Measurement device

Abstract

A measurement device is provided with: a light source that emits light; an interference optical system that separates the light emitted from the light source into reference light and irradiation light for irradiating an object, and generates interference light by causing reflected light, which is generated by reflecting the irradiation light by the object, to interfere with the reference light; an output fiber connected to the interference optical system and configured to guide the irradiation light; an optical element connected to the output fiber and emitting the irradiation light; a first housing that houses the light source and the interference optical system; and a second housing that accommodates the first housing. The output fiber is directly led out from the first housing.

Description

Technical Field

[0001] The present disclosure relates to a measuring device. Background Art

[0002] In the past, there was a LiDAR (Light Detection and Ranging) technology that generates measurement data related to the distance and / or speed of an object by illuminating an object with light and detecting the reflected light from the object. A typical example of a measuring device using LiDAR technology includes a light source, a photodetector, and a processing circuit. The light source emits light for illuminating an object. The photodetector detects the reflected wave from the object and outputs a signal corresponding to the time delay of the reflected wave. The processing circuit generates measurement data related to the distance and speed of the object based on the signal output from the photodetector, for example, using FMCW (Frequency Modulated Continuous Wave) technology. Patent documents 1 and 2 and non-patent document 1 disclose examples of measuring devices using FMCW technology.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent No. 6274368

[0006] Patent Document 2: Japanese Patent Application Publication No. 2019-45200

[0007] Non-patent literature

[0008] Non-patent document 1: Christopher V et.al., OFC 2016, W4E.3 Summary of the invention

[0009] Problems to be solved by the invention

[0010] The present disclosure provides a measuring device that emits irradiation light for irradiating an object to the outside and can reduce the possibility of unwanted light leaking to the outside.

[0011] Means used to solve problems

[0012] A measuring device related to a technical solution of the present disclosure comprises: a light source that emits light; an interference optical system that separates the light emitted from the light source into reference light and irradiation light for irradiating an object, and generates interference light by causing reflected light generated by reflection of the irradiation light by the object to interfere with the reference light; an output fiber connected to the interference optical system to guide the irradiation light; an optical element connected to the output fiber to emit the irradiation light; a first shell that accommodates the light source and the interference optical system; and a second shell that accommodates the first shell; the output fiber is directly led out from the first shell.

[0013] The inclusive or specific form of the present disclosure may be implemented by a system, device, method, integrated circuit, computer program, or a recording medium such as a computer-readable recording disk, or may be implemented by any combination of systems, devices, methods, integrated circuits, computer programs, and recording media. Computer-readable recording media may include non-volatile recording media such as CD-ROMs (Compact Disc-Read Only Memory). A device may also be composed of more than one device. In the case where a device is composed of more than two devices, the two or more devices may be configured in one device or separately configured in two or more separate devices. In this specification and claims, "device" may refer not only to one device but also to a system composed of multiple devices.

[0014] Effects of the Invention

[0015] According to the technology of the present disclosure, it is possible to realize a measuring device that emits irradiation light for irradiating an object to the outside and can reduce the possibility of undesired light leaking to the outside. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a block diagram schematically showing the configuration of a measuring device according to the exemplary embodiment 1 of the present disclosure.

[0017] Figure 2 This is a diagram schematically showing the temporal change in the frequencies of the reference light and the reflected light when the object is stationary.

[0018] Figure 3 This is a flowchart schematically showing an example of a measurement operation executed by a processing circuit.

[0019] Figure 4A It is used to illustrate Figure 1 A diagram of multiple light flows generated within the measurement device shown.

[0020] Figure 4B It is used to illustrate Figure 1Graph showing the optical path lengths of multiple light flows generated within the measurement device.

[0021] Figure 5 It is a block diagram schematically showing the configuration of a measuring device according to a comparative example.

[0022] Fig. 6A It is used to illustrate Figure 5 A diagram of multiple light flows generated within the measurement device shown.

[0023] Figure 6B It is used to illustrate Figure 5 Graph showing the optical path lengths of multiple light flows generated within the measurement device.

[0024] Fig. 7A This is a diagram schematically showing an example of a spectrum of a detection signal according to the first embodiment.

[0025] Figure 7B It is a diagram schematically showing an example of a spectrum of a detection signal of a comparative example.

[0026] Figure 8 This is a block diagram schematically showing the configuration of a measuring device according to an exemplary embodiment 2 of the present disclosure.

[0027] Fig. 9 This is a block diagram schematically showing the structure of a measuring device according to an exemplary embodiment 3 of the present disclosure.

[0028] Fig.10 This is a block diagram schematically showing the structure of a measuring device according to an exemplary embodiment 4 of the present disclosure.

[0029] Fig.11 This is a block diagram schematically showing the structure of a measuring device according to an exemplary embodiment 5 of the present disclosure.

[0030] Fig.12 This is a block diagram schematically showing the structure of a measuring device according to an exemplary embodiment 6 of the present disclosure.

[0031] Fig.13 This is a block diagram schematically showing the structure of a measuring device according to an exemplary embodiment 7 of the present disclosure. DETAILED DESCRIPTION

[0032] In the present disclosure, all or part of a circuit, unit, device, component or part, or all or part of a functional block in a block diagram may be performed by one or more electronic circuits including a semiconductor device, a semiconductor integrated circuit (IC) or an LSI (large scale integration). LSI or IC may be integrated on one chip or may be composed of a combination of multiple chips. For example, functional blocks other than storage elements may also be integrated on one chip. Here, it is called LSI or IC, but the name may vary depending on the degree of integration, and may also be called system LSI, VLSI (very large scale integration) or ULSI (ultra large scale integration). A Field Programmable Gate Array (FPGA) programmed after the manufacture of the LSI, or a reconfigurable logic device capable of reconfiguring the bonding relationship within the LSI or setting the circuit division within the LSI may be used for the same purpose.

[0033] Furthermore, all or part of the functions or operations of a circuit, unit, device, component or part can be executed by software processing. In this case, the software is recorded in one or more non-transitory recording media such as ROM, optical disk, hard disk drive, etc. When the software is executed by a processing device (processor), the functions determined by the software are executed by the processing device (processor) and peripheral devices. The system or device has one or more non-transitory recording media with software recorded, a processing device (processor) and necessary hardware devices such as interfaces.

[0034] In the present disclosure, "light" means electromagnetic waves including not only visible light (wavelength of about 400nm to about 700nm), but also ultraviolet light (wavelength of about 10nm to about 400nm) and infrared light (wavelength of about 700nm to about 1mm). In the present specification, ultraviolet light is also referred to as "ultraviolet light" and infrared light is also referred to as "infrared light".

[0035] Hereinafter, illustrative embodiments of the present disclosure are described. In addition, the embodiments described below all represent inclusive or specific examples. The numerical values, shapes, constituent elements, configuration positions and connection forms of constituent elements, steps, the order of steps, etc. shown in the following embodiments are examples and are not intended to limit the present disclosure. In addition, regarding the constituent elements of the following embodiments that are not recorded in the independent claims representing the highest concept, they are set as arbitrary constituent elements for description. In addition, each figure is a schematic diagram and is not necessarily a strict illustration. Furthermore, in each figure, the same reference numerals are given to substantially the same constituent elements, and there are cases where repeated descriptions are omitted or simplified.

[0036] First, the knowledge that is the basis of the present disclosure is described. Patent document 1 discloses a laser radar device that measures the distance from the device to the object by irradiating the object to be measured with light and receiving the reflected light generated by the irradiation. Patent document 2 discloses a distance measuring device using FMCW technology that accurately measures the distance from the device to the object by removing the influence of the nonlinear chirp of the laser. Non-patent document 1 discloses a distance measuring device using FMCW technology that can achieve miniaturization of the device by configuring the optical system in an on-chip manner.

[0037] In recent years, FMCW-LiDAR technology has been developed that can achieve both a wide dynamic range and high resolution for distance, is not easily affected by interference, and can detect the speed of high-speed moving objects. By using light instead of millimeter waves, the spot diameter of the light irradiating the object can be relatively small, and the measurement data of the object can be obtained more accurately.

[0038] The measuring device using FMCW-LiDAR technology has a light source and an interference optical system. The interference optical system separates the laser emitted from the light source into reference light and irradiation light, and generates interference light by superimposing the reflected light generated by the irradiation light irradiating the object with the reference light. By detecting the interference light with a photodetector, the measurement data of the object can be obtained.

[0039] The intensity of laser light emitted from the measuring device to the outside is classified into each level according to, for example, JIS (Japanese Industrial Standards) C6802 "Safety Standards for Laser Products". The intensity of laser light emitted to the outside is preferably in level 1 from the perspective of eye safety, i.e., eye safety.

[0040] Even if the intensity of the laser light emitted to the outside satisfies Level 1, there are cases where the laser light source emits a laser light with an intensity exceeding Level 1 in the measuring device. In this case, from the viewpoint of eye safety, it is desirable that the unwanted light from the light source and / or the interference optical system leaks to the outside of the measuring device. In the measuring device, when the laser light source emits a laser light with an intensity that satisfies Level 1, if the unwanted light leaks to the outside of the measuring device, the object may not be correctly measured due to the reflected light generated by the object being irradiated by the leaked light.

[0041] Because of the above situation, it is desirable to reduce the possibility of unwanted light leaking to the outside from a measuring device that emits irradiation light to illuminate an object. The inventors of the present invention have conceived a measuring device of an embodiment of the present disclosure that can reduce such a possibility. The measuring device of the present embodiment using FMCW-LiDAR technology includes a light source, an interference optical system, a first shell that accommodates the light source and the interference optical system, and a second shell that accommodates the first shell. In the measuring device of the present embodiment, compared with a structure that does not include a first shell that accommodates the light source and the interference optical system, the possibility of unwanted light from the light source and the interference optical system leaking to the outside of the measuring device can be reduced. The measuring device of an embodiment of the present disclosure is described below.

[0042] The measuring device related to the first item comprises: a light source for emitting light; an interference optical system for separating the light emitted from the light source into reference light and irradiation light for irradiating an object, and causing the reflected light generated by the irradiation light reflected by the object to interfere with the reference light to generate interference light; an output fiber connected to the interference optical system for guiding the irradiation light; an optical element connected to the output fiber for emitting the irradiation light; a first housing for accommodating the light source and the interference optical system; and a second housing for accommodating the first housing. The output fiber is directly led out from the first housing.

[0043] In this measuring device, the possibility of unwanted light leaking to the outside can be reduced. Furthermore, since the output fiber is directly drawn out from the first housing, noise can be reduced in the spectrum of the detection signal.

[0044] The measuring device according to item 2 is the measuring device according to item 1, wherein the output fiber is led out from the first housing and the second housing, and the optical element is disposed outside the second housing.

[0045] In this measuring device, even if the optical element is arranged outside the second housing, noise can be reduced in the spectrum of the detection signal.

[0046] The measuring device according to item 3 is the measuring device according to item 1, wherein the output fiber is led out from the first housing, the optical element is arranged outside the first housing and inside the second housing, and the second housing has a light-transmitting window through which the irradiated light passes.

[0047] In this measuring device, even if the optical element is arranged outside the first housing and inside the second housing, noise can be reduced in the spectrum of the detection signal.

[0048] The measuring device related to item 4 is a measuring device related to any one of items 1 to 3, wherein the optical element emits the irradiation light and receives the reflected light. The interference optical system includes a first light separator, a second light separator, and a circulator or a third light separator. The first light separator separates the reference light and the irradiation light and outputs them, inputs the output reference light to the second light separator, and inputs the output irradiation light to the circulator or the third light separator. The circulator or the third light separator outputs the irradiation light from the first light separator and inputs the irradiation light to the optical element, outputs the reflected light from the optical element and inputs the reflected light to the second light separator. The second light separator causes the reflected light from the circulator or the third light separator to interfere with the reference light from the first light separator to generate the interference light.

[0049] In this measuring device, interference light can be generated by using the first light splitter, the second light splitter, and the circulator, or by using the first light splitter, the second light splitter, and the third light splitter.

[0050] The measuring device according to item 5 is a measuring device according to item 4, wherein the optical path length of the first path from the first light separator to the photodetector for detecting the interference light is d 1 , let the optical path length of the second path from the second optical separator to the optical element be d 2 , let the optical path length of the third path from the optical element to the photodetector be d 3 , let the optical path length of the fourth path from the first optical separator via the noise optical path of the circulator or the third optical separator to the optical detector be d 4 When, meet

[0051] |d 2 +d 3 -d 1 |≤|d 4 -d 1 |relationship.

[0052] In this measuring device, it is possible to accurately acquire measurement data of an object without narrowing the distance range in which the distance and / or speed of the object can be measured.

[0053] The measuring device related to item 6 is a measuring device related to any one of items 1 to 5, further comprising: a signal fiber that guides the above-mentioned interference light from the above-mentioned interference optical system; and a light detector connected to the above-mentioned signal fiber to detect the above-mentioned interference light.

[0054] In this measuring device, the interference light can be detected by the photodetector.

[0055] The measuring device according to item 7 is the measuring device according to item 6, wherein the photodetector is arranged outside the first housing and inside the second housing.

[0056] In this measuring device, since the photodetector is arranged outside the first housing, maintenance of the photodetector is easy.

[0057] The measuring device according to item 8 is the measuring device according to item 7, wherein the signal fiber includes two connectors and a socket for connecting the two connectors, and the socket is mounted on the first housing.

[0058] In this measuring device, the photodetector can be attached and detached.

[0059] The measuring device according to item 9 is the measuring device according to item 6, wherein the photodetector is arranged inside the first housing.

[0060] In this measuring device, since the signal fiber connecting the photodetector and the interference optical system does not need to include a connector and a socket, the components of the measuring device can be simplified and the cost of components can be kept low.

[0061] The measuring device according to item 10 is the measuring device according to item 9, wherein the interference optical system and the photodetector are configured on-chip.

[0062] In this measuring device, the measuring device can be miniaturized.

[0063] The measuring device related to item 11 is further provided with a processing circuit in the measuring device related to item 6, which controls the operation of the above-mentioned light source and the operation of the above-mentioned light detector and processes the signal output from the above-mentioned light detector, and is located on the outside of the above-mentioned first shell and the inside of the above-mentioned second shell.

[0064] In this measuring device, heat generated in the processing circuit can be effectively released to the outside through the second housing.

[0065] The measuring device according to item 12 is the measuring device according to item 11, wherein the light source can change the frequency of the light over time.

[0066] This measuring device can measure the distance and / or speed of an object using the FMCW-LiDAR technology.

[0067] The measuring device related to item 13 comprises: a light source that emits light; an interference optical system that separates the light emitted from the above-mentioned light source into reference light and irradiation light for irradiating an object, and makes the reflected light generated by the above-mentioned irradiation light reflected by the above-mentioned object interfere with the above-mentioned reference light to generate interference light; an output fiber connected to the above-mentioned interference optical system to guide the above-mentioned irradiation light; an optical element connected to the above-mentioned output fiber to emit the above-mentioned irradiation light; a photodetector to detect the above-mentioned interference light; a first shell that accommodates the above-mentioned light source and the above-mentioned interference optical system; a second shell that accommodates the above-mentioned first shell; and a processing circuit that controls the operation of the above-mentioned light source and the operation of the above-mentioned photodetector and processes the signal output from the above-mentioned photodetector, and is arranged on the outside of the above-mentioned first shell and the inside of the above-mentioned second shell.

[0068] In this measuring device, the possibility of unwanted light leaking to the outside can be reduced. Furthermore, the heat generated by the processing circuit can be effectively released to the outside through the second housing.

[0069] The measuring device according to item 14 is the measuring device according to item 13, wherein the output fiber is a single continuous optical fiber.

[0070] In this measuring device, noise can be reduced in the spectrum of the detection signal by using one continuous optical fiber.

[0071] The measuring device according to item 15 is the measuring device according to item 13 or 14, wherein the light source can change the frequency of the light over time.

[0072] This measuring device can measure the distance and / or speed of an object using the FMCW-LiDAR technology.

[0073] The measuring device related to item 16 comprises: a light source that emits light; an interference optical system that separates the light emitted from the light source into reference light and irradiation light for irradiating an object, and generates interference light by causing the reflected light generated by the irradiation light reflected by the object to interfere with the reference light; an output fiber connected to the interference optical system to guide the irradiation light; an optical element connected to the output fiber to emit the irradiation light; a first shell that accommodates the light source and the interference optical system; and a second shell that accommodates the first shell. The output fiber is arranged on the inner side of the first shell. The optical element is arranged on the inner side of the first shell. The first shell has a first light-transmitting window that allows the irradiation light to pass through. The second shell has a second light-transmitting window that allows the irradiation light to pass through.

[0074] In this measuring device, the possibility of unwanted light leaking to the outside can be reduced. Furthermore, since a fiber lead-out portion for leading out the output fiber is not required, the components of the measuring device can be simplified and the cost of components can be kept low.

[0075] (Implementation Method 1)

[0076] [Measuring device]

[0077] First, refer to Figure 1 , describing a configuration example of a measuring device according to a first embodiment of the present disclosure. Figure 1 Schematically shows the structure of the measuring device according to the exemplary embodiment 1 of the present disclosure. Figure 1 In FIG. 1 , a person is shown as the object 10 to be measured. The object 10 may be any object other than a person, such as a vehicle or a building.

[0078] Figure 1 The measuring device 100A shown in the figure includes a light source 20, an interference optical system 30, an optical element 40, an output fiber 42, a photodetector 50, two signal fibers 52, a processing circuit 60, and a memory 62. The measuring device 100A further includes a first housing 70a that accommodates the light source 20, the interference optical system 30, the photodetector 50, the processing circuit 60, and the memory 62, and a second housing 70b that accommodates the first housing 70a. Figure 1 The bold line shown represents an optical fiber connecting two components to each other. Figure 1 The solid lines with arrows shown represent the transmission and reception of signals. Figure 1 The dashed lines with arrows shown in the figure represent the flow of light. It is also possible to manufacture and / or sell a part of the components and the remaining components of the measuring device 100A of embodiment 1 separately. The part of the components may be, for example, at least one of the photodetector 50, the processing circuit 60, and the memory 62.

[0079] In the measuring device 100A of the first embodiment, by emitting the irradiation light 20L2 for irradiating the object 10 and receiving the reflected light 20L3 generated by the irradiation light 20L2 on the object 10, it is possible to obtain measurement data related to the distance and / or speed of the object 10. In the measuring device 100A of the first embodiment, compared with a structure that does not include the first housing 70a for accommodating the light source 20 and the interference optical system 30, the possibility of undesired light from the light source 20 and the interference optical system 30 leaking to the outside of the measuring device 100A can be reduced.

[0080] Hereinafter, components of the measuring device 100A will be described.

[0081] <Light Source 20>

[0082] The light source 20 emits a laser 20L0. The light source 20 can change the frequency of the laser 20L0. The frequency can change with time in a certain time period, for example, in a triangular wave or sawtooth shape. The time period can be, for example, more than 1 μ second and less than 10 ms. The time period can also be unchanged. The frequency variation range can be, for example, more than 100 MHz and less than 1 THz.

[0083] The wavelength of the laser 20L0 may be included in the wavelength domain of near-infrared light, for example, between 700 nm and 2000 nm. Sunlight has near-infrared light and visible light, and the amount of near-infrared light is less than that of visible light. Therefore, if near-infrared light is used as the laser 20L0, the effect of sunlight as noise can be reduced. The wavelength of the laser 20L0 does not necessarily need to be included in the wavelength domain of near-infrared light. The wavelength of the laser 20L0 may be included in the wavelength domain of visible light between 400 nm and 700 nm, or in the wavelength domain of ultraviolet light.

[0084] The light source 20 includes, for example, a distributed feedback (DFB) laser diode or an external resonator (EC) laser diode. These laser diodes are cheap and small devices that can perform single-mode oscillation and can modulate the frequency of the laser 20L0 according to the amount of current applied. If a laser diode that can emit a high-intensity laser exceeding level 1 is used as the light source 20, the frequency of the laser 20L0 can be stably modulated. The intensity of the laser 20L0 emitted from the light source 20 is adjusted so that the intensity of the laser emitted to the outside meets level 1.

[0085] The light source 20 is connected to the first light separator 32a. An attenuator for adjusting the intensity of the laser light 20L0 may be disposed between the light source 20 and the first light separator 32a.

[0086] <Interference optical system 30>

[0087] The interference optical system 30 includes a first light separator 32a, a second light separator 32b, and an optical circulator 34. The first light separator 32a separates the laser light 20L0 emitted from the light source 20 into a reference light 20L1 and an irradiation light 20L2 for irradiating the object 10, and outputs the reference light 20L1 and the irradiation light 20L2. The intensity of the reference light 20L1 may be, for example, 1% to 10% of the intensity of the laser light 20L0 input to the first light separator 32a. The first light separator 32a inputs the output reference light 20L1 to the second light separator 32b, and inputs the output irradiation light 20L2 to the optical circulator 34. The first light separator 32a is connected to the second light separator 32b and the optical circulator 34.

[0088] The optical circulator 34 outputs the irradiation light 20L2 from the first optical separator 32a, and inputs the irradiation light 20L2 to the optical element 40 via the output fiber 42. The optical circulator 34 also outputs the reflected light 20L3 generated by the irradiation light 20L2 being reflected by the object 10, and inputs the reflected light 20L3 to the second optical separator 32b. The optical circulator 34 is connected to the first optical separator 32a, the second optical separator 32b, and the optical element 40.

[0089] The second optical separator 32b inputs interference light 20L4 obtained by superimposing reference light 20L1 and reflected light 20L3 and interfering them to the photodetector 50 via two signal fibers 52. The second optical separator 32b is connected to the first optical separator 32a, the optical circulator 34 and the photodetector 50.

[0090] <Optical element 40>

[0091] The optical element 40 emits the irradiation light 20L2 from the optical circulator 34 to the outside through the output fiber 42. The optical element 40 also receives the reflected light 20L3 and inputs the reflected light 20L3 to the optical circulator 34 through the output fiber 42. The optical element 40 may be, for example, a collimating lens that collimates the irradiation light 20L2. In this specification, "collimation" refers not only to making the irradiation light 20L2 parallel light, but also to reducing the diffusion of the irradiation light 20L2.

[0092] The optical element 40 may be a focusing lens that focuses the irradiation light 20L2, or a diffusion lens that diffuses the irradiation light 20L2. The optical element 40 may also be a diffraction grating that emits the irradiation light 20L2 as 0th-order diffracted light and / or ±Nth-order diffracted light (N is a natural number) to the outside. By measuring the distance and / or speed of the object 10 using a plurality of diffracted lights emitted in different directions, the angular range of the distance and / or speed measurement of the object 10 can be expanded. The optical element 40 may also have a structure that combines at least two of a collimating lens, a focusing lens, a diffusion lens, and a diffraction grating.

[0093] The measuring device 100A may further include an optical deflector that changes the direction of the irradiation light 20L2 emitted from the optical element 40. The optical deflector may be one selected from the group consisting of a galvanometer scanner, an optical polygon scanner, a MEMS scanner, a phase modulation scanner, a refractive index modulation scanner, and a wavelength modulation scanner, for example.

[0094] In the measuring device 100A, the path of the irradiated light 20L2 from the interference optical system 30 to the object 10 overlaps with the path of the reflected light 20L3 from the object 10 to the interference optical system 30. By adopting such a coaxial optical system, the structure of the measuring device 100A can be simplified, and stable measurement can be achieved.

[0095] <Output fiber 42>

[0096] The output fiber 42 is a continuous optical fiber that guides the irradiation light 20L2 from the optical circulator 34 and the reflected light 20L3 from the optical element 40. The output fiber 42 is connected to the interference optical system 30, more specifically, to the optical circulator 34, and the optical element 40 is connected to the output fiber 42.

[0097] The output fiber 42 has a connector 42a at one of the two ends located on opposite sides. The optical element 40 has a receptacle 40a for connecting the connector 42a of the output fiber 42. Since the optical element 40 and the output fiber 42 can be detached, the manufacture and maintenance of the measuring device 100A become easy. Alternatively, the output fiber 42 can also be directly connected to the optical element 40 through a coupling lens, for example. The type of connecting the output fiber 42 to the optical element 40 by such a method is called a pigtail type.

[0098] <Photodetector 50>

[0099] The photodetector 50 detects the interference light 20L4 from the second optical separator 32b via two signal fibers 52, and outputs a signal corresponding to the intensity of the interference light 20L4. The photodetector 50 includes one or more photodiodes. The photodiode outputs a signal corresponding to the intensity of the interference light 20L4. The photodetector 50 may also include a preamplifier for amplifying the signal.

[0100] exist Figure 1 In the example shown, the photodetector 50 is a balanced photodiode having two ports. Since the photodetector 50 detects the difference of light input from the two ports, the common phase noise can be reduced. In addition, the photodetector 50 may be a photodiode having one port other than a balanced photodiode.

[0101] <Signal Fiber 52>

[0102] The two signal fibers 52 equally separate and guide the interference light 20L4 from the second optical separator 32b. Each signal fiber 52 is connected to the second optical separator 32b, and the photodetector 50 is connected to the two signal fibers 52. Each signal fiber 52 has a connector 52a at one of the two ends located on opposite sides. The photodetector 50 has two sockets 50a for connecting the connectors 52a of the two signal fibers 52, respectively.

[0103] Each signal fiber 52 has two connectors 52b and a socket 52c between the two ends mentioned above. The socket 52c is a component located between the two connectors 52b and used to connect the two connectors 52b. The socket 52c is mounted on the first housing 70a. Through the two connectors 52b and the socket 52c, the part of each signal fiber 52 connected to the photodetector 50 and the part connected to the second optical separator 32b can be detached. As a result, the manufacturing and maintenance of the measuring device 100A become easy. Alternatively, each signal fiber 52 can also be directly connected to the photodetector 50 through a coupling lens, for example. Each signal fiber 52 can also be a continuous optical fiber like the output fiber 42. In the case where the photodetector 50 is a photodiode with one port, the number of signal fibers 52 is one.

[0104] <Processing Circuit 60>

[0105] The processing circuit 60 includes a control circuit 60a, a drive circuit 60b, and a signal processing circuit 60c. The control circuit 60a controls the operation of the drive circuit 60b, the signal processing circuit 60c, and the photodetector 50. In this specification, the operation of the control circuit 60a, the drive circuit 60b, and the signal processing circuit 60c is sometimes described as the operation of the processing circuit 60. The drive circuit 60b drives the light source 20. It can also be said that the control circuit 60a controls the operation of the light source 20 via the drive circuit 60b.

[0106] The signal processing circuit 60c uses the FMCW-LiDAR technology to process the signal output from the photodetector 50. Based on the signal, the processing circuit 60 generates and outputs measurement data related to the distance and / or speed of the object 10. Specifically, the signal processing circuit 60c performs Fourier transform on the time waveform of the detection signal to generate data representing its frequency spectrum, and based on the data, generates and outputs measurement data.

[0107] Alternatively, the signal processing circuit 60c may input the outputted measurement data to a display (not shown), and the display may display information related to the distance and / or speed of the object 10. Alternatively, the signal processing circuit 60c may input the outputted measurement data to another device, and the other device may perform a specific action based on the measurement data. The other device may be, for example, a vehicle or an industrial robot.

[0108] The details of the operation of the processing circuit 60 will be described later. The computer program executed by the control circuit 60a and the signal processing circuit 60c is stored in a memory 62 such as a ROM or RAM (Random Access Memory). In this way, the measuring device 100A has a processing device including a processing circuit 60 and a memory 62. The processing circuit 60 and the memory 62 can be integrated into one circuit substrate or provided on different circuit substrates. The control circuit 60a, the drive circuit 60b and the signal processing circuit 60c included in the processing circuit 60 can also be dispersed in multiple circuits. The processing device or a part thereof can also be provided in a remote location away from other components to control the operation of the light source 20 and the light detector 50 via a wired or wireless communication network.

[0109] <First Shell 70a and Second Shell 70b>

[0110] The first housing 70a houses the light source 20 and the interference optical system 30 for the following reasons. The light source 20 and the first optical separator 32a are connected by an optical fiber. The same applies to the first optical separator 32a and the second optical separator 32b, the first optical separator 32a and the optical circulator 34, and the second optical separator 32b and the optical circulator 34. If the optical fiber connecting the two components is damaged, for example, by breaking, light may leak from the damaged portion. As described above, from the viewpoint of stably modulating the frequency of the laser 20L0, a laser diode capable of emitting high-intensity laser light may be used as the light source 20. When laser light having an intensity exceeding Class 1 is emitted from the light source 20, it is undesirable for the laser light to leak from the damaged portion of the optical fiber to the outside of the measuring device 100A from the viewpoint of eye safety. When laser light having an intensity that satisfies Class 1 is emitted from the light source 20, if undesirable light leaks to the outside of the measuring device, the measurement data of the object may not be correctly acquired due to the reflected light generated by the object being irradiated by the leaked light.

[0111] Here, in the measuring device 100A of the present embodiment, it is assumed that the intensity of the irradiation light 20L2 emitted from the optical element 40 is I out , assuming that the intensity of the irradiation light 20L2 output from the optical circulator 32a is I rad1In addition, the light intensity lost by the optical element 40 due to loss and reflection is assumed to be L ele If the optical fiber loss is small enough to be ignored, out Such as I out =I rad1 -L ele Since part of the optical path of the irradiation light 20L2 output from the optical circulator 32a exists outside the first housing 70a, it is desirable that I rad1 Satisfies level 1. If the light intensity that satisfies the upper limit of level 1 is I limit , then due to I limit ≥I rad1 =I out +L ele , so I out Become Satisfied out ≤I limit -L ele Usually, L ele with I out Since the intensity is sufficiently smaller than that (for example, smaller by several tens of dB or more), the irradiation light 20L2 can be emitted from the optical element 40 at an intensity close to the upper limit satisfying the level 1.

[0112] In the measuring device 100A of the first embodiment, the possibility of unwanted light from the light source 20 and the interference optical system 30 leaking to the outside of the measuring device 100A can be reduced compared to a structure that does not include the first housing 70a for housing the light source 20 and the interference optical system 30. In the case where the first housing 70a houses the light source 20 and the interference optical system 30 in a sealed state without a gap, the possibility of unwanted light leaking to the outside of the measuring device 100A can be effectively reduced.

[0113] The first housing 70a and the second housing 70b are provided with a first fiber lead-out portion 72a and a second fiber lead-out portion 72b for leading out the output fiber 42, respectively. A continuous output fiber 42 is led out from the first housing 70a and the second housing 70b to the outside via the first fiber lead-out portion 72a and the second fiber lead-out portion 72b. The first fiber lead-out portion 72a and the second fiber lead-out portion 72b are provided with a structure capable of directly leading out the continuous output fiber 42 from the first housing 70a and the second housing 70b, respectively. In the first fiber lead-out portion 72a and the second fiber lead-out portion 72b, a connector and a socket for detachably attaching and detaching the output fiber 42 are not used. Therefore, in the output fiber 42, when the irradiation light 20L2 is guided, the reflection of the irradiation light 20L2 is hardly generated. The effect brought about by the almost no reflection of the irradiation light 20L2 will be described later.

[0114] The fiber lead-out portions 72a and 72b may be, for example, rubber sleeves. A hole is formed in the rubber sleeve, and when the output fiber 42 is passed through the hole, the gap between the outer covering portion of the output fiber 42 and the hole of the rubber sleeve is filled by the elastic force of the rubber. The fiber lead-out portions 72a and 72b may be, for example, covers that block the gap between the hole formed in the housing 70a and 70b and the outer covering portion of the output fiber passing through the hole, in addition to the rubber sleeve.

[0115] The optical element 40 is connected to the output fiber 42 drawn from the housings 70a and 70b via the fiber draw-out portions 72a and 72b. Therefore, the optical element 40 is arranged outside the second housing 70b. With such a structure, the direction of the irradiation light 20L2 emitted from the optical element 40 can be easily adjusted independently of the installation direction of the measuring device 100A according to the position of the object 10.

[0116] The first housing 70a further includes a wiring lead-out portion 74 for leading out wiring for sending signals from the drive circuit 60b to the light source 20. The drive circuit 60b and the light source 20 are electrically connected by the wiring. The wiring lead-out portion 74 may be, for example, an electrical connector. By providing a hole in the first housing 70a and providing a cover that blocks the gap between the hole and the electrical connector, the possibility of unwanted light leakage can be reduced.

[0117] Due to the above, the first housing 70a can contain the light source 20 and the interference optical system 30 in a sealed state without gaps. Furthermore, the irradiation light 20L2 can be taken out to the outside through the output fiber 42 through the first housing 70a and the second housing 70b. In this way, it is possible to block the leakage light from the light source 20 and the interference optical system 30 and take out the irradiation light 20L2 to the outside. Since the output fiber 42 is an optical fiber directly drawn out from the first housing 70a and the second housing 70b, the irradiation light 20L2 is almost not reflected but guided in the output fiber 42.

[0118] The photodetector 50 and the processing circuit 60 are arranged outside the first housing 70a and inside the second housing 70b. The photodetector 50 may include components such as photodiodes and preamplifiers that do not generate much heat. In contrast, the processing circuit 60 may include computing elements such as CPUs or FPGAs that generate relatively much heat.

[0119] Unlike the measuring device 100A of the first embodiment, in the structure in which the processing circuit 60 is sealed and housed in the first housing 70a, the heat generated by the processing circuit 60 cannot be effectively released to the outside, and the operation of the processing circuit 60 may become unstable. Furthermore, if the temperature inside the first housing 70a rises, the length of the optical fiber inside the first housing 70a changes by the order of micrometers. As a result, errors may occur in the measurement data of the object 10 depending on the distance range and / or speed measurement of the object 10 and the distance resolution.

[0120] In contrast, in the measuring device 100A of the first embodiment, since the processing circuit 60 is arranged outside the first housing 70a, the heat generated from the processing circuit 60 during operation can be effectively released to the outside through the second housing 70b. The second housing 70b may also include a ventilation port or a fan for heat dissipation. Since the heat generated from the processing circuit 60 can be effectively released to the outside, the processing circuit 60 can be operated more stably, and the change in the length of the optical fiber in the first housing 70a can be suppressed to accurately obtain the measurement data of the object 10. Furthermore, since the light detector 50 and the processing circuit 60 are arranged outside the first housing 70a, the light detector 50 and the processing circuit 60 are easy to maintain.

[0121] [FMCW-LiDAR technology]

[0122] Next, refer to Figure 2 The FMCW-LiDAR technology will be briefly described. For example, Non-Patent Document 1 discloses the details of the FMCW-LiDAR technology.

[0123] Figure 2 2 is a diagram schematically showing time changes in the frequencies of the reference light 20L1 and the reflected light 20L3 when the object 10 is stationary. The solid line represents the reference light 20L1, and the dotted line represents the reflected light 20L3. Figure 2 The frequency of the reference light 20L1 shown in the figure repeatedly changes with time in a triangular wave shape. That is, the frequency of the reference light 20L1 repeatedly chirs up and down. The increase in frequency during the up-chirp period and the decrease in frequency during the down-chirp period are equal to each other. The frequency of the reflected light 20L3 changes in the positive direction along the time axis compared with the frequency of the reference light 20L1. The amount of time variation of the reflected light 20L3 is equal to the time it takes for the irradiated light 20L2 to be emitted from the measuring device 100A to the outside, reflected by the object 10, and returned as the reflected light 20L3. As a result, the interference light 20L4 obtained by the superposition and interference of the reference light 20L1 and the reflected light 20L3 has a frequency equivalent to the frequency difference between the frequency of the reflected light 20L3 and the frequency of the reference light 20L1. Figure 2The double arrow line shown indicates the frequency difference between the two. The light detector 50 outputs a signal indicating the intensity of the interference light 20L4. This signal is called a beat signal. The frequency of the beat signal, i.e., the beat frequency, is equal to the frequency difference mentioned above. The processing circuit 60 can generate measurement data related to the distance and / or speed of the object 10 based on the beat frequency.

[0124] When the object 10 is stationary, the beat frequency during the up-chirp period is equal to the beat frequency during the down-chirp period. If the increase or decrease in the frequency of the light during the up-chirp period or the down-chirp period is Δf, the time required for the change of Δf is Δt, the speed of light is c, and the difference between the optical path length of the reference light 20L1 and the total value of the optical path length of the irradiated light 20L2 and the optical path length of the reflected light 20L3 is 2d, then the beat frequency f during the up-chirp period or the down-chirp period is beat It is represented by the following formula (1).

[0125] [Formula 1]

[0126]

[0127] The beat frequency f of formula (1) is beat The frequency can be obtained by multiplying the time rate of change Δf / Δt of the frequency by the time (2d / c) for the irradiation light 20L to be emitted from the measuring device 100A to the outside, reflected by the object 10, and returned as the reflected light 20L3.

[0128] When the object 10 moves, the frequency of the reflected light 20L3 is Doppler shifted in the positive or negative direction along the frequency axis compared to the frequency of the reference light 20L1. In this case, the beat frequency during the up-chirp period is different from the beat frequency during the down-chirp period. The processing circuit 60 can generate measurement data related to the speed and distance of the object 10 based on the frequency difference and average value of these beat frequencies.

[0129] [Measurement Operation Executed by Processing Circuit 60]

[0130] Next, refer to Figure 3 An example of the measurement operation executed by the processing circuit 60 in the first embodiment will be described. Figure 3 1 is a flowchart schematically showing an example of a measurement operation executed by the processing circuit 60. The processing circuit 60 executes Figure 3 The actions of steps S101 to S103 are shown.

[0131] <Step S101>

[0132] The processing circuit 60 causes the light source 20 to emit the laser light 20L0 whose frequency changes with time. Specifically, the control circuit 60a causes the driving circuit 60b to drive the light source 20 so that the light source 20 emits the laser light 20L0 whose frequency changes with time.

[0133] <Step S102>

[0134] The processing circuit 60 causes the photodetector 50 to detect the interference light 20L4. The photodetector 50 outputs a signal corresponding to the intensity of the interference light 20L4. Specifically, the control circuit 60a causes the photodetector 50 to detect the interference light 20L4.

[0135] <Step S103>

[0136] The processing circuit 60 generates measurement data related to the distance and / or speed of the object 10 based on the signal output from the photodetector 50. Specifically, the control circuit 60a causes the signal processing circuit 60c to generate measurement data based on the signal output from the photodetector 50.

[0137] Through the above-described operation of the processing circuit 60 , the distance and / or speed of the object 10 can be measured.

[0138] [Flow of Light in Measurement Device 100A]

[0139] Next, refer to Figure 4A and Figure 4B , indicating that Figure 1 The flows of multiple lights generated in the measuring device 100A and their optical path lengths are shown. Figure 4A It is used to illustrate Figure 1 FIG. 1 is a diagram of the flows of multiple lights generated within the measuring device 100A. Figure 4A In FIG. 1 , for simplicity, the signal fiber 52 connecting the second optical splitter 32b and the photodetector 50 is shown as one optical fiber. In other figures, the optical fiber connecting the two may be shown as one optical fiber. Figure 4A The dashed lines with arrows shown represent the flow of light. Figure 4A As shown, a plurality of light flows α to δ are generated in the measuring device 100A.

[0140] The light flow α is a flow of the reference light 20L1 from the first light separator 32a to the photodetector 50. The light flow β is a flow of the irradiation light 20L2 from the first light separator 32a to the object 10 and a flow of the reflected light 20L3 from the object 10 to the photodetector 50.

[0141] On the other hand, the light flows γ and δ cause noise in the detection signal. The light flow γ is a flow in which a part of the irradiation light 20L2 is reflected from the first light separator 32a by the optical element 40 and reaches the light detector 50. Such reflection Figure 1The light flow δ is a flow of another part of the irradiation light 20L2 from the first optical separator 32a through the noise light path inside the optical circulator 34 to the light detector 50. The noise light path can be considered as a path passing through the optical circulator 34, more specifically, a path in which the leakage light of the irradiation light 20L2 toward the optical element 40 in the optical circulator 34 travels while being multiply scattered inside.

[0142] As described above, a part of the irradiation light 20L2 is reflected by the optical element 40, and another part is multiply scattered inside the optical circulator 34, so the remaining part of the irradiation light 20L2 is actually emitted to the outside from the optical element 40. However, in this specification, as long as there is no misunderstanding, it is described as "the optical element 40 emits the irradiation light 20L2 to the outside".

[0143] Figure 4B It is used to illustrate Figure 1 The optical path lengths of the plurality of light flows α to δ generated in the measuring device 100A are shown in FIG. 1 The second optical path length of the second path from the first optical separator 32a to the optical element 40 is d 2 The third optical path length of the third path from the optical element 40 to the photodetector 50 is d 3 The optical path length of the fourth path from the first optical separator 32a through the noise light path inside the interference optical system 30, more specifically, through the noise light path inside the optical circulator 34 to the photodetector 50 is denoted as the fourth optical path length d. 4 Assume that the reciprocating distance between the optical element 40 and the object 10 is 2L. The distance L is Figure 1 The distance L is the distance from the socket 40a of the optical element 40 to the portion of the object 10 irradiated by the irradiation light 20L2. Therefore, when the object 10 is in contact with the optical element 40, the distance L corresponds to the length of the optical element 40. The optical path length of the light flow α is d 1 , the optical path length of the light flow β is d 2 +d 3 +2L, the optical path length of the light flow γ is d 2 +d 3 , the optical path length of the light flow δ is d 4 .

[0144] The frequency of the beat signal caused by the reflected light 20L3 reflected by the object 10 is expressed by the following equation (2). 2 +d 3 +2L-d 1| is the difference in optical path length between the light flow β and the light flow α.

[0145] [Formula 2]

[0146]

[0147] The frequency f of the beat signal caused by the light reflected by the optical element 40 in the irradiation light 20L2 is opt It is represented by the following formula (3). 2 +d 3 -d 1 | is the difference in optical path length between the light flow γ and the light flow α.

[0148] [Formula 3]

[0149]

[0150] The frequency f of the beating signal caused by the multi-scattered light generated inside the optical circulator 34 is cir It is represented by the following formula (4). 4 -d 1 | is the difference in optical path length between the light flow δ and the light flow α.

[0151] [Formula 4]

[0152]

[0153] The influence of the optical path length of the path of the light flow α to δ in the measuring device 100A on the distance range in which the distance and / or speed of the object 10 can be measured is described in detail in Japanese Patent Application No. 2022-010910 (filing date: January 27, 2022). The entire disclosure of Japanese Patent Application No. 2022-010910 is cited in this specification.

[0154] [Comparative Example]

[0155] Here, refer to Figures 5 to 6B The following describes a measurement device of a comparative example to explain a problem that occurs when an output fiber having a connector and a socket between two ends located on opposite sides is used instead of using the output fiber 42 directly led out from the first housing 70a and the second housing 70b.

[0156] Figure 5 It is a block diagram schematically showing the configuration of a measuring device according to a comparative example. Figure 5 The measuring device 90 shown is Figure 1 The measuring device 100A shown is different in that the measuring device 90 does not have Figure 1 The output fiber 42 shown has Figure 5The output fiber 43 shown in FIG. 4 is provided with a first connector 43a at one of the two ends located on opposite sides. The first connector 43a is connected to the socket 40a of the optical element 40. The output fiber 43 is also provided with two second connectors 43b and a first socket 43c between the two ends mentioned above. The first socket 43c is a component located between the two second connectors 43b and used to connect the two second connectors 43b. The first socket 43c is mounted on the first housing 70a. The output fiber 43 is also provided with two third connectors 43d and a second socket 43e between the two ends mentioned above. The second socket 43e is a component located between the two third connectors 43d and used to connect the two third connectors 43d. The second socket 43e is mounted on the second housing 70b.

[0157] Since the portion connected to the optical element 40, the portion connected to the optical circulator 34, and the portion located between these two portions in the output fiber 43 are detachable, the manufacturing and maintenance of the measuring device 90 are easy. On the other hand, since the output fiber 43 is not an optical fiber directly drawn out from the first housing 70a and the second housing 70b, when the irradiation light 20L2 is guided, the irradiation light 20L2 is reflected at the first socket 43c and the second socket 43e.

[0158] Fig. 6A It is used to illustrate Figure 5 FIG. 9 is a diagram of the flow of multiple lights generated within the measuring device 90. Fig. 6A As shown, in the measuring device 90, in addition to the light flows α to δ, light flows γ' and γ" are also generated to cause noise in the detection signal. As described above, the light flows γ and δ are respectively caused by a part and another part of the irradiation light 20L2. The light flow γ' is the flow of another part of the irradiation light 20L2 reflected from the first socket 43c from the first optical separator 32a and reaching the light detector 50. The light flow γ" is the flow of another part of the irradiation light 20L2 reflected from the second socket 43e from the first optical separator 32a and reaching the light detector 50.

[0159] Figure 6B It is used to illustrate Figure 5 d is a graph showing the optical path lengths of a plurality of light flows generated in the measuring device 90. Assuming that the fifth optical path length of the fifth path from the first optical splitter 32a to the first socket 43c is d 21 The sixth optical path length of the sixth path from the first socket 43c to the photodetector 50 is d 31 The seventh optical path length of the seventh path from the first optical splitter 32a to the second socket 43e is d 22 The length of the eighth optical path from the second socket 43e to the photodetector 50 is d 32The optical path length of the light flow γ' is d 21 +d 31 , the optical path length of the light flow γ" is d 22 +d 32 .

[0160] The frequency f of the beat signal caused by the light reflected by the first socket 43c in the irradiation light 20L2 is r1 It is represented by the following formula (5). 21 +d 31 -d 1 | is the optical path length difference between the light flow γ' and the light flow α.

[0161] [Formula 5]

[0162]

[0163] The frequency f of the beat signal caused by the light reflected by the second socket 43e in the irradiation light 20L2 is r2 It is represented by the following formula (6). 22 +d 32 -d 1 | is the difference in optical path length between the light flow γ" and the light flow α.

[0164] [Formula 6]

[0165]

[0166] In the measuring device 90 of the comparative example, the light source 20 and the interference optical system 30 can be accommodated in a sealed state without a gap through the first housing 70a. Furthermore, the irradiation light 20L2 can be taken out to the outside through the output fiber 43 through the first housing 70a and the second housing 70b. In this way, it is possible to take into account both the blocking of the leakage light from the light source 20 and the interference optical system 30 and the taking out of the irradiation light 20L2 to the outside. On the other hand, since the output fiber 43 is not an optical fiber directly led out from the first housing 70a and the second housing 70b, and has connectors 43b, 43d and sockets 43c, 43e, when the irradiation light 20L2 is guided, a part of the irradiation light 20L2 may be reflected by the sockets 43c, 43e.

[0167] Next, refer to Fig. 7A and Figure 7B Examples of the spectrum of the detection signal of Embodiment 1 and Comparative Example are described respectively. Fig. 7A and Figure 7B The diagrams schematically show examples of the spectrum of the detection signal of the first embodiment and the comparative example. The vertical axis represents the intensity of the detection signal, and the horizontal axis represents the frequency. The frequency is above zero and corresponds to the distance from the optical element 40 to the object 10. Fig. 7A and Figure 7B In the example shown, the second optical path length d 2 and the third optical path length d 3 The sum of the lengths is equal to the first optical path length d 1 That is, d 2 +d 3 =d 1 According to formula (3), f opt =0Hz. Figure 1 The socket 40a of the optical element 40 shown is 0 m, and the distance from the optical element 40 to the object 10 can be measured. When the object 10 is in contact with the optical element 40, the distance from the optical element 40 to the object 10 is equivalent to the length of the optical element 40, so the peaks β and γ do not overlap each other.

[0168] In f opt ≠0Hz, the frequency ratio f opt The low frequency range is not used as a frequency range corresponding to the distance range in which the distance and / or speed of the object 10 can be measured. opt =0 Hz, since there is no such unused frequency range, the distance range in which the distance and / or speed of the object 10 can be measured can be expanded to the maximum.

[0169] exist Fig. 7A In the example shown, the spectrum of the detection signal shows peaks β, γ, and δ, which are caused by the light flows β, γ, and δ, respectively. The peak frequency of the peak β is f obj , the peak frequency of the peak γ is f opt , the peak frequency of the peak value δ is f cir The difference in optical path length through the flow of light β to δ, frequency f obj 、f opt and f cir are different from each other. Peak values ​​γ and δ are noise. If the frequency f obj Not at frequency f cir If the frequency f is close to , the measurement data of the object 10 can be obtained correctly. cir The frequency range other than the vicinity of corresponds to the distance range in which the distance and / or speed of the object 10 can be measured. cir The frequency range near may vary depending on the environment in which the distance and / or speed of the object 10 is measured. cir For example, the frequency range around corresponds to the frequency f cir The distance range is 1m, 10cm or within 1cm from the distance.

[0170] In contrast, Figure 7BIn the example shown, the spectrum of the detection signal includes not only peaks β, γ, and δ but also peaks γ and γ" due to light flows γ' and γ", respectively. The peak frequency of the peak γ' is f r1 , the peak frequency of the peak value γ" is f r2 The difference in optical path length through the light flow β, γ, γ', γ" and δ, the frequency f obj 、f opt 、f r1 、f r2 and f cir Different from each other. Figure 7B In the example shown, f r2 <f r1 And f r1 <f cir The peak values ​​γ and γ” are noise. Even if the frequency f obj Not at frequency f cir Near the frequency f r1 or r2 In the case of being near , it is not easy to correctly obtain the measurement data of the object 10. Figure 7B In the example shown, the frequency f obj Possibly with frequency f r1 or r2 In this way, the peak values ​​γ and γ" narrow the distance range in which the distance and / or speed of the object 10 can be measured.

[0171] In the above example, it is d 2 +d 3 =d 1 , but it can be either 2 +d 3 ≠d 1 , the same discussion as above also holds true. However, the frequency f obj 、f opt 、f r1 、f r2 and f cir Under the condition of the following formula (7), if the output fiber 43 of the comparative example is used, then Figure 7B In the example shown, the frequency f obj 、f r1 、f r2 and f cir Present at a specific frequency f opt High frequency side. Therefore, the frequency f obj Possibly with frequency f r1 or r2 overlapping.

[0172] [Formula 7]

[0173] |d2 +d 3 -d 1 |≤|d 4 -d 1 | (7))

[0174] When the condition of formula (7) is satisfied, if the output fiber 42 of embodiment 1 is used, then Fig. 7A Similarly, if the frequency f obj Not at frequency f cir , it is possible to accurately acquire the measurement data of the object 10 without narrowing the distance range in which the distance and / or speed of the object 10 can be measured. In the measurement device 100A of the first embodiment, the condition of the formula (7) is not essential.

[0175] As described above, in the measuring device 100A according to the first embodiment, the following effects (1) to (3) can be obtained.

[0176] (1) By housing the light source 20 and the interference optical system 30 in the first housing 70 a , the possibility of undesired light leaking to the outside can be reduced.

[0177] (2) By arranging the processing circuit 60 outside the first housing 70a and inside the second housing 70b, it is possible to effectively release heat generated by the processing circuit 60 to the outside. As a result, the processing circuit 60 can operate more stably and the variation in the length of the optical fiber in the first housing 70a can be suppressed, so that the measurement data of the object 10 can be accurately acquired.

[0178] (3) By using the output fiber 42 directly led out from the first housing 70a and the second housing 70b, noise can be reduced in the spectrum of the detection signal. As a result, the measurement data of the object 10 can be accurately acquired without narrowing the distance range in which the distance and / or speed of the object 10 can be measured.

[0179] Patent Documents 1 and 2 and Non-Patent Document 1 do not describe that the light source 20 and the interference optical system 30 are housed in the first housing 70a for the purpose of reducing the possibility of unwanted light leaking to the outside. Similarly, Patent Documents 1 and 2 and Non-Patent Document 1 do not describe that the processing circuit 60 is arranged outside the first housing 70a and inside the second housing 70b, and that the output fiber 42 is directly led out from the first housing 70a and the second housing 70b.

[0180] In addition, when the heat generated by the processing circuit 60 is not much, it is not necessary to emphasize effect (2) among effects (1) to (3). In this case, the processing circuit 60 may be arranged inside the first housing 70a. Furthermore, in the output fiber 43 having connectors 43b, 43d and sockets 43c, 43e, when the amount of light reflected by the sockets 43c, 43e by the irradiation light 20L2 is not much, it is not necessary to emphasize effect (3) among effects (1) to (3). In this case, instead of using the output fiber 42 directly led out from the first housing 70a and the second housing 70b, it is also possible to use the output fiber 43 having connectors 43b, 43d and sockets 43c, 43e.

[0181] (Implementation Method 2)

[0182] Next, refer to Figure 8 , the configuration example of the measuring device according to the second embodiment of the present disclosure will be described centering on the points that are different from the measuring device according to the first embodiment. Figure 8 This is a block diagram schematically showing the configuration of a measuring device according to an exemplary embodiment 2 of the present disclosure. Figure 8 The measuring device 100B shown in the figure is different from the Figure 1 The measuring device 100A shown in FIG. 1 is different. The first point is that the first housing 70a not only accommodates the light source 20 and the interference optical system 30, but also accommodates the photodetector 50. The second point is that the first housing 70a includes not only the first wiring lead-out portion 74a, but also the second wiring lead-out portion 74b. The first wiring lead-out portion 74a is a portion for leading out wiring for sending signals from the drive circuit 60b to the light source 20. The second wiring lead-out portion 74b is a portion for leading out wiring for sending signals from the control circuit 60a to the photodetector 50 and wiring for sending signals from the photodetector 50 to the signal processing circuit 60c. The first wiring lead-out portion 74a and the second wiring lead-out portion 74b may be, for example, the above-mentioned electrical connectors.

[0183] The photodetector 50 may include components such as a photodiode and a preamplifier. These components do not generate much heat. Therefore, even if the photodetector 50 is disposed inside the first housing 70a, there is no problem that the operation of the photodetector 50 becomes unstable or the length of the optical fiber in the first housing 70a changes, causing errors in the measurement data of the object 10.

[0184] In the measuring device 100B of the second embodiment, the above-mentioned effects (1) to (3) can be obtained similarly to the measuring device 100A of the first embodiment. Furthermore, in the measuring device 100B of the second embodiment, unlike the measuring device 100A of the first embodiment, the signal fiber 52 does not need to have two connectors 52b and a socket 52c. Therefore, the components of the measuring device 100B can be simplified, and the cost of the components can be suppressed to a low level.

[0185] (Implementation method 3)

[0186] Next, refer to Fig. 9 , the configuration example of the measuring device according to the third embodiment of the present disclosure will be described centering on the points that are different from the measuring device according to the second embodiment. Fig. 9 This is a block diagram schematically showing the structure of a measuring device according to an exemplary embodiment 3 of the present disclosure. Fig. 9 The measuring device 100C shown in FIG. Figure 8 The measuring device 100B shown is different in that the measuring device 100C further includes a chip 80 that supports the interference optical system 30 and the photodetector 50. That is, the interference optical system 30 and the photodetector 50 are configured on a chip. In the chip 80, an optical waveguide is used instead of an optical fiber as a connecting component. Fig. 9 The bold lines within the illustrated chip 80 represent optical waveguides.

[0187] The chip 80 includes a first optical coupling section 82a, a second optical coupling section 82b, and a signal electrode 84. The first optical coupling section 82a inputs the laser light 20L0 emitted from the light source 20 to the first optical separator 32a. The second optical coupling section 82b inputs the irradiated light 20L2 from the optical circulator 34 to the optical element 40 via the output fiber 42, and inputs the reflected light 20L3 from the optical element 40 to the optical circulator 34 via the output fiber 42. The first optical coupling section 82a and the second optical coupling section 82b may be, for example, end faces of optical waveguides or grating couplers. The signal electrode 84 inputs the signal output from the control circuit 60a to the photodetector 50, and inputs the signal output from the photodetector 50 to the signal processing circuit 60c.

[0188] In the measuring device 100C of the third embodiment, the above-mentioned effects (1) to (3) can be obtained similarly to the measuring device 100A of the first embodiment. Furthermore, in the measuring device 100C of the third embodiment, unlike the measuring device 100B of the second embodiment, the interfering optical system 30 and the photodetector 50 are configured on a chip, so that the measuring device 100C can be miniaturized.

[0189] (Implementation 4)

[0190] Next, refer to Fig.10, the configuration example of the measuring device according to the fourth embodiment of the present disclosure will be described centering on the points that are different from the measuring device according to the first embodiment. Fig.10 This is a block diagram schematically showing the structure of a measuring device according to an exemplary embodiment 4 of the present disclosure. Fig.10 The measuring device 100D shown in FIG. Figure 1 The measuring device 100 shown is different in that the measuring device 100D does not have Figure 1 The optical circulator 34 shown in FIG. Fig.10 The third optical separator 32c is shown.

[0191] The intensity of the reflected light 20L3 input from the third optical separator 32c to the second optical separator 32b is lower than the intensity of the reflected light 20L3 input from the optical circulator 34 to the second optical separator 32b. When the branching ratio of the third optical separator 32c is 50:50, the intensity of the reflected light 20L3 output from the third optical separator 32c is half the intensity of the reflected light 20L3 input to the third optical separator 32c. Therefore, the intensity of the flapping signal caused by the object 10 becomes low. On the other hand, since the third optical separator 32c is cheaper than the optical circulator 34, the cost of components can be suppressed to be low.

[0192] When the third optical splitter 32c is used instead of the optical circulator 34, part of the reflected light 20L3 may return to the light source 20 via the first optical splitter 32a. Such return light may be removed by providing an optical isolator between the light source 20 and the first optical splitter 32a.

[0193] In the measuring device 100D of the fourth embodiment, the above-mentioned effects (1) to (3) can be obtained similarly to the measuring device 100A of the first embodiment. Furthermore, in the measuring device 100D of the fourth embodiment, since the third optical splitter 32c is used instead of the optical circulator 34, the cost of components can be kept low.

[0194] (Implementation method 5)

[0195] Next, refer to Fig.11 , the configuration example of the measuring device according to the fifth embodiment of the present disclosure will be described centering on the points that are different from the measuring device according to the first embodiment. Fig.11 This is a block diagram schematically showing the structure of a measuring device according to an exemplary embodiment 5 of the present disclosure. Fig.11 The measuring device 100E shown in the figure is different from the Figure 1The measuring device 100A shown in FIG. 1 is different. The first point is that the optical element 40 is located outside the first shell 70a and inside the second shell 70b. The second point is that the second shell 70b has a light-transmitting window 76 that allows the irradiation light 20L2 emitted from the optical element 40 and the reflected light 20L3 reflected by the object 10 to pass through. The light-transmitting window 76 can be an optical substrate that is transparent to the irradiation light 20L2 and the reflected light 20L3, or it can be an opening. The optical substrate has a transmittance of 60% or more, more preferably 80% or more, to the irradiation light 20L2 and the reflected light 20L3, for example.

[0196] In the measuring device 100E, the output fiber 42 is drawn out only from the fiber drawing portion 72 of the first housing 70a. The fiber drawing portion 72 has Figure 1 The output fiber 42 of the measuring device 100E can be made shorter than the measuring device 100A. When the irradiation light 20L2 is guided from the output fiber 42, due to defects inside the fiber, a small amount of undesired reflection of the irradiation light 20L2 may occur. As a result, noise may occur in the spectrum of the detection signal. There is a tendency that the longer the output fiber 42 is, the wider the frequency band in which noise may occur. In the measuring device 100E, since the output fiber 42 cannot be made shorter, the possibility of generating noise in the spectrum of the detection signal can be reduced.

[0197] In the measuring device 100E of the fifth embodiment, the above-mentioned effects (1) to (3) can be obtained in the same manner as the measuring device 100A of the first embodiment. However, the effect (3) is obtained by the output fiber 42 that is directly drawn out from the first housing 70a but not drawn out from the second housing 70b. Furthermore, in the measuring device 100E of the fifth embodiment, unlike the measuring device 100A of the first embodiment, the second fiber draw-out portion 72b is not required. Therefore, the components of the measuring device 100E can be simplified, and the cost of the components can be suppressed to a low level. Furthermore, since the output fiber 42 is short, the possibility of generating noise in the spectrum of the detection signal can be reduced.

[0198] (Implementation 6)

[0199] Next, refer to Fig.12 , the configuration example of the measuring device according to the sixth embodiment of the present disclosure will be described centering on the points that are different from the measuring device according to the first embodiment. Fig.12 This is a block diagram schematically showing the structure of a measuring device according to an exemplary embodiment 6 of the present disclosure. Fig.12 The measuring device 100F shown in the figure is different from the Figure 1The first point is that the optical element 40 is located inside the first housing 70a. The second point is that the first housing 70a has a first light-transmitting window 76a, and the second housing 70b has a second light-transmitting window 76b. The first light-transmitting window 76a and the second light-transmitting window 76b have the same Fig.11 The light-transmitting window 76 shown has the same structure.

[0200] In the measuring device 100F, there is no portion for extracting the output fiber 42. Therefore, in the measuring device 100F, the output fiber 42 can be made shorter than in the measuring device 100E, and the possibility of generating noise in the spectrum of the detection signal can be further reduced.

[0201] exist Fig.12 In the example shown, since the optical element 40 is directly fixed to the first light transmission window 76a, the possibility of light other than the irradiation light 20L2 emitted from the optical element 40 leaking from the first housing 70a can be reduced. Alternatively, the optical element 40 may be disposed away from the first light transmission window 76a.

[0202] In the measuring device 100F of the sixth embodiment, the above-mentioned effects (1) to (3) can be obtained in the same manner as the measuring device 100A of the first embodiment. However, the effect (3) is obtained by not having a continuous output fiber 42 drawn out from the first housing 70a and the second housing 70b. Furthermore, in the measuring device 100F of the sixth embodiment, unlike the measuring device 100A of the first embodiment, the first fiber draw-out portion 72a and the second fiber draw-out portion 72b are not required. Therefore, the components of the measuring device 100E can be simplified, and the cost of the components can be suppressed to a low level. Furthermore, since the output fiber 42 is short, the possibility of generating noise in the spectrum of the detection signal can be reduced.

[0203] (Implementation 7)

[0204] Next, refer to Fig.13 , the structural example of the measuring device of the seventh embodiment of the present disclosure will be described centering on the points that are different from the measuring device of the first embodiment. Fig.13 This is a block diagram schematically showing the structure of a measuring device according to an exemplary embodiment 7 of the present disclosure. Fig.13 The measuring device 100G shown is different from Figure 1The measuring device 100G of the present embodiment is different from the measuring device 100A shown in the figure. In the measuring device 100G of the present embodiment, the second optical separator 32b and the optical circulator 34 constituting the interference optical system 30 are located outside the first housing 70a and inside the second housing 70b. In this embodiment, the fiber that guides the reference light 20L1 output from the first optical separator 32a and the fiber that guides the irradiation light 20L2 are led out of the first housing 70a. The fiber that guides the reference light 20L1 and the fiber that guides the irradiation light 20L2 are directly led out from the third fiber lead-out portion 72c of the first housing 70a, respectively, but a connector and a socket may be provided instead of the third fiber lead-out portion 72c to lead out.

[0205] The second housing 70b includes a second fiber lead-out portion 72b for leading out the output fiber 42. A continuous output fiber 42 is led out from the second housing 70b to the outside via the second fiber lead-out portion 72b. The second fiber lead-out portion 72b has a structure that enables the continuous output fiber 42 to be directly led out from the second housing 70b. In the second fiber lead-out portion 72b, a connector and a socket for detachably attaching and detaching the output fiber 42 are not used. Therefore, in the output fiber 42, when the irradiation light 20L2 is guided, almost no reflection of the irradiation light 20L2 occurs.

[0206] In the measuring device 100G of the seventh embodiment, it is assumed that the intensity of the irradiation light 20L2 emitted from the optical element 40 is I out , assuming that the intensity of the irradiation light 20L2 output from the first light separator 32a is I rad2 Assume that the light intensities lost by loss and reflection in the optical element 40 and the optical circulator 34 are L ele and L cir If the optical fiber loss is small enough to be ignored, out Such as I out =I rad2 -L cir -L ele Since part of the optical path of the irradiation light 20L2 output from the first optical separator 32a exists outside the first housing 70a, rad2 It is necessary to meet level 1. If the light intensity that meets the upper limit of level 1 is I limit , then due to I limit ≥I rad2 =I out +L ele +L cir , so I out Become Satisfied out ≤I limit -L ele -L cir Strength. Usually L ele and Lcir with I out Since the intensity is sufficiently smaller than that (for example, smaller by several tens of dB or more), the irradiation light 20L2 can be emitted from the optical element 40 at an intensity close to the upper limit satisfying the level 1 in this embodiment.

[0207] The structure of this embodiment is characterized in that the light source 20 and the first optical separator 32a are housed in the first housing 70a. In the measuring device 100G of the seventh embodiment, the above-mentioned effects (1) and (2) can be obtained in the same manner as the measuring device 100A of the first embodiment. In addition, by providing the output fiber 42 outside the first housing 70a and using the output fiber 42 directly led out from the second housing 70b, noise can be reduced in the spectrum of the detection signal. Furthermore, in this embodiment, since the optical components housed in the first housing 70a can be reduced, the first housing 70a can be made smaller, and there is an advantage that the first housing 70a can be manufactured at a low cost.

[0208] The components of the measuring devices 100A to 100F described above may be combined arbitrarily as long as there is no contradiction. For example, the structure in which the first housing 70a of the measuring device 100B accommodates not only the light source 20 and the interference optical system 30 but also the photodetector 50 may be applied to the measuring devices 100D to 100F. Alternatively, the structure in which the interference optical system 30 and the photodetector 50 of the measuring device 100C are supported by the chip 80 may be applied to the measuring devices 100D to 100F. Alternatively, the structure in which the interference optical system 30 of the measuring device 100D does not include the optical circulator 34 but includes the third optical separator 32c may be applied to the measuring devices 100E and 100F.

[0209] Industrial Applicability

[0210] The measuring device of the embodiment of the present disclosure can be used in a distance measurement system mounted on a vehicle such as a car, UAV (Unmanned Aerial Vehicle) or AGV (Automated Guided Vehicle), or a security system installed on an infrastructure side. The security system can detect a person or a vehicle, for example.

[0211] Description of symbols

[0212] 10 Objects

[0213] 20 Light Sources

[0214] 20L0 Laser

[0215] 20L1 reference light

[0216] 20L2 irradiation light

[0217] 20L3 reflected light

[0218] 20L4 Interference Light

[0219] 30Interference optical system

[0220] 32a 1st optical separator

[0221] 32b Second optical separator

[0222] 32c 3rd optical separator

[0223] 34 Light Circulator

[0224] 40 optical elements

[0225] 42 output fibers

[0226] 50 light detectors

[0227] 52 signal fibers

[0228] 60 processing circuit

[0229] 60a control circuit

[0230] 60b drive circuit

[0231] 60c signal processing circuit

[0232] 62 Memory

[0233] 70a 1st shell

[0234] 70b Second housing

[0235] 80 chips

[0236] 90, 100A~100G measuring device

Claims

1. A measuring device, characterized in that: have: Light source, emitting light; an interference optical system that separates the light emitted from the light source into reference light and irradiation light for irradiating an object, and generates interference light by causing reflected light generated by the irradiation light being reflected by the object to interfere with the reference light; An output fiber connected to the interference optical system to guide the irradiation light; an optical element connected to the output fiber and emitting the irradiation light; The first housing accommodates the light source and the interference optical system; as well as A second housing for housing the first housing; The output fiber is directly led out from the first housing.

2. The measuring device according to claim 1, wherein: The output fiber is led out from the first shell and the second shell; The optical element is arranged outside the second housing.

3. The measuring device according to claim 1, wherein: The output fiber is led out from the first shell; The optical element is arranged on the outer side of the first shell and the inner side of the second shell; The second housing includes a light-transmitting window that transmits the irradiated light.

4. The measuring device according to any one of claims 1 to 3, characterized in that The optical element emits the irradiated light and receives the reflected light; The interference optical system comprises a first light separator, a second light separator, and a circulator or a third light separator; The first optical separator separates the reference light and the irradiation light and outputs the separated reference light, inputs the output reference light to the second optical separator, and inputs the output irradiation light to the circulator or the third optical separator; The circulator or the third optical separator outputs the irradiated light from the first optical separator and inputs the irradiated light to the optical element, outputs the reflected light from the optical element and inputs the reflected light to the second optical separator; The second light separator generates the interference light by causing the reflected light from the circulator or the third light separator to interfere with the reference light from the first light separator.

5. The measuring device according to claim 4, characterized in that Assuming that the optical path length of the first path from the first optical separator to the optical detector detecting the interference light is d1, Assuming that the optical path length of the second path from the second light separator to the optical element is d2, Assuming that the optical path length of the third path from the optical element to the photodetector is d3, Assuming that the optical path length of the fourth path from the first optical separator via the noise optical path of the circulator or the third optical separator to the photodetector is d4, The relationship |d2+d3-d1|≤|d4-d1|.

6. The measuring device according to any one of claims 1 to 3, characterized in that Also available: a signal fiber for guiding the interference light from the interference optical system; and The optical detector is connected to the signal fiber and detects the interference light.

7. The measuring device according to claim 6, characterized in that The photodetector is disposed outside the first housing and inside the second housing.

8. The measuring device according to claim 7, characterized in that The signal fiber includes two connectors and a socket for connecting the two connectors, and the socket is mounted on the first housing.

9. The measuring device according to claim 6, wherein: The photodetector is disposed inside the first housing.

10. The measuring device according to claim 9, characterized in that The interference optical system and the photodetector are configured on-chip.

11. The measuring device according to claim 6, wherein: A processing circuit is further provided, which controls the operation of the light source and the operation of the photodetector and processes the signal output from the photodetector, and is located outside the first housing and inside the second housing.

12. The measuring device according to claim 11, wherein: The light source is capable of changing the frequency of the light over time.

13. A measuring device, characterized in that: have: Light source, emitting light; an interference optical system that separates the light emitted from the light source into reference light and irradiation light for irradiating an object, and generates interference light by causing reflected light generated by the irradiation light being reflected by the object to interfere with the reference light; An output fiber connected to the interference optical system to guide the irradiation light; an optical element connected to the output fiber and emitting the irradiation light; A light detector for detecting the interference light; The first housing accommodates the light source and the interference optical system; a second housing for housing the first housing; and The processing circuit controls the operation of the light source and the operation of the photodetector and processes the signal output from the photodetector, and is disposed outside the first housing and inside the second housing.

14. The measuring device according to claim 13, wherein: The output fiber is a continuous optical fiber.

15. The measuring device according to claim 13 or 14, characterized in that: The light source is capable of changing the frequency of the light over time.

16. A measuring device, characterized in that: have: Light source, emitting light; an interference optical system that separates the light emitted from the light source into reference light and irradiation light for irradiating an object, and generates interference light by causing reflected light generated by the irradiation light being reflected by the object to interfere with the reference light; An output fiber connected to the interference optical system to guide the irradiation light; an optical element connected to the output fiber and emitting the irradiation light; The first housing accommodates the light source and the interference optical system; as well as A second housing for housing the first housing; The output fiber is arranged inside the first shell; The optical element is arranged inside the first shell; The first housing includes a first light-transmitting window for transmitting the irradiated light; The second housing includes a second light-transmitting window that transmits the irradiated light.

17. A measuring device, characterized in that: have: Light source, emitting light; an interference optical system including a separator for separating the light emitted from the light source into reference light and irradiation light for irradiating an object, and causing reflected light generated by reflection of the irradiation light by the object to interfere with the reference light to generate interference light; An output fiber connected to the interference optical system to guide the irradiation light; an optical element connected to the output fiber and emitting the irradiation light; A first housing, accommodating the light source and the separator; and A second housing for housing the first housing; The output fiber is directly led out from the second housing.

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