Shape measuring device

Abstract

To provide a shape measuring device capable of reconstructing a shape of a target object with high accuracy.SOLUTION: A shape measuring device 1A comprises a light source 2, an irradiation optical system 3, an imaging optical system 4, a spatial optical modulator 5, a condensing optical system 6, a linear sensor 7, and a processing section 9A. The irradiation optical system 3 forms light into a line shape and irradiates a target object S with the light. The imaging optical system 4 forms an image by inputting the light reflected on the target object S. The spatial optical modulator 5 has a one-dimensional intensity modulation pattern set on an optical modulation surface, performs spatial intensity modulation of the light input to the optical modulation surface, and outputs the light. The condensing optical system 6 condenses the light output from the spatial optical modulator 5 in the line shape. The linear sensor 7 receives the light condensed in the line shape by the condensing optical system 6 by a plurality of pixels. The processing section 9A analyzes each of the plurality of pixels of the linear sensor 7 by a compressed sensing technique on the basis of the intensity modulation pattern and an output signal from the linear sensor 7.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a shape measuring device. [Background technology]

[0002] The light section method is a technology for measuring the shape of an object. In the light section method, light output from a light source is irradiated onto the object in a line extending in one direction, the light reflected by the object is received by an area sensor (an image sensor with multiple pixels arranged in a two-dimensional array) and captured, and the two-dimensional image captured is analyzed to measure the shape of the object. When analyzing the image captured by capturing, the position where the line-shaped light is irradiated on the object is determined by performing a center of gravity calculation for each row. In addition, the three-dimensional shape of the object can be measured by moving the object relatively and determining the shape of the object at each position during the movement.

[0003] 3D shape measurement using the light section method is used, for example, for product inspection on factory lines, and is used in a variety of product inspections in the automobile, steel, construction, food, etc. As the automation of manufacturing and inspection progresses through factory automation, product inspection using the light section method is becoming increasingly important.

[0004] In image analysis using the light-section method, the number of pixels containing the necessary information in the image (information about the position of the line-shaped light on the object) is extremely small compared to the total number of pixels, but image analysis is performed after reading out the signals from all pixels.

[0005] On the other hand, when the number of pixels having necessary information in an image is very small compared to the total number of pixels (when sparse), the number of pixels from which signals should be read out can be reduced by applying compressed sensing technology.For example, by using the technology described in Non-Patent Document 1, an image formed by reflected light from an object is spatially intensity-modulated by a two-dimensional spatial light modulator, the modulated light is made into a line shape by a cylindrical lens, received by a linear sensor (an image sensor in which multiple pixels are arranged one-dimensionally) and imaged, and the one-dimensional image obtained by imaging can be analyzed by compressed sensing technology to measure the shape of the object. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] Hidetaka Shiomi et al., "Proposal of Vector Pixel Imaging", Optical Society of Japan, Optics & Photonics Japan 2020, Abstract 17aB7 Summary of the Invention [Problem to be solved by the invention]

[0007] Shape measurement using the technique described in Non-Patent Document 1 is constrained by the sparseness of the entire image, and therefore the accuracy of image reconstruction is low.

[0008] The present invention has been made to solve the above-mentioned problems, and aims to provide a shape measurement device that can reconstruct the shape of an object with high accuracy by using the light section method and compressed sensing technology. [Means for solving the problem]

[0009] A first aspect of the present invention is a shape measuring device for measuring a shape of an object, the shape measuring device including: (1) a light source that outputs light; (2) an irradiation optical system that irradiates the object with the light output from the light source in a line shape extending in a first direction; (3) an imaging optical system that inputs light that is irradiated onto the object by the irradiation optical system and reflected by the object in a direction different from the irradiation direction and forms an image; (4) a spatial light modulator that is set with a one-dimensional intensity modulation pattern in a direction different from the first direction, inputs light that has passed through the imaging optical system, and outputs the input light after spatially intensity modulating the input light based on the intensity modulation pattern; (5) a focusing optical system that inputs light output from the spatial light modulator and focuses the input light in a line shape extending in the first direction; (6) a linear sensor having a plurality of pixels that each include a photodiode and are one-dimensionally arranged, the plurality of pixels receiving the light focused in a line shape by the focusing optical system, and outputting a signal according to the amount of light received by each of the plurality of pixels; and (7) and a processing unit that performs analysis using compressed sensing technology on each of a plurality of pixels of the linear sensor based on a signal output from the linear sensor when each of a plurality of intensity modulation patterns is set in the spatial light modulator, to determine the shape of the object.

[0010] A shape measuring device of a second aspect of the present invention is a device for measuring the shape of an object, and includes: (1) a light source that outputs light; (2) an irradiation optical system that irradiates the object with the light output from the light source in a line shape extending in a first direction; (3) an imaging optical system that inputs light that is irradiated onto the object by the irradiation optical system and reflected by the object in a direction different from the irradiation direction and forms an image; (4) an area sensor having a plurality of pixels that each include a photodiode and are arranged two-dimensionally, the light that has passed through the imaging optical system being received by the plurality of pixels, and accumulating signals in the column direction according to the amount of light received by each pixel in the row, where a control signal given for each row has a first logical value, and outputting the signals for each column; and (5) a processing unit that performs analysis using compressed sensing technology for each column of the area sensor based on the signals accumulated for each column and output from the area sensor when each of a plurality of control signal patterns is set in the area sensor, to determine the shape of the object.

[0011] In the shape measuring device of the second aspect of the present invention, it is preferable that the area sensor accumulates signals in the column direction corresponding to the amount of light received by each pixel in a row in which the control signal given to each row is a second logical value, and outputs the signals for each column, and the processing unit performs analysis using compressed sensing technology for each column of the area sensor based on the signals accumulated for each column from the area sensor for each logical value of the control signal when each of the multiple control signal patterns is set in the area sensor, to determine the shape of the object.

[0012] In the shape measuring device of the first and second aspects of the present invention, it is preferable that the irradiation optical system irradiates the object with a plurality of light beams in a line shape extending in a first direction. Also, it is preferable that a transport mechanism is provided for relatively transporting the object in a direction different from the first direction, and the processing unit obtains the shape of the object at each position of the object when transported by the transport mechanism. Effect of the Invention

[0013] According to the present invention, the shape of an object can be reconstructed with high accuracy by utilizing the light section method and compressed sensing technology. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a diagram showing the configuration of a profile measuring apparatus 1A according to the first embodiment. [Diagram 2] FIG. 2 is a diagram showing a schematic view of a target object S being irradiated with a line-shaped light L. As shown in FIG. [Diagram 3] FIG. 3 is a diagram for explaining an image of the line-shaped light L on the light modulation surface of the spatial light modulator 5 and an intensity modulation pattern. [Figure 4] FIG. 4 is a diagram for explaining the relationship between an image of the line-shaped light L on the light modulation surface of the spatial light modulator 5 and each pixel of the linear sensor 7. As shown in FIG. [Diagram 5] FIG. 5 is a diagram showing the configuration of a profile measuring apparatus 1B according to the second embodiment. [Figure 6] FIG. 6 is a diagram for explaining an image of the line-shaped light L on the light modulation surface of the spatial light modulator 5. As shown in FIG. [Figure 7] FIG. 7 is a diagram for explaining another example of the image of the line-shaped light L on the light modulation surface of the spatial light modulator 5. In FIG. [Figure 8] FIG. 8 is a diagram showing the configuration of a profile measuring apparatus 1C according to the third embodiment. [Figure 9] FIG. 9 is a diagram showing the configuration of the area sensor 8. As shown in FIG. [Figure 10] FIG. 10 is a diagram showing an example of a circuit configuration of the column readout unit 32. As shown in FIG. [Figure 11] FIG. 11 is a diagram showing another example of the circuit configuration of the column readout section 32. In FIG. [Figure 12] FIG. 12 is a diagram showing yet another example of the circuit configuration of the column readout section 32. In FIG. [Figure 13] FIG. 13 is a diagram showing an example of a circuit configuration of the row control unit 21. As shown in FIG. [Figure 14] FIG. 14 is a diagram showing an example of the circuit configuration of pixel Pm,n. [Figure 15] FIG. 15 is a diagram showing an example of the aspect of timing from exposure to readout when charges are output from all pixels in the example circuit configuration of pixel Pm,n shown in FIG. [Figure 16] FIG. 16 is a diagram showing an example of the aspect of timing from exposure to readout when charges are output from all pixels in the example circuit configuration of pixel Pm,n shown in FIG. [Figure 17] FIG. 17 is a diagram showing an example of the aspect of timing from exposure to readout when charges are output from all pixels in the example circuit configuration of pixel Pm,n shown in FIG. [Figure 18] FIG. 18 is a diagram showing an example of the aspect of timing from exposure to readout when charges are output from all pixels in the example circuit configuration of pixel Pm,n shown in FIG. [Figure 19] FIG. 19 is a diagram showing another example of the circuit configuration of pixel Pm,n. [Figure 20] FIG. 20 is a diagram showing the configuration of a profile measuring apparatus 1D according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, the embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are given the same reference numerals, and duplicated descriptions are omitted. The present invention is not limited to these examples, but is indicated by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0016] 1 is a diagram showing the configuration of a profile measuring apparatus 1A according to the first embodiment. The profile measuring apparatus 1A is an apparatus for measuring the profile of an object S being transported by a transport mechanism 100, and includes a light source 2, an irradiation optical system 3, an imaging optical system 4, a spatial light modulator 5, a focusing optical system 6, a linear sensor 7, and a processing unit 9A.

[0017] The transport mechanism 100 is, for example, a belt conveyor that places and transports the object S relatively. For convenience of explanation, this figure shows an xyz Cartesian coordinate system in which the transport direction is the z direction. The direction perpendicular to the surface on which the object S is placed is the y direction.

[0018] The light source 2 outputs light to be irradiated onto the object S. The light source 2 may be any type, such as a laser diode or a light emitting diode. The irradiation optical system 3 irradiates the object S with the light output from the light source 2 in a line shape extending in a first direction (x direction). The irradiation optical system 3 may be configured to include a cylindrical lens. The direction (z direction) in which the object S is transported by the transport mechanism 100 is different from the direction (x direction) in which the line-shaped light irradiated onto the object S by the irradiation optical system 3 extends. FIG. 2 is a schematic diagram showing the state in which the line-shaped light L is irradiated onto the object S.

[0019] The imaging optical system 4 receives light that is irradiated onto the object S by the irradiation optical system 3 and reflected by the object S in a direction different from the irradiation direction, and forms an image. The imaging optical system 4 may be configured to include a spherical lens. In this case, the image of the line-shaped light L on the object S formed by the imaging optical system 4 is viewed in a direction different from the irradiation direction of the object S, and therefore corresponds to the shape of the object S.

[0020] The spatial light modulator 5 inputs the light that has passed through the imaging optical system 4 to the light modulation surface, and outputs the input light after spatially modulating the intensity based on the intensity modulation pattern. The spatial light modulator 5 may set a two-dimensional intensity modulation pattern on the light modulation surface, but in this embodiment, a one-dimensional intensity modulation pattern in a direction different from the first direction (x direction) is set. The intensity modulation pattern may be set randomly or based on a Hadamard matrix or the like. The spatial light modulator 5 may be of a reflective type as shown in FIG. 1, or of a transmissive type. The spatial light modulator 5 may be a DMD (Digital Micromirror Device) manufactured by MEMS technology, or may be a spatial light modulator using liquid crystal.

[0021] The light collecting optical system 6 receives the light output from the spatial light modulator 5 and collects the received light into a line shape extending in the first direction (x direction). The light collecting optical system 6 may be configured to include a cylindrical lens.

[0022] The linear sensor 7 has a plurality of pixels arranged one-dimensionally. Each of the plurality of pixels includes a photodiode that generates an electric charge in response to receiving light. The linear sensor 7 receives light focused in a line shape by the light focusing optical system 6 with the plurality of pixels, and outputs a signal according to the amount of light received by each of the plurality of pixels.

[0023] The processing unit 9A sequentially sets a plurality of intensity modulation patterns in the spatial light modulator 5. The processing unit 9A performs an analysis by compressed sensing technology on each of a plurality of pixels of the linear sensor 7 based on a signal output from the linear sensor 7 when each of a plurality of intensity modulation patterns is set in the spatial light modulator 5. Through this analysis, the processing unit 9A obtains an image of the line-shaped light L on the object S formed by the imaging optical system 4, and obtains the shape of the object S. The processing unit 9A can also obtain the three-dimensional shape of the object S by obtaining the shape of the object S at each position of the object S during transport by the transport mechanism 100.

[0024] The processing unit 9A may be a computer. The processing unit 9A includes a storage unit (e.g., a hard disk drive, a RAM, a ROM, etc.) for storing the intensity modulation pattern and the restored image obtained by the analysis, a display unit (e.g., a liquid crystal display, etc.) for displaying the intensity modulation pattern and the restored image, an input unit (e.g., a keyboard, a mouse, etc.) for receiving an instruction to start measurement and input of measurement conditions, and a control unit (e.g., a CPU, an FPGA, etc.) for controlling the operation of the entire device.

[0025] 3 is a diagram illustrating the image of the line-shaped light L on the light modulation surface of the spatial light modulator 5 and the intensity modulation pattern. In this diagram, multiple rectangles divided vertically represent pixels on the light modulation surface of the spatial light modulator 5. The intensity modulation pattern is represented by the presence or absence of hatching in each pixel. For example, the spatial light modulator 5 does not allow light input to hatched pixels to enter the linear sensor 7, and allows light input to non-hatched pixels to enter the linear sensor 7.

[0026] 4 is a diagram illustrating the relationship between the image of the line-shaped light L on the light modulation surface of the spatial light modulator 5 and each pixel of the linear sensor 7. In this diagram, a plurality of rectangles divided in the horizontal direction typically represent pixels of the linear sensor 7. The light input to the n-th pixel of the linear sensor 7 is light that arrives from a region of the linear sensor 7 that corresponds to the n-th pixel among pixels (pixels not hatched) designated by the intensity modulation pattern on the light modulation surface of the spatial light modulator 5 in FIG. 3.

[0027] In the following, the number of pixels of the spatial light modulator 5 is N, the number of pixels of the linear sensor 7 is N, and the number of intensity modulation patterns is M. The matrix representing the intensity modulation pattern is Φ, the signal value output from the linear sensor 7 is y, and the image to be restored by compressed sensing technology (the image on the light modulation surface of the spatial light modulator 5) is x. In this case, the relationship of the following formula (1) holds between these.

[0028]

number

[0029]

Equation

[0030]

Equation

[0031]

Equation

[0032] In this embodiment, a spatial light modulator capable of setting a one-dimensional intensity modulation pattern is used as the spatial light modulator 5, so that the device can be constructed inexpensively, power consumption can be reduced, and the frame rate can be increased. In addition, in this embodiment, compressed sensing technology is applied to each column, so parallel processing is possible, and parallel processing can further increase the frame rate.

[0033] In this embodiment, height position measurement with one-pixel accuracy is possible if the line light in the image on the light modulation surface is sufficiently thin compared to the pixel size of the spatial light modulator 5. However, since an image can be reconstructed even if a line light thicker than the pixel size of the spatial light modulator 5 is incident, height position measurement with sub-pixel accuracy is possible by further performing a center of gravity calculation.

[0034] FIG. 5 is a diagram showing the configuration of a shape measuring device 1B of the second embodiment. Compared with the shape measuring device 1A of the first embodiment (FIG. 1), the shape measuring device 1B of the second embodiment (FIG. 5) is different in that it includes a plurality of sets of light sources 2 and an irradiation optical system 3, and irradiates the target S with a plurality of light beams in a line shape extending in a first direction (x direction). FIG. 6 is a diagram explaining an image of a line-shaped light L on the light modulation surface of the spatial light modulator 5 in the case of the second embodiment. In the second embodiment, as shown in this figure, a plurality of images of the line-shaped light L appear on the light modulation surface of the spatial light modulator 5, but if the image x for each column is sparse (or becomes sparse by a linear transformation such as a Fourier transform), the image x can be restored by a compressed sensing technology in the same manner as in the first embodiment. In the second embodiment, the number of measurements can be reduced by using a plurality of line lights, and therefore the measurement time can be reduced.

[0035] FIG. 7 is a diagram illustrating another example of an image of the line-shaped light L on the light modulation surface of the spatial light modulator 5. Such an image is obtained, for example, when the target object includes a semi-transparent object such as glass and an object behind the semi-transparent object. In this case, light reflected by the semi-transparent object and light transmitted through the semi-transparent object and reflected by the object behind the semi-transparent object may reach the light modulation surface of the spatial light modulator 5. Even in such a case, if the image x for each column is sparse (or becomes sparse by a linear transformation such as a Fourier transform), the image x can be restored by the compressed sensing technology in the same manner as in the first embodiment.

[0036] Fig. 8 is a diagram showing the configuration of a profile measuring apparatus 1C of the third embodiment. The profile measuring apparatus 1C is an apparatus for measuring the profile of an object S being transported by a transport mechanism 100, and includes a light source 2, an irradiation optical system 3, an imaging optical system 4, an area sensor 8, and a processing unit 9C. Compared with the profile measuring apparatus 1A of the first embodiment (Fig. 1), the profile measuring apparatus 1C of the third embodiment (Fig. 8) differs in that it includes an area sensor 8 instead of the spatial light modulator 5, the focusing optical system 6, and the linear sensor 7, and in that it includes a processing unit 9C instead of the processing unit 9A.

[0037] The area sensor 8 has a plurality of pixels arranged two-dimensionally. Each of the plurality of pixels includes a photodiode that generates an electric charge in response to receiving light. The area sensor 8 receives light that has passed through the imaging optical system 4 by the plurality of pixels. The area sensor 8 accumulates signals in the column direction according to the amount of light received by each pixel in a row in which a control signal given to each row is a first logical value, and outputs the accumulated signals for each column. The area sensor 8 may also accumulate signals in the column direction according to the amount of light received by each pixel in a row in which a control signal given to each row is a second logical value, and output the accumulated signals for each column. One of the first logical value and the second logical value is a logical value H, and the other is a logical value L.

[0038] The processing unit 9C sequentially sets a plurality of patterns of the control signal given to each row of the area sensor 8. The processing unit 9C performs an analysis by the compressed sensing technique for each column of the area sensor 8 based on the signal output from the area sensor 8 after integrating for each column when each of the plurality of control signal patterns is set in the area sensor 8. Alternatively, the processing unit 9C performs an analysis by the compressed sensing technique for each column of the area sensor 8 based on the signal output from the area sensor 8 after integrating for each column when the control signal is a first logical value and a second logical value when each of the plurality of control signal patterns is set in the area sensor 8. The processing unit 9C obtains an image of the line-shaped light L on the object S by the imaging optical system 4 through this analysis, and obtains the shape of the object S. The processing unit 9C can also obtain the three-dimensional shape of the object S by obtaining the shape of the object S at each position of the object S during transport by the transport mechanism 100.

[0039] 9 is a diagram showing the configuration of the area sensor 8. The area sensor 8 includes a pixel array section 10, a row control section 21, and a column readout section 32.

[0040] The pixel array unit 10 is a two-dimensional array of N 2 Pixels P 1,1 ~P N,N Includes: N 2 Pixels P 1,1 ~PN,N The pixels P n1,n2 is located in the n1th row and n2th column. Each pixel includes a photodiode that generates an electric charge in response to received light, and a switch that selects whether to output the electric charge generated by the photodiode. Here, N is an integer of 2 or more. n, n1, and n2 are each integers of 1 or more and N or less.

[0041] The row control unit 21 selects N pixels P n,1 ~P n,N and the nth row control line 23 n The row control unit 21 is connected to the n-th row control line 23. n The n-th row control signal is sent to the n-th row of N pixels P n,1 ~P n,N The row control unit 21 designates a row to which the electric charge generated in the photodiode should be output, using the first to Nth row control signals.

[0042] The column readout unit 32 reads N pixels P 1,n ~P N,n and nth column output line 34 n The column readout section 32 is connected to the n-th column output line 34. n Through the n-th column, N pixels P 1,n ~P N,n The column readout unit 32 inputs a charge output from any one of the pixels in the column readout unit 32. The column readout unit 32 may include a charge amplifier that outputs a voltage value according to the amount of input charge, and an AD converter that outputs a digital value according to the voltage value output from the charge amplifier.

[0043] In this area sensor 8, one of the first to Nth rows is selected by a control signal output from the row control unit 21, and N pixels P n,1 ~P n,N The charges output from the first to Nth column output lines 341 to 34 N At this time, when multiple rows are selected, the pixels of the selected multiple rows are input to the column readout unit 32 via the n-th column output line 34. n The charges output to the column readout section 32 are added together and input to the column readout section 32.

[0044] Next, an example of the circuit configuration of the column readout section 32 will be described with reference to Figs. 10 to 12. Fig. 10 is a diagram showing an example of the circuit configuration of the column readout section 32. The column readout section 32 shown in this figure includes NMOS transistors 411 to 41. N and a conversion unit 49. NMOS transistor 41 n The drain of the nth column output line 34 n The NMOS transistor 41 is connected to n The source of the NMOS transistor 41 is connected to the conversion unit 49. n acts as a switch that sets the connection between the drain and source to either conductive (ON) or non-conductive (OFF) depending on the level of a signal applied to the gate.

[0045] The conversion unit 49 includes NMOS transistors 411 to 41 N The conversion unit 49 is connected to the sources of the respective input charges. The conversion unit 49 includes a charge amplifier that outputs a voltage value according to the amount of input charge, and an AD converter that outputs a digital value according to the voltage value output from the charge amplifier.

[0046] NMOS transistors 411-41 N When any of the NMOS transistors 41 and 42 is in an on state, the NMOS transistor 41 in the on state n and nth column output line 34 n N pixels P in the nth column are connected via 1,n ~P N,n The charge output from any one of the pixels is input to the conversion unit 49, and a digital value according to the amount of the charge is output from the conversion unit 49. N may be turned on simultaneously or one by one in sequence.

[0047] This diagram shows NMOS transistors 481 to 48 N Also shown is NMOS transistor 48 n The drain of the NMOS transistor 48 is connected to the power supply potential supply terminal. n The source of the nth column output line 34n NMOS transistor 48 is connected to n NMOS transistor 48 also acts as a switch. n When in the on state, the n-th column output line 34 n The N pixels P in the nth column connected to 1,n ~P N,n The charge generated in each photodiode can be initialized.

[0048] 11 is a diagram showing another example of the circuit configuration of the column readout section 32. The column readout section 32 shown in this diagram includes NMOS transistors 411 to 41 N In addition to the conversion unit 49, NMOS transistors 421 to 42 N and capacitors 431 to 43 N NMOS transistor 42 n The drain of the nth column output line 34 n NMOS transistor 42 is connected to n The source of the NMOS transistor 41 n The drain of the capacitor 43 is connected to the n 42 NMOS transistor n The NMOS transistor 42 is provided between the source of the NMOS transistor 42 and the ground potential supply terminal. n also acts as a switch.

[0049] In this circuit configuration example, the NMOS transistor 41 n When is in the off state, the NMOS transistor 42 n When the n-th column output line 34 is in the ON state, n The charge arriving from capacitor 43 n Then, the NMOS transistor 42 n When the NMOS transistor 41 is in the off state, n When the on state, the capacitor 43 n The charge stored in the NMOS transistors 411 to 411 is input to the conversion unit 49, and a digital value corresponding to the amount of the charge is output from the conversion unit 49. Nmay be turned on simultaneously or one by one in sequence.

[0050] 12 is a diagram showing yet another example of the circuit configuration of the column readout section 32. The column readout section 32 shown in this diagram includes NMOS transistors 411 to 41 N , NMOS transistors 421 to 42 N , Capacitor 431 to 43 N , NMOS transistors 441 to 44 N , NMOS transistors 451 to 45 N , Capacitor 461 to 46 N , NMOS transistors 471 to 47 N and a conversion unit 49. NMOS transistor 44 n ,45 n and Capacitor 46 n 41 NMOS transistor n ,42 n and Capacitor 43 n The NMOS transistor 47 has a similar structure. n The drain of the NMOS transistor 41 n ,44 n The conversion unit 49 includes NMOS transistors 471 to 47 N Each is connected to a different source.

[0051] In this circuit configuration example, the n-th column output line 34 n 2 capacitors for 43 n ,46 n By providing the n-th column output line 34 n While the electric charge arriving from the NMOS transistor 41 is transferred to and stored in one of the capacitors, the electric charge stored in the other capacitor is input to the conversion unit 49, and a digital value according to the amount of the electric charge is output from the conversion unit 49. For example, n ,45 n When is in the off state, the NMOS transistor 42 n When the n-th column output line 34 is in the ON state, n The charge arriving from capacitor 43 nand stored in the NMOS transistor 44. n ,47 n When is in the on state, the capacitor 46 n The charge stored in the input buffer 44 is input to the conversion unit 49, which then outputs a digital value according to the amount of charge.

[0052] The column readout section 32 may be provided with only one conversion section that outputs a digital value according to the amount of charge, or the column readout section 32 may be provided with one conversion section for each column.

[0053] Next, a description will be given of an example of the circuit configuration of the row control unit 21. The row control unit 21 controls first to N-th row control signals X1 to X N Parallel input of nth row control signal X n The nth row control line 23 n , and the first to Nth row control signals X1 to X N is input as serial data to generate the nth row control signal X n The nth row control line 23 n The row control unit 21 may preferably have a configuration shown in FIG.

[0054] 13 is a diagram showing an example of a circuit configuration of the row control unit 21. The row control unit 21 shown in this diagram includes a shift register 51 and flip-flops 521 to 52. N The shift register 51 includes the first to Nth row control signals X1 to X N is input serially to generate the nth row control signal X n Flip Flop 52 n Flip-flop 52 n is the n-th row control signal X output from the shift register 51. n and the latched n-th row control signal X n The nth row control line 23 n Output to.

[0055] Flip Flop 52 n is preferably an RS flip-flop. In this case, flip-flop 52 nWhen the latch is on, the nth row control signal X n The nth row control line 23 n The flip-flop 52 n When set is on, the logic value H is applied to the n-th row control line 23 n By outputting to pixel P n,1 ~P n,N Also, flip-flop 52 can be reset. n When reset is on, the logic value L is applied to the n-th row control line 23 n By outputting to pixel P n,1 ~P n,N can be turned off.

[0056] As shown in this circuit configuration example, the row control unit 21 includes a shift register 51 and flip-flops 521 to 52 N If it contains, flip-flop 52 n to n-th row control signal X n The nth row control line 23 n While outputting the next first to Nth row control signals X1 to Y N can be input serially.

[0057] Next, pixel P m,n An example of the circuit configuration of pixel P m,n Each pixel P includes a photodiode that generates an electric charge in response to light reception, and a switch that selects whether or not the electric charge generated by the photodiode is output to a column output line. m,n FIG. 1 is a diagram showing an example of a circuit configuration of a pixel P m,n includes a photodiode PD and a switch SW. The switch SW may be configured with a MOS transistor.

[0058] The switch SW connects the photodiode PD to the column output line 34. n The row control line 23 is connected to the row control unit 21. m Line control signal X sent via mWhen the logic value of is H, the switch SW is turned on and the charge generated in the photodiode PD is transferred to the column output line 34 n The row control signal X m When the logic value of the photodiode PD is L, the switch SW is turned off and the charge generated in the photodiode PD is transferred to the column output line 34 n Do not output to .

[0059] Pixel P shown in FIG. m,n In the circuit configuration example, each row control signal X m By inverting the logical value of , it is possible to read out charges from all pixels. This makes it possible to shorten the measurement time. Figures 15 to 18 are diagrams showing examples of the timing from exposure to readout when charges are output from all pixels.

[0060] In the example of the timing shown in FIG. 15, all pixels start exposure at the same time, and charges are read out from pixels in one or more rows after a certain period of time. After the first charge readout is completed, charges are read out from pixels in other rows (pixels in rows that were not read out the first time). The exposure times of the pixels in the row where charge readout was performed the first time and the pixels in the row where charge readout was performed the second time are different, but the difference in exposure times can be easily corrected when solving an optimization problem using compressed sensing technology. This timing example can be applied to the circuit configuration example of the column readout unit 32 shown in FIG. 10.

[0061] In the example of the timing shown in Fig. 16, the exposure time of all pixels is made constant by resetting each pixel at an appropriate timing. Charges are read out from pixels in one or more rows after a certain period of exposure has been completed. After this first charge readout is completed, charges are read out from pixels in other rows (pixels in rows whose charges were not read out the first time). This timing example is applicable to the circuit configuration example of the column readout unit 32 shown in Fig. 11 when the exposure time is equal to or longer than the readout time.

[0062] In the example of the timing shown in FIG. 17, the exposure time of all pixels is made constant by resetting each pixel at an appropriate timing. Charges are transferred from one or more rows of pixels that have been exposed for a certain period of time to the column readout section 32, and then a digital value according to the amount of charge is output from the column readout section 32. After the first charge transfer is completed, pixels in other rows (pixels in rows that have not been read out the first time) are reset and exposed for a certain period of time, and then charges are transferred to the column readout section 32, and then a digital value according to the amount of charge is output from the column readout section 32. This timing example can be applied to the circuit configuration example of the column readout section 32 shown in FIG. 11, and can also be applied even when the exposure time is shorter than the readout time.

[0063] In the example of the timing shown in FIG. 18, the exposure time of all pixels is made constant by resetting each pixel at an appropriate timing. After a certain period of exposure, charge is transferred from one or more rows of pixels to the column readout section 32, and then a digital value according to the amount of charge is output from the column readout section 32. After resetting and exposure for a certain period of time, charge is transferred to the column readout section 32 from the other rows of pixels (rows of pixels that did not undergo the first charge readout), and then a digital value according to the amount of charge is output from the column readout section 32. After the first charge transfer, a second charge transfer is performed. This timing example can be applied to the circuit configuration example of the column readout section 32 shown in FIG. 12.

[0064] Next, pixel P m,n Another circuit configuration example of the pixel P m,n FIG. 1 is a diagram showing another example of the circuit configuration of the pixel P m,n includes a photodiode PD and two switches SW1 and SW2. The switches SW1 and SW2 may be configured by MOS transistors.

[0065] Row control signal X m When the row control signal X is at a logical value H, the switch SW1 is in an on state and the switch SW2 is in an off state. mWhen the logical value of the switch SW1 is L, the switch SW1 is in an OFF state, and the switch SW2 is in an ON state. When one of the switches SW1 and SW2 is in an ON state, the other is in an OFF state. When the switch SW1 is in an ON state, the charge generated in the photodiode PD is transferred to the column output line 34. n,1 When the switch SW2 is in the on state, the charge generated in the photodiode PD is output to the column output line 34. n,2 Output to.

[0066] In this circuit configuration example, the area sensor 8 can accumulate signals in the column direction corresponding to the amount of light received by each pixel in a row where the control signal given to each row is a logical value H, and output the signals to a column output line for each column, and can accumulate signals in the column direction corresponding to the amount of light received by each pixel in a row where the control signal given to each row is a logical value L, and output the signals to a different column output line for each column.

[0067] Then, the processing unit 9C can perform an analysis by compressed sensing technology for each column of the area sensor 8 based on the signal output from the area sensor 8 after integrating each logical value of the control signal for each column when each of a plurality of control signal patterns is set in the area sensor 8, and can obtain the shape of the target S. This can shorten the measurement time.

[0068] In this embodiment as well, the image of the line-shaped light L on the light receiving surface of the area sensor 8 is restored by applying the compressed sensing technique to each column. That is, in this embodiment as well, instead of using the sparsity of the entire image as a constraint, the image is divided into a plurality of columns and the sparsity of each column is used as a constraint, so that it is possible to reduce the possibility of there being a column in which all values ​​are 0, and the accuracy of image reconstruction is high.

[0069] In this embodiment, since there is no need to use a spatial light modulator, the device can be constructed more inexpensively and easily, and power consumption can be further reduced. Also, in this embodiment, compressed sensing technology is applied to each column, so parallel processing is possible, and parallel processing can further increase the frame rate.

[0070] In this embodiment, too, height position measurement with one-pixel accuracy is possible if the line light in the image on the light receiving surface is sufficiently thin compared to the pixel size of the area sensor 8. However, since an image can be reconstructed even if a line light thicker than the pixel size of the area sensor 8 is incident, height position measurement with sub-pixel accuracy is possible by further performing a center of gravity calculation.

[0071] FIG. 20 is a diagram showing the configuration of a shape measuring device 1D of the fourth embodiment. Compared with the shape measuring device 1C of the third embodiment (FIG. 8), the shape measuring device 1D of the fourth embodiment (FIG. 20) is different in that it includes a plurality of sets of light sources 2 and an irradiation optical system 3, and irradiates a target S with a plurality of light beams in a line shape extending in a first direction (x direction). The image of the line-shaped light L on the light receiving surface of the area sensor 8 in the fourth embodiment is similar to that shown in FIG. 6. In the fourth embodiment, as shown in FIG. 6, a plurality of images of the line-shaped light L appear on the light receiving surface of the area sensor 8, but if the image x for each column is sparse (or becomes sparse by a linear transformation such as a Fourier transform), the image x can be restored by a compressed sensing technique in the same manner as in the third embodiment. In the fourth embodiment, the number of measurements can be reduced by using a plurality of line lights, and therefore the measurement time can be reduced.

[0072] Furthermore, for example, when the target object includes a translucent object such as glass and an object behind this translucent object, even if the image of the line-shaped light L on the light receiving surface of the area sensor 8 is as shown in FIG. 7, if the image x for each column is sparse (or if it is made sparse by a linear transformation such as a Fourier transform), the image x can be restored using compressed sensing technology in the same manner as in the first embodiment. [Explanation of symbols]

[0073] 1A to 1D... shape measuring device, 2... light source, 3... irradiation optical system, 4... imaging optical system, 5... spatial light modulator, 6... focusing optical system, 7... linear sensor, 8... area sensor, 9A, 9C... processing unit, 10... pixel array unit, 21... row control unit, 23... row control line, 32... column readout unit, 34... column output line, P 1,1 ~P N,N ...pixels.

Claims

1. An apparatus for measuring the shape of an object, comprising: A light source that outputs light; an illumination optical system that illuminates the object with light output from the light source in a line shape extending in a first direction; an imaging optical system that inputs light irradiated onto the object by the irradiation optical system and reflected by the object in a direction different from the irradiation direction and forms an image; a spatial light modulator which is set with a one-dimensional intensity modulation pattern in a direction different from the first direction, inputs light having passed through the imaging optical system, and spatially intensity-modulates the input light based on the intensity modulation pattern and outputs the modulated light; a focusing optical system that receives light output from the spatial light modulator and focuses the received light into a line shape extending in the first direction; a linear sensor having a plurality of pixels arranged one-dimensionally, each pixel including a photodiode, receiving light focused in a line shape by the focusing optical system with the plurality of pixels, and outputting a signal corresponding to an amount of light received by each of the plurality of pixels; a processing unit that performs an analysis using a compressed sensing technique on each of the pixels of the linear sensor based on a signal output from the linear sensor when each of the intensity modulation patterns is set in the spatial light modulator, to obtain a shape of the object; A shape measuring device comprising:

2. The irradiation optical system irradiates the object with a plurality of light beams in a line shape extending in a first direction. The shape measuring apparatus according to claim 1 .

3. a conveying mechanism configured to relatively convey the object in a direction different from the first direction, The processing unit determines a shape of the object at each position of the object when the object is transported by the transport mechanism.

3. The shape measuring apparatus according to claim 1 or 2.

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