Measuring device and measuring method

Abstract

To enable high-precision measurement of a dynamic phenomenon of an object.SOLUTION: A high-speed object measurement device 1 comprises: a light irradiation unit 10 configured to irradiate a moving object 100 with light with a temporally changing wavelength; and an image capturing unit 20 configured to capture an image of the light from the object 100 irradiated with the light from the light irradiation unit 10 to obtain wavelength information for each pixel. The image capturing unit 20 continuously acquires temporal change in wavelength.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] One aspect of the present invention relates to a measurement apparatus and a measurement method. [Background technology]

[0002] Cited Document 1 describes a high-speed photography method that enables continuous photography of single-shot phenomena that change in an ultrashort time range of nanoseconds or less. Specifically, the high-speed photography system describes a method in which a plurality of strobe lights with different wavelengths are continuously irradiated onto an object, the light from the object (a plurality of lights with different wavelengths) is spatially separated by wavelength while retaining image information, and each separated light is incident on a light receiving surface of an imaging element at different positions to detect it. With such a high-speed photography system, a dynamic phenomenon is measured based on image information of each detected light (each wavelength). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-41784 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the high-speed imaging system described above, multiple lights with different wavelengths from an object are spatially separated by wavelength. When a method of separating light in this way is used, the measurement of a dynamic phenomenon based on the image information of each detected light (each wavelength) becomes discrete rather than continuous. This may make it difficult to measure the dynamic phenomenon of the object with high accuracy.

[0005] One aspect of the present invention has been made in consideration of the above-mentioned circumstances, and has an object to measure dynamic phenomena of an object with high accuracy. [Means for solving the problem]

[0006] A measuring device according to one embodiment of the present invention includes a light irradiation unit that irradiates a moving object with light whose wavelength changes over time, and an imaging unit that images the light from the object that has received the light irradiated by the light irradiation unit and acquires wavelength information for each pixel, and the imaging unit continuously acquires the change in wavelength over time.

[0007] In a measurement device according to an aspect of the present invention, a moving object is irradiated with light whose wavelength changes over time, and the light from the object is captured to obtain wavelength information for each pixel. In the measurement device, the light whose wavelength changes over time is not detected by, for example, spatially separated, but the wavelength information is obtained as is for each pixel, so that the change in wavelength over time is not discrete but is obtained continuously. This allows the timing and position of the object to be estimated with high accuracy based on the change in the acquired wavelength information. As described above, the measurement device according to an aspect of the present invention can measure the dynamic phenomenon of the object with high accuracy.

[0008] In addition, even in the method of spatially separating light whose wavelength changes over time and causing each separated light to be incident at different positions on the light receiving surface of the imaging unit, it is possible to prevent the temporal change in wavelength from becoming as discrete as possible by, for example, finely separating time (i.e., wavelength). However, in such a method, the finer the time separation, the larger the light receiving area of ​​the imaging unit is required, which causes problems such as a limited number of frames, a narrower field of view, and a reduced number of pixels in the image. In other words, there is a trade-off between increasing the number of temporal separations to measure the dynamic phenomenon of the object with high accuracy and reducing the light receiving area, and it has been difficult to achieve both in the past. In this regard, as described above, according to the measurement device according to one aspect of the present invention, light whose wavelength changes over time is not spatially separated and detected, but wavelength information is detected for each pixel as it is, so that the dynamic phenomenon of the object can be measured with high accuracy without causing the problems caused by the light receiving area described above.

[0009] The light irradiating unit may irradiate light whose wavelength changes over one or more periods within the exposure time of the imaging unit. With this configuration, it is possible to measure (save) a dynamic phenomenon of an object with the time width of the light whose wavelength changes over time within one frame of the imaging unit.

[0010] The light irradiation unit may be disposed so that the optical axis of the light from the light irradiation unit toward the object is perpendicular to the optical axis of the light from the object toward the imaging unit. With this configuration, for example, when the object moves in the same direction as the optical axis direction of the light from the light irradiation unit toward the object, light can be irradiated to a certain point (e.g., an edge portion) of the object, and the change in wavelength of the light from the point over time can be detected by different pixels in the imaging unit. In other words, while avoiding light from entering the same pixel multiple times, the dynamic phenomenon of the object can be measured with high accuracy based on the detection results of each pixel.

[0011] The light irradiation unit is arranged so that the optical axis of the light from the light irradiation unit to the object and the optical axis of the light from the object to the imaging unit intersect obliquely, and the measurement device further includes a slit arranged on the optical axis of the light from the object to the imaging unit, and the slit may change the area through which the light passes over time. When the above-mentioned two optical axes intersect obliquely, when light is irradiated onto the surface of a moving object, light may enter the same pixel at multiple times. In this regard, by arranging a slit on the optical axis of the light from the object to the imaging unit and changing the area through which the slit passes over time, it is possible to prevent light from entering the same pixel at multiple times, and it is possible to measure the dynamic phenomenon of the object with high accuracy even when light is irradiated onto the surface of a moving object.

[0012] The light irradiation unit may have a first irradiation unit that irradiates light in a first wavelength range with a period in which the wavelength changes as a first period, and a second irradiation unit that irradiates light in a second wavelength range different from the first wavelength range with a period in which the wavelength changes as a second period different from the first period. In this way, by irradiating the object with light having different wavelength ranges with different periods in which the wavelength changes, the location of the object can be estimated from information on the wavelengths of the two lights, and therefore, compared to the case where estimation is made from only one light, the time resolution can be improved and the dynamic phenomenon of the object can be measured with higher accuracy.

[0013] The imaging unit may have a first camera that captures the light from the object that receives the light irradiated by the first irradiating unit, and a second camera that captures the light from the object that receives the light irradiated by the second irradiating unit. According to this configuration, the information on the wavelengths of the above-mentioned two lights is captured by the two cameras, respectively, and an image based on the changes in the wavelengths of the two lights can be appropriately generated. This makes it possible to measure the dynamic phenomenon of the object with higher accuracy.

[0014] The light emitting unit may have a white light source and change the wavelength over time by optically selecting the wavelength of the white light. With this simple configuration, it is possible to generate light whose wavelength changes over time.

[0015] The light irradiation unit may have a pulsed light source and may change the wavelength over time by wavelength dispersion of the pulsed light. With this simple configuration, it is possible to generate light whose wavelength changes over time.

[0016] The imaging unit may have a separation optical element that separates light from the object by transmitting or reflecting it according to the wavelength, and has a predetermined edge transition width, which is the width of a wavelength band whose transmittance and reflectance change according to the change in wavelength, and may image the light transmitted by the separation optical element in a first imaging region and the light reflected by the separation optical element in a second imaging region. According to this configuration, the light separated by the separation optical element whose transmittance and reflectance change according to the change in wavelength are each imaged, and the wavelength can be appropriately detected based on each imaging result.

[0017] A measurement method according to one aspect of the present invention includes the steps of irradiating a moving object with light whose wavelength changes over time, and capturing an image of the light from the object that receives the light to acquire wavelength information for each pixel, wherein in the step of acquiring the wavelength information, the change in wavelength over time is continuously acquired. Effect of the Invention

[0018] According to a measurement device and a measurement method according to an aspect of the present invention, dynamic phenomena of an object can be measured with high accuracy. [Brief description of the drawings]

[0019] [Figure 1] 1 is a diagram illustrating a schematic diagram of a high-speed object measuring device according to an embodiment of the present invention. [Diagram 2] 2 is a diagram showing a schematic diagram of an example of a light irradiation unit included in a camera system of the high-speed object measuring device of FIG. 1. FIG. [Diagram 3] 2 is a diagram showing a schematic diagram of an example of an imaging unit included in a camera system of the high-speed object measuring device of FIG. 1. FIG. [Figure 4] 1A and 1B are diagrams illustrating the characteristics of an inclined dichroic mirror. [Diagram 5] FIG. 2 is a diagram showing an example of a captured image. [Figure 6] FIG. 2 is a diagram showing a schematic view of a camera system of a high-speed object measuring device according to a first modified example. [Figure 7]FIG. 13 is a diagram showing a schematic view of a camera system of a high-speed object measuring device according to a second modified example. [Figure 8] FIG. 8 is a diagram showing a schematic diagram of a slit included in the camera system of FIG. 7. [Figure 9] FIG. 13 is a diagram showing a schematic view of a camera system of a high-speed object measuring device according to a third modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and duplicated explanations will be omitted.

[0021] FIG. 1 is a schematic diagram of a high-speed object measuring device 1 according to the present embodiment. The high-speed object measuring device 1 is a device that irradiates a target object 100, which is a fast-moving object, with light whose wavelength changes over time, and captures the light from the target object 100, thereby recording the movement of the target object 100 on a two-dimensional image and measuring the dynamic phenomenon of the target object 100. That is, in the high-speed object measuring device 1, the time and the wavelength are associated with each other for the irradiated light, so that when the light from the target object 100 is captured and the wavelength is specified, it is possible to estimate the position of the target object 100 at what time, and measure the dynamic phenomenon of the target object 100. The target object 100 is, for example, a flying object or a fragment, and the dynamic phenomenon of the target object 100 may be, for example, a phenomenon in which a flying object passes or recoils, or a phenomenon in which multiple fragments scatter, etc.

[0022] 1, the high-speed object measuring device 1 includes a camera system 2 and a control device 80. The camera system 2 includes a light irradiation section 10 and an imaging unit 20 (imaging section). The camera system 2 will be described in detail with reference to FIGS. 2 to 4.

[0023] The light irradiation unit 10 is configured to irradiate the moving object 100 with light whose wavelength changes over time (wavelength sweep). In FIG. 1, the light L emitted from the light irradiation unit 10 changes in wavelength over time as different colors. In the example of FIG. 1, one period in which the wavelength of the light L changes is shown, with the first wavelength L1 of the period being the shortest wavelength, the wavelength gradually increasing, and the last wavelength L2 of the period being the longest wavelength. As an example, the light irradiation unit 10 irradiates light in a wavelength range of 600 nm to 700 nm, but is not limited thereto, and may irradiate light in any wavelength range included in the wavelength range of visible light (380 nm to 780 nm), for example.

[0024] As shown in FIG. 1, the light irradiation unit 10 is disposed so that the optical axis (first optical axis) of the light from the light irradiation unit 10 toward the object 100 and the optical axis (second optical axis) of the light from the object 100 toward the imaging unit 20 are orthogonal to each other. The direction of the first optical axis is approximately the same as the direction in which the object 100 moves. The above-mentioned first optical axis and second optical axis being orthogonal to each other may be orthogonal to each other at any timing while the moving object 100 is being irradiated with light. For example, the light irradiation unit 10 may continuously scan the object 100 with light and issue a trigger to the imaging unit 20 at a specific timing during scanning, thereby causing the imaging unit 20 to start exposure in synchronization with the light whose wavelength changes over time. Alternatively, the light irradiation unit 10 may start scanning with the light whose wavelength changes over time in synchronization with the exposure of the imaging unit 20 by receiving a trigger from the imaging unit 20. The light irradiation section 10 irradiates light whose wavelength changes over one or more periods within the exposure time of the imaging unit 20 .

[0025] Fig. 2 is a diagram showing a schematic example of the light irradiation unit 10 included in the camera system 2. As shown in Fig. 2, the light irradiation unit 10 may be configured to include, for example, a pulsed light source 11 and a dispersion compensation module 12. The pulsed light source 11 is, for example, a femtosecond laser light source. Since the femtosecond laser has a wavelength width of several hundred nm, the pulsed light source 11 can be used to configure a wavelength scanning light source with a time width exceeding 200 ns.

[0026] The dispersion compensation module 12 expands the broadband pulsed light emitted from the pulsed light source 11, and gives each wavelength a different delay (difference in arrival time). The dispersion compensation module 12 is composed of, for example, a high-dispersion fiber, and changes the wavelength over time by dispersing the pulsed light. For example, in the case of a single-mode fiber, a delay of about 17 ps / nm per km is generated for each wavelength. High-dispersion fibers that compensate for this, including those for 100 km, are commonly available, and in this case, a delay of about 1700 ps / nm can be generated.

[0027] Of the two graphs shown in FIG. 2, the left side shows the state of the pulsed light emitted from the pulsed light source 11, and the right side shows the state of the light that has passed through the dispersion compensation module 12. In the two graphs shown in FIG. 2, the horizontal axis is time, and the vertical axis is luminous intensity. In the right diagram of FIG. 2, the change in wavelength of the light L over time is shown as different colors. As shown in the right diagram of FIG. 2, the light emitted from the pulsed light source 11 passes through the dispersion compensation module 12, so that the light has a time width and a different delay is given to each wavelength. That is, the light that has passed through the dispersion compensation module 12 is light whose wavelength changes over time. Note that it is also possible to obtain light whose wavelength changes over time by converting high-intensity pulsed light of about picoseconds into light with a wavelength width by a nonlinear effect and inputting the converted light into the dispersion compensation module 12.

[0028] The configuration of the light irradiation unit 10 that irradiates light whose wavelength changes over time is not limited to the configuration shown in FIG. 2. For example, the light irradiation unit 10 may be configured to include a white light source and a plurality of bandpass filters arranged spatially continuously. In such a light irradiation unit 10, the wavelength of the white light is optically selected by moving and switching the plurality of bandpass filters, and light whose wavelength changes over time is obtained. In addition, the light irradiation unit 10 may be configured to include a white light source and a single bandpass filter. In such a light irradiation unit 10, for example, the single bandpass filter is rotated to optically select the wavelength of the white light, and light whose wavelength changes over time is obtained. In addition, the light irradiation unit 10 may be configured to have a plurality of light irradiation units that emit light with different wavelengths. In such a light irradiation unit 10, the plurality of light irradiation units are switched over time, and light whose wavelength changes over time is obtained. When the object 100 has a certain reflectance in the range of observation wavelengths, a plurality of light irradiating units having different wavelengths may simultaneously irradiate light and continuously change the ratio of the light amounts to obtain light whose wavelength changes over time. The light irradiating unit 10 may also be configured to include a white light source and a diaphragm.

[0029] Returning to Fig. 1, the imaging unit 20 is configured to capture light from the object 100 that receives light irradiated by the light irradiation unit 10, and acquire wavelength information for each pixel. The imaging unit 20 is configured to be able to acquire wavelength information for each pixel in addition to normal image information. The imaging unit 20 continuously acquires temporal changes in wavelength.

[0030] Fig. 3 is a diagram showing a schematic diagram of the imaging unit 20 included in the camera system 2. As shown in Fig. 3, the imaging unit 20 includes an imaging element 21, an infinity correction lens 22, an inclined dichroic mirror 23 (separating optical element), a total reflection mirror 24, and an imaging lens 25.

[0031] The infinity correction lens 22 is a collimator lens that converts the light from the object 100 into parallel light. The infinity correction lens 22 is aberration-corrected so as to obtain parallel light. The light output from the infinity correction lens 22 is incident on the inclined dichroic mirror 23.

[0032] The inclined dichroic mirror 23 is a mirror made of a special optical material, and separates the light from the object 100 by transmitting or reflecting it according to its wavelength. For example, the inclined dichroic mirror 23 reflects light of a specific wavelength and transmits light of other wavelengths.

[0033] FIG. 4 is a diagram for explaining the characteristics of the inclined dichroic mirror 23. In FIG. 4, the horizontal axis indicates the wavelength, and the vertical axis indicates the transmittance. As shown by the characteristic X4 of the inclined dichroic mirror 23 in FIG. 4, in the inclined dichroic mirror 23, the transmittance (and reflectance) of light changes gradually in a specific wavelength band (a wavelength band of wavelengths λ1 to λ2) in response to a change in wavelength, and the transmittance (and reflectance) of light is constant regardless of a change in wavelength in wavelength bands other than the specific wavelength band (i.e., on the lower wavelength side than the wavelength λ1 and the higher wavelength side than the wavelength λ2). Since the transmittance and the reflectance are in a negative correlation in which one changes in a larger direction and the other changes in a smaller direction, hereinafter, the terms "transmittance (and reflectance)" may not be used, but may simply be used as "transmittance". Note that "the transmittance of light is constant regardless of a change in wavelength" includes not only a case where it is completely constant, but also a case where the change in transmittance for a change in wavelength of 1 nm is 0.1% or less, for example. On the wavelength side lower than the wavelength λ1, the light transmittance is approximately 0% regardless of the change in wavelength, and on the wavelength side higher than the wavelength λ2, the light transmittance is approximately 100% regardless of the change in wavelength. Note that "the light transmittance is approximately 0%" includes a transmittance of about 0%+10%, and "the light transmittance is approximately 100%" includes a transmittance of about 100%-10%. In the following, the width of the wavelength band in which the light transmittance changes according to the change in wavelength may be described as the "edge transition width". As described above, the inclined dichroic mirror 23 is a separation optical element in which the edge transition width, which is the width of the wavelength band in which the transmittance changes according to the change in wavelength, has a predetermined width (the width of the wavelengths λ1 to λ2).

[0034] The total reflection mirror 24 is an optical element that reflects the light reflected by the inclined dichroic mirror 23 toward the imaging lens 25 .

[0035] The imaging lens 25 is a lens that images the light that has passed through the inclined dichroic mirror 23 and the light that has been reflected by the inclined dichroic mirror 23 and further reflected by the total reflection mirror 24, and guides these lights to the imaging element 21.

[0036] The imaging element 21 captures the light transmitted through the inclined dichroic mirror 23 in a first imaging region, and captures the light reflected by the inclined dichroic mirror 23 and further reflected by the total reflection mirror 24 in a second imaging region different from the first imaging region. The imaging element 21 captures the light transmitted through the inclined dichroic mirror 23 and the light reflected by the total reflection mirror 24 by detecting an image formed by the imaging lens 25. The imaging element 21 is an imaging element for capturing light in a predetermined wavelength range, and is, for example, an area image sensor such as a CCD or a MOS. The imaging element 21 may also be configured with a line sensor or a TDI (Time Delay Integration) sensor. In this embodiment, the imaging element 21 is described as a single imaging element having a first imaging region and a second imaging region, but an imaging element related to the first imaging region and an imaging element related to the second imaging region may be provided separately (two sets may be provided). In this case, two sets of imaging lenses are also provided corresponding to the imaging elements. The imaging element 21 outputs an image, which is the imaging result, to the control device 80.

[0037] 5 is a diagram showing an example of a captured image P1. In the image P1, an image DI of a dynamic phenomenon of the object 100 is shown. In the image DI of the dynamic phenomenon, the movement of the object 100 is shown by a change in color (change in wavelength). Since time and wavelength are associated in advance with respect to the irradiated light, when the wavelength is identified from the image DI of the dynamic phenomenon, it is possible to estimate the position and timing of the object 100, and measure the dynamic phenomenon of the object 100.

[0038] Returning to Fig. 1, the control device 80 is a computer, and is physically configured to include memories such as RAM and ROM, a processor (arithmetic circuit) such as a CPU, a communication interface, and a storage unit such as a hard disk. The control device 80 functions by executing a program stored in the memory with the CPU of a computer system. The control device 80 may be configured with a microcomputer or FPGA.

[0039] The control device 80 calculates and outputs the wavelength (emission wavelength centroid) based on the amount of light of each pixel (each pixel of the image formed within the field of view) of the image obtained by the camera system 2, which is the image obtained by the camera system 2. An example of the calculation principle of the emission wavelength centroid will be described in detail below.

[0040] As described above, the inclined dichroic mirror 23 reflects all light at wavelengths shorter than λ1 and transmits all light at wavelengths longer than λ2, and the transmittance of light changes linearly according to the wavelength in the wavelength band from λ1 to λ2. In this case, the transmittance h(λ) in relation to the wavelengths λ1 and λ2 is expressed by the following formula (1), and the reflectance 1-h(λ) is expressed by the following formula (2). h(λ)=(λ-λ1) / (λ2-λ1) (1) 1-h(λ)=(λ2-λ) / (λ2-λ1) (2)

[0041] In addition, the wavelength λ at which the reflectance becomes 50% 50% It is clear that the equation (3) below shows that λ 50% =(λ2+λ1) / 2 (3)

[0042] When an emission spectrum f(λ) is between λ1 and λ2 and wavelengths shorter than λ1 and longer than λ2 can be ignored (for example, when the wavelength band of the emission spectrum f(λ) is limited by a bandpass filter (not shown) or the like), the following equation (4) is established if it is assumed that the amount of reflected light is equal to the amount of transmitted light. ∫f(λ)h(λ)dλ=∫f(λ)(1-h(λ))dλ (4) Transforming equation (4) gives us equation (5) below. 2∫f(λ)h(λ)dλ=∫f(λ)dλ (5)

[0043] Substituting equation (1) into equation (5), we get 2∫f(λ)(λ-λ1) / (λ2-λ1)dλ=∫f(λ)dλ Further dividing both sides by 2∫f(λ)dλ / (λ2-λ1), we get ∫f(λ)(λ-λ1)dλ / ∫f(λ)dλ= (λ2-λ1) / 2 ∫f(λ)λdλ / ∫f(λ)dλ= (λ2+λ1) / 2 (6) It becomes.

[0044] Considering equation (3), the right-hand side of equation (6) is λ 50% It is clear that the left side of the equation is the center of gravity of f(λ), which is an arbitrary function in general. f From the above, for any spectrum that passes through a dichroic mirror whose transmittance is inclined linearly with respect to wavelength, if the amount of transmitted light is equal to the amount of reflected light, the center of gravity λ of the spectrum is f is λ 50% As shown in the figure.

[0045] Next, consider the second emission spectrum g(λ). The emission spectrum g(λ) is also entirely contained between λ1 and λ2. Now, calculate the difference between the normalized difference between the transmitted light and the reflected light for the emission spectra f(λ) and g(λ). Let the transmitted light of f(λ) be T f , reflected light R f , total light amount is A f , the difference between the transmitted light and the reflected light is D f Let the transmitted light of g(λ) be T g , reflected light R g , total light amount is A g , the difference between the transmitted light and the reflected light is D g Let the center of gravity of g(λ) be λ g In this case, T f , R f , T g , R g is the measured value, and A f , A g , D f , D g These values ​​can also be calculated directly from the measured values. T f =∫f(λ)h(λ)dλ=∫f(λ)(λ-λ1) / (λ2-λ1)dλ (7) T g=∫g(λ)h(λ)dλ=∫g(λ)(λ-λ1) / (λ2-λ1)dλ (8) R f =∫f(λ)(1-h(λ))dλ=∫f(λ)(λ2-λ) / (λ2-λ1)dλ (9) R g =∫g(λ)(1-h(λ))dλ=∫g(λ)(λ2-λ) / (λ2-λ1)dλ (10) A f =∫f(λ)dλ (11) A g =∫g(λ)dλ (12) D f =T f -R f =2 / (λ2-λ1)*∫λf(λ)dλ-(λ2+λ1) / (λ2-λ1)*∫f(λ)dλ (13) D g =T g -R g =2 / (λ2-λ1)*∫λg(λ)dλ-(λ2+λ1) / (λ2-λ1)*∫g(λ)dλ (14)

[0046] Here, normalizing the difference between transmitted light and reflected light means D f A f , D g A g If the difference between them is R, then the following equation (15) holds: R=D g / A g -D f / A f ={∫g(λ)λdλ / ∫g(λ)dλ-∫f(λ)λdλ / ∫f(λ)dλ}*2 / (λ2-λ1) =2(λ g -λ f ) / (λ2-λ1) (15)

[0047] Wavelength center of gravity λ of emission spectrum f(λ) f and the wavelength centroid λ of the emission spectrum g(λ) g If the difference between these is δλ, then the following equations (16) and (17) hold. R = 2δλ / (λ2-λ1) (16) δλ=R(λ2-λ1) / 2 (17) As described above, it has been shown that the difference in the center of gravity of two arbitrary spectra f(λ) and g(λ) can be obtained from a calculation that takes into account the amount of transmitted light and the amount of reflected light.

[0048] And the center of gravity of f(λ) is λ 50% When the amount of reflected light is equal to the amount of transmitted light, D f is 0. In other words, the wavelength centroid λ of any spectrum g(λ) g is expressed by the following equation (18). λ g =δλ+λ 50% (18)

[0049] In this way, the center of gravity of the emission spectrum can be calculated from the design value of the filter, the amount of transmitted light, and the amount of reflected light. Based on the above principle, the wavelength of the light incident on each pixel (emission wavelength center of gravity) can be determined with high accuracy. Then, by identifying the wavelength of the light incident on each pixel, as described above, it is possible to estimate the timing and position of the object 100, and to measure the dynamic phenomenon of the object 100.

[0050] Next, the effects of this embodiment will be described.

[0051] The high-speed object measuring device 1 of this embodiment includes a light irradiation unit 10 that irradiates a moving object 100 with light whose wavelength changes over time, and an imaging unit 20 that images the light from the object 100 that has received the light irradiated by the light irradiation unit 10 and acquires wavelength information for each pixel, and the imaging unit 20 continuously acquires the temporal change in wavelength.

[0052] In the high-speed object measuring device 1 according to the present embodiment, a moving object 100 is irradiated with light whose wavelength changes over time, and the light from the object is imaged to obtain wavelength information for each pixel. In the high-speed object measuring device 1, the light whose wavelength changes over time is not detected by, for example, spatially separated, but the wavelength information is obtained as is for each pixel, so that the change in wavelength over time is not discrete but is obtained continuously. This allows the timing and position of the object 100 to be estimated with high accuracy based on the change in the acquired wavelength information. As described above, the high-speed object measuring device 1 according to the present embodiment can measure the dynamic phenomenon of the object 100 with high accuracy.

[0053] In addition, even in the method of spatially separating light whose wavelength changes over time and causing each separated light to be incident at different positions on the light receiving surface of the imaging unit, it is possible to prevent the temporal change in wavelength from becoming as discrete as possible by, for example, finely separating time (i.e., wavelength). However, in such a method, the finer the time separation, the larger the light receiving area of ​​the imaging unit is required, which causes problems such as a limited number of frames, a narrower field of view, and a reduced number of pixels in the image. In other words, there is a trade-off between increasing the number of time separations to measure the dynamic phenomenon of the object with high accuracy and reducing the light receiving area, and it has been difficult to achieve both in the past. In this regard, as described above, according to the high-speed object measuring device 1 according to this embodiment, light whose wavelength changes over time is not spatially separated and detected, but wavelength information is obtained for each pixel as it is, so that the dynamic phenomenon of the object 100 can be measured with high accuracy without causing the problems caused by the light receiving area described above.

[0054] The light irradiation unit 10 may irradiate light whose wavelength changes over one or more periods within the exposure time of the imaging unit 20. With this configuration, it is possible to measure (store) a dynamic phenomenon of the target object 100 with the time width of the light whose wavelength changes over time within one frame of the imaging unit.

[0055] The light irradiation unit 10 may be disposed so that the optical axis of the light from the light irradiation unit 10 toward the object 100 is perpendicular to the optical axis of the light from the object 100 toward the imaging unit 20. According to such a configuration, for example, when the object 100 moves in the same direction as the optical axis direction of the light from the light irradiation unit 10 toward the object 100, light can be irradiated to a certain point (for example, an edge portion) of the object 100, and a change in wavelength of the light from the point over time can be detected by different pixels in the imaging unit 20. That is, while avoiding light from entering the same pixel multiple times, a dynamic phenomenon of the object 100 can be measured with high accuracy based on the detection results of each pixel.

[0056] The light irradiation unit 10 may have a white light source and change the wavelength over time by optically selecting the wavelength of the white light. With this simple configuration, it is possible to generate light whose wavelength changes over time.

[0057] The light irradiation unit 10 may have a pulsed light source and may change the wavelength over time by dispersing the pulsed light. With this simple configuration, it is possible to generate light whose wavelength changes over time.

[0058] The imaging unit 20 may have an inclined dichroic mirror 23 that separates light from the object 100 by transmitting or reflecting it according to the wavelength, has an edge transition width that is a wavelength band width whose transmittance and reflectance change according to the change in wavelength and has a predetermined width, and may image the light transmitted by the inclined dichroic mirror 23 in a first imaging region, and image the light reflected by the inclined dichroic mirror 23 in a second imaging region. According to such a configuration, each of the lights separated by the inclined dichroic mirror 23, whose transmittance and reflectance change according to the change in wavelength, is imaged, and the wavelength can be appropriately detected based on each imaging result.

[0059] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. Hereinafter, first to third modified examples will be described as aspects different from the above embodiment.

[0060] FIG. 6 is a diagram showing a camera system 2A of a high-speed object measuring device according to a first modified example. The camera system 2A has two light irradiating units, a first irradiating unit 10A and a second irradiating unit 10B. The first irradiating unit 10A irradiates light in a first wavelength range with a period in which the wavelength changes as a first period. The second irradiating unit 10B irradiates light in a second wavelength range different from the first wavelength range with a period in which the wavelength changes as a second period different from the first period. Specifically, the first irradiating unit 10A irradiates light in a wavelength range of, for example, 600 nm to 700 nm with a period in which the wavelength changes as a first period. The second irradiating unit 10B irradiates light in a wavelength range of, for example, 400 nm to 500 nm with a period in which the wavelength changes as a second period. As described above, the first period and the second period are different from each other. For example, the first period and the second period may be set so that the first irradiation unit 10A scans once with light in the wavelength range of 600 nm to 700 nm in one exposure time, while the second irradiation unit 10B scans 10 times with light in the wavelength range of 400 nm to 500 nm in one exposure time. Note that such a period is an example, and the first period and the second period are not limited to the above as long as they are different from each other.

[0061] The camera system 2A shown in FIG. 6 has two cameras, a first camera 20A and a second camera 20B, as imaging units. The first camera 20A captures light from the object 100 that receives light irradiated by the first irradiating unit 10A. The second camera 20B captures light from the object 100 that receives light irradiated by the second irradiating unit 10B. The first camera 20A and the second camera 20B capture light in wavelength ranges that do not overlap with each other. That is, the first camera 20A captures light irradiated by the first irradiating unit 10A, that is, light in the wavelength range of 600 nm to 700 nm. The first camera 20A may be set with a bandpass filter so as not to capture light outside the above wavelength range. The second camera 20B captures light irradiated by the second irradiating unit 10B, that is, light in the wavelength range of 400 nm to 500 nm. The second camera 20B may be provided with a bandpass filter so as not to capture light outside the above wavelength range.

[0062] Such a configuration is a configuration that improves the time resolution in measuring the dynamic phenomenon of the object 100. For example, in a configuration with one light irradiation unit and one imaging unit, the resolution is about 1 / 100 in one frame due to the size of the full well of the camera, the shot noise limit, and the readout noise. This is because the shot noise limit of S / N is the square root of the number of electrons in the well, and in the case of an image with sufficient brightness, the readout noise is less than the shot noise and can be ignored. In addition, since the well size of a measurement camera is usually tens of thousands of electrons, the brightness of the actual image is used at less than half of that in order to avoid saturation of the image. As a device to exceed this limit, as shown in the configuration shown in FIG. 6, light having different wavelength ranges is irradiated onto the object 100 with different periods of wavelength change (scanning the wavelengths at different speeds), and the position of the object can be estimated from the information on the wavelengths of the two lights, thereby improving the time resolution. For example, as described above, in the case where the first irradiation unit 10A scans once with light in the wavelength range of 600 nm to 700 nm in one exposure time while the second irradiation unit 10B scans ten times with light in the wavelength range of 400 nm to 500 nm in one exposure time, the time resolution can be improved tenfold compared to the case where estimation is made from only one light, and the dynamic phenomenon of the object 100 can be measured with higher accuracy.

[0063] FIG. 7 is a diagram showing a camera system 2B of a high-speed object measuring device according to a second modified example. In the camera system 2B, the light irradiation unit 10 is arranged so that the optical axis (first optical axis) of the light from the light irradiation unit 10 to the object 100 and the optical axis (second optical axis) of the light from the object 100 to the imaging unit 20 intersect obliquely. The above-mentioned first optical axis and second optical axis intersect obliquely with each other at any timing while the moving object 100 is being irradiated with light. Note that the direction of the first optical axis does not coincide with the direction in which the object 100 moves. In the example shown in FIG. 7, the object 100 moves in the horizontal direction, while both the light irradiation unit 10 and the imaging unit 20 are provided above the object 100. In the case where the first optical axis and the second optical axis intersect obliquely, when light is irradiated onto the surface of the moving object 100, light may enter the same pixel of the imaging element 21 of the imaging unit 20 that captures the light from the object 100 at different timings. That is, light from multiple positions of the moving object 100 may overlap and enter the same pixel. In this case, the timing of the movement of the object 100 may not be properly acquired, and the dynamic phenomenon of the object 100 may not be measured with high accuracy.

[0064] As a configuration for solving such a problem, the camera system 2B further includes a slit 60 arranged on the optical axis (second optical axis) of light traveling from the object 100 to the imaging unit 20, and a lens 50 provided between the slit 60 and the object 100. The slit 60 changes the area through which light passes over time. FIG. 8 is a diagram showing the slit 60 included in the camera system 2B of FIG. 7. FIG. 8 is a diagram showing the slit 60 in plan view. As shown in FIG. 8, the slit 60 is substantially circular in plan view, and the slit 60 has light passing portions 60a formed at predetermined intervals along the circumferential direction. The slit 60 changes the area through which light passes over time by rotating. The exposure time of the imaging unit 20 is set to be equal to or less than the time it takes for the slit 60 to rotate and advance one step (to the next light passing portion 60a). The rotational operation of the slit 60 and the imaging unit 20 do not have to be synchronized. By providing such a slit 60, even when the first optical axis and the second optical axis intersect obliquely (when light is irradiated onto the surface of the moving object 100), it is possible to prevent light from entering the same pixel at multiple times, and the dynamic phenomenon of the object 100 can be measured with high accuracy.

[0065] So far, an example has been described in which the moving object 100 is irradiated with light whose wavelength changes over time. However, the high-speed object measuring device is not limited to this aspect. That is, the high-speed object measuring device may include a light irradiating unit that irradiates the moving object 100 with light whose state of light changes over time, and an imaging unit that captures the light from the object that has received the light irradiated by the light irradiating unit to acquire the state of light for each pixel, and the imaging unit may continuously acquire the change in the state of light over time. According to this configuration, based on the acquired state of light, it is possible to highly accurately estimate the timing and position of the object 100, and to measure the dynamic phenomenon of the object 100 with high accuracy. The high-speed object measuring device may include, for example, a light irradiating unit that irradiates the moving object 100 with light whose polarization direction changes over time, and an imaging unit that captures the light from the object 100 that has received the light irradiated by the light irradiating unit to acquire the polarization direction for each pixel, and the imaging unit may continuously acquire the change in the polarization direction over time. Hereinafter, such an aspect will be described as a third modified example with reference to FIG. 9.

[0066] FIG. 9 is a diagram showing a camera system 2C of a high-speed object measuring device according to a third modified example. The camera system 2C has a light source 210, a polarizer 230, and a 1 / 2 wavelength plate 240 as a configuration of a light irradiation unit. The light source 210 emits linearly polarized light. The 1 / 2 wavelength plate 240 rotates continuously in synchronization with the measurement start timing of the frame of the polarization camera 220. This causes the polarization direction of the light irradiated to the object 100 to change over time. That is, it is possible to create a situation in which light is irradiated with a different polarization direction for each position of the moving object 100, and it is possible to identify where the object 100 was at which timing of the exposure timing. The camera system 2C has a polarization camera 220 as an imaging unit (imaging unit). The polarization camera 220 is set for every four pixels, for example, and polarizers different by 45° are formed in each of the four pixels. Then, the polarization camera 220 obtains, from the light intensity ratio of the four pixels, what kind of linear polarization or what kind of elliptical polarization the polarization direction of the light incident at this position was. With this configuration, it is possible to estimate with high accuracy what time and where the object 100 was located based on the detected polarization direction, and it is possible to measure the dynamic phenomenon of the object 100 with high accuracy. This rotation of the polarization direction may be performed using a liquid crystal element (LCOS) or a spatial light variable element other than a half-wave rotation, or the Faraday effect may be used to change the strength of the magnetic field applied to the Faraday element through which the illumination passes. [Explanation of symbols]

[0067] 1...high-speed object measuring device (measuring device), 10...light irradiation section, 11...pulse light source, 20...imaging unit (imaging section), 23...inclined dichroic mirror (separating optical element), 60...slit, 100...object.

Claims

1. a light irradiation unit that irradiates a moving object with light whose wavelength changes over time; an imaging unit that captures an image of light from the object that has received the light irradiated by the light irradiation unit, and acquires wavelength information for each pixel; The imaging unit is a measurement device that continuously acquires a change in wavelength over time.

2. The measurement device according to claim 1 , wherein the light irradiating section irradiates light whose wavelength changes over a period of at least one cycle within an exposure time of the imaging section.

3. The measurement device according to claim 1 , wherein the light irradiating unit is disposed so that an optical axis of light traveling from the light irradiating unit to the object is perpendicular to an optical axis of light traveling from the object to the imaging unit.

4. the light irradiation unit is disposed such that an optical axis of light traveling from the light irradiation unit to the object and an optical axis of light traveling from the object to the imaging unit intersect obliquely; the measurement device further includes a slit disposed on an optical axis of light traveling from the object to the imaging unit, 3. The measuring device according to claim 1, wherein the slit changes an area through which light passes over time.

5. The light irradiation unit includes: a first irradiating unit that irradiates light in a first wavelength range with a period in which the wavelength changes as a first period; The measurement device according to any one of claims 1 to 4, further comprising: a second irradiation unit that irradiates light in a second wavelength range different from the first wavelength range with a period in which the wavelength changes, the period being a second period different from the first period.

6. The imaging unit includes: a first camera that captures an image of light from the object that receives the light irradiated by the first irradiating unit; The measurement device according to claim 5 , further comprising: a second camera configured to capture an image of light from the object receiving the light irradiated by the second irradiating section.

7. 7. The measurement device according to claim 1, wherein the light irradiating section has a white light source and changes the wavelength over time by optically selecting a wavelength of the white light.

8. 7. The measuring device according to claim 1, wherein the light irradiating section has a pulsed light source and changes the wavelength over time by wavelength dispersion of pulsed light.

9. The imaging unit includes: A separation optical element that separates light from the object by transmitting or reflecting it according to the wavelength, and has an edge transition width, which is the width of a wavelength band in which the transmittance and reflectance change according to the change in wavelength, having a predetermined width; The measurement device according to any one of claims 1 to 8, wherein light transmitted through the separation optical element is imaged in a first imaging region, and light reflected by the separation optical element is imaged in a second imaging region.

10. Irradiating a moving object with light having a wavelength that changes over time; capturing an image of the light from the object receiving the light and acquiring wavelength information for each pixel; A measuring method, wherein in the step of acquiring wavelength information, a temporal change in wavelength is continuously acquired.

Images