Measuring device and electronic apparatus

Abstract

The present invention provides technology that achieves more accurate measurement while preventing luminance saturation.　The present technology provides a measurement device, etc., comprising a light source capable of switching between pulse operation and CW operation, and a control unit that controls the switching between pulse operation and CW operation, wherein the light source includes a saturable absorber that exhibits a quantum-confined Stark effect (QCSE). The control unit may control a voltage applied to the saturable absorber to switch between pulse operation and CW operation.

Description

Measuring Device and Electronic Device

[0001] The technology according to the present disclosure (hereinafter also referred to as "the present technology") relates to a measuring device and an electronic device.

[0002] In recent years, optical measurement technologies such as LiDAR (Light Detection and Ranging) have been widely used in fields such as autonomous driving technology and industrial robots. In order to achieve longer-distance and higher-precision distance measurement, these optical measurement systems require high-output light sources.

[0003] However, as the output of the light source increases, a phenomenon occurs where the photodetector saturates at close range, resulting in a problem of reduced measurement accuracy.

[0004] For example, in Patent Documents 1 to 4, methods for dealing with the saturation of the photodetector have been proposed.

[0005] Japanese Patent Application Laid-Open No. 61-176813, Japanese Patent Application Laid-Open No. 2023-532441, Japanese Patent Application Laid-Open No. 2023-68471, Japanese Patent Application Laid-Open No. 2022-510695

[0006] In Patent Document 1, a method of reducing the light intensity of the light source when saturated is shown, but specific implementation means are not shown, and implementation is difficult.

[0007] In Patent Document 2, a technique of performing closed-loop control of the exposure time of the light receiver so as not to saturate has been proposed. However, for example, in the field of LiDAR, the exposure time has been extremely shortened and is now as short as about 1 nanosecond. Therefore, there are limitations to countermeasures against saturation by further shortening the exposure time, and the response speed of the photodetector is approaching the physical limit.

[0008] In Patent Document 3, a semiconductor laser is used as the light source, and when not saturated, measurement is performed by pulse driving, and when saturated, switching to CW driving is proposed to obtain measurement values. A method of synthesizing measurement values at the time of saturation and non-saturation to form a distance measurement image has also been proposed. However, while the range of luminance saturation due to increased output expands, the amount of light below the threshold does not increase, so there are limitations to the long-distance measurement range and areas that cannot be dealt with occur.

[0009] Patent Document 4 describes a method using a DPSS (solid-state laser) as a light source and changing the amplification factor of the photodetector when saturation occurs. However, changing the amplification factor is difficult when using photon counting. For this reason, especially in the d-ToF (Direct Time of Flight) method, adjusting the amplification factor is difficult and it does not provide sufficient effectiveness as a saturation countermeasure.

[0010] Therefore, the primary objective of this technology is to provide a method that enables more accurate measurements while preventing brightness saturation.

[0011] This technology provides a measuring device comprising a light source capable of switching between pulse operation and continuous wave (CW) operation, and a control unit that controls the switching between the pulse operation and the CW operation, wherein the light source includes a saturable absorber exhibiting the quantum confinement Stark effect (QCSE). The control unit may switch between the pulse operation and the CW operation by controlling the voltage applied to the saturable absorber. The measuring device further comprises a photodetector that detects the brightness of reflected laser light from the light source, wherein the light source may perform the pulse operation when the reflected light is not brightness saturated, and the light source may perform the CW operation when the reflected light is brightness saturated. The photodetector may be configured with SPADs (Single Photon Avalanche Diodes) arranged in a two-dimensional array. The light source further includes a gain medium for amplifying light, and when the light source performs the pulse operation, the control unit may apply a first current to the gain medium and a first voltage to the saturable absorber, and when the light source performs the CW operation, the control unit may apply a second current to the gain medium and a second voltage to the saturable absorber. When the reflected light of the laser beam from the light source is saturated in brightness, the control unit may reduce the light output by controlling the voltage applied to the saturable absorber. When the reflected light of the laser beam from the light source is saturated in brightness, the control unit may reduce the light output by reducing the current to the gain medium. The measuring device further includes a calculation unit, and when the light source performs the pulse operation, the calculation unit may measure the distance to the object, and when the light source performs the CW operation, the calculation unit may measure the velocity of the object. The measuring device further includes an image analysis unit that analyzes an image acquired when the light source is performing the CW operation, and the image analysis unit may analyze the speckle contrast in the image to measure the velocity of the object. The image may be an image acquired after the convergence of relaxation vibrations that occur when switching to the CW operation.The measuring device further comprises a calculation unit, the image analysis unit analyzes the speckle contrast based on the images acquired at multiple exposure times, the calculation unit calculates a correlation time based on the change in the speckle contrast, and measures the velocity of the object based on the correlation time and the wavelength of light from the light source. The calculation unit may correct the measured velocity based on the distance to the measured object. The measuring device may measure the distance to the object using the d-ToF (Direct Time of Flight) method. The light source further comprises a gain medium for amplifying light and an excitation light source having a wavelength corresponding to the gain medium, the gain medium includes an optical crystal, and the excitation light source may excite the gain medium. The excitation light source may have a light-emitting element using a III-V compound semiconductor. The light source may be a pulsed laser light source. The measuring device may be a LiDAR. Furthermore, this technology provides an electronic device comprising a light source capable of switching between pulse operation and continuous wave (CW) operation, and a control unit that controls the switching between the pulse operation and the CW operation, wherein the light source includes a saturable absorber that exhibits the quantum confinement Stark effect (QCSE).

[0012] This is a block diagram showing an example configuration of a measuring device according to one embodiment of this technology. This is a schematic diagram showing an example configuration of a light source 1 according to one embodiment of this technology. This is a schematic perspective view showing an example configuration of a light source 1 according to one embodiment of this technology. This is a block diagram showing an example configuration of a control unit 2 according to one embodiment of this technology. This is a graph showing an example of L-I characteristics corresponding to the voltage applied to the saturable absorber 12 according to one embodiment of this technology. This is a schematic diagram showing an example of the switching sequence of operation of the light source 1 according to one embodiment of this technology. This is a graph showing an example of L-I characteristics corresponding to the voltage applied to the saturable absorber 12 according to one embodiment of this technology. This is a schematic diagram showing an example of the switching sequence of operation of the light source 1 according to one embodiment of this technology. This is a schematic diagram showing an example configuration of a photodetector 3 according to one embodiment of this technology. This shows a histogram generated based on the light reception result by the photodetector 3 according to one embodiment of this technology. This is a schematic diagram for explaining the speckle generation mechanism. Figure 12A is a diagram showing an example of the speckle phenomenon. Figure 12B is a histogram showing the result of detecting the brightness at each pixel. This shows a schematic diagram of a speckle image projected onto a 2D sensor during camera shooting. This is a schematic diagram showing 3x3 pixels. This is a graph showing the relationship between exposure time and contrast value according to speckle analysis of this technology. These are the parameters used for measurement. This is a schematic diagram showing the transition between the relaxation vibration state R and the steady state S associated with the operating state of the light source. This is a flowchart showing an example of the flow of distance and velocity measurement using a light source and photodetector according to one embodiment of this technology. This is a schematic diagram showing an example of the configuration of the light source 1 according to one embodiment of this technology. This is a characteristic diagram showing the relationship between the voltage applied to the saturable absorber 12 and the optical output of the excitation light source 18 in the light source 1 according to this embodiment. This is a block diagram showing a schematic example of the configuration of a vehicle control system, which is an example of a mobile control system to which this technology may be applied. This is a diagram showing an example of the installation position of the imaging unit.

[0013] Hereinafter, preferred embodiments for implementing this technology will be described with reference to the drawings. The embodiments described below are merely examples of typical embodiments of this technology and do not limit the scope of this technology. Furthermore, this technology can be implemented by combining any of the following embodiments and their modifications.

[0014] In the following description of embodiments, configurations may be described using terms with "approximately" attached, such as "approximately parallel" and "approximately orthogonal." For example, "approximately parallel" means not only that they are perfectly parallel, but also that they are substantially parallel, that is, that is, they are deviated from a perfectly parallel state by, for example, a few percent. The same applies to other terms with "approximately." Also, each figure is a schematic diagram and is not necessarily a strictly accurate representation. The scale of the drawings is exaggerated to make the technical features easier to understand. Therefore, it should be noted that the scale of the drawings and the scale of the actual device are not necessarily the same.

[0015] Unless otherwise specified, in drawings, "up" means the upper direction or upper side in the drawing, "down" means the lower direction or lower side in the drawing, "left" means the left direction or left side in the drawing, and "right" means the right direction or right side in the drawing. In addition, in drawings, the same or equivalent elements or components are denoted by the same reference numeral, and redundant explanations are omitted.

[0016] The embodiments described below represent typical embodiments of the Technology and should not be interpreted as narrowing the scope of the Technology. The effects described herein are illustrative and not limiting, and other effects may also exist.

[0017] The explanation will proceed in the following order: 1. First Embodiment of the Technology (Example 1 of a Measurement Device) (1) Overall Configuration of the Measurement Device (2) Overall Configuration of the Light Source (3) Control Unit (4) Example 1 of Switching Method (5) Example 2 of Switching Method (6) Photodetector (7) LiDAR 2. Second Embodiment of the Technology (Example 2 of a Measurement Device) 3. Third Embodiment of the Technology (Example 3 of a Measurement Device) 4. Fourth Embodiment of the Technology (Example of an Electronic Device)

[0018] [1. First Embodiment of the Technology (Example 1 of Measurement Device)] [(1) Overall Configuration of the Measurement Device] An example of the configuration of a measurement device according to one embodiment of the Technology will be described with reference to Figure 1. Figure 1 is a block diagram showing an example of the configuration 100 of a measurement device according to one embodiment of the Technology. As shown in Figure 1, the measurement device 100 according to one embodiment of the Technology includes a light source 1, a control unit 2, a photodetector 3, and a calculation unit 4, etc.

[0019] Light source 1 is a light source for irradiating laser light for measurement, and is configured to perform both pulsed and continuous wave (CW) operation.

[0020] The control unit 2 is the part that controls the operation of the light source 1, and is responsible for switching between pulse operation and continuous wave operation of the light source 1 based on the light reception results of the photodetector 3.

[0021] The photodetector 3 is used to detect light emitted from the light source 1 and reflected from the object.

[0022] The calculation unit 4 is the part that analyzes the data obtained from the photodetector 3 and calculates the distance to the target object, etc.

[0023] [(2) Overall configuration of the light source] This technology relates to a technology using a pulsed laser light source. A pulsed laser is, for example, one that supplies a constant current and controls the emission of light in a pulsed manner. Specifically, even though a DC current is continuously supplied, the laser light repeatedly emits and extinguishes light intermittently. This is called pulse operation, and a laser that performs such operation is called a pulsed laser.

[0024] This technology employs a light source that can switch not only between pulsed operation and continuous wave (CW) operation, which provides continuous light output. This technology provides a measuring device comprising a light source that can switch between pulsed and CW operation, and a control unit that controls the switching between pulsed and CW operation, wherein the light source includes a saturable absorber that exhibits the quantum confinement Stark effect (QCSE). This makes it possible to achieve optimal light output according to the conditions and distance of the object being measured.

[0025] An example of the configuration of this light source will be explained with reference to Figure 2. Figure 2 is a schematic diagram showing an example of the configuration of a light source 1 according to one embodiment of this technology. Figure 2 shows the structure of an end-emitting semiconductor laser, which is an example of a light source 1.

[0026] As shown in Figure 2, the light source 1 includes a gain medium 11, a saturable absorber 12, a high-reflectivity coating 13, and a mirror 14, etc.

[0027] The high-reflectivity coating 13 is provided at one end of the optical resonator and is a coating designed to efficiently reflect laser light. This high-reflectivity coating 13 is designed so that light is reflected without leaking out, and the laser light is amplified as it travels back and forth many times within the resonator. This high-reflectivity coating 13 has extremely high reflectivity, which improves the output efficiency of the laser and maintains the stability of the light emission.

[0028] Mirror 14 is located at the other end of the optical resonator and has the function of reflecting a portion of the laser light while emitting a portion to the outside. The reflectivity of this mirror 14 is designed to be slightly lower than that of the high-reflection coating 13, so that only the necessary amount of light is output outside the resonator. With the installation of this mirror 14, the light inside the resonator is appropriately amplified and finally emitted to the outside as laser light.

[0029] In this structure, a high-reflection coating 13 is placed at one end of the laser resonator and a mirror 14 at the other end. This combination enables efficient laser oscillation of the light source 1. By appropriately adjusting the high-reflection coating 13 and the mirror 14, the light emission intensity and output efficiency can be improved.

[0030] The gain medium 11 is excited by the application of an external current or voltage and plays a role in amplifying light. When a forward voltage is applied to the gain medium 11, photoelectric conversion and light amplification occur, causing laser oscillation. On the other hand, the saturable absorber 12 is a structure that controls the oscillated light and has the function of preventing brightness saturation by absorbing light below a certain light intensity.

[0031] A voltage opposite to the voltage applied to the gain medium 11 is applied to the saturable absorber 12. This reverse voltage causes it to absorb the light emitted from the gain medium 11, and when it exceeds a certain light intensity, its absorption rate decreases, resulting in a saturable state. As a result, the transmittance of the oscillating light is controlled, and brightness saturation is suppressed even at high output.

[0032] This saturable absorber is made of a material that exhibits the Quantum Confined Stark Effect (QCSE) using a quantum well structure. QCSE is a phenomenon in which, when an external electric field is applied to a semiconductor material with a quantum confinement structure, the energy states of electrons and holes in the material change. Specifically, when an external electric field is applied to a semiconductor material, electrons and holes are attracted in opposite directions, changing the transition energy between energy bands, and as a result, the wavelength of light absorption fluctuates. This phenomenon is particularly pronounced in semiconductors with quantum well structures, making it possible to control the light absorption characteristics with an electric field.

[0033] The configuration example of this light source will be further explained with reference to Figure 3. Figure 3 is a schematic perspective view showing a configuration example of a light source 1 according to one embodiment of this technology. Figure 3 shows a schematic structure of a GaN (gallium nitride) based end-face emission laser diode. This laser diode includes a gain medium 11 and a saturable absorber 12, with an anti-reflective coating on the gain side end face and a high-reflectivity coating on the saturable absorber side end face. By placing a mirror on the gain medium side, a laser light source with the configuration shown in Figure 2 is obtained.

[0034] This light source 1 is equipped with a p-type electrode 15 and an n-type electrode 16, and a GaInN multiple quantum well (MQW) active layer 17 is positioned in the center. The active layer 17 has the role of generating and amplifying light, and the oscillating light is emitted as an optical pulse OP.

[0035] The gain medium 11 is current I g When applied, it plays a role in amplifying the light generated in the active layer 17.

[0036] The saturable absorber 12 absorbs light according to the light intensity in the light source 1 and plays a role in controlling the amount of absorption. A reverse voltage V is applied to this saturable absorber 12. sa A voltage is applied, and the absorption characteristics change depending on the magnitude of the applied voltage.

[0037] In this technology, the operation of the light source 1 is switched between pulse operation and continuous wave (CW) operation to enable brightness switching. This switching allows the brightness of the light emitted from the light source 1 to be changed. In pulse operation, the light is emitted strongly instantaneously, making it suitable for long-distance measurements. On the other hand, in CW operation, continuous emission occurs, resulting in lower brightness, but it is suitable for stable measurement of objects at close range.

[0038] This operation is switched by applying a voltage to the saturable absorber 12 that indicates QCSE. The control unit, which will be described later, controls the voltage applied to the saturable absorber 12, changing the magnitude and polarity of the voltage, thereby switching the operation of the light source between pulse operation and CW operation.

[0039] The saturable absorber 12 is located at a specific position within the light source 1, and by manipulating the voltage, it can be switched from pulse operation to continuous wave (CW) operation, or vice versa. This switching allows for control of the light intensity (luminance), providing the optimal brightness according to the distance to the object being measured.

[0040] In this structure, the gain medium 11 and the saturable absorber 12 are arranged adjacent to each other. By effectively combining the light amplification effect within the gain medium 11 and the light absorption effect of the saturable absorber 12, the output of the light source can be controlled, enabling high-precision distance measurement while preventing brightness saturation. Furthermore, this technology prevents brightness saturation by switching the brightness of the light source 1, enabling even higher-precision measurements. This technology enables appropriate measurements for both short and long distances, allowing measurements at various distances with a single light source. As a result, it is expected to significantly improve the performance of measurement devices such as LiDAR.

[0041] [(3) Control Unit] A configuration example of the control unit 2 that controls the voltage applied to the saturable absorber 12 will be described while referring to FIG. 4. FIG. 4 is a block diagram showing a configuration example of the control unit 2 according to an embodiment of the present technology.

[0042] As shown in FIG. 4, the control unit 2 according to an embodiment of the present technology includes a voltage supply circuit 21, a control signal generation unit 22, a microcontroller 23, a sensor unit 24, a feedback circuit 25, and the like.

[0043] The voltage supply circuit 21 provides a power source for applying an appropriate voltage to the saturable absorber 12. Thereby, the absorption rate of the saturable absorber 12 is controlled, and the operating state of the light source 1 is appropriately switched.

[0044] The control signal generation unit 22 generates a control signal necessary for switching between the pulse operation and the CW operation. This control signal is sent to the voltage supply circuit 21, and the applied voltage is changed.

[0045] The microcontroller 23 is used as the center of the control unit 2. This microcontroller 23 selects an operation mode and adjusts the applied voltage based on the input information from the sensor unit 24 and external commands.

[0046] The sensor unit 24 acquires environmental information such as the distance of the measurement target. Thereby, the optimization of the operation mode of the light source 1 is performed in real time. For example, based on the output of a photodetector (described later), it determines whether the light is saturated and plays a role of passing the result to the control signal generation unit 22.

[0047] The feedback circuit 25 monitors whether the voltage output by the control unit 2 is appropriately applied. The feedback circuit 25 monitors the actually applied voltage and the operating state of the light source in real time, and sends an adjustment command to the microcontroller 23 as necessary. With this feedback, the switching of the operation mode is performed quickly and stably.

[0048] [(4) Example of Switching Method 1] An example of a method for switching the operation of the light source 1 by the control unit 2 will be explained with reference to Figure 5. Figure 5 is a graph showing an example of L-I characteristics according to the voltage applied to the saturable absorber 12 according to one embodiment of this technology. L-I characteristics are characteristics that represent the relationship between the current applied to the gain medium 11 and the optical output of the light source 1. The horizontal axis shows the current I applied to the gain medium 11, and the vertical axis shows the average optical output L.

[0049] In Figure 5, "M1" indicates the voltage applied to the saturable absorber 12 when CW operation is performed. CW operation occurs when the voltage applied to the saturable absorber 12 is close to zero. In this state, absorption by the saturable absorber 12 is suppressed, and a continuous optical output is obtained.

[0050] In "M2," the area where the slope is gentler in the thick line indicates the voltage applied to the saturable absorber 12 when pulse operation is performed. In this area, the applied voltage is set to an appropriate value, and after the saturable absorber 12 absorbs an appropriate amount of light, it instantaneously transmits the light (absorption saturates), thus generating pulsed light.

[0051] "M3" indicates the voltage applied to the saturable absorber 12 when CW operation is performed again. If the applied voltage is too high, electron-hole pairs are generated when light is incident on the saturable absorber 12, but this process does not proceed sufficiently, and the amount of absorption does not decrease (absorption does not saturate), so the pulse operation stops and only CW operation is performed. In this state, because the applied voltage is set high, the saturable absorber 12 cannot effectively absorb light, a continuous light output is obtained, and pulse operation does not occur.

[0052] Based on this characteristic, while the current value to the gain medium 11 is set to A, the pulse operation and CW operation can be switched by changing the voltage applied to the saturable absorber 12. Specifically, while maintaining the current value A, pulse operation is performed by setting the voltage applied to the saturable absorber 12 to "M2", and switching to CW operation is performed by changing the applied voltage to "M1".

[0053] In this way, by changing the voltage applied to the saturable absorber 12, it is possible to flexibly switch between pulse operation and CW operation. With this switching method, there is no need to change the current value; the operation is controlled only by changing the applied voltage. This novel driving method enables efficient light source control while preventing brightness saturation by switching between pulse operation and CW operation solely through voltage control.

[0054] Furthermore, it is desirable to measure the L-I characteristics with respect to the applied voltage to the saturable absorber 12 in advance after assembly and adjustment. This is also the case in other embodiments described later. By measuring these L-I characteristics, it becomes possible to accurately calculate the peak light intensity during pulse operation.

[0055] Furthermore, since the output characteristics of the light source may fluctuate over time, it is effective to place a reference photodetector near the light source 1 in order to maintain a stable light output. This reference photodetector allows for a comparison between the initial value measured during assembly and the output during operation. If output fluctuations are detected, the output of the light source can be stabilized by appropriately correcting the drive current and applied voltage based on the data from the reference photodetector.

[0056] This correction mechanism enables the light source of this technology to maintain stable pulse and CW operation over long periods, thereby achieving highly accurate optical measurement.

[0057] An example of the pulse operation and CW operation sequence in this switching method will be explained with reference to Figure 6. Figure 6 is a schematic diagram showing an example of the operation switching sequence of the light source 1 according to one embodiment of this technology.

[0058] First, "A" represents the current value applied to the gain medium 11, similar to Figure 5, and this current value A is kept constant during operation.

[0059] Next, "M1" indicates the voltage applied to the saturable absorber 12 when CW operation is performed as in Figure 5. In this state, the voltage applied to the saturable absorber 12 is set to almost zero or a very low value. In this state, the saturable absorber 12 absorbs almost no light, and a continuous light output is obtained. In this state, the brightness is stable, and an effective light output is obtained for objects at close range.

[0060] On the other hand, "M2" indicates the voltage applied to the saturable absorber 12 when pulse operation is performed, similar to Figure 5. The voltage applied to the saturable absorber 12 is set to an appropriate value. With this voltage, the saturable absorber 12 partially absorbs light and then instantaneously transmits it (absorption saturates), resulting in the generation of pulsed light. In this region, pulse operation occurs stably as the applied voltage increases.

[0061] "M3" indicates the voltage applied to the saturable absorber 12 when CW operation is performed. When the applied voltage increases, the absorption amount of the saturable absorber 12 does not decrease (absorption does not saturate), the pulse operation stops, and only CW operation is performed. In this state, high-intensity continuous light is applied to distant objects.

[0062] [(5) Example of switching method 2] An example of a method for switching the operation of the light source 1 by the control unit 2 will be explained with reference to Figure 7. Figure 7 is a graph showing an example of L-I characteristics according to the voltage applied to the saturable absorber 12 according to one embodiment of this technology. The horizontal axis shows the current I applied to the gain medium 11, and the vertical axis shows the average optical output L.

[0063] Figure 7 shows a method for switching between pulsed and continuous wave (CW) operation of the light source. In this method, the operation of the light source 1 is switched by adjusting not only the voltage applied to the saturable absorber 12, but also the current I applied to the gain medium 11.

[0064] For example, when the light source 1 operates in pulse mode, the control unit 2 applies a first current to the gain medium 11 and a first voltage to the saturable absorber 12. When the light source 1 operates in CW mode, the control unit 2 applies a second current to the gain medium 11 and a second voltage to the saturable absorber 12.

[0065] Specifically, when performing pulse operation, a first current "A" is applied to the gain medium 11 and a first voltage "M2" is applied to the saturable absorber 12. When performing CW operation, a second current "B" is applied to the gain medium 11 and a second voltage "M1" is applied to the saturable absorber 12.

[0066] An example of the pulse operation and CW operation sequence in this switching method will be explained with reference to Figure 8. Figure 8 is a schematic diagram showing an example of the operation switching sequence of the light source 1 according to one embodiment of this technology.

[0067] The basic operation shown in Figure 8 involves controlling pulse operation and CW operation by switching the current applied to the gain medium 11 and the voltage applied to the saturable absorber 12.

[0068] When performing pulse operation, a first current "A" is applied to the gain medium 11, and a first voltage "M2" is applied to the saturable absorber 12. With this setting, the saturable absorber 12 absorbs some of the light, then transmits the light in a pulsed manner, resulting in the generation of pulsed light.

[0069] When performing CW operation, a second current "B" is applied to the gain medium 11, and a second voltage "M1" is applied to the saturable absorber 12. With this setting, absorption by the saturable absorber 12 is almost eliminated, and a continuous optical output is obtained.

[0070] A key feature of this switching method is that the optical output during CW operation can be precisely controlled by adjusting the current value of the gain medium 11. For example, in the switching method shown in Figure 5, the optical output during CW operation may be too bright, posing a risk of saturation of the photodetector, which will be discussed later. On the other hand, in the method shown in Figure 7, the current of the gain medium 11 can be reduced, thereby lowering the optical output during CW operation. As a result, saturation of the photodetector can be prevented, enabling stable measurements.

[0071] This switching method allows for flexible adjustment of the light output for each operating mode, enabling the maintenance of more appropriate light intensity for both short-range and long-range measurements. Furthermore, by controlling the current of the gain medium 11, efficient light source control is achieved while preventing brightness saturation.

[0072] [(6) Photodetector] The measuring device according to this technology preferably further includes a photodetector that detects the brightness of reflected light from a laser light source. An example of a photodetector used in this technology is a SPAD (Single Photon Avalanche Diode). A SPAD is a very sensitive photodetector that outputs an amplified current using the avalanche effect when a single photon is incident on it. Due to this characteristic, it is possible to detect even weak optical signals and is particularly suitable when measuring the distance to an object using the d-ToF method.

[0073] Time of Flight (TF) is a method for calculating the distance to an object by measuring the time it takes for light emitted from a light source to reach the object and for the reflected light to return to the photodetector. In this method, since the speed of light propagation is known, the distance to the object is determined based on the time taken for the round trip.

[0074] A key feature of the Time-of-Flight (TOF) method is its wide distance measurement range, making it suitable for measuring the distance to long-distance objects. Furthermore, ToF sensors acquire distance information by emitting high-speed light pulses and measuring the arrival time of the reflected signals.

[0075] d-ToF is a type of ToF measurement, particularly a method for measuring the round-trip time of direct light with high precision. The d-ToF method uses a high-speed photodetector (e.g., SPAD) to directly measure the time from the emission of a light pulse to the detection of reflected light. This method allows for higher accuracy in distance measurement than the standard ToF method.

[0076] The main feature of d-Time-of-F (d-ToF) is its high time resolution on the order of nanoseconds, which allows for the detection of even very small changes in distance.

[0077] Because SPAD responds with high sensitivity to incident photons, this technology enables highly accurate distance measurement in its measuring device. Specifically, laser light emitted from a light source is reflected by an object and detected by SPAD. By measuring the time until the reflected light is detected, the distance to the object can be accurately measured.

[0078] While other photodetectors such as photodiodes (PDs) and PIN diodes can also be used, SPADs are particularly suitable for applications requiring highly accurate distance measurement due to their high sensitivity and fast response.

[0079] An example of the configuration of a photodetector according to one embodiment of this technology will be described with reference to Figure 9. Figure 9 is a schematic diagram showing an example of the configuration of a photodetector 3 according to one embodiment of this technology.

[0080] Figure 9 shows an example of a two-dimensional array type photodetector, illustrating a configuration in which distance and light intensity are detected for each pixel. The shaded area in the figure indicates that a specific pixel is receiving light. This photodetector 3 is configured, for example, by arranging SPADs in a two-dimensional array, and there are no particular restrictions on the number of pixels.

[0081] The photodetector 3 has a matrix structure in which multiple pixels are arranged, and each pixel can independently detect light. Each pixel receives light reflected from the light source 1 and acquires information about distance and light intensity.

[0082] This technology enables wide-area measurements by arranging SPADs in a two-dimensional array, allowing for the acquisition of individual distance data for each pixel. This makes it possible to measure objects with complex shapes or at different distances simultaneously. Furthermore, since the SPADs operate in photon counting mode, signal noise is extremely low, and high-precision measurements can be expected.

[0083] Furthermore, since the SPAD enters an avalanche state when a photon is incident on it, it is capable of extremely fast response. This fast response is ideal for the measurement device in this technology, and is particularly effective when a rapid response is required when switching between pulsed and continuous wave operation of the light source 1.

[0084] Figure 10 shows a histogram generated based on the light reception results by the photodetector 3 in one embodiment of this technology. This histogram represents the brightness values ​​of the received light along the time axis, with the horizontal axis representing the measurement time and the vertical axis representing the brightness value. As the amount of received light increases, the brightness value increases, and the peak of the histogram also rises. Based on this data, the pulse operation and CW operation of the light source are controlled.

[0085] Figure 10A shows a state where the luminance value has not reached the saturation level, and the photodetector 3 is not luminance saturated. In this case, since the reflected light is not luminance saturated, the light source 1 operates in pulsed mode. During pulsed operation, the photodetector 3 does not experience luminance saturation, enabling distance measurement using stable light pulses. At this time, the peak of the luminance value in the histogram fluctuates within the normal range and does not become excessively high.

[0086] Figure 10B shows a state where the luminance value has reached the saturation level, and the photodetector 3 is luminance saturated. In this case, since the reflected light is luminance saturated, the light source 1 switches to continuous wave (CW) operation. By having the light source operate continuously in CW mode, it becomes possible to continue measurements while avoiding luminance saturation of the photodetector 3.

[0087] Furthermore, if the reflected laser light from the light source 1 is saturated in brightness, the control unit 2 can reduce the light output by adjusting the voltage applied to the saturable absorber 12. This makes it possible to suppress the output to a light intensity that does not saturate the photodetector 3.

[0088] Furthermore, if the reflected laser light from the light source 1 is saturated in brightness, the control unit 2 can further suppress the light output by reducing the current to the gain medium 11. This reduces the light emission intensity of the light source 1 itself, effectively preventing brightness saturation of the photodetector 3.

[0089] [(7) LiDAR] The measuring device according to this embodiment can be configured as a LiDAR using a pulsed laser light source 1 and a photodetector 3, and can measure the distance and velocity of an object with high precision. The light source 1 of the device has a function to switch between pulse operation and CW operation, and by irradiating the object with pulsed light and receiving the reflected light with the detector, distance measurement by ToF, especially d-ToF, can be performed.

[0090] Furthermore, the measuring device according to this embodiment, equipped with multiple light sources and photodetectors, is capable of measuring the position and velocity of objects over a wide range in two-dimensional and three-dimensional space, and can be applied to the surrounding environment recognition of autonomous vehicles, robots, drones, and other devices.

[0091] The above description of the measuring device according to the first embodiment of this technology can be applied to other embodiments of this technology, unless there are any particular technical inconsistencies.

[0092] [2. Second Embodiment of the Technology (Example 2 of the Measuring Device)] The measuring device according to one embodiment of the Technology can measure not only the distance to the object but also the speed at which the object moves.

[0093] This technology further includes a calculation unit 4 to enable distance and velocity measurement according to the operating mode of the light source. The calculation unit 4 functions to measure both distance and velocity according to the pulse and CW operation of the light source. Specific examples of the configuration of the calculation unit 4 include a DSP (Digital Signal Processor) and an FPGA (Field Programmable Gate Array). These are processors suitable for real-time processing of measurement data and signal analysis.

[0094] First, when the light source operates in pulsed mode, the calculation unit 4 calculates the time difference, or Time of Flight (TF), between the pulsed light emitted from the light source and its reflection back from the object. By analyzing this time difference, the distance to the object is measured with high precision.

[0095] Next, when the light source operates in CW mode, the calculation unit 4 measures the velocity of the object based on speckle analysis and the Doppler effect of the continuously emitted laser light. For example, the calculation unit 4 detects the object's velocity by analyzing the changes in the speckle pattern that occur when the object moves and the frequency changes obtained from the Doppler shift.

[0096] Furthermore, the FPGA-based arithmetic unit 4 processes specific algorithms at the hardware level, enabling parallel processing and customization of signals, and achieving highly accurate measurements even in more complex measurement environments. For example, the logic incorporated into the FPGA can efficiently process distance and velocity calculations in response to input signals from a light source.

[0097] Therefore, in this technology, the calculation unit 4 provides the following functions according to the operating mode of the light source. During pulse operation, the calculation unit 4 uses the pulsed light from the light source to measure the distance to the object. Based on the ToF algorithm, high-speed and highly accurate distance measurement is possible.

[0098] On the other hand, during CW operation, the calculation unit 4 uses the continuous light from the light source to measure the velocity of the object. The velocity is detected in real time based on speckle analysis and the Doppler effect.

[0099] This technology enables the simultaneous measurement of the distance and velocity of an object using a light source and a high-performance calculation unit 4, resulting in a highly accurate measuring device.

[0100] A measuring device according to one embodiment of this technology may further include an image analysis unit that analyzes images acquired when the light source is operating in CW (continuous wave) mode. This image analysis unit can analyze the speckle contrast in the image to measure the velocity of the object.

[0101] Figure 11 is a schematic diagram illustrating the speckle generation mechanism. Laser light is used for illumination, and for example, when a semiconductor laser light source with a transverse fundamental mode is used as light source 1, the emission mode at its emission point is close to that of a point source, and the emitted light propagates as a spherical wave. This spherical wave is represented by the curved surface shown by the dotted line in the figure.

[0102] Although the surface of object O often appears flat to the naked eye, it typically has minute irregularities corresponding to the wavelength of the laser light. Due to these minute irregularities, the reflection angle of the incident laser light varies depending on the location. As shown by the arrows in the diagram, the reflected light travels in various directions and is scattered with different optical path lengths.

[0103] Where reflected light with different optical path lengths intersect, interference occurs depending on the phase difference of the light waves. Specifically, where the phases match, reinforcement occurs, and where the phases differ, destructive interference occurs, resulting in light and dark areas. This generates a speckled pattern of light and dark, known as a speckle pattern.

[0104] This speckle phenomenon occurs because laser light has high coherence, and the intensity distribution of the pattern formed by interference depends on the fine structure and surface shape of the object.

[0105] Figure 12A shows an example of the speckle phenomenon, visually illustrating the mottled pattern of light and dark that occurs when a laser is used for illumination. This figure shows a speckle image actually acquired using laser light. Due to the high coherence of laser light, the light reflected from the surface of the object interferes, generating an image with a random distribution of light and dark. This mottled pattern is called the speckle phenomenon, and this pattern is determined by the fine surface structure of the illuminated object.

[0106] Figure 12B is a histogram showing the results of detecting the brightness of each pixel. The horizontal axis represents the number of pixels, and the vertical axis represents the brightness value of each pixel in 8-bit grayscale, quantifying the degree of brightness. In the histogram, areas with large brightness fluctuations indicate bright regions due to constructive interference, while areas with small fluctuations indicate dark regions due to destructive interference. This shows the details of the random brightness fluctuations generated by the speckle phenomenon.

[0107] By utilizing such speckle images and their luminance histograms, it is possible to analyze the surface structure and light interference characteristics of an object. This speckle image analysis can be applied, for example, to measuring the velocity of an object.

[0108] Figure 13 shows a schematic diagram of the speckle image projected onto the image sensor during shooting. The shaded circular areas in the figure indicate the brightness and darkness of the speckle pattern, and their size is determined by wavelength / NA (Numerical Aperture). NA is half the reciprocal of the camera lens's aperture value (F-number), meaning that the size of the speckles is determined by the lens characteristics.

[0109] Speckle images are mottled patterns caused by the interference of laser light, and various information can be obtained by analyzing the light and dark distribution of the captured image. The circular areas indicated by multiple diagonal lines in the figure represent speckles that occurred in different locations.

[0110] The speckle contrast is used as an index to evaluate speckle images. This speckle contrast K is calculated by the following equation (1).

[0111]

[0112] Speckle contrast is expressed as the ratio of the variation in brightness (standard deviation) detected on the sensor to its average value. This index allows for the quantitative evaluation of the variation in brightness of speckles. In Figure 13, the lens aperture is set so that the shaded area spans multiple pixels of the sensor, and the speckle contrast is analyzed.

[0113] Figure 14 shows a method for detecting a speckle image using a 3x3 pixel grid and calculating the speckle contrast based on the brightness of each pixel. In this example, each pixel is numbered from 1 to 9, and the average and standard deviation of the brightness can be calculated using the light intensity (brightness) obtained from each pixel.

[0114] The light intensity of each pixel is I jThe mean and standard deviation of the luminance can be calculated using the following equations (2) and (3) as (the light intensity of the j-th pixel).

[0115]

[0116]

[0117] Using these values, the speckle contrast K can be calculated using the above equation (1). The speckle contrast K calculated in this way is affected by the subject's speed and other parameters. For example, the speckle contrast K can be expressed by the following relation (4).

[0118]

[0119] Here, τ is the correlation time and T is the exposure time. Correlation time is the timescale that indicates how long it takes for the speckle pattern formed by light interference to change over time, and it is determined in relation to the movement of the object. As shown in equation (5) below, the correlation time τ depends on the velocity of the subject.

[0120]

[0121] In equation (5), α is a coefficient, λ is the wavelength of the illumination, and V is the relative velocity between the subject and the camera.

[0122] Based on this relationship between correlation time and exposure time, the speed of the subject can be estimated from the speckle contrast obtained by changing the exposure time. As shown in Figure 14, by acquiring brightness data for every 3x3 pixels and calculating the speckle contrast, the speckle pattern for the entire image can be analyzed and used for motion analysis and speed estimation.

[0123] In this way, the image analysis unit analyzes the speckle contrast based on images acquired at multiple exposure times. Then, the calculation unit 4 calculates the correlation time τ based on the change in this speckle contrast, and can measure the velocity of the object based on the correlation time τ and the wavelength λ of light from the light source.

[0124] Figure 15 is a graph showing the relationship between exposure time and contrast value obtained by speckle analysis using this technology. This graph depicts four different cases depending on the velocity of the object. The horizontal axis shows the exposure time [seconds] on a logarithmic scale, and the vertical axis shows the relative contrast value. Figure 16 shows the parameters used for the measurement.

[0125] Figure 15 shows that the relative contrast value decreases as the speed of the object increases. By utilizing this characteristic, it is possible to measure the change in contrast with respect to exposure time and estimate the speed of the subject.

[0126] This technology demonstrates that the velocity of an object can be detected with high accuracy by analyzing the relationship between the contrast value and exposure time of speckle images obtained using laser light. By acquiring contrast values ​​while varying the exposure time, the velocity can be estimated based on the characteristic curve shown in the graph.

[0127] Furthermore, in this technology, the calculation unit 4 can correct the measured speed based on the distance to the measured object. The distance to the object can be measured by the light source performing pulse operation. This correction improves the accuracy of measuring the object's speed and optimizes the performance of the measuring device.

[0128] Specifically, as distance increases, the intensity of reflected light decreases, reducing the contrast of the speckle pattern. Therefore, the speckle contrast is corrected based on the measured distance information. This enables highly accurate speed measurement even for objects at long distances.

[0129] Figure 17 is a schematic diagram illustrating the transition from the relaxation oscillation state R to the steady state S as the light source operates. This schematic diagram visually explains the conditions for velocity detection using speckle analysis.

[0130] As shown in Figure 17, immediately after current is applied to the light source, the output of the light source exhibits a temporary transient change, and relaxation oscillations occur. These relaxation oscillations are output fluctuations in the initial state and decay over time. While these relaxation oscillations persist, the fluctuations of the longitudinal modes of the light source are large, and the degree of coherence is low, resulting in low speckle contrast. Therefore, accurate velocity detection is difficult in the relaxation oscillation state R, and it is not suitable for measurements using speckle analysis.

[0131] On the other hand, as time passes, the relaxation oscillations dampen and transition to a steady state S. In the steady state S, fluctuations in the longitudinal modes of the light source are reduced, and the stability of the wavefront improves, resulting in higher coherence. This also increases the speckle contrast, enabling more accurate speckle image analysis. Speckle analysis in this steady state S allows for highly accurate estimation of the subject's velocity. Therefore, it is preferable that the image analyzed by the image analysis unit is an image acquired after the relaxation oscillations that occur when switching to CW operation have subsided.

[0132] From the above, it is understood that this technology enables high-precision distance measurement and velocity detection while avoiding brightness saturation by switching from pulse operation to continuous wave (CW) operation and acquiring speckle images in a steady state where a stable optical output can be obtained during CW operation.

[0133] Thus, this technology is characterized by its ability to accurately measure the speed and distance of an object by appropriately switching the operation of the light source between pulsed and continuous wave (CW) operation and optimizing the speckle contrast.

[0134] Figure 18 is a flowchart showing an example of a distance and velocity measurement flow using a light source and photodetector according to one embodiment of this technology.

[0135] First, in step S101, the light source 1 performs pulse operation, and the calculation unit 4 measures the distance to each pixel.

[0136] Next, in step S102, the photodetector 3 measures the time difference, or ToF value, that the pulse light takes to reflect back from the object. Based on this ToF value, the calculation unit 4 calculates the distance to the object.

[0137] Next, in step S103, it is determined whether the photodetector 3 is luminance saturated. If it is not luminance saturated (step S103: No), in step S109, the calculation unit 4 records the ToF value of that pixel and determines whether to perform velocity detection.

[0138] If velocity detection is not required (Step S109: No), in Step S112, the calculation unit 4 determines whether the analysis of all pixels has been completed. If the analysis of all pixels has not been completed (Step S112: No), in Step S113, the measurement continues by moving to the next pixel. If the analysis of all pixels has been completed (Step S112: Yes), the process ends.

[0139] If velocity detection is required (step S109: Yes), in step S110, the light source 1 is switched to CW operation. In CW operation, the light source 1 continuously emits light, making it suitable for speckle analysis.

[0140] Next, in step S111, during CW operation, the photodetector 3 detects reflected light and analyzes the speckle image. This analysis estimates the velocity of the object. If velocity detection is complete, in step S112, it is determined whether the analysis of all pixels has been completed. If the analysis of all pixels has not been completed (step S112: No), in step S113, the measurement continues by moving to the next pixel. If the analysis of all pixels has been completed (step S112: Yes), the process is terminated.

[0141] Even after switching the light source 1 to CW operation in step S104, ToF measurement is performed in step S105, and it is determined in step S106 whether the photodetector 3 is luminance saturated.

[0142] If brightness saturation occurs (step S106: Yes), in step S107, the gain current of the light source 1 and the voltage applied to the saturable absorber are adjusted to adjust the output in order to prevent brightness saturation. Steps S105 to S107 are repeated until brightness saturation is no longer present.

[0143] If the brightness is not saturated (step S106: No), or if velocity detection is required (step S108: Yes), in step S111, the calculation unit 4 performs speckle image analysis. Then, in step S112, the calculation unit 4 determines whether the analysis of all pixels has been completed. If the analysis of all pixels has not been completed (step S112: No), in step S113, the measurement moves to the next pixel and continues. If the analysis of all pixels has been completed (step S112: Yes), the process ends.

[0144] This flowchart demonstrates that this technology enables high-precision detection of distance and speed while avoiding brightness saturation by appropriately switching between pulse and continuous wave (CW) operation. Furthermore, stable measurements are achieved by controlling the output of the light source by changing the driving conditions (adjusting the gain and applied voltage) when brightness saturation occurs.

[0145] The above description of the measuring device according to the second embodiment of this technology can be applied to other embodiments of this technology, unless there are any particular technical inconsistencies.

[0146] [3. Third Embodiment of the Technology (Example 3 of a Measuring Device)] An example of the configuration of a light source according to one embodiment of the Technology will be described with reference to Figure 19. Figure 19 is a schematic diagram showing an example of the configuration of a light source 1 according to one embodiment of the Technology.

[0147] As shown in Figure 19, the light source 1 includes an excitation light source 18, a lens 19, a mirror 14, a gain medium 11, and a saturable absorber 12, etc.

[0148] The excitation light source 18 supplies energy to excite the gain medium 11 and has a wavelength corresponding to the gain medium 11. For example, the excitation light source 18 can have a light-emitting element using a III-V compound semiconductor. The wavelength of the excitation light source 18 is selected to match the characteristics of the gain medium 11.

[0149] The gain medium 11 contains an optical crystal such as YAG:Nd (neodymium:yttrium aluminum garnet). The gain medium 11 absorbs the light energy supplied from the excitation light source 18, amplifies it, and outputs it. The gain medium 11 receives light from the excitation light source 18, amplifies light of a specific wavelength, and generates high-power light. This increases the output of the light source 1.

[0150] The saturable absorber 12 exhibiting QCSE is composed of, for example, a III-V compound semiconductor, has a pn junction, and has an active layer that absorbs light emitted from the gain medium 11. The saturable absorber 12 has the characteristic that when the light intensity exceeds a certain level, its absorption rate decreases and its light transmittance increases. This characteristic makes it possible to switch the output of the light source to pulse operation.

[0151] A reverse voltage is applied to the saturable absorber 12, and its absorption characteristics change depending on the magnitude of the voltage. By adjusting this reverse voltage, the operating state of the light source can be controlled.

[0152] Light emitted from the excitation light source 18 is incident on the gain medium 11 via a lens 19, etc., where it is amplified before reaching the saturable absorber 12. The saturable absorber 12 absorbs or transmits light according to the intensity of the input light, and as a result the overall output of the light source 1 is controlled. This configuration allows switching between pulse operation and continuous wave (CW) operation.

[0153] The mirrors 14 are placed at both ends of the optical resonator, which is composed of a gain medium 11 and a saturable absorber 12, and efficiently reflect the laser light. This laser light is amplified by repeatedly passing back and forth within the resonator. With the installation of these mirrors 14, the light inside the resonator is appropriately amplified and finally emitted to the outside as laser light.

[0154] The relationship between the applied voltage and the optical output will be explained with reference to Figure 20. Figure 20 is a characteristic diagram showing the relationship between the applied voltage to the saturable absorber 12 and the optical output of the excitation light source 18 in the light source 1 according to this embodiment.

[0155] As shown in Figure 20, the output characteristics of the light source 1 are determined by the relationship between the voltage applied to the saturable absorber 12 and the optical output of the excitation light source 18. This has the advantage that the same operation can be performed in the light source 1 of this embodiment by replacing the injection current of the gain medium 11 in the light source 1 of the first embodiment with the optical output of the excitation light source 18.

[0156] The horizontal axis represents the amount of light L incident from the excitation light source 18 onto the gain medium 11.

[0157] The vertical axis represents the voltage V applied to the saturable absorber 12. By adjusting this applied voltage V, the absorption characteristics of the saturable absorber 12 change. The degree to which the saturable absorber 12 absorbs light changes with the change in the applied voltage V, and the light output is controlled.

[0158] "M4" indicates the voltage applied to the saturable absorber 12 when CW operation is performed. CW operation occurs when the voltage applied to the saturable absorber 12 is close to zero. In this state, absorption by the saturable absorber 12 is suppressed, and a continuous light output is obtained.

[0159] In "M5," the area where the slope is gentler in the thick line indicates the voltage applied to the saturable absorber 12 when pulse operation is performed. In this area, the applied voltage is set to an appropriate value, and after the saturable absorber 12 absorbs an appropriate amount of light, it instantaneously transmits the light (absorption saturates), thus generating pulsed light.

[0160] "M6" indicates the voltage applied to the saturable absorber 12 when CW operation is performed again. If the applied voltage is too high, the absorption amount of the saturable absorber 12 does not decrease (absorption does not saturate), the pulse operation stops, and only CW operation is performed. In this state, since the voltage is set high, a continuous optical output is obtained, and pulse operation is not performed.

[0161] Based on this characteristic, the pulse operation and CW operation can be switched by changing the voltage applied to the saturable absorber 12 while maintaining the amount of incident light L to the gain medium 11.

[0162] The above description of the measuring device according to the third embodiment of this technology can be applied to other embodiments of this technology, unless there are any particular technical inconsistencies.

[0163] [4. Fourth Embodiment of the Technology (Example of an Electronic Device)] The technology provides an electronic device comprising a light source that can switch between pulse operation and CW operation, and a control unit that controls the switching between the pulse operation and the CW operation, wherein the light source includes a saturable absorber that exhibits the quantum confinement Stark effect (QCSE).

[0164] In other words, this technology provides an electronic device equipped with a measuring device according to any one of the first to third embodiments.

[0165] This technology can be applied to a variety of products. For example, it may be implemented as a device mounted on any type of mobile vehicle, such as automobiles, electric vehicles, hybrid electric vehicles, motorcycles, bicycles, personal mobility devices, airplanes, drones, ships, or robots.

[0166] Figure 21 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile control system to which the technology described herein may be applied.

[0167] The vehicle control system 12000 comprises a plurality of electronic control units connected via a communication network 12001. In the example shown in Figure 21, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an external information detection unit 12030, an internal information detection unit 12040, and an integrated control unit 12050. The functional configuration of the integrated control unit 12050 is shown in the figure, which includes a microcomputer 12051, an audio / image output unit 12052, and an in-vehicle network interface 12053.

[0168] The drivetrain control unit 12010 controls the operation of devices related to the vehicle's drivetrain according to various programs. For example, the drivetrain control unit 12010 functions as a control device for a drivetrain generating device that generates driving force for the vehicle, such as an internal combustion engine or a drive motor; a drivetrain transmission mechanism that transmits driving force to the wheels; a steering mechanism that adjusts the steering angle of the vehicle; and a braking device that generates braking force for the vehicle.

[0169] The body system control unit 12020 controls the operation of various devices mounted on the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for a keyless entry system, a smart key system, a power window system, or various lamps such as headlights, reverse lights, brake lights, turn signals, or fog lights. In this case, the body system control unit 12020 may receive radio waves transmitted from a portable device that replaces a key or signals from various switches. The body system control unit 12020 receives these radio waves or signals and controls the vehicle's door lock system, power window system, lamps, etc.

[0170] The external information detection unit 12030 detects information from outside the vehicle equipped with the vehicle control system 12000. For example, an imaging unit 12031 is connected to the external information detection unit 12030. The external information detection unit 12030 causes the imaging unit 12031 to capture images of the outside of the vehicle and receives the captured images. Based on the received images, the external information detection unit 12030 may perform object detection processing such as detecting people, cars, obstacles, signs, or characters on the road surface, or distance detection processing.

[0171] The imaging unit 12031 is a light sensor that receives light and outputs an electrical signal corresponding to the amount of light received. The imaging unit 12031 can output the electrical signal as an image or as distance measurement information. The light received by the imaging unit 12031 may be visible light or invisible light such as infrared light.

[0172] The in-vehicle information detection unit 12040 detects information inside the vehicle. The in-vehicle information detection unit 12040 is connected to, for example, a driver status detection unit 12041 that detects the driver's state. The driver status detection unit 12041 includes, for example, a camera that captures images of the driver, and the in-vehicle information detection unit 12040 may calculate the driver's level of fatigue or concentration, or determine whether the driver is drowsy, based on the detection information input from the driver status detection unit 12041.

[0173] The microcomputer 12051 can calculate control target values ​​for the drive force generator, steering mechanism, or braking device based on information inside and outside the vehicle acquired by the external information detection unit 12030 or the internal information detection unit 12040, and output control commands to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing ADAS (Advanced Driver Assistance System) functions, including collision avoidance or impact mitigation, following driving based on distance between vehicles, maintaining vehicle speed, vehicle collision warning, or vehicle lane departure warning.

[0174] Furthermore, the microcomputer 12051 can perform cooperative control for purposes such as autonomous driving, where the vehicle drives autonomously without driver intervention, by controlling the drive force generating device, steering mechanism, or braking device, etc., based on information about the vehicle's surroundings acquired by the external information detection unit 12030 or the internal information detection unit 12040.

[0175] Furthermore, the microcomputer 12051 can output control commands to the body system control unit 12020 based on external information acquired by the external information detection unit 12030. For example, the microcomputer 12051 can control the headlights according to the position of a preceding or oncoming vehicle detected by the external information detection unit 12030, and perform coordinated control aimed at reducing glare, such as switching from high beams to low beams.

[0176] The audio-image output unit 12052 transmits at least one of audio and image output signals to an output device capable of visually or audibly notifying information to the vehicle's occupants or to those outside the vehicle. In the example shown in Figure 21, the output devices are exemplified as an audio speaker 12061, a display unit 12062, and an instrument panel 12063. The display unit 12062 may include, for example, at least one of an onboard display and a head-up display.

[0177] Figure 22 shows an example of the installation position of the imaging unit 12031.

[0178] In Figure 22, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104, and 12105.

[0179] The imaging units 12101, 12102, 12103, 12104, and 12105 are installed, for example, on the front nose, side mirrors, rear bumper, back door, and the upper part of the windshield inside the vehicle 12100. The imaging unit 12101 installed on the front nose and the imaging unit 12105 installed on the upper part of the windshield inside the vehicle mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 installed on the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 installed on the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The imaging unit 12105 installed on the upper part of the windshield inside the vehicle is mainly used for detecting preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, or lanes.

[0180] Figure 22 shows an example of the imaging range of imaging units 12101 to 12104. Imaging range 12111 indicates the imaging range of imaging unit 12101 located on the front nose, imaging ranges 12112 and 12113 indicate the imaging ranges of imaging units 12102 and 12103 located on the side mirrors, respectively, and imaging range 12114 indicates the imaging range of imaging unit 12104 located on the rear bumper or back door. For example, by superimposing the image data captured by imaging units 12101 to 12104, an overhead view image of the vehicle 12100 can be obtained.

[0181] At least one of the imaging units 12101 to 12104 may have a function for acquiring distance information. For example, at least one of the imaging units 12101 to 12104 may be a stereo camera consisting of multiple image sensors, or an image sensor having pixels for phase difference detection.

[0182] For example, the microcomputer 12051, based on distance information obtained from the imaging units 12101 to 12104, can determine the distance to each object within the imaging range 12111 to 12114 and the temporal change of this distance (relative speed to the vehicle 12100). In particular, it can extract the closest object on the vehicle 12100's path that is traveling in approximately the same direction as the vehicle 12100 at a predetermined speed (e.g., 0 km / h or more) as the preceding vehicle. Furthermore, the microcomputer 12051 can set a predetermined distance to be maintained before the preceding vehicle and perform automatic braking control (including follow-and-stop control) and automatic acceleration control (including follow-and-start control), etc. In this way, cooperative control aimed at autonomous driving, where the vehicle drives autonomously without driver intervention, can be performed.

[0183] For example, the microcomputer 12051 can use distance information obtained from imaging units 12101 to 12104 to classify and extract three-dimensional object data related to three-dimensional objects, such as motorcycles, passenger cars, large vehicles, pedestrians, utility poles, and other three-dimensional objects, and use this data for automatic obstacle avoidance. For example, the microcomputer 12051 identifies obstacles around the vehicle 12100 into obstacles that are visible to the driver of the vehicle 12100 and obstacles that are difficult to see. The microcomputer 12051 then determines the collision risk, which indicates the degree of risk of collision with each obstacle. If the collision risk is above a set value and there is a possibility of collision, the microcomputer 12051 can provide driving assistance to avoid collisions by outputting a warning to the driver via the audio speaker 12061 or the display unit 12062, or by performing forced deceleration or evasive steering via the drive system control unit 12010.

[0184] At least one of the imaging units 12101 to 12104 may be an infrared camera that detects infrared light. For example, the microcomputer 12051 can recognize pedestrians by determining whether or not pedestrians are present in the images captured by the imaging units 12101 to 12104. Such pedestrian recognition is performed, for example, by a procedure to extract feature points from the images captured by the imaging units 12101 to 12104 as infrared cameras, and a procedure to perform pattern matching on a series of feature points that indicate the contour of an object to determine whether or not it is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the images captured by the imaging units 12101 to 12104 and recognizes a pedestrian, the audio-image output unit 12052 controls the display unit 12062 to superimpose a rectangular contour line for emphasis on the recognized pedestrian. The audio-image output unit 12052 may also control the display unit 12062 to display an icon indicating a pedestrian at a desired position.

[0185] The above describes an example of a vehicle control system to which this technology may be applied. This technology can be applied to, for example, the imaging unit 12031 in the configuration described above.

[0186] The specific numerical values, shapes, materials (including composition), etc., described herein are examples only and are not limited to these.

[0187] Furthermore, this technology can also take the following configurations: [1] A measuring device comprising a light source capable of switching between pulse operation and CW operation, and a control unit that controls the switching between the pulse operation and the CW operation, wherein the light source includes a saturable absorber that exhibits the quantum confinement Stark effect (QCSE). [2] The measuring device according to [1], wherein the control unit controls the voltage applied to the saturable absorber to switch between the pulse operation and the CW operation. [3] The measuring device according to [2], further comprising a photodetector that detects the brightness of reflected laser light from the light source, wherein the light source performs the pulse operation when the reflected light is not brightness saturated, and the light source performs the CW operation when the reflected light is brightness saturated. [4] The measuring device according to [3], wherein the photodetector is configured by arranging SPADs (Single Photon Avalanche Diodes) in a two-dimensional array. [5] The measuring device according to any one of [2] to [4], wherein the light source further includes a gain medium for amplifying light, and when the light source performs the pulse operation, the control unit applies a first current to the gain medium and applies a first voltage to the saturable absorber, and when the light source performs the CW operation, the control unit applies a second current to the gain medium and applies a second voltage to the saturable absorber. [6] The measuring device according to [5], wherein when the reflected light of the laser beam from the light source is saturated in brightness, the control unit reduces the light output by controlling the voltage applied to the saturable absorber. [7] The measuring device according to [5] or [6], wherein when the reflected light of the laser beam from the light source is saturated in brightness, the control unit reduces the light output by reducing the current to the gain medium. [8] The measuring device according to any one of [2] to [7], further comprising a calculation unit, wherein the calculation unit measures the distance to an object when the light source performs the pulse operation, and the calculation unit measures the velocity of an object when the light source performs the CW operation.[9] The measuring device according to any one of [2] to [8], further comprising an image analysis unit that analyzes an image acquired when the light source is performing the CW operation, wherein the image analysis unit analyzes the speckle contrast in the image to measure the velocity of the object.

[10] The measuring device according to [9], wherein the image is an image acquired after the convergence of relaxation vibrations that occur when switching to the CW operation.

[11] The measuring device according to [9] or

[10] , further comprising a calculation unit, wherein the image analysis unit analyzes the speckle contrast based on the images acquired at multiple exposure times, the calculation unit calculates a correlation time based on the change in the speckle contrast, and measures the velocity of the object based on the correlation time and the wavelength of light from the light source.

[12] The measuring device according to

[11] , wherein the calculation unit corrects the measured velocity based on the distance to the measured object.

[13] A measuring device according to any one of [2] to

[12] , wherein the distance to an object is measured using the d-ToF (Direct Time of Flight) method.

[14] A measuring device according to any one of [2] to

[13] , wherein the light source further includes a gain medium for amplifying light and an excitation light source having a wavelength corresponding to the gain medium, the gain medium includes an optical crystal, and the excitation light source excites the gain medium.

[15] A measuring device according to

[14] , wherein the excitation light source has a light-emitting element using a III-V compound semiconductor.

[16] A measuring device according to any one of [1] to

[15] , wherein the light source is a pulsed laser light source.

[17] A measuring device according to any one of [1] to

[16] , wherein the light source is a LiDAR.

[18] An electronic device comprising a light source that can switch between pulse operation and CW operation, and a control unit that controls the switching between pulse operation and CW operation, wherein the light source includes a saturable absorber that exhibits the quantum confinement Stark effect (QCSE).

[0188] 1. Light source 11. Gain medium 12. Saturable absorber 13. High-reflection coating 14. Mirror 15. p-type electrode 16. n-type electrode 17. Active layer 18. Excitation light source 2. Control unit 3. Photodetector 4. Calculation unit 100. Measurement device

Claims

1. A measuring device comprising a light source capable of switching between pulse operation and continuous wave operation, and a control unit that controls the switching between the pulse operation and the continuous wave operation, wherein the light source includes a saturable absorber that exhibits the quantum confinement Stark effect (QCSE).

2. The measuring device according to claim 1, wherein the control unit controls the voltage applied to the saturable absorber to switch between the pulse operation and the CW operation.

3. The measuring device according to claim 2, further comprising a photodetector for detecting the brightness of reflected laser light from the light source, wherein the light source performs the pulse operation when the reflected light is not brightness saturated, and the light source performs the CW operation when the reflected light is brightness saturated.

4. The measuring device according to claim 3, wherein the photodetector is configured with SPADs (Single Photon Avalanche Diodes) arranged in a two-dimensional array.

5. The measuring device according to claim 2, wherein the light source further includes a gain medium for amplifying light, and when the light source performs the pulse operation, the control unit applies a first current to the gain medium and applies a first voltage to the saturable absorber, and when the light source performs the CW operation, the control unit applies a second current to the gain medium and applies a second voltage to the saturable absorber.

6. The measuring device according to claim 5, wherein, when the reflected light of the laser beam from the light source is saturated in brightness, the control unit reduces the light output by controlling the voltage applied to the saturable absorber.

7. The measuring device according to claim 5, wherein when the reflected light of the laser beam from the light source is saturated in brightness, the control unit reduces the light output by reducing the current to the gain medium.

8. The measuring device according to claim 2, further comprising a calculation unit, wherein the calculation unit measures the distance to an object when the light source performs the pulse operation, and the calculation unit measures the velocity of an object when the light source performs the CW operation.

9. The measuring device according to claim 2, further comprising an image analysis unit that analyzes an image acquired when the light source is performing the CW operation, wherein the image analysis unit analyzes the speckle contrast in the image to measure the velocity of an object.

10. The measuring device according to claim 9, wherein the image is an image acquired after the easing vibrations that occur when the device switches to the CW operation have subsided.

11. The measuring device according to claim 9, further comprising a calculation unit, wherein the image analysis unit analyzes the speckle contrast based on the images acquired at multiple exposure times, the calculation unit calculates a correlation time based on the change in the speckle contrast, and measures the velocity of an object based on the correlation time and the wavelength of light from the light source.

12. The measuring device according to claim 11, wherein the calculation unit corrects the measured speed based on the distance to the measured object.

13. The measuring device according to claim 2, which measures the distance to an object using the d-ToF (Direct Time of Flight) method.

14. The measuring device according to claim 2, wherein the light source further comprises a gain medium for amplifying light and an excitation light source having a wavelength corresponding to the gain medium, the gain medium comprising an optical crystal, and the excitation light source exciting the gain medium.

15. The measuring apparatus according to claim 14, wherein the excitation light source has a light-emitting element using a group III-V compound semiconductor.

16. The measuring device according to claim 1, wherein the light source is a pulsed laser light source.

17. The measuring device according to claim 1, wherein it is a LiDAR.

18. An electronic device comprising a light source capable of switching between pulse operation and continuous wave operation, and a control unit that controls the switching between the pulse operation and the continuous wave operation, wherein the light source includes a saturable absorber that exhibits the quantum confinement Stark effect (QCSE).

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