Light emitting device and measurement device

Abstract

In this light emitting device, red light of an infrared light-emitting element is made less visible in a simpler manner. This light emitting device comprises: a first light-emitting element that emits, in a first direction, first visible light in a first polarization state; a second light-emitting element that emits, in the first direction, second visible light in a second polarization state that is different from the first polarization state; and a light-emitting optical system which has different refractive indices depending on the polarization state of incoming light, which is disposed on the first direction side with respect to the first light-emitting element and the second light-emitting element, and through which the first visible light emitted by the first light-emitting element and the second visible light emitted by the second light-emitting element transmit. The positional relationship among the first light-emitting element, the second light-emitting element, and the light-emitting optical system satisfies a condition in which the entire irradiation range of the first visible light transmitted through the light-emitting optical system is included in the irradiation range of the second visible light transmitted through the light-emitting optical system at an arbitrary position separated from the light-emitting optical system toward the first direction side by a reference distance or more.

Description

Light-emitting device, measuring device

[0001] The technology disclosed in this specification relates to a light-emitting device and a measuring device.

[0002] In order to know the situation in front of a vehicle, a light-emitting device mounted on the vehicle and emitting infrared light is known. The light-emitting device includes an infrared light-emitting element that emits infrared light. There is a possibility that red light may be visible from in front of the light-emitting device for the infrared light emitted from the light-emitting device.

[0003] In order to make the red light visible from in front of the emitting device less conspicuous, the light-emitting device may emit white light in the same direction as the direction in which the infrared light is emitted. As such a light-emitting device, there is known a light-emitting device including an infrared light-emitting element for projecting infrared light around the vehicle, a white light-emitting element that emits white light, and a reflector formed of a transparent member having a surface on which vapor deposition is performed. Specifically, in the light-emitting device, either one of the infrared light-emitting element or the white light-emitting element is disposed at the focus of the reflecting surface, and the other is disposed close to the reflector so as to project light into the transparent member. And such a light-emitting device is configured to leak light inside the transparent member from at least a part of the reflecting surface (see Patent Document 1).

[0004] Japanese Unexamined Patent Application Publication No. 2010-67372

[0005] There was room for improvement in the light-emitting device that makes the above-described red light less conspicuous. Such a problem is a common problem not only for a light-emitting device that emits red light but also for a light-emitting device that emits visible light that can be visually recognized.

[0006] This specification discloses a technology capable of solving the above-described problems.

[0007] The technology disclosed in this specification can be realized, for example, in the following forms.

[0008] (1) The light-emitting device disclosed herein comprises a first light-emitting element that emits first visible light in a first polarization state in a first direction, a second light-emitting element that emits second visible light in a second polarization state different from the first polarization state in the first direction, and a light-emitting optical system having different refractive indices depending on the polarization state of the incident light. The light-emitting optical system is arranged on the first direction side with respect to the first light-emitting element and the second light-emitting element, and transmits the first visible light emitted by the first light-emitting element and the second visible light emitted by the second light-emitting element. The positional relationship between the first light-emitting element, the second light-emitting element and the light-emitting optical system is such that, at any position at a reference distance or more away from the light-emitting optical system in the first direction, the entire irradiation range of the first visible light transmitted through the light-emitting optical system is included in the irradiation range of the second visible light transmitted through the light-emitting optical system, satisfying the condition. With this light-emitting device, the irradiation range of the first visible light is included in the irradiation range of the second visible light, making the first visible light difficult to see.

[0009] (2) In the above-described light-emitting device, the first polarization state may be circularly polarized and the second polarization state may be unpolarized, and the light-emitting optical system may be configured to convert incident circularly polarized light into parallel light and incident light other than circularly polarized light into diffuse light. With this configuration, the light-emitting optical system converts the first circularly polarized visible light into parallel light and the second unpolarized visible light into diffuse light, so that the irradiation range of the first visible light is included in the irradiation range of the second visible light.

[0010] (3) The above-mentioned light-emitting device may be configured to include a diffusion lens positioned on the first direction side, which further transmits the first visible light and the second visible light that have passed through the light-emitting optical system. With this configuration, by passing the first visible light and the second visible light that have passed through the light-emitting optical system through the diffusion lens, the irradiation range of the first visible light can be included in the irradiation range of the second visible light with a shorter optical path compared to a configuration without a diffusion lens.

[0011] (4) The above measuring device may be configured to include the above-mentioned light-emitting device, a light-receiving receiver, and a controller. With this configuration, when the first visible light is received by the light-receiving receiver of the measuring device, the first visible light of the measuring device becomes difficult to see.

[0012] Furthermore, the technologies disclosed herein can be implemented in various forms, for example, in the form of a light-emitting device, a measuring device, and the like.

[0013] Schematic diagram of the entire vehicle equipped with the measuring device in the embodiment. A schematic block diagram showing the measuring device in the embodiment. An explanatory diagram of the light-emitting device in the embodiment. An explanatory diagram of the light emitted from the light-emitting device in the embodiment. An explanatory diagram of the measuring device in a comparative configuration.

[0014] A. Embodiments: Embodiments will be described with reference to Figures 1 to 4. Figure 1 shows mutually orthogonal X, Y, and Z axes for specifying directions. The positive X-axis direction is forward, and the negative X-axis direction is backward. The positive Y-axis direction is left, and the negative Y-axis direction is right. Also, the positive Z-axis direction is upward, and the negative Z-axis direction is downward.

[0015] Figure 1 is a perspective view of a vehicle 1 equipped with a measuring device 10 in an embodiment. The vehicle 1 is equipped with a pair of headlamps 70. The pair of headlamps 70 are each located on both sides in the left-right direction at the front end of the vehicle 1. Each headlamp 70 comprises a low-beam lamp unit 61, a high-beam lamp unit 62, and a measuring device 10. The low-beam lamp unit 61, the high-beam lamp unit 62, and the measuring device 10 are arranged in this order from the center side to the side side of the vehicle. The measuring device 10 in this embodiment also functions as a vehicle width lamp for the vehicle 1.

[0016] A-1. Configuration of the measuring device 10: Figure 2 is a schematic block diagram showing the measuring device 10 in an embodiment. The measuring device 10 in this embodiment is a LiDAR. The measuring device 10 is installed, for example, in a vehicle equipped with AD (automated drive) or ADAS (advanced driver assistance system). The measuring device 10 assists in the detection of objects such as people and other vehicles while the vehicle is in motion, and provides various types of information useful for ensuring the safety of the vehicle driver and those around the vehicle, and for reducing damage to objects in the surrounding area while the vehicle is in motion, to other devices and users.

[0017] As shown in Figure 2, the measuring device 10 includes a light emitter 100, a light receiver 400, an information processing device 500, a communication interface 600, and a cover 50.

[0018] (Floodlight) The floodlight 100 comprises a light-emitting device 110 and a control circuit board 210. The light-emitting device 110 is a device that emits light outside the vehicle 1. The configuration of the light-emitting device 110 will be described in detail later.

[0019] The control circuit board 210 is a circuit board on which electronic components for controlling the light emission of the light-emitting device 110 are mounted. The control circuit board 210 controls the power supply circuit (not shown) of the light-emitting device 110, as well as the infrared light-emitting element 22, which will be described later.

[0020] (Photodetector, etc.) As shown in Figure 2, the photodetector 400 includes a photodetecting optical system 410, a photodetector 420, and a TOF measuring device 430.

[0021] The light-receiving optical system 410 is an optical system for receiving reflected laser light Lre, which is light emitted from the infrared light-emitting element 22 of the light-emitting device 110 (for example, a light beam (laser light), hereinafter referred to as "near-infrared light L1"), reflected back from the object to be measured W after being irradiated from the vehicle 1, into the light-receiving unit 420. The light-receiving optical system 410 may be various lenses such as focusing lenses, various filters such as wavelength filters, or reflective mirrors.

[0022] The light-receiving unit 420 is equipped with a light-receiving element. The light-receiving element is, for example, a photodiode. The light-receiving unit 420 receives reflected laser light Lre incident from the light-receiving optical system 410, converts it into a received signal corresponding to the intensity and reception timing of the reflected laser light Lre, and outputs it.

[0023] The cover 50 protects the light-emitting device 110 and the light-receiving device 400 from the external environment of the vehicle 1. The cover 50 transmits near-infrared light L1 emitted from the light-emitting device 110. The cover 50 emits the transmitted near-infrared light L1 to the outside of the vehicle 1 and transmits the reflected laser light Lre reflected from the measurement target W. The cover 50 is positioned in front of the light-emitting device 110 and the light-receiving device 400 (positive X-axis direction). The cover 50 is, for example, a flat plate parallel to the YZ plane. The cover 50 is made of a material that transmits light emitted from the light-emitting device 110 and reflected laser light Lre. The cover 50 is made of, for example, a transparent material (e.g., plastic).

[0024] The TOF measuring device 430 has, for example, a time measurement IC (integrated circuit) equipped with a TDC (time-to-digital converter) circuit. The TOF measuring device 430 is communicatively connected to the control circuit board 210 and the light receiving unit 420. The TOF measuring device 430 receives a timing signal indicating the emission timing output from the control circuit board 210 and a light receiving signal output from the light receiving unit 420, and based on these, it determines the difference between the timing at which near-infrared light L1 was emitted and the timing at which reflected laser light Lre was received, that is, the time of flight (TOF) of the laser light. The TOF measuring device 430 outputs a signal corresponding to the determined TOF and the light receiving signal received from the light receiving unit 420.

[0025] The information processing device 500 has a processor. The processor may be, for example, a CPU (central processing unit), an MPU (microprocessing unit), an ASIC (application specific integrated circuit), an FPGA (field programmable gate array), a DSP (digital signal processor), etc. The information processing device 500 is communicatively connected to the TOF measuring device 430. The information processing device 500 receives the signal corresponding to TOF output by the TOF measuring device 430 and the received signal, and generates various information such as the distance to the measurement target W based on these. This information may be, for example, a histogram used in time-correlated single photon counting, the distance to each point of the measurement target W, point cloud information, etc. The information generated by the information processing device 500 is transmitted via the communication interface 600 to an external device 700 that uses this information. The information processing device 500 is a controller.

[0026] The external device 700 may be, for example, a device that creates an environmental map using a point cloud, or a device that performs self-localization (SLAM: Simultaneous Localization and Mapping) using scan matching algorithms such as NDT (Normal Distributions Transform) and ICP (Iterative Closest Point).

[0027] A-2. Configuration of the light-emitting device 110: Figure 3 is an explanatory diagram of the light-emitting device 110 in an embodiment. Specifically, Figure 3 is a schematic diagram of the light-emitting device 110 viewed from above the vehicle 1 in the downward direction (negative Z-axis direction). The light-emitting device 110 includes a light-emitting unit 20, a light-emitting optical system 30, and a diffusion lens 40.

[0028] The light-emitting unit 20 includes an infrared light-emitting element 22, a white light-emitting element 24, and a light-emitting circuit board 26. The infrared light-emitting element 22 is an example of a first light-emitting element. The white light-emitting element 24 is an example of a second light-emitting element. The infrared light-emitting element 22 and the white light-emitting element 24 are arranged in the left-right direction relative to the vehicle 1. The infrared light-emitting element 22 and the white light-emitting element 24 are arranged on the light-emitting circuit board 26.

[0029] The infrared light-emitting element 22 emits near-infrared light L1. The near-infrared light L1 is circularly polarized (an example of a first polarization state). The wavelength of the near-infrared light is, for example, 750 nm or more and less than 1000 nm. A specific example of the wavelength of the near-infrared light L1 in this embodiment is 750 nm or more and 850 nm or less. The wavelength of the near-infrared light L1 may also be 750 nm or more and 900 nm or less. Furthermore, the wavelength of the near-infrared light L1 may also be 750 nm or more and 950 nm or less.

[0030] The white light-emitting element 24 emits white light L2. The white light L2 is unpolarized (an example of a second polarization state) and includes various polarization states. The white light L2 is visible light. The wavelength of visible light is less than 750 nm. A specific example of the wavelength of white light L2 in this embodiment is 380 nm or more and 700 nm or less. Alternatively, a specific example of the wavelength of white light L2 may be 400 nm or more and 700 nm or less. Furthermore, a specific example of the wavelength of white light L2 may be 400 nm or more and 740 nm or less. White light L2 is an example of a second visible light.

[0031] The infrared light-emitting element 22 and the white light-emitting element 24 each emit light in the same direction. The direction of the emitted light is the forward direction of the vehicle 1 (an example of the first positive X-axis direction). Near-infrared light L1 has an optical axis Ax1 which is the center of the near-infrared light beam L1. White light L2 has an optical axis Ax2 which is the center of the white light beam L2.

[0032] The infrared light-emitting element 22 includes a near-infrared light source 27 and a polarizing element 28. The near-infrared light source 27 is a light source that outputs near-infrared light L1. The near-infrared light L1 output from the near-infrared light source 27 is unpolarized. The near-infrared light source 27 is, for example, a laser diode, a light-emitting diode, a surface light-emitting element (for example, a VCSEL (Vertical Cavity Surface Emitting Laser), or a surface light-emitting element array (for example, a VCSEL array) in which multiple surface light-emitting elements are arranged one-dimensionally or two-dimensionally on a substrate (semiconductor substrate, ceramic substrate, etc.). In this embodiment, the measuring device 10 is a FLASH-type LiDAR, and the light-emitting device 110 can also be configured by arranging, for example, multiple near-infrared light-emitting elements 27 linearly (one-dimensionally) or planarly (two-dimensionally).

[0033] The polarizing element 28 receives near-infrared light L1 emitted from the near-infrared light source 27. The polarizing element 28 is an element that converts the near-infrared light L1 emitted from the infrared light-emitting element 22 into circularly polarized light. The polarizing element 28 faces the near-infrared light source 27. The polarizing element 28 has a polarizing plate and a quarter-wave plate. The polarizing element 28 is arranged with the polarizing plate and the quarter-wave plate in that order from the side into which the near-infrared light L1 is incident. The polarizing plate converts the incident light into a wave that vibrates in a certain direction. The quarter-wave plate imparts a phase difference of λ / 4 (one-quarter of a wavelength) to the different vibrational components of the incident light.

[0034] The white light-emitting element 24 has a white light source 29. The white light source 29 emits white light L2. The white light-emitting element 24 is, for example, a light-emitting diode.

[0035] The light-emitting optical system 30 is positioned opposite the infrared light-emitting element 22 and the white light-emitting element 24 on the optical axes Ax1 and Ax2. The light-emitting optical system 30 is incident on near-infrared light L1 emitted from the infrared light-emitting element 22 and white light L2 emitted from the white light-emitting element 24. The light-emitting optical system 30 is an optical system that has different refractive indices depending on the polarization state of the incident light. In this embodiment, the light-emitting optical system 30 makes the light parallel when the incident light is circularly polarized. On the other hand, the light-emitting optical system 30 makes the light diffuse when the incident light is not circularly polarized. The light-emitting optical system 30 is, for example, a porographic element including liquid crystal. The light-emitting optical system 30 changes the refractive index of the incident light depending on the polarization state by adjusting the type of material constituting the liquid crystal and its arrangement (manetic, smectic, choletic, etc.).

[0036] The diffusion lens 40 is positioned opposite the light-emitting optical system 30 on the optical axes Ax1 and Ax2. The diffusion lens 40 receives near-infrared light L1 and white light L2 that have passed through the light-emitting optical system 30. The diffusion lens 40 diffuses the near-infrared light L1 and white light L2. For example, the emitting side of the diffusion lens 40 is concave. The diffusion lens 40 is made of, for example, quartz glass.

[0037] The positional relationship between the infrared light-emitting element 22, the white light-emitting element 24, the light-emitting optical system 30, and the diffusion lens 40 is such that, in the cover 50 positioned in the forward direction of the vehicle 1 from the light-emitting device 110, the entire irradiation range Ar1 of the near-infrared light L1 emitted from the light-emitting device 110 is included in the irradiation range Ar2 of the white light L2 emitted from the light-emitting device 110 (see Figure 4).

[0038] Specifically, as shown in Figure 3, in the Y-axis direction of the cover 50 (the left-right direction of the vehicle 1), the irradiation width Aw11 of the near-infrared light L1 (the width between the first near-infrared light L11 at the left end of the near-infrared light L1 and the second near-infrared light L12 at the right end of the near-infrared light L1 on the cover 50) is inside the irradiation width Aw21 of the white light L2 (the width between the first white light L21 at the left end of the white light L2 and the second white light L22 at the right end of the white light L2 on the cover 50).

[0039] A-3. Operation of the light-emitting device 110: As shown in Figure 3, the light-emitting device 110 emits near-infrared light L1 from the near-infrared light source 27 of the light-emitting unit 20 toward the front of the vehicle 1 (positive X-axis direction). The emitted near-infrared light L1 is unpolarized diffuse light. The near-infrared light L1 emitted from the near-infrared light source 27 is converted into circularly polarized near-infrared light L1 by the polarizing element 28. The circularly polarized near-infrared light L1 is emitted from the infrared light-emitting element 22.

[0040] As shown in Figure 3, the light-emitting device 110 emits white light L2 from the white light source 29 of the light-emitting unit 20 toward the front of the vehicle 1 (positive X-axis direction). The white light L2 is unpolarized diffuse light. The white light L2 emitted from the white light source 29 is emitted from the white light-emitting element 24.

[0041] As shown in Figure 3, the near-infrared light L1, after being emitted from the infrared light-emitting element 22, diffuses to the left and right of the vehicle 1 as it moves forward (positive X-axis direction). That is, the width between the first near-infrared light L11 and the second near-infrared light L12 widens as it moves forward. The white light L2, after being emitted from the white light-emitting element 24, diffuses to the left and right of the vehicle 1 as it moves forward. That is, the width between the first white light L21 and the second white light L22 widens as it moves forward.

[0042] Near-infrared light L1 and white light L2 emitted from the light-emitting unit 20 both enter the light-emitting optical system 30. The circularly polarized near-infrared light L1 is selectively converted into parallel light by the light-emitting optical system 30, as shown in Figure 3. On the other hand, the unpolarized white light L2 is converted into diffuse light by the light-emitting optical system 30. The near-infrared light L1 that has passed through the light-emitting optical system 30 is emitted from the light-emitting optical system 30 as parallel light. On the other hand, the white light L2 that has passed through the light-emitting optical system 30 is emitted from the light-emitting optical system 30 as diffuse light.

[0043] The near-infrared light L1 and the white light L2 emitted from the light-emitting optical system 30 both enter the diffusing lens 40. The near-infrared light L1 that has passed through the diffusing lens 40 diffuses again. That is, the near-infrared light L1 that has passed through the diffusing lens 40 becomes diffused light. On the other hand, the white light L2 that has passed through the diffusing lens 40 diffuses further. The near-infrared light L1 and the white light L2 emitted from the diffusing lens 40 are irradiated outside the vehicle 1 through the cover 50.

[0044] FIG. 4 is an explanatory diagram of the light emitted from the light-emitting device 110 in the embodiment. That is, FIG. 4 is a distribution diagram of the irradiation ranges of the near-infrared light L1 and the white light L2 irradiated from the light-emitting device 110 on the cover 50.

[0045] As shown in FIG. 4, at the position of the cover 50, the entire irradiation range Ar1 of the near-infrared light L1 irradiated from the light-emitting device 110 is included in the irradiation range Ar2 of the white light L2. An example of an arbitrary position at a reference distance or more from the front direction of the vehicle 1 from the light-emitting optical system 30 is the cover 50.

[0046] The relationship between the irradiation range Ar1 of the near-infrared light L1 and the irradiation range Ar2 of the white light L2 is as shown in FIG. 4 when the light-emitting device 110 is the vehicle width lamp of the vehicle 1. Specifically, at the position facing the front of the vehicle 1 (negative X-axis direction), the white light L2 spreads at an angle of 80° to the right and 45° to the left with respect to the optical axis Ax1 in the left-right direction (Y-axis direction) of the vehicle 1. On the other hand, the near-infrared light L1 spreads at an angle of 20° to the left and right with respect to the optical axis Ax1. Also, in the up-down direction (Z-axis direction) toward the vehicle 1, the white light L2 spreads at an angle of 15° to the up and down with respect to the optical axis Ax1. On the other hand, the near-infrared light L1 spreads at an angle of 10° to the left and right with respect to the optical axis Ax1. In order to have the relationship between the irradiation range Ar1 of the near-infrared light L1 and the irradiation range Ar2 of the white light L2 as described above, for example, the infrared light-emitting element 22 and the white light-emitting element 24 set the directions in which the near-infrared light L1 and the white light L2 are emitted as the front direction of the vehicle 1, and arrange the emission positions of the respective lights in the left-right direction. That is, the positions of the optical axis Ax1 and the optical axis Ax2 are adjusted.

[0047] A-4. Near-infrared light L1: The near-infrared light L1 is emitted from the infrared light-emitting element 22 of the light-emitting device 110. The near-infrared light L1 is irradiated forward (in the positive X-axis direction) of the vehicle 1 through the cover 50. The irradiated near-infrared light L1 uses a light source for the purpose of emitting infrared light, which is invisible light, at the irradiation stage. On the other hand, when the near-infrared light L1 is irradiated without irradiating the white light L2 from the light-emitting device 110, it may be visually recognized as red light, which is visible light (hereinafter referred to as "red light", an example of "first visible light"), by a person outside the vehicle 1 (such as a pedestrian or a driver of an oncoming vehicle). As examples of the causes, the following two points can be mentioned. - The near-infrared light source 27 emits not only the near-infrared light L1 but also red light, which is visible light. - When the near-infrared light L1 emitted from the near-infrared light source 27 passes through optical elements (such as the polarizing element 28, the light-emitting optical system 30, the diffusing lens 40, etc.) or air, a part of the near-infrared light L1 becomes red light due to wavelength fluctuation. Therefore, the red light is visually recognized on the cover 50.

[0048] In order not to allow the above-mentioned red light to be visually recognized from outside the vehicle 1, when the light-emitting device 110 emits the near-infrared light L1 from the near-infrared light source 27, it also emits the white light L2 from the white light source 29. Specifically, the light-emitting device 110 has, as an optical system, a polarizing element 28, a light-emitting optical system 30, and a diffusing lens 40. With such a light-emitting device 110, the near-infrared light L1 and the red light are included in the white light L2 on the cover 50. That is, the entire irradiation range Ar1 of the near-infrared light L1 and the red light irradiated from the light-emitting device 110 is included in the irradiation range Ar2 of the white light L2 (see FIG. 4). Therefore, the red light is less likely to be visually recognized from outside the vehicle 1.

[0049] (Comparative form) FIG. 5 is an explanatory diagram of the light-emitting device 110 in the comparative form. FIG. 5 is an explanatory diagram of the light-emitting device 110 in the embodiment, in which the light-emitting optical system 30 is changed to a general collimating lens 35. The light-emitting device 110 in the comparative form is the same except that the light-emitting optical system 30 is changed to a general collimating lens 35.

[0050] In the comparative configuration of the light-emitting device 110, the collimating lens 35 converts the white light L2 into parallel light rather than diffuse light. That is, the near-infrared light L1 and white light L2 transmitted through the collimating lens 35 become parallel light between the collimating lens 35 and the diffusion lens 40. Subsequently, the near-infrared light L1 and white light L2 become diffuse light together through the diffusion lens 40. The near-infrared light L1 is irradiated to the outside of the car 1 via the cover 50. The white light L2 is irradiated to the outside of the car 1 via the cover 50. As shown in Figure 5, the irradiation width Aw12 of the near-infrared light L1 irradiated to the outside of the car 1 is not included inside the irradiation width Aw22 of the white light L2. In other words, a portion of the near-infrared light L1 leaks out from the irradiation range Ar2 of the white light L2. That is, the red light of the visible light portion of the near-infrared light L1 is visible from the front of the car 1.

[0051] A-5. Effects of this embodiment: As described above, the light-emitting device 110 of this embodiment includes an infrared light-emitting element 22 that emits near-infrared light L1 and red light, which are in a first polarization state, in front of the car, a white light-emitting element 24 that emits white light L2, which is in a second polarization state, in a first direction, and a light-emitting optical system 30 having different refractive indices depending on the polarization state of the incident light. The light-emitting optical system 30 is positioned on the first direction side relative to the infrared light-emitting element 22 and the white light-emitting element 24, and transmits the near-infrared light L1 emitted by the infrared light-emitting element 22 and the white light L2 emitted by the white light-emitting element 24. The positional relationship between the infrared light-emitting element 22, the white light-emitting element 24 and the light-emitting optical system 30 is such that, for example, at the position of the cover 50, the entire irradiation range of the near-infrared light L1 and red light transmitted through the light-emitting optical system 30 is included in the irradiation range of the white light L2 transmitted through the light-emitting optical system 30, thus satisfying the condition. According to the light-emitting device 110 of this embodiment, the irradiation range Ar1 of near-infrared light L1 and red light is included in the irradiation range Ar2 of the second visible light, making the red light difficult to see. Furthermore, the near-infrared light L1 and red light become part of the various wavelengths of white light L2. Therefore, people outside the car 1 perceive it as white light, and the red light becomes invisible. In addition, the light-emitting device 110 can have a single light-emitting optical system 30. Therefore, the light-emitting device 110 does not need to have a complex structure and can be made more compact.

[0052] In the light-emitting device 110 of this embodiment, the first polarization state is circularly polarized and the second polarization state is unpolarized, and the light-emitting optical system 30 may be configured to convert incident circularly polarized light into parallel light and incident light other than circularly polarized light into diffuse light. According to the light-emitting device 110 of this embodiment, the light-emitting optical system 30 converts circularly polarized near-infrared light L1 into parallel light and unpolarized white light L2 into diffuse light, so that the irradiation range Ar1 of the near-infrared light L1 and red light is included in the irradiation range Ar2 of the second visible light.

[0053] In this embodiment, the light-emitting device 110 may be configured to include a diffusion lens 40 positioned in the first direction, which further transmits the near-infrared light L1 and white light L2 that have passed through the light-emitting optical system 30. According to the light-emitting device 110 of this embodiment, by passing the near-infrared light L1 and white light L2 that have passed through the light-emitting optical system 30 further through the diffusion lens 40, the illumination range Ar1 of the near-infrared light L1 and red light can be included in the illumination range Ar2 of the second visible light with a shorter optical path compared to a configuration without a diffusion lens 40. In addition, the diffusion lens 40 converts the near-infrared light L1 that has passed through the light-emitting optical system 30 from parallel light to diffused light. As a result, as the intensity of the diffused white light L2 gradually weakens with distance from the car 1, the intensity of the diffused near-infrared light L1 also weakens.

[0054] In this embodiment, the system may be configured to include the light-emitting device 110, a light-receiving receiver 400, and an information processing device 500 which is a controller. With this configuration, when near-infrared light L1 is received by the light-receiving receiver 400 of the measuring device 10, the red light of the measuring device 10 becomes difficult to see.

[0055] B. Modifications: The technology disclosed herein is not limited to the embodiments described above, and can be modified in various forms without departing from its essence, for example, the following modifications are possible: (1) In the above embodiment, a FLASH-type LiDAR was described as an example of the measuring device 10, but it is not limited to this, and may be a scan-type LiDAR, or an optical measuring device 10 other than a LiDAR. (2) The measuring device 10 in the above embodiment is a vehicle side lamp of the vehicle 1, but is not limited to a vehicle side lamp. For example, it may be a low-beam lamp unit 61 or a high-beam lamp unit 62. (3) In the above embodiment, the direction in which the near-infrared light L1 and white light L2 are emitted from the light-emitting device 110 (first direction) is the front of the vehicle 1, but may be the rear of the vehicle 1 or the side of the vehicle. (4) The "first light-emitting element that emits a first visible light in a first polarization state in a first direction" is not limited to an element that emits visible light (and near-infrared light L1), but may also be an element that emits only near-infrared light L1 and causes wavelength fluctuations when it passes through an optical system (polarizing element 28, light-emitting optical system 30, diffusion lens 40, etc.) or air, thereby irradiating the cover 50 with red light. (5) The white light-emitting element 24 in the above embodiment emits white light L2, but it does not have to be white light; it may be light of a specific color. For example, it may be orange light (for example, light with a wavelength of 590 nm or more and 630 nm or less) or green light (for example, light with a wavelength of 500 nm or more and 560 nm or less). (6) In the above embodiment, the white light source 29 is a light-emitting diode, but it may also be a halogen lamp or an incandescent light bulb. (7) In the above embodiment, the infrared light-emitting element 22 and the white light-emitting element 24 are arranged in the left-right direction with respect to the car 1, but are not limited to the left-right direction. For example, the direction may be vertical or horizontal. Also, although the infrared light-emitting element 22 and the white light-emitting element 24 are arranged on the same substrate, they may be arranged on separate substrates. (8) In the above embodiment, the infrared light-emitting element 22 and the white light-emitting element 24 each emit light in the same direction, but on the first direction side, the near-infrared light L1 and the white light L2 emitted by each do not need to be parallel.(9) In the above embodiment, the near-infrared light L1 is circularly polarized and the white light L2 is unpolarized, but the embodiment is not limited to these, as long as the polarization state of the near-infrared light L1 and the polarization state of the white light L2 are different. For example, the near-infrared light L1 may be linearly polarized in the Y-axis direction and the white light L2 may be linearly polarized in the Z-axis direction, or vice versa. Also, when controlling the polarization state of the white light L2, the white light-emitting element 24 that emits the white light L2 may be equipped with a polarizing element 28. (10) In the above embodiment, the infrared light-emitting element 22 has a polarizing element 28, but the polarizing element 28 does not have to be arranged on the infrared light-emitting element 22. The polarizing element 28 may be arranged as a separate member on the front side of the vehicle 1, which is the first direction side of the infrared light-emitting element 22. Also, in the above embodiment, the polarizing element 28 is composed of a polarizing plate and a quarter-wave plate, but this can be changed as appropriate depending on the polarization state of the near-infrared light L1. For example, if the near-infrared light L1 is linearly polarized, the polarizing element 28 may consist only of a polarizing plate. (11) In the above embodiment, the light-emitting optical system 30 uses parallel light for the near-infrared light L1 and diffuse light for the white light L2, but is not limited to this. For example, the near-infrared light L1 may be diffuse light, and the white light L2 may be diffuse light that is even more diffuse than the near-infrared light L1. (12) In the above embodiment, the cover 50 is positioned in front of the light-emitting device 110 and the light-receiving device 400, but may be positioned only in front of the light-emitting device 110. In that case, a separate cover may be provided for the light-receiving device 400. Also, in the above embodiment, the cover 50 is made of a transparent material, but may be made of other materials as long as it transmits the near-infrared light L1. For example, in order to make the light irradiated from the light-emitting device 110 orange, the material of the cover 50 may be orange. Furthermore, although the cover 50 has a shape that extends across the YZ plane of the vehicle 1, it does not have to be a flat surface; it may be a curved surface. (13) In the above embodiment, the entire irradiation range Ar1 of the near-infrared light L1 and red light irradiated from the light-emitting device 110 is included in the irradiation range Ar2 of the white light L2 irradiated from the light-emitting device 110. However, the position for determining whether the entire irradiation range Ar1 of the near-infrared light L1 and red light is included in the irradiation range Ar2 of the white light L2 does not have to be the cover 50. It is sufficient that the position is at least a certain distance away from the direction in which the near-infrared light L1 and white light L2 are irradiated from the light-emitting device 110 (forward of the vehicle 1).Specifically, the distance from car 1 (or cover 50) may be 10 m or 30 m. (14) In the above embodiment, the light-emitting device 110 is a component of the measuring device 10, but the light-emitting device 110 can be used for purposes other than measuring devices. For example, the light-emitting device 110 can also be used as a device for improving the sensitivity of an image sensor. In addition, the light-emitting device 110 can be used in a system for detecting the relative positions of cars by mounting the light receiver on a car other than car 1.

[0056] This international application claims priority based on Japanese Patent Application No. 2024-229669, filed on 26 December 2024, and the entire contents of said Japanese Patent Application No. 2024-229669 are incorporated herein by reference.

[0057] The above description of specific embodiments of the present invention is provided for illustrative purposes only. It is not intended to be exhaustive or to limit the invention to the forms described. Numerous modifications and changes are possible in light of the above description, as will be obvious to those skilled in the art.

[0058] 1: Car 10: Measuring device 20: Light-emitting unit 22: Infrared light-emitting element 24: White light-emitting element 26: Light-emitting circuit board 27: Near-infrared light source 28: Polarizing element 29: White light source 30: Light-emitting optical system 35: Collimating lens 40: Diffusing lens 50: Cover 61: Low beam lamp unit 62: High beam lamp unit 70: Headlamp 100: Floodlight 110: Light-emitting device 210: Control circuit board 400: Light receiver 410: Light-receiving optical system 420: Light-receiving unit 430: TOF measuring device 500: Information processing device 600: Communication interface 700: External device L11: First near-infrared light L12: Second near-infrared light L1: Near-infrared light L21: First white light L22: Second white light L2: White light Lre: Reflected laser light W: Target of measurement

Claims

1. A light-emitting device comprising: a first light-emitting element that emits a first visible light having a first polarization state in a first direction; a second light-emitting element that emits a second visible light having a second polarization state different from the first polarization state in the first direction; and a light-emitting optical system having different refractive indices depending on the polarization state of incident light, which is arranged on the first direction side with respect to the first light-emitting element and the second light-emitting element, and through which the first visible light emitted by the first light-emitting element and the second visible light emitted by the second light-emitting element are transmitted, wherein the positional relationship between the first light-emitting element, the second light-emitting element and the light-emitting optical system is such that, at any position at or beyond a reference distance from the light-emitting optical system in the first direction side, the entire irradiation range of the first visible light transmitted through the light-emitting optical system is included in the irradiation range of the second visible light transmitted through the light-emitting optical system, thus satisfying the condition.

2. A light-emitting device according to claim 1, wherein the first polarization state is circularly polarized and the second polarization state is unpolarized, and the light-emitting optical system converts incident circularly polarized light into parallel light and incident light other than circularly polarized light into diffuse light.

3. A light-emitting device according to claim 2, comprising a diffusion lens arranged on the first direction side and further transmitting the first visible light and the second visible light that have been transmitted through the light-emitting optical system.

4. A measuring device comprising a light-emitting device according to any one of claims 1 to 3, a light-receiving device, and a controller.

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