 5, wherein the optical member further includes an absorbing portion on the inner circumferential surface of the through hole.

7. An optical system according to claim 1 or 2, wherein the first region reflects the electromagnetic wave and the second region transmits the reflected wave.

8. An optical system according to any one of claims 1 to 7, wherein the first region is located near the center of the optical member, and the second region is located around the first region.

9. An optical system according to any one of claims 1 to 8, wherein electromagnetic waves radiated from the radiating portion are propagated in a first direction from a first region of the first surface, and reflected waves whose bandwidth overlaps with the electromagnetic waves incident on the second region of the first surface from the opposite direction to the first direction are propagated in a second direction different from the first direction.

10. An optical system according to any one of claims 1 to 9, wherein the first region propagates electromagnetic waves radiated from the radiating portion at a rate exceeding 50% of the light intensity, or the second region propagates reflected waves reflected by the object at a rate exceeding 50% of the light intensity.

11. An optical system according to any one of claims 1 to 10, wherein the propagation axis of the reflected wave propagating in the second direction is parallel to the detection axis of the detection unit.

12. An electromagnetic wave detection device comprising: an optical system according to any one of claims 1 to 11; and a scanning unit for changing the radiation direction of the electromagnetic wave traveling in the first direction.

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