Measurement device, projector, measurement method, measurement program, and computer-readable recording medium with computer program recorded thereon

Abstract

To suppress deterioration in measurement accuracy of a distance to a measurement object due to a time difference between light emission timing at which a seed laser emits a seed laser beam and output timing at which an output laser beam is output from an optical fiber.SOLUTION: A measurement device comprises: a projector that includes a seed laser, an optical fiber, and an excitation laser, and emits an output laser beam output from the optical fiber to the outside; a light receiver that receives a reflected laser beam obtained by reflecting the output laser beam emitted by the projector on a measurement object and returning; and a controller. The controller executes: timing determination processing of determining output timing at which the output laser beam is output from the optical fiber to which a seed laser beam is input; and measurement processing of measuring a distance to the measurement object on the basis of a time difference between the determined output timing and light reception timing at which the light receiver receives the reflected laser beam.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The technology disclosed in this specification relates to a measurement device, a projector, a measurement method, a measurement program, and a computer-readable recording medium on which a computer program is recorded. [Background technology]

[0002] With the progress of AD (Autonomous Driving) and ADAS (Advanced Driver-Assistance Systems), research and development of LiDAR (Light Detection And Ranging) is being conducted as one of the measurement devices used for grasping the surrounding environment and estimating the vehicle's self-position while driving. LiDAR includes a projector that projects (irradiates) laser light onto a measurement target, and a receiver that receives the reflected light of the laser light reflected off the measurement target. LiDAR outputs information about the measurement target by measuring the distance to the measurement target based on the time difference between the projection timing of the projector emitting the laser light and the reception timing of the receiver receiving the reflected light. The projector includes a fiber laser (see, for example, Patent Document 1). The fiber laser includes a seed laser that emits seed laser light, an optical fiber that is doped with a rare earth element and through which the seed laser light passes, and an excitation laser that emits excitation light that excites the rare earth element of the optical fiber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 117912 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventionally, a measurement device using a projector equipped with a fiber laser is configured to regard the timing at which the seed laser emits seed laser light as the light projection timing of the projector, and measure the distance to the measurement target based on the time difference between the emission timing and the reception timing of the seed laser light. However, in such a configuration, a time lag occurs depending on the length of the fiber between the emission timing of the seed laser light and the output timing at which the output laser light is actually output from the projector. For this reason, the conventional measurement device has a problem that the measurement accuracy of the distance to the measurement target is reduced.

[0005] This specification discloses a technique that can solve the above-mentioned problems. [Means for solving the problem]

[0006] The technology disclosed in this specification can be realized, for example, in the following forms.

[0007] (1) A measurement device disclosed in this specification includes a seed laser that emits seed laser light, an optical fiber doped with a rare earth element and into which the seed laser light emitted by the seed laser is input, and an excitation laser that emits excitation light that excites the rare earth element in the optical fiber, and includes a projector that emits output laser light output from the optical fiber to the outside, a photoreceiver that receives reflected laser light that is reflected by a measurement target and returns from the output laser light output by the projector, and a controller. The controller executes a timing determination process that determines an output timing at which the output laser light is output from the optical fiber into which the seed laser light is input, and a measurement process that measures a distance to the measurement target based on a time difference between the determined output timing and a receiving timing at which the photoreceiver receives the reflected laser light.

[0008] According to this measuring device, the distance to the measurement target is measured using the output timing at which the output laser light is output from the optical fiber to which the seed laser light is input, rather than the light emission timing at which the seed laser emits the seed laser light. This makes it possible to suppress a decrease in the measurement accuracy of the distance to the measurement target caused by the time difference between the light emission timing at which the seed laser emits the seed laser light and the output timing at which the output laser light is output from the optical fiber (hereinafter referred to as "timing difference").

[0009] (2) The above measuring device may further include a sensor for detecting the output laser light output from the optical fiber, and the controller may determine the output timing based on the detection timing of the output laser light detected by the sensor in the timing determination process. With this measuring device, even if the timing difference varies due to, for example, a change in the surrounding environment (such as temperature), it is possible to suppress a decrease in the measurement accuracy of the distance to the measurement target due to the timing difference.

[0010] (3) The above measuring device may further include a reflecting mirror disposed on the output side of the optical fiber and reflecting a portion of the output laser light output from the optical fiber, and the sensor is configured to detect the portion of the output laser light reflected by the reflecting mirror. According to this measuring device, the reflecting mirror can be used to suppress a decrease in the measurement accuracy of the distance to the measurement target caused by a timing time difference.

[0011] (4) The above measuring device may further include a splitter provided on the output side of the optical fiber for splitting the output laser light output from the optical fiber into a plurality of beams, and the sensor may be configured to detect a portion of the output laser light split by the splitter. This measuring device can suppress a decrease in the measurement accuracy of the distance to the measurement target due to a timing difference while suppressing an increase in size of the device caused by using an optical element such as a reflecting mirror independent of the optical fiber.

[0012] (5) In the above measurement device, the controller may be configured to determine, in the timing determination process, a delay timing that is delayed from an emission timing at which the seed laser emits the seed laser light by a delay time corresponding to a time for the seed laser light to pass through the optical fiber as the output timing. According to this measurement device, it is possible to suppress a decrease in measurement accuracy of the distance to the measurement target caused by a timing time difference without providing, for example, a separate optical element or the like.

[0013] (6) A light projector disclosed in this specification includes a seed laser that emits seed laser light, an optical fiber doped with a rare earth element and into which the seed laser light emitted by the seed laser is input, and an excitation laser that emits excitation light that excites the rare earth element in the optical fiber, and emits output laser light output from the optical fiber to the outside, and further includes a sensor that detects the output laser light output from the optical fiber and outputs a detection signal according to the detection result. According to this light projector, it is possible to notify the outside of the output timing at which the output laser light is output from the optical fiber into which the seed laser light is input, rather than the light emission timing at which the seed laser emits the seed laser light.

[0014] (7) The measurement method disclosed in this specification includes a light projecting and receiving process of inputting seed laser light emitted by a seed laser into an optical fiber, emitting output laser light from the optical fiber to the outside, and receiving reflected laser light reflected from an object to be measured, an output timing determination process of determining the output timing at which the output laser light is output from the optical fiber into which the seed laser light is input, and a measurement process of measuring the distance to the object to be measured based on the time difference between the determined output timing and the receiving timing of the reflected laser light.

[0015] (8) The measurement program disclosed in this specification causes a computer possessed by a measurement device including a light projector having a seed laser that emits seed laser light and an optical fiber, and a light receiver that receives reflected laser light that is output from an object to be measured and reflected back from the output laser light emitted by the light projector, to execute a timing determination process that determines the output timing at which the output laser light is output from the optical fiber to which the seed laser light is input, and a measurement process that measures the distance to the object to be measured based on the time difference between the determined output timing and the receiving timing at which the reflected laser light is received by the light receiver.

[0016] The technology disclosed in this specification can be realized in various forms, for example, a measurement device, a spotlight, a measurement method, a measurement program, a computer-readable recording medium on which the measurement program is recorded, etc. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a block diagram showing a schematic configuration of a measurement device 10 according to a first embodiment. [Diagram 2] FIG. 2 is an explanatory diagram illustrating a schematic configuration of a projector 20. [Diagram 3] Flowchart showing measurement process [Figure 4] 11 is a flowchart showing a measurement process in the second embodiment. [Diagram 5] FIG. 13 is an explanatory diagram illustrating a schematic configuration of a floodlight 20A according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] A. First embodiment: A-1. Configuration of the measuring device 10: 1 is a block diagram showing a schematic configuration of a measuring device 10 according to the first embodiment. The measuring device 10 is a scan-type LiDAR. The measuring device 10 measures the difference between the timing at which the light projector 20 emits the output laser light Lout and the timing at which the light receiver 30 receives the input laser light Lin (time of flight of the laser light, hereinafter referred to as "TOF" (Time of Flight)) to acquire information about the measuring object W.

[0019] The measuring device 10 is mounted on, for example, a vehicle (not shown) equipped with AD or ADAS. For example, while the vehicle is traveling, the measuring device 10 assists in the detection of objects such as people and other vehicles, and provides various types of information to other devices and users that are useful for ensuring the safety of the driver of the vehicle and those around the vehicle, and for reducing damage to surrounding objects while the vehicle is being driven.

[0020] The measuring device 10 includes a light projector 20, a light receiver 30, a scanner (beam deflector) 40, and a mirror 50.

[0021] The projector 20 includes a fiber laser 22 that outputs an output laser light Lout, and a light-projection control device 26 (see FIG. 2 described later). The light-projection control device 26 controls the emission of the fiber laser 22. The light-projection control device 26 also inputs a signal indicating the timing of light projection at which the fiber laser 22 emits light to a TOF measurement device 36 described later. The light-projection control device 26 periodically and repeatedly emits light from the fiber laser 22, for example, by periodically repeating the on-off control of a current flowing through the fiber laser 22 (a seed laser 110 described later). A detailed configuration of the projector 20 will be described later.

[0022] The scanner 40 has an optical scanning optical system that deflects the optical path (direction) of the output laser light Lout output by the projector 20, and scans the output laser light Lout in a predetermined direction. The scanner 40 has a polygon mirror 42 and a scanning mirror 46 as an optical scanning optical system. The polygon mirror 42 has a plurality of reflecting surfaces 44 (four in FIG. 1), and is a rotating body that is provided so as to be rotatable about a first rotation axis G1. The scanning mirror 46 is provided so as to be rotatable about a second axis G2. The output laser light Lout output by the projector 20 is reflected by a reflecting surface 48 of the scanning mirror 46, reflected by one reflecting surface 44 of the rotating polygon mirror 42, and emitted toward the measurement object W. The input laser light Lin reflected by the measurement object W is again reflected by one reflecting surface 44 of the rotating polygon mirror 42, and reflected by the reflecting surface 48 of the scanning mirror 46.

[0023] The mirror 50 reflects the input laser light Lin reflected by the reflecting surface 48 of the scanning mirror 46 and guides it to the photoreceiver 30. Specifically, the input laser light Lin reflected by the reflecting surface 48 of the scanning mirror 46 is reflected by the reflecting surface 52 of the mirror 50 and heads toward the photoreceiver 30.

[0024] The light receiver 30 includes a light receiving optical system 34, a light receiving section 32, and a TOF measurement device 36.

[0025] The light receiving optical system 34 collects the input laser light Lin to form a spot on the light receiving unit 32. The light receiving optical system 34 is configured using optical components such as various lenses such as a collecting lens, various filters such as a wavelength filter, and a reflecting mirror.

[0026] The light receiving unit 32 is a receiving light source having one or more light receiving elements (not shown), or one or more light receiving element arrays (for example, light receiving elements arranged linearly (one-dimensionally) or planarly (two-dimensionally)). The light receiving elements are, for example, photodiodes, SPADs (Single Photon Avalanche Diodes), balanced photodetectors, etc. The light receiving unit 32 photoelectrically converts the input laser light Lin incident from the light receiving optical system 34 to generate a current corresponding to the intensity of the input laser light Lin (hereinafter referred to as a "light receiving current"). The light receiving unit 32 inputs to the TOF measurement device 36 a signal indicating the light receiving timing at which the light receiving elements constituting the light receiving unit 32 received the input laser light Lin, and the light receiving current generated by the light receiving elements.

[0027] The TOF measurement device 36 obtains the TOF based on a signal indicating the light projection timing input from the light projection control device 26 and a signal indicating the light reception timing input from the light receiving unit 32. The TOF measurement device 36 has, for example, a time measurement IC (Integrated Circuit) equipped with a TDC (Time to Digital Converter) circuit. The TOF measurement device 36 inputs the obtained TOF and the light reception current input from the light receiving unit 32 to the information processing unit 54.

[0028] With the above configuration, the irradiation position of the output laser light Lout on the measurement object W can be moved in a first scanning direction (e.g., vertical direction on the paper in FIG. 1) according to a change in the rotation angle (θx) accompanying the rotation of the polygon mirror 42, thereby obtaining image information of the measurement object W in the first scanning direction. Also, the irradiation position of the output laser light Lout on the measurement object W can be moved in a second scanning direction (e.g., a direction perpendicular to the first scanning direction, the depth direction on the paper in FIG. 1) according to a change in the rotation angle (θy) accompanying the rotation of the scanning mirror 46, thereby obtaining information of the measurement object W in the second scanning direction.

[0029] The measuring device 10 further includes an information processing unit 54 and a communication I / F (Interface) 56.

[0030] The information processing unit 54 has a processor (such as a central processing unit (CPU), a micro processing unit (MPU), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), and a digital signal processor (DSP)). The information processing unit 54 generates information used for various measurements such as detection and distance measurement of the measurement target W based on the light receiving current and TOF input from the TOF measurement device 36. The information is, for example, a histogram used in time correlated single photon counting, a distance to each point of the measurement target W, a point cloud (point cloud information), and the like. The information processing unit 54 also controls the light projection control device 26 and the light receiving unit 32. The information processing unit 54 controls, for example, the light projection control device 26 and the light receiving unit 32 to control the light projection timing and the light receiving timing described above so that the processing for generating the histogram is accelerated or optimized. The information generated by the information processing unit 54 is provided (transmitted) via the communication I / F 56 to a device that uses the information (hereinafter, referred to as "various use devices 60").

[0031] The various utilization devices 60 perform, for example, creating an environmental map using a point cloud, self-position estimation (SLAM (Simultaneous Localization and Mapping)) using a scan matching algorithm (NDT (Normal Distributions Transform), ICP (Iterative Closest Point), etc.), and the like.

[0032] A-2. Configuration of projector 20: Fig. 2 is an explanatory diagram that shows a schematic configuration of the projector 20. As shown in Fig. 2, the projector 20 includes a fiber laser 22, a light projection optical system 24, and the light projection control device 26.

[0033] The projection optical system 24 adjusts the light distribution of the output laser light Lout by, for example, applying an optical effect (such as refraction, scattering, or diffraction) to the light emitted by the fiber laser. The projection optical system 24 is configured using optical components such as various lenses, such as a collimator lens, and a reflector (mirror).

[0034] The fiber laser includes a seed laser 110, a pump laser 120, a first optical fiber F1, and a second optical fiber F2.

[0035] The seed laser 110 emits seed light La having a peak wavelength included in the near-infrared range, for example. In this embodiment, the wavelength of the seed light La is 1550 nm, but is not limited to this and may be, for example, 900 nm.

[0036] The first optical fiber F1 and the second optical fiber F2 are doped with a rare earth element, and the seed light La passes through them. The first optical fiber F1 and the second optical fiber F2 are arranged in series. The optical fibers F1 and F2 are doped with at least one of ytterbium (Yb) and erbium (Er) as a rare earth element. The length of each of the optical fibers F1 and F2 is, for example, about 5 m.

[0037] The pumping laser 120 emits pumping light Lb (for example, 940 nm) that excites the rare earth elements contained in the optical fibers F1 and F2.

[0038] More specifically, the fiber laser 22 has a first optical isolator (ISO) 130, a first wavelength division multiplexer (WDM) 140, a wavelength division multiplexer (TAP) 150, a second optical isolator 160, and a second multiplexer 170.

[0039] The seed laser 110 is optically coupled to the first multiplexer 140 via a normal optical fiber (not shown) that is not doped with a rare earth element. A first optical isolator 130 is provided between the seed laser 110 and the first multiplexer 140. The first multiplexer 140 is coupled to an input portion of a first optical fiber F1. An output portion of the first optical fiber F1 is optically coupled to a second multiplexer 170. A second optical isolator 160 is provided between the first multiplexer 140 and the second multiplexer 170. The second multiplexer 170 is coupled to an input portion of a second optical fiber F2. An output portion of the second optical fiber F2 is directed toward the light projection optical system 24.

[0040] The pumping laser 120 is optically coupled to the splitter 150 via a normal optical fiber (not shown) that is not doped with a rare earth element. The splitter 150 splits the pumping light Lb emitted by the pumping laser 120 into multiple lights. The splitter 150 is optically coupled to the first multiplexer 140 and the second multiplexer 170. The first multiplexer 140 combines the seed light La emitted by the seed laser 110 and the pumping light Lb from the splitter 150. The second multiplexer 170 combines the seed light La amplified by the first optical fiber F1 and the pumping light Lb from the splitter 150.

[0041] With this configuration, in the fiber laser 22, the rare earth elements in the first optical fiber F1 and the second optical fiber F2 are excited by the excitation light Lb emitted by the excitation laser 120. The seed light La of the seed laser 110 is incident on the first optical fiber F1 and the second optical fiber F2 in the excited state, whereby the seed light La is amplified in two stages. As a result, a high-power output laser light Lout is output via the projection optical system 24.

[0042] A-3. Configuration for detecting the output timing of the output laser light Lout: 2, the floodlight 20 of this embodiment further includes a reflecting mirror 300 and a sensor 310. The reflecting mirror 300 is disposed on the optical path between the other end (output end) of the second optical fiber F2 and 24. The reflecting mirror 300 reflects a part of the output laser light Lout output from the second optical fiber F2 and transmits the remainder of the output laser light Lout. The reflecting mirror 300 is, for example, a one-way mirror (mirror glass, half mirror) or a partial mirror formed of a light-transmitting material as a whole and having a mirror finish or the like applied to a part of the area where the output laser light Lout is incident.

[0043] The sensor 310 is a light receiving sensor that detects a portion of the output laser light Lout (hereinafter referred to as "partial output laser light Ld") reflected by the reflecting mirror 300. The sensor 310 has a light receiving element such as a photodiode, and outputs a detection signal S indicating the timing at which the partial output laser light Ld is received.

[0044] A-4. Measurement process: Fig. 3 is a flowchart showing the measurement process. When the information processing unit 54 receives an instruction to start measurement from, for example, the utilization device 60, the light-projection control device 26 starts light emission control of the fiber laser 22 as shown in Fig. 3 (S110). Specifically, as described above, the light-projection control device 26 makes the pumping laser 120 start emitting the pumping light Lb to change the rare earth elements contained in the first optical fiber F1 and the second optical fiber F2 from the ground state to the excited state. Then, the light-projection control device 26 makes the seed laser 110 start a light-emitting operation to periodically emit the seed light La. The seed light La emitted by the seed laser 110 passes through the first optical fiber F1 and the second optical fiber F2 to reach the reflecting mirror 300. Most of the seed light La that reaches the reflecting mirror 300 passes through the reflecting mirror 300 and is output from the projection optical system 24 to the scanner 40, and a portion of the seed light La that reaches the reflecting mirror 300 (partial output laser light Ld) is reflected by the reflecting mirror 300 and detected by the sensor 310.

[0045] The light-projection control device 26 acquires a detection signal S output at the detection timing when the sensor 310 detects the partial output laser light Ld (S120). This detection timing by the sensor 310 is synchronized with the output timing of the seed light La from the optical fiber (second optical fiber F2) of the fiber laser 22 (hereinafter simply referred to as the "output timing of the seed light La"). Therefore, the light-projection control device 26 can specify the output timing of the seed light La based on the timing at which the detection signal S is acquired. The light-projection control device 26 inputs the detection signal S indicating the output timing of the seed light La to the TOF measurement device 36 as a signal indicating the projection timing.

[0046] The TOF measurement device 36 determines the output timing of the seed light La based on the timing of receiving the detection signal S from the light projection control device 26. This process is an example of a timing determination process. In this embodiment, since the seed laser 110 periodically emits the seed light La, the sensor 310 periodically detects the partial output laser light Ld and outputs the detection signal S. The emission order of the periodically emitted multiple seed lights La corresponds to the output order of the multiple detection signals S periodically output from the sensor 310. Therefore, based on the correspondence between the emission order and the output order, it is possible to identify at which emission timing each detection signal S corresponds to the seed light La emitted.

[0047] The TOF measurement device 36 acquires the light receiving timing input from the light receiving unit 32 (S130). Then, the TOF measurement device 36 measures the distance to the measurement target W based on the time difference between the determined output timing and light receiving timing of the seed light La (S140). This process is an example of a measurement process. The light projection control device 26 and the TOF measurement device 36 are an example of a controller.

[0048] A-5. Advantages of this embodiment: As described above, according to the measurement device 10 of this embodiment, the distance to the measurement target W is measured using the output timing at which the output laser light Lout is output from the optical fibers F1, F2 to which the seed light La is input, rather than the emission timing at which the seed laser 110 emits the seed light La (see FIGS. 2 and 3). This makes it possible to suppress a decrease in the measurement accuracy of the distance to the measurement target W caused by a time difference (hereinafter referred to as a "timing difference") between the emission timing at which the seed laser 110 emits the seed light La and the output timing at which the output laser light Lout is output from the optical fiber.

[0049] In the present embodiment, in the timing determination process, the output timing is determined based on the detection timing at which the sensor 310 detects the output laser light Lout. Therefore, according to the present embodiment, even if the timing time difference varies due to, for example, a change in the surrounding environment (such as temperature), it is possible to suppress a decrease in the measurement accuracy of the distance to the measurement target W due to the timing time difference.

[0050] B. Second embodiment: A measurement device (not shown) in the second embodiment differs from the measurement device 10 (FIG. 2) in the first embodiment described above in that the projector 20 does not have the reflecting mirror 300 and the sensor 310. That is, the projector in the second embodiment does not have a physical configuration for detecting the output timing of the output laser light Lout. In the following, among the configuration and processing of the measurement device of the second embodiment, the description of the same configuration and processing as the measurement device 10 of the first embodiment described above will be omitted as appropriate.

[0051] Fig. 4 is a flowchart showing the measurement process in the second embodiment. As shown in Fig. 4, in the measurement process in the second embodiment, the light-projection control device 26 does not execute the process of acquiring the detection signal S of the sensor 310 (S120 in Fig. 3) after starting the light emission control of the fiber laser 22 (S110). The light-projection control device 26 inputs a signal indicating the emission timing of the seed light La from the seed laser 110 to the TOF measurement device 36, as in the conventional technology.

[0052] The TOF measurement device 36 determines a delay timing that is delayed by the delay time from the emission timing of the seed light La as the output timing of the seed light La (S120A). This process is an example of a timing determination process. The delay time is the time required for the seed light La to pass through the first optical fiber F1 and the second optical fiber F2, and the TOF measurement device 36 has a delay correction value that correlates with the delay time in advance. Note that this delay correction value may be calculated from the lengths of the first optical fiber F1 and the second optical fiber F2 and the speed of the seed light La, or may be experimentally determined from the time difference between the emission timing of the seed light La and the detection timing of the detection signal S using the projector 20 of the first embodiment, for example.

[0053] After acquiring the light receiving timing at the light receiving unit 32 (S130), the TOF measurement device 36 measures the distance to the measurement target W based on the time difference between the output timing and the light receiving timing of the corrected seed light La (S140A). According to this embodiment, for example, without providing a separate optical element or the like, it is possible to suppress a decrease in the measurement accuracy of the distance to the measurement target W caused by the timing time difference.

[0054] C. Variations: The technology disclosed in this specification is not limited to the above-described embodiments, and can be modified in various forms without departing from the spirit of the invention. For example, the following modifications are also possible.

[0055] The configuration of the measuring device 10 in the above embodiment is merely an example, and various modifications are possible. For example, the projector 20 is of a scanning type equipped with the scanner 40, but is not limited to this, and may be of a flash type or the like.

[0056] In each of the above embodiments, the fiber laser 22 has a first optical fiber F1 and a second optical fiber F2, and is configured to amplify the seed light La in two stages, but this is not limited to this, and the fiber laser 22 may be configured to amplify the seed light La in only one stage, or may be configured to amplify the seed light La in three or more stages.

[0057] In the above embodiment, the first optical fiber F1 and the second optical fiber F2 having a total length of 10 m are exemplified as the optical fiber, but the length of the optical fiber may be less than 10 m or may be 10 m or more. However, when the length of the optical fiber is 10 m or more, the effect on the measurement accuracy caused by the time difference between the emission timing of the seed laser and the output timing from the optical fiber is large, so the present invention is particularly effective.

[0058] FIG. 5 is an explanatory diagram that shows a schematic configuration of a projector 20A in a modified example. As shown in FIG. 5, the projector 20A is different from the projector 20 in the above embodiment in that it has a splitter (TAP) 300A instead of the reflecting mirror 300. Specifically, the splitter 300A is provided on the output side of the second optical fiber F2 and splits the output laser light Lout from the second optical fiber F2 into two. One of the split output laser light Lout is output to the outside via the third optical fiber F3 and the projection optical system 24. The other split output laser light Lout is detected by the sensor 310 via the fourth optical fiber F4. According to this configuration, it is possible to suppress the size of the device from being increased by using an optical element such as a reflecting mirror independent of the optical fiber, while suppressing the measurement accuracy of the distance to the measurement target W from being reduced due to the timing time difference.

[0059] In the above embodiment, the materials used to form the components are merely examples, and the components may be formed from other materials. [Explanation of symbols]

[0060] 10: Measuring device 20, 20A: Light projector 22: Fiber laser 24: Light projecting optical system 26: Light projecting control device 30: Light receiver 32: Light receiving section 34: Light receiving optical system 36: TOF measuring device 40: Scanner 42: Polygon mirror 46: Scanning mirror 50: Mirror 54: Information processing section 60: Utilization device 110: Seed laser 120: Excitation laser 130: First optical isolator 140: First multiplexer 150, 300A: Demultiplexer 160: Second optical isolator 170: Second multiplexer 300: Reflecting mirror 310: Sensor F1: First optical fiber F2: Second optical fiber F3: Third optical fiber F4: Fourth optical fiber

Claims

1. a light projector including a seed laser that emits seed laser light, an optical fiber that is doped with a rare earth element and into which the seed laser light emitted by the seed laser is input, and a pumping laser that emits pumping light that excites the rare earth element in the optical fiber, the light projector emitting an output laser light output from the optical fiber to the outside; a light receiver that receives a reflected laser beam that is the output laser beam emitted by the light projector and reflected by a measurement target and returns to the measurement target; A measurement device comprising: The controller: a timing determination process for determining an output timing at which the output laser light is output from the optical fiber to which the seed laser light is input; and a measurement process for measuring a distance to the measurement object based on a time difference between the determined output timing and a light receiving timing at which the light receiver receives the reflected laser light.

2. 2. The measuring device according to claim 1, Further, a sensor for detecting the output laser light output from the optical fiber is provided. The controller determines the output timing based on a detection timing at which the sensor detects the output laser light in the timing determination process.

3. The measuring device according to claim 2, a reflecting mirror disposed on an output side of the optical fiber and configured to reflect a portion of the output laser light output from the optical fiber; The sensor is configured to detect a portion of the output laser light reflected by the reflecting mirror.

4. The measuring device according to claim 2, a splitter provided on an output side of the optical fiber and splitting the output laser light output from the optical fiber into a plurality of beams, The sensor is configured to detect a portion of the output laser light split by the splitter.

5. 2. The measuring device according to claim 1, In the timing determination process, the controller determines as the output timing a delay timing that is delayed from the emission timing at which the seed laser emits the seed laser light by a delay time corresponding to the time it takes for the seed laser light to pass through the optical fiber.

6. A light projector comprising: a seed laser that emits seed laser light; an optical fiber that is doped with a rare earth element and into which the seed laser light emitted by the seed laser is input; and an excitation laser that emits excitation light that excites the rare earth element in the optical fiber, the light projector emitting an output laser light output from the optical fiber to the outside, The light projector further comprises a sensor that detects the output laser light output from the optical fiber and outputs a detection signal according to the detection result.

7. a light projection and reception step of inputting seed laser light emitted by a seed laser into an optical fiber, emitting output laser light output from the optical fiber to the outside, and receiving reflected laser light reflected by a measurement target and returning; an output timing determination step of determining an output timing at which the output laser light is output from the optical fiber to which the seed laser light is input; and a measuring step of measuring a distance to the object based on a time difference between the determined output timing and a receiving timing of the reflected laser light.

8. A measuring device including a light projector having a seed laser that emits a seed laser beam and an optical fiber, and a light receiver that receives a reflected laser beam that is output from the light projector and reflected by a measurement target and returns, the measuring device having a computer, a timing determination process for determining an output timing at which the output laser light is output from the optical fiber to which the seed laser light is input; and a measurement process for measuring a distance to the measurement object based on a time difference between the determined output timing and a light receiving timing at which the light receiver receives the reflected laser light.

9. A computer-readable recording medium having recorded thereon a computer program for controlling a measurement device including: a light projector having a seed laser that emits seed laser light and an optical fiber; and a light receiver that receives a reflected laser light that is an output laser light emitted by the light projector and reflected back from a measurement target, the computer-readable recording medium comprising: a timing determination process for determining an output timing at which the output laser light is output from the optical fiber to which the seed laser light is input; A computer-readable recording medium having a computer program recorded thereon, which causes the measuring device to execute a measurement process of measuring the distance to the measurement object based on the time difference between the determined output timing and the reception timing at which the receiver receives the reflected laser light.

Images