Measuring device and measuring method

Abstract

To obtain information about objects with sufficient resolution and FPS using TOF.SOLUTION: A measuring device 1000 has: a light source unit 12; splitting means 13 for splitting illumination light from the light source unit into a plurality of pieces of light to be irradiated toward a plurality of points on an object; control means 31 for controlling irradiation of the plurality of pieces of light onto the object; detection means 23 having a plurality of photoelectric conversion units arranged in two dimensions and for detecting a plurality of pieces of reflection light from the plurality of points; and processing means 51, 61 for acquiring information about the object for each photoelectric conversion unit based on a light flight time from irradiation of the plurality of pieces of light to detection of the reflection light for each photoelectric conversion unit.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a technique for acquiring information about an object using optical time of flight (TOF). [Background technology]

[0002] If light from a light source can be irradiated onto an object to be measured and the reflected light from the object can be detected, it is possible to obtain distance information to the object using TOF from the irradiation of light onto the object to the detection of the reflected light. Patent Document 1 discloses a distance measuring device using TOF, which obtains two-dimensional distance information by scanning an object two-dimensionally while deflecting a laser beam with a scanning mirror and obtaining the laser beam reflected by the object.

[0003] Furthermore, as a surface emitting laser light source that can be used in a distance measuring device using TOF, there is a VCSEL array in which a plurality of vertical cavity surface emitting lasers (VCSELs) are arranged two-dimensionally. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-122689 A [Patent Document 2] JP 2023-522559 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the distance measuring device of Patent Document 1, since the object is scanned two-dimensionally with laser light, it takes time from the start to the end of the scan, and sufficient resolution and frame rate (FPS) cannot be obtained. Although it is possible to simultaneously irradiate multiple laser beams to multiple positions on an object using a VCSEL array, the irradiation positions of the laser beams on the object become discrete according to the discrete arrangement of the VCSELs in the VCSEL array, so sufficient resolution cannot be obtained.

[0006] The present invention provides a measurement device and a measurement method that use TOF to obtain information about an object to be measured with sufficient resolution and FPS. [Means for solving the problem]

[0007] A measuring device as one aspect of the present invention is characterized in that it has a light source unit, a splitting means for splitting illumination light from the light source unit into multiple lights that are irradiated toward multiple points on an object, a control means for controlling the irradiation of the multiple lights onto the object, a detection means having multiple photoelectric conversion units arranged in two dimensions and detecting multiple reflected lights from the multiple points, and a processing means for acquiring information about the object for each photoelectric conversion unit based on the light flight time from the irradiation of the multiple lights to the detection of the reflected light for each photoelectric conversion unit.

[0008] A measurement method according to another aspect of the present invention includes splitting illumination light from a light source unit into a plurality of lights that are irradiated toward a plurality of points on an object, controlling the irradiation of the plurality of lights onto the object, detecting a plurality of reflected lights from the plurality of points using a plurality of photoelectric conversion units arranged two-dimensionally, and acquiring information about the object for each photoelectric conversion unit based on the light flight time from the irradiation of the plurality of lights to the detection of the reflected light for each photoelectric conversion unit. Note that a program for causing a computer to execute processing according to the above measurement method also constitutes another aspect of the present invention. Effect of the Invention

[0009] According to the present invention, information about the object being measured can be obtained with sufficient resolution and FPS using TOF. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram showing a configuration of a measurement device according to an embodiment. [Diagram 2] FIG. 2 is a diagram showing a configuration of a pixel region of a light detection unit in the embodiment. [Diagram 3] 5A to 5C are diagrams for explaining drive pulses for a light detection unit in the embodiment. [Figure 4] FIG. 1 is a diagram showing the configuration of a measurement device according to a first embodiment. [Diagram 5] 4 is a flowchart showing a process executed in the first embodiment. [Figure 6] FIG. 13 is a diagram showing the configuration of a measurement device according to a second embodiment. [Figure 7] FIG. 11 is a diagram showing the configuration of a division unit in the second embodiment. [Figure 8] FIG. 11 is another diagram showing the configuration of the division unit in the second embodiment. [Figure 9] 11 is a flowchart showing a process executed in the second embodiment. [Figure 10] 5A and 5B are diagrams for explaining the intensities and detection times of reflected light from an object and other light; [Figure 11] FIG. 4 is a diagram showing the configuration of a division unit in the first and second embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0012] First, an overview of a measurement device according to an embodiment will be described with reference to Fig. 1. The measurement device 1000 shown in Fig. 1 has an illumination unit 11, a light detection unit 21, a timing control unit 31, a signal processing unit 41, an arithmetic processing unit 51, a control unit 61, a display unit 71, and a storage unit 81. The timing control unit 31 and the control unit 61 constitute a control means, and the signal processing unit 41, the arithmetic processing unit 51, and the control unit 61 constitute a processing means.

[0013] The illumination unit 11 has a light source unit 12 and a splitting unit (splitting means) 13. The light source unit 12 emits illumination light to be irradiated onto an object to be measured. The object may be a person, an automobile, a plant, a mold, a board, or the like, and the type of the object is not particularly limited.

[0014] In this embodiment, the light source 12 is a laser light source, and the laser light emitted from the laser light source is collimated by a collimator lens and emitted. The light source unit 12 may emit a composite of two or more colors of laser light, or may collimate and emit light from a light source other than a laser light source, such as an LED or a mercury lamp.

[0015] The light source unit 12 emits illumination light in response to receiving a light emission control signal transmitted from the timing control unit 31. For example, the light source unit 12 emits a light beam of a specific wavelength as pulsed light having a pulse width of several picoseconds to several tens of n seconds.

[0016] The illumination light emitted from the light source unit 12 is divided by the division unit 13 into multiple lights that have uniform intensity (light amount) and are distributed two-dimensionally, and are irradiated onto multiple points on the object. Note that the uniform intensity does not need to be completely the same intensity, but may have a difference that can be considered to be the same in distance measurement. For example, the intensity difference may be within 10 percent.

[0017] The splitting unit 13 is configured using a liquid crystal panel, a digital mirror device, a diffraction element, etc. The specific configuration of the splitting unit 13 will be described later.

[0018] The light detection unit 21 receives a plurality of reflected lights irradiated to a plurality of points on the object and reflected at each point. The light detection unit 21 has a distance measurement optical system 22 and a sensor unit 23. The distance measurement optical system 22 irradiates a plurality of lights from the division unit 13 to a plurality of points on the object, and guides a plurality of reflected lights from the plurality of points on the object to the sensor unit 23, forming an optical image of the plurality of points on the object on the sensor unit 23. The sensor unit 23 has a plurality of pixels each including a photoelectric conversion unit, and outputs a light reception signal (voltage pulse) from each pixel every time light is incident on the pixel. The light detection unit 21 counts the number of photons for each pixel of the sensor unit 23 based on the light reception signal, and outputs the count value (intensity of received light) and information on the detection time, which is the time when the photon count was performed, to the signal processing unit 41.

[0019] The sensor unit 23 is exposed to light for a predetermined exposure time when performing one light receiving operation. The sensor unit 23 starts and ends exposure in response to receiving an exposure control signal transmitted from the timing control unit 31. During the exposure time from the start to the end of exposure, the light source unit 12 emits illumination light at least once with the above-mentioned pulse width, and the sensor unit 23 receives the reflected light.

[0020] In this embodiment, a SPAD array in which a plurality of SPAD (Single Photon Avalanche Diode) pixels are arranged in two-dimensional directions (X direction and Y direction) as shown in Fig. 2 is used as the sensor unit 23. Details of the SPAD array will be described later. Note that, in this embodiment, a sensor unit 23 using an avalanche photodiode that avalanche-doubles light will be described, but the sensor unit may be configured with a photodiode that does not avalanche-double light.

[0021] Moreover, the splitting unit 13 and the sensor unit 23 are disposed at conjugate positions with respect to the distance measuring optical system 22 .

[0022] The timing control unit 31 transmits a light emission control signal to the illumination unit 11 to control the light emission timing of the illumination unit 11, and transmits an exposure control signal to the light detection unit 21 to control the reception timing of the reflected light at the light detection unit 21.

[0023] The signal processing unit 41 performs signal processing such as noise removal on the light reception signal output from the sensor unit 23. The signal processing unit 41 also maps the photon count value for each pixel and the detection time of the reflected light output from the sensor unit 23 for pixels in the entire pixel region or a part of the pixel region of the sensor unit 23. This allows two-dimensional light detection information (first information) to be obtained.

[0024] The calculation processing unit 51 is composed of a computer such as a CPU, and has an information calculation unit 52 and an image construction unit 53. In this embodiment, a TOF method is adopted in which spatial information (second information) regarding an object, such as distance information of the object, is acquired based on the time of flight of light (TOF) from the irradiation time when the illumination light is irradiated toward the object (the light source unit 12 emits light) to the detection time when the reflected light is received by the light detection unit 21. The information calculation unit 52 calculates distance information (light ray flight distance) indicating the optical path length of the light received by each pixel, based on the irradiation time of the illumination light acquired from the timing control unit 31 and the detection time of the reflected light for each pixel of the sensor unit 23 obtained from the two-dimensional light detection information.

[0025] Image construction unit 53 constructs a shape from distance information for each pixel as a distance measurement result calculated by information calculation unit 52, and outputs image data for displaying the shape (distance image data) to display unit 71. Display unit 71 displays the distance image data. Storage unit 81 accumulates the distance image data.

[0026] The control unit 61 controls the entire measuring device 1000. The control unit 61 includes a computer such as a CPU, and executes a program to control the illumination unit 11, the light detection unit 21, and the calculation processing unit 51. The control unit 61, together with the signal processing unit 41 and the calculation processing unit 51, may be configured as an integrated computer.

[0027] 2 shows a configuration of a portion of the entire pixel region in the sensor unit 23 (SPAD array). On the SPAD array, a plurality of SPAD pixels 103 are arranged in the X and Y directions. Each SPAD pixel 103 has a photoelectric conversion unit (avalanche photodiode) 201, a quench element 202, a control unit 210, a counter / memory 211, and a readout unit 212.

[0028] A potential VH higher than the voltage VL supplied to the anode is supplied to the cathode of the photoelectric conversion unit 201. That is, a potential is supplied to the anode and cathode so that a reverse bias is applied so that photons incident on the photoelectric conversion unit 201 are avalanche multiplied. By performing photoelectric conversion in a state where such a reverse bias potential is supplied, charges generated by the incident light (photons) undergo avalanche multiplication, generating an avalanche current.

[0029] When a reverse bias potential is applied, and the potential difference between the anode and cathode is greater than the breakdown voltage, the avalanche diode operates in Geiger mode. A SPAD is an avalanche diode that uses Geiger mode operation to quickly detect weak signals at the single photon level.

[0030] The control unit 210 determines whether or not to count the number of photons based on the light reception signal output from the photoelectric conversion unit 201. In this embodiment, the control unit 210 is a switch (gate circuit) provided between the photoelectric conversion unit 201 and the counter / memory 211. The gate of the switch is connected to the pulse line 124, and the control unit 210 is switched on and off according to the signal input to the pulse line 124. The gates of the switches of all pixel columns are controlled by inputting a signal based on an exposure control signal from the timing control unit 31 to the pulse line 124 of each pixel column. This collectively controls the start and end of light detection (exposure) of all SPAD pixels 103.

[0031] The control unit 210 may be configured with a logic circuit instead of a switch. For example, if an AND circuit is provided as the logic circuit, and the first input of the AND circuit is the output from the photoelectric conversion unit 201 and the second input is the signal of the pulse line 124, it becomes possible to switch whether or not to count the number of photons based on the light receiving signal from the photoelectric conversion unit 201.

[0032] Furthermore, the control unit 210 does not need to be provided between the photoelectric conversion unit 201 and the counter / memory 211, and may be a circuit that inputs a signal that switches the counter in the counter / memory 211 between operation and non-operation.

[0033] The counter / memory 211 counts the number of photons that have entered the photoelectric conversion unit 201, and holds the count value as digital data.

[0034] The readout unit 212 is connected to the readout signal line 123 via the counter / memory 211. In response to a control pulse supplied from a vertical scanning circuit unit (not shown) provided in the SPAD array via a control line 214, the readout unit 212 switches whether or not to output the count value of the counter / memory 211 to the readout signal line 123. The readout unit 212 includes a buffer circuit for outputting a signal, and the like.

[0035] The read signal line 123 may be a signal line that outputs the count value from the light detection unit 21 to the arithmetic processing unit 51, or may be a signal line that outputs the count value to the signal processing unit 41. Furthermore, the vertical scanning circuit unit and a horizontal scanning circuit unit (not shown) may be provided on the substrate on which the SPAD array is provided, or may be provided on a substrate different from the substrate on which the SPAD array is provided.

[0036] 3 shows the timing when illumination light (pulsed light) from illumination unit 11 is irradiated toward an object, and the timing when the illumination light is reflected by the object and the reflected light is received (photodetected) and photocounted by sensor unit 23. At time t11, illumination light is irradiated toward the object and photodetection by sensor unit 23 is started, and photodetection ends at time t12 after a predetermined counting period. By the time the reflected light reaches sensor unit 23, sensor unit 23 is performing photodetection, and the reflected light is detected.

[0037] The light receiving timing of the multiple SPAD pixels provided in the sensor unit 23 may be controlled collectively for all the pixels or may be controlled for each pixel.

[0038] A set of data including information on the intensity (amount of light) of reflected light and information on the detection time when the reflected light is received can be obtained for each SPAD pixel arranged two-dimensionally in the sensor unit 23. By combining data from all pixels (within the XY plane), it is possible to obtain two-dimensional light detection information, which is information on the intensity of reflected light for each position (X, Y) in the XY plane and the detection time t. Then, by using the two-dimensional light detection information, it is possible to obtain information about an object with sufficient resolution and FPS. EXAMPLES

[0039] 4 shows the configuration of a measuring device 1000A according to the first embodiment. The measuring device 1000A has an illumination unit 11 including a light source unit 12 consisting of a laser light source U101 and a collimator lens U201, and a splitting unit 13 consisting of a transmissive liquid crystal panel U103 and a polarizing plate U104. The measuring device 1000A also has a distance measuring optical system 22 consisting of a polarizing beam splitter U105 and an objective optical system U106, and a light detection unit 21 including a sensor unit 23 having a light receiving surface arranged on an image plane IP.

[0040] The illumination light emitted from the laser light source U101 is collimated by a collimator lens U201 as a collimating means and is irradiated onto the transmissive liquid crystal panel U103. The transmissive liquid crystal panel U103 has a plurality of optical modulation sections (corresponding to pixels) adjacent to each other, and the illumination light is incident on and transmitted through these optical modulation sections, thereby splitting the illumination light into a plurality of lights having uniform intensity. A lens array may be disposed to collect each of the plurality of lights transmitted through the transmissive liquid crystal panel U103.

[0041] Generally, a laser light source emits laser light having a Gaussian intensity distribution, and the illumination light collimated from the laser light also has an intensity distribution in which the intensity is high at the center and low at the periphery. In order to improve the uniformity of the intensity of a plurality of lights, it is desirable that the intensity distribution of the collimated illumination light is uniform. The laser light source U101 is composed of a laser element, a first deflection element, and a second deflection element. The radiation light having a Gaussian intensity distribution from the laser element is deflected by the first deflection element into radiation light having a uniform intensity distribution, and collimated by the second deflection element. Each deflection element is an optical element such as a metasurface, a diffraction element, or an aspheric collimator lens. The first deflection element and the second deflection element may be provided on both sides of one element. The cross section of a general collimated light has a circular or elliptical shape, but it is desirable to shape the collimated light into a collimated light having a rectangular cross section by the second deflection element.

[0042] In this embodiment, the illumination light emitted from the laser light source U101 is polarized light polarized in the y direction in the figure. The illumination light polarized in the y direction is perpendicularly incident on the transmissive liquid crystal panel U103. The transmissive liquid crystal panel U103 can modulate the polarization state of the light passing through the light modulation section. The polarized light polarized in the x direction among the light passing through the transmissive liquid crystal panel U103 passes through the polarizing plate U104 and is irradiated onto the object U107 via the distance measurement optical system 22. On the other hand, the polarized light polarized in the y direction among the light passing through the transmissive liquid crystal panel U103 is absorbed by the polarizing plate U104.

[0043] By using the transmissive liquid crystal panel U103, it is possible to split the illumination light from the light source unit 12 into multiple lights of uniform intensity, and to control the timing (irradiation time) at which these lights are irradiated toward the object U107.

[0044] The multiple light beams (polarized light beams) transmitted through the polarizing plate U104 are reflected by the polarization separation surface of the polarizing beam splitter U105 and are irradiated onto multiple points on the object via the objective optical system U106. The reflected light beams specularly reflected from the multiple points enter the polarizing beam splitter U105 from the objective optical system U106, transmit through the polarization separation surface, and reach the light receiving surface (IP) of the sensor unit 23.

[0045] In this embodiment, a bending optical system including a polarizing beam splitter U105 is used as the distance measuring optical system 22, which enables the distance measuring device 1000A to be miniaturized. In this embodiment, the transparent liquid crystal panel U103 and the sensor unit 23 are disposed at conjugate positions with respect to the objective optical system U106.

[0046] The flowchart in FIG. 5 shows the process (measurement method) that the timing control section 31 and the control section 61 execute according to a program in this embodiment.

[0047] First, in step S101, the control unit 61 causes the light source unit 12 to emit light and irradiates the object U107 with illumination light as a plurality of lights via the splitting unit 13 and the distance measuring optical system 22. Specifically, the control unit 61 causes the timing control unit 31 to transmit a light emission control signal to the light source unit 12.

[0048] Next, in step S102, the control unit 61 determines whether or not illumination light has been emitted from the light source unit 12 and distance measurement (light detection by the sensor unit 23) has started, and if so, proceeds to step S103.

[0049] In step S103, the control unit 61 obtains time information indicating the irradiation time when the light source unit 12 emitted light.

[0050] Next, in step S104, the control unit 61 controls each light modulation unit of the transmissive liquid crystal panel U103. Specifically, each light modulation unit is controlled so as to transmit polarized light having a polarization direction in the x direction in the transmissive liquid crystal panel T103. As a result, the illumination light incident on the transmissive liquid crystal panel U103 is split into multiple lights and emitted from the transmissive liquid crystal panel T103. That is, by controlling each light modulation unit of the transmissive liquid crystal panel T103, it is possible to control the irradiation time of the illumination light (multiple lights) on the object. The multiple lights emitted from the transmissive liquid crystal panel T103 are irradiated to multiple points on the object with uniform intensity.

[0051] Next, in step S105, the control unit 61 causes the sensor unit 23 to detect reflected light from an object, and acquires two-dimensional light detection information.

[0052] Next, in step S106, the control unit 61 obtains time information indicating the detection time of the reflected light for each pixel in the sensor unit 23 from the two-dimensional light detection information.

[0053] Next, in step S107, control unit 61 causes calculation processing unit 51 to calculate the TOF from the irradiation time acquired in step S103 to the detection time acquired in step S106 for each pixel of sensor unit 23. Then, calculation processing unit 51 calculates distance information based on the TOF calculated for each pixel of sensor unit 23, and further causes processing unit 51 to generate distance image data using the distance information and display unit 71.

[0054] The order of the processes in steps S103 and S104 may be reversed, and the order of the processes in steps S105 and S106 may be reversed.

[0055] Also, the control unit 61 may calculate distance information for each pixel using the time information obtained in steps S103 and S106 only when the intensity of the reflected light is equal to or greater than a threshold value as a predetermined value in the light detection information obtained for each pixel of the sensor unit 23 in step S105. Also, the control unit 61 may calculate distance information only for pixels whose detection time obtained in step S106 is equal to or greater than a threshold value as a predetermined value from the irradiation time obtained in step S103. In other words, if the TOF is too short for the distance to the object, the distance information is not calculated using the TOF. This makes it possible to avoid erroneous calculation of distance information caused by the detection of unnecessary light other than the reflected light from the object by the sensor unit 23.

[0056] Furthermore, in this embodiment, the transmissive liquid crystal panel U103 is used for the dividing section 13, but a reflective liquid crystal panel may be used instead. EXAMPLES

[0057] FIG. 6 shows the configuration of a measuring device 1000B according to the second embodiment. The measuring device 1000B has an illumination unit 11 including a light source unit 12 consisting of a laser light source U101 and a collimator lens U201, and a splitting unit 13 consisting of a light guide U212 and a digital micromirror device (hereinafter simply referred to as a mirror device) U231. The measuring device 1000B also has a distance measuring optical system 22 consisting of a polarizing beam splitter U105 and an objective optical system U106, and a light detection unit 21 including a sensor unit 23 having a light receiving surface arranged on an image plane IP. The measuring device 1000B according to the second embodiment has a different configuration of the splitting unit 13 from that according to the first embodiment, and the other configurations are the same. In this embodiment, the mirror device U231 and the sensor unit 23 are arranged at conjugate positions with respect to the objective optical system U106.

[0058] 7 shows the configuration of the light guide U212. The light guide U212 has a first surface on the light source side and a second surface on the mirror device side, which is the opposite side to the first surface. On the second surface, a first dielectric film U212a, a second dielectric film U212b, a third dielectric film U212c, a fourth dielectric film U212d, and a sixth dielectric film U212f are formed in different regions. On the first surface, a fifth dielectric film U212e is formed as a reflecting portion.

[0059] The first to third dielectric films U212a to U212c are each a separation section that has the property of dividing the incident illumination light at a predetermined ratio (transmitting a portion and reflecting the remainder). Ideally, the transmittance of the first dielectric film U212a is 25%, the transmittance of the second dielectric film is 33.3%, and the transmittance of the third dielectric film is 50%. In this embodiment, the refractive index n of the material of the light guide U212 is 1.52, and the angle θ is 21.6°.

[0060] The illumination light L11 incident from the light source unit 12 into the light guide U212 from a region of the first surface where the fifth dielectric film U212e is not formed propagates through the light guide U212 while being reflected between the sixth dielectric film U212f and the fifth dielectric film U212e. The fifth dielectric film U212e and the sixth dielectric film U212f have a property of reflecting the illumination light at an angle θ.

[0061] The illumination light L13a (75% of L11) reflected by the first dielectric film U212a is reflected by the fifth dielectric film U212e and enters the second dielectric film U212b at an angle θ. The illumination light L12a (25% of L11) transmitted through the first dielectric film U212a is directed toward the mirror device U231 at an angle θa. The illumination light L13b (50% of L11) reflected by the second dielectric film U212b is reflected by the fifth dielectric film U212e and enters the third dielectric film U212c at an angle θ. The illumination light L12b (25% of L11) transmitted through the second dielectric film U212b is directed toward the mirror device U231 at an angle θa. Furthermore, the illumination light L13c (25% of L11) reflected by the third dielectric film U212c is reflected by the fifth dielectric film U212e and enters the fourth dielectric film U212d at an angle θ. At this time, the illumination light L12c (25% of L11) transmitted through the third dielectric film U212c travels toward the mirror device U231 at an angle θa. The fourth dielectric film U212d is an anti-reflection film, and transmits the incident illumination light L13c as illumination light L12d (25% of L11) at an angle θa. In this way, the illumination light from the light source unit 12 is divided into multiple lights having uniform intensity.

[0062] Fig. 8 shows how illumination light incident on the mirror device U231 from the light guide U212 passes through the light guide U212 and travels toward the polarizing beam splitter U105 shown in Fig. 6. The mirror device U231 has multiple light modulation sections made up of tiny movable mirrors, and controls the reflection direction of the incident light by changing the tilt angle of each movable mirror. This example shows a case where light incident at an angle θa = 34° when the movable mirror has a deflection angle of 17° is emitted at an exit angle of 0° (the angle at which light is perpendicularly incident on the first and second surfaces of the light guide plate U212).

[0063] In this embodiment, three types of dielectric films with different transmittances (reflectances) are used as the first to third dielectric films U212a to U212c that separate the incident light, but two or more types of dielectric films N may be used. The N types of dielectric films are the first dielectric film, the second dielectric film, ..., the Nth dielectric film, and the transmittance at the angle of the principal ray of the principal wavelength incident on the Mth dielectric film is T[M]. In this case, T[N] / T[N-1]>1.1 (1) When T[N] / T[N-1] falls below the lower limit of formula (1), the ratio of the amount of light transmitted through the (N-1)th dielectric film and the Nth dielectric film deviates from 1, causing intensity unevenness in the illumination light (plural light beams) reaching the mirror device U231.

[0064] It is more preferable that the numerical range of formula (1) is as follows:

[0065] T[N] / T[N-1]>1.2 (1a) Moreover, it is more preferable that the numerical range of the formula (1) is as follows:

[0066] T[N] / T[N-1]>1.3 (1b) In order to make the light guide U212 thin, it is necessary to increase the angle θ of the illumination light propagating inside. According to Snell's law, the smaller the refractive index is for the same incident angle, the larger the angle θ becomes. Therefore, the refractive index n of the material of the light guide U212 is given by n<1.80 (2) It is desirable to satisfy the following.

[0067] It is more preferable that the numerical range of the formula (2) is as follows:

[0068] n<1.60 (2a) The flowchart in FIG. 9 shows the process (measurement method) that the timing control section 31 and the control section 61 execute according to a program in this embodiment.

[0069] First, in step S201, the control unit 61 causes the light source unit 12 to emit light, and irradiates the object U107 with illumination light as a plurality of lights via the splitting unit 13 and the distance measuring optical system 22. Specifically, the control unit 61 causes the timing control unit 31 to transmit a light emission control signal to the light source unit 12.

[0070] Next, in step S202, the control unit 61 determines whether or not illumination light has been emitted from the light source unit 12 and distance measurement (light detection by the sensor unit 23) has started, and if so, proceeds to step S203.

[0071] In step S203, the control unit 61 obtains time information indicating the irradiation time when the light source unit 12 emits light.

[0072] Next, in step S204, the control unit 61 controls the angle (tilt) of each movable mirror in the mirror device U231. Specifically, each movable mirror is controlled so that each of the multiple beams of light split by the light guide U212 with uniform intensity is reflected by the movable mirror and irradiated to multiple points on the object. By controlling the angle of each movable mirror in the mirror device U231 in this manner, it is possible to control the irradiation time of the illumination light (multiple beams of light) on the object.

[0073] Next, in step S205, the control unit 61 causes the sensor unit 23 to detect reflected light from an object, and acquires two-dimensional light detection information.

[0074] Next, in step S206, the control unit 61 obtains time information indicating the detection time of the reflected light for each pixel in the sensor unit 23 from the two-dimensional light detection information.

[0075] Next, in step S207, the control unit 61 determines whether or not the intensity of the reflected light from the object U107 in the light detection information acquired in step S205 is equal to or greater than a threshold for each pixel of the sensor unit 23. Then, in step S208, the control unit 61 selects pixels whose intensity is equal to or greater than the threshold.

[0076] Next, in step S208, the control unit 61 determines whether or not the detection time acquired in step S206 is a time that is a predetermined threshold value or more after the irradiation time acquired in step S203 for each pixel selected in step S207. Then, in step S209, the control unit 61 selects pixels whose detection times are a threshold value or more after the irradiation time.

[0077] Next, in step S211, control unit 61 causes processing unit 51 to calculate, for each pixel selected in step S208, the TOF from the irradiation time acquired in step S203 to the detection time acquired in step S206. Then, processing unit 51 calculates distance information based on the TOF calculated for each pixel, generates distance image data using the distance information, and displays the distance image data on display unit 71.

[0078] The order of the processes in steps S203 and S204 may be reversed, and the order of the processes in steps S205 and S206 may be reversed.

[0079] 10 shows an example in which unwanted light generated in the polarizing beam splitter U105 and the objective optical system U106 and reflected light (normal light) from an object U107 are detected by the light detection unit 21. The vertical axis indicates the intensity (or number of photons) of the detected light, and the horizontal axis indicates the detection time relative to the irradiation time.

[0080] The intensity threshold is a threshold used to determine the intensity of reflected light from the object U107 in step S207 in Fig. 9. The time threshold is a threshold used to determine the detection time in step S208.

[0081] At least one of the light whose intensity is less than the intensity threshold and the light whose time of flight (TOF) from the time of irradiation to the time of detection is shorter than the time threshold is regarded as unwanted light and is not used in distance calculation.Light whose intensity is equal to or greater than the intensity threshold and whose time of flight from the time of irradiation to the time of detection is equal to or greater than the time threshold is regarded as normal light and is used in distance calculation.

[0082] 11 shows a schematic configuration of the division unit 13 (transmissive liquid crystal panel U103 and mirror device U231) in Examples 1 and 2. U131 shows one rectangular light modulation unit of the division unit 13, and U132 shows a rectangular cross section of light transmitted or reflected by the light modulation unit. W1 shows the diagonal length of the light modulation unit U131, and W2 shows the width (diagonal length or diameter) in the diagonal length direction of the cross section of light U132.

[0083] In Examples 1 and 2, 0.7 <W2 / W1≦1.0 (3) It is preferable to satisfy the following condition. By satisfying the condition of formula (3), it is possible to split the illumination light from the light source unit 12 into a plurality of light beams with sufficiently close spacing, and to irradiate the plurality of light beams onto a plurality of points on the object U107 with sufficiently close spacing. This makes it possible to solve the problem that irradiation of a plurality of light beams onto an object becomes discrete when the above-mentioned VCSEL array is used as the light source unit. That is, according to the first and second embodiments, it is possible to perform highly accurate distance measurement with sufficient resolution and FPS compared to the case of using a VCSEL array.

[0084] It is more preferable that the numerical range of the formula (3) is as follows:

[0085] 0.75 <W2 / W1<0.98 (3a) The above embodiment includes the following configurations.

[0086] (Configuration 1) A light source unit; a splitting means for splitting the illumination light from the light source unit into a plurality of lights to be irradiated toward a plurality of points on an object; A control means for controlling irradiation of the plurality of light beams onto the object; A detection means having a plurality of photoelectric conversion units arranged two-dimensionally and detecting a plurality of reflected light beams from the plurality of points; and a processing means for acquiring information about the object for each of the photoelectric conversion units based on the time of light flight from irradiation of the multiple light beams to detection of the reflected light for each of the photoelectric conversion units. (Configuration 2) an optical system that irradiates the object with the plurality of light beams and guides the plurality of reflected light beams to the detection means; 2. The measuring apparatus according to configuration 1, wherein the splitting means and the detecting means are disposed at conjugate positions with respect to the optical system. (Configuration 3) 3. The measuring apparatus according to claim 1, wherein the splitting means splits the illumination light into the plurality of light beams having uniform intensity. (Configuration 4) 4. The measurement device according to any one of configurations 1 to 3, wherein the splitting means has a plurality of optical modulation units and splits the illumination light incident on the plurality of optical modulation units into the plurality of lights. (Configuration 5) the splitting means is a liquid crystal panel capable of modulating the polarization state of light for each of the light modulation sections, The measuring device according to configuration 4, wherein the control means controls the light modulation section to thereby control the irradiation time. (Configuration 6) The dividing means is a light guide having a reflecting portion on a first surface and a plurality of separation portions that transmit a portion of light incident on a second surface opposite to the first surface and reflect the remainder; a mirror device having a plurality of movable mirrors constituting the light modulation unit; In the light guide, the illumination light is propagated by reflection at the reflecting portion and the plurality of separation portions, and the light transmitted through each of the plurality of separation portions is emitted toward the mirror device; The light from each of the plurality of separation units is reflected by the plurality of movable mirrors of the mirror device and emitted as the plurality of light beams; 5. The measuring apparatus according to claim 4, wherein the control means controls the movable mirror to control the irradiation time. (Configuration 7) When the diagonal length of the optical modulation unit is W1 and the width of the light emitted from the optical modulation unit is W2, 7 <W2 / W1≦1.0 7. The measuring device according to any one of configurations 4 to 6, wherein the following conditions are satisfied: (Configuration 8) 8. The measuring device according to any one of configurations 1 to 7, wherein the information relating to the object is a distance to the object. (Configuration 9) The measuring device according to any one of configurations 1 to 8, wherein the processing means acquires information about the object using a photoelectric conversion unit among the plurality of photoelectric conversion units of the detection means in which at least one of the intensity of the reflected light and the time of flight of light is equal to or greater than a predetermined value. (Configuration 10) 10. The measuring device according to any one of configurations 1 to 9, wherein the photoelectric conversion unit is configured by an avalanche photodiode. (Other Examples) The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions.

[0087] The embodiments described above are merely representative examples, and various modifications and alterations are possible for each embodiment when implementing the present invention. [Explanation of symbols]

[0088] 1000,1000A,1000B measuring device 12 Light source section 13 Division 22 Ranging optical system 23 Sensor section 31 Timing control section 51 Processing unit 61 Control section U103 Transmissive LCD panel U212 light guide U231 Digital Micromirror Device

Claims

1. A light source unit; a splitting means for splitting the illumination light from the light source unit into a plurality of lights to be irradiated toward a plurality of points on an object; A control means for controlling irradiation of the plurality of light beams onto the object; A detection means having a plurality of photoelectric conversion units arranged two-dimensionally and detecting a plurality of reflected light beams from the plurality of points; and a processing means for acquiring information about the object for each of the photoelectric conversion units based on the time of light flight from irradiation of the multiple light beams to detection of the reflected light for each of the photoelectric conversion units.

2. an optical system that irradiates the plurality of light beams toward the object and guides the plurality of reflected light beams to the detection means; 2. The measuring apparatus according to claim 1, wherein the splitting means and the detecting means are disposed at conjugate positions with respect to the optical system.

3. 2. The measuring apparatus according to claim 1, wherein the splitting means splits the illumination light into the plurality of lights having uniform intensity.

4. 2. The measuring apparatus according to claim 1, wherein the splitting means has a plurality of optical modulation sections, and splits the illumination light incident on the plurality of optical modulation sections into the plurality of light beams.

5. the splitting means is a liquid crystal panel capable of modulating the polarization state of light for each of the light modulation sections, 5. The measuring device according to claim 4, wherein the control means controls the irradiation by controlling the light modulation section.

6. The dividing means is a light guide having a reflecting portion on a first surface and a plurality of separation portions that transmit a portion of light incident on a second surface opposite to the first surface and reflect the remainder; a mirror device having a plurality of movable mirrors constituting the light modulation unit; In the light guide, the illumination light is propagated by reflection at the reflecting portion and the plurality of separation portions, and the light transmitted through each of the plurality of separation portions is emitted toward the mirror device; The light from each of the plurality of separation units is reflected by the plurality of movable mirrors of the mirror device and emitted as the plurality of light beams; 5. The measuring apparatus according to claim 4, wherein the control means controls the irradiation by controlling the movable mirror.

7. When the diagonal length of the optical modulation unit is W1 and the width of the light emitted from the optical modulation unit is W2, 0.7<W2 / W1≦1.0 5. The measuring apparatus according to claim 4, wherein the following condition is satisfied:

8. 2. The measuring device according to claim 1, wherein the information about the object is a distance to the object.

9. The measuring device according to claim 1, characterized in that the processing means acquires information about the object using a photoelectric conversion unit among the multiple photoelectric conversion units of the detection means in which at least one of the intensity of the reflected light and the time of flight of light is equal to or greater than a predetermined value.

10. 2. The measuring device according to claim 1, wherein the photoelectric conversion section is constituted by an avalanche photodiode.

11. Dividing the illumination light from the light source unit into multiple lights that are irradiated toward multiple points on the object; Controlling irradiation of the plurality of lights onto the object; detecting a plurality of reflected lights from the plurality of points using a plurality of photoelectric conversion units arranged two-dimensionally; A measurement method characterized by obtaining information about the object for each photoelectric conversion unit based on a time of light flight from irradiation of the multiple light beams to detection of the reflected light for each photoelectric conversion unit.

12. A program causing a computer to execute a process according to the measurement method according to claim 11.

Images