JP2013044689A - Shape measurement device and shape measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shape measurement device capable of performing shape measurement of an object in a non-contact manner and with high precision, and to provide a shape measurement method.SOLUTION: An inventive shape measurement device 1 comprises: a light source array 11 with at least five light sources arranged at equal intervals in line; a grating plate 12 having a lattice plane of a one-dimensional lattice; a camera 13 capturing a measurement object 21 on which the one-dimensional lattice is projected; and a control unit 50. The control unit 50 sets two light source groups consisting of at least four neighboring light sources among at least five light sources, controls the light source array 11 so that the light sources in the two light source groups are lit one by one successively, controls the camera 13 so that one-dimensional lattices projected on the measurement object 21 are captured, respectively, calculates the phase of the one-dimensional lattices projected on the measurement object 21 by two light source groups form captured images, respectively, and obtains height coordinates relating to the measurement object 21 on the basis of a predetermined conversion formula by using the difference between the two phases as a phase shift amount.

Description

  The present invention relates to a shape measuring apparatus and a shape measuring method that can perform shape measurement of an object in a non-contact and high accuracy.

  Conventionally, there is a method using a phase shift method as a method for non-contact and three-dimensionally measuring the shape of a measurement target object such as an object or a human body. In the phase shift method, a lattice image and an interference fringe image are sequentially photographed by one camera while changing the phase, and a phase distribution of the lattice is obtained based on a plurality of lattice images and interference fringe images whose phases are changed. Is.

  As a method using the phase shift method, for example, using a camera and a projector, in order to perform highly accurate shape measurement without being affected by lens aberration of these cameras or projectors, a reference plate on which a grating is drawn is used. Rather than calculating the lens center coordinates of the camera or projector from the image, the optical path through which the line of sight for each pixel of the camera passes from the two-dimensional grid fixed to each reference plane in the plurality of reference planes, and the light projected from the projector There are known a shape measuring method and a shape measuring apparatus that calculate all of the optical paths and calculate spatial coordinates as intersections of these optical paths (see, for example, Patent Document 1).

  There is another technique for measuring the shape of an object based on a plurality of reference planes using a camera and a projector. For example, a plurality of reference planes having X and Y axis planes orthogonal to each other are set at predetermined intervals in the normal direction of the reference plane (that is, the Z axis direction perpendicular to the X and Y axis planes) and measured. A line of sight of a camera that shoots a point S on the object in order to determine the coordinates of the point S on the surface of the object by arranging the power object between the reference surfaces located at both ends of the plurality of reference surfaces And a point where each of the light rays from the projector passing through the point S on the object intersects the plurality of reference planes, and a line formed by the intersecting points on the line of sight of the camera and the intersecting point on the light rays from the projector A technique is known in which an intersection point with a straight line is obtained, two reference planes closest to the point are selected from the Z coordinate of the intersection point, and the shape of the object is measured using the two selected reference planes. (For example, refer to Patent Document 2).

  On the other hand, as yet another technique for measuring the shape of an object based on a plurality of reference planes using a camera and a projector, when a reference plane having X and Y axis planes is translated by a minute amount in the normal direction By using a predetermined two-dimensional pattern or a spatial division pattern for the plurality of reference planes, even if the luminance distribution of the spatial division pattern projected onto the object is not cosine-like, the spatial division pattern projected onto the object 2. Description of the Related Art A shape measuring apparatus that can accurately measure a shape even when the pitch is unequal is known (see, for example, Patent Document 3).

Japanese Patent No. 2913021 Japanese Patent No. 3446020 JP 2008-281491 A

  In the technologies disclosed in Patent Documents 1 to 3 described above, it is considered as a typical embodiment to use a moving mechanism of a substrate (grating substrate) on which a grating for performing phase shift is drawn. For example, in the technique disclosed in Patent Document 1, a grating substrate is provided on a moving mechanism to perform a phase shift, and the grating substrate is mechanically moved. This moving mechanism is not only very expensive because it consists of, for example, a piezo stage, but it is not suitable for performing phase shift of the grating at high speed, and it is difficult to measure the shape of an object moving at high speed It becomes a necessary component.

  Further, in order to perform shape measurement based on the phase shift, a device for obtaining the phase shift amount with higher accuracy is required.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a shape measuring device and a shape measuring method capable of measuring the shape of an object in a non-contact and highly accurate manner.

  In the present invention, at least five light sources are arranged in a line at equal intervals, and among these, at least two light source sets composed of at least four light sources adjacent to each other are set, and each light source in the two light source sets is sequentially turned on to be measured. The grid projected on the object is photographed, the phase of the grid by each light source set is calculated, and the height coordinate is obtained based on a predetermined conversion formula using the phase difference between the two obtained grids as a phase shift amount. . Moreover, it is good also as three or more light source groups. Thereby, the phase shift of the grating is accelerated by the light source switching control, and the shape measurement of the measurement target object is made highly accurate because at least two light source sets are used. In the present invention, since the grating is phase-shifted by sequentially lighting the at least four light sources for each light source set composed of at least four light sources, the phase shift amount is an integer of 2π as in the conventional phase shift method. It is dependent on the distance from the straight line passing through the at least four light sources rather than being divided by the above, and is different from the conventional phase shift method using a conversion formula that does not depend on the distance between the spatial coordinates and the phase. It is a method.

  That is, the shape measuring device of the present invention is a shape measuring device that measures the shape of a measurement target object in a non-contact manner, and includes a light source array in which at least five light sources are linearly arranged at equal intervals, and the at least five light sources. A grid plate having a grid surface of a one-dimensional grid configured by arranging light transmission regions composed of straight lines perpendicular to the straight lines arranged at equal intervals with respect to the light shielding region, and sequentially lighting the at least five light sources Two sets of light source sets each including a camera that captures the measurement target object projected on the measurement target object by the one-dimensional grating and at least four light sources adjacent to each other among the at least five light sources, The light source array is controlled so that each light source in the two light source groups is sequentially turned on, and each light source is turned on sequentially to photograph a projected one-dimensional lattice. Controlling the camera to calculate the phase of the one-dimensional grating projected onto the measurement target object by the two sets of light sources, and using the calculated difference between the two phases as a phase shift amount, And a control unit for obtaining a height coordinate related to the measurement target object based on a predetermined conversion formula for determining a distance from a phase shift amount. Here, each light source is composed of a plurality of LEDs, and the plurality of LEDs can be configured as point light sources to increase the luminance. Further, it is possible to further increase the brightness by arranging the plurality of LEDs in parallel to the light transmission region formed of a straight line.

Further, in the shape measuring apparatus of the present invention, the predetermined conversion formula for determining the distance from the phase shift amount is that each light of the grating plate has one point on the straight line where the at least five light sources are arranged as the origin. The arrangement direction of the transmission region is the X axis, the straight line of the light transmission region is the Y axis, and the normal direction of the lattice plane of the lattice plate is the Z axis, and the origin from the light source array to the surface of the measurement target object The distance in the Z-axis direction is z, the interval between the light sources in the light source array is l, the distance in the Z-axis direction from the origin of the light source array to the grating plane is d, the phase shift amount is Ψ, and the one-dimensional grating is When the interval is p,

In the shape measuring apparatus of the present invention, the control unit has means for obtaining a height coordinate related to the measurement target object based on a predetermined conversion formula for determining a distance from the phase of the projected one-dimensional grating. Then, with one point on the straight line where the at least five light sources are arranged as the origin, the arrangement direction of the light transmission regions of the lattice plate is the X axis, the straight line of the light transmission region is the Y axis, and the lattice plate The normal direction of the lattice plane is the Z-axis, the distance in the Z-axis direction from the origin of the light source array to the surface of the object to be measured is z, and the Z-axis direction from the origin of the light source array to the lattice plane The distance is d, the phase of the one-dimensional grating is Φ, the interval of the one-dimensional grating is p, the distance in the X-axis direction from the origin to the surface of the object to be measured is x, and each of the elements constituting the one-dimensional grating Light transmission area The shortest distance from the Z-axis of the center position when the e of,

  The shape measurement apparatus of the present invention further includes a reference plate having a reference surface arranged so that the one-dimensional grating is projected, and the control unit includes at least four of the at least five light sources arranged adjacent to each other. Two sets of light sources consisting of two light sources are set, and the light source array is controlled so that the respective light sources in the two sets of light sources are sequentially turned on, and the respective light sources are turned on sequentially and projected onto the reference plane. Means for controlling the camera to photograph a one-dimensional grating, calculating a phase of the one-dimensional grating projected on the reference plane by the two sets of light sources, and holding them in a memory; For each light source set, the phase of the one-dimensional grating projected onto the reference plane held in the memory and the phase of the one-dimensional grating projected onto the measurement target object Min is calculated and further comprising a means for determining height coordinates for advance the measurement object on the basis of the conversion formula determined for determining the distance from said difference.

Further, in the shape measuring apparatus of the present invention, the predetermined conversion formula for determining the distance from the difference is that each light transmission region of the lattice plate has an origin at one point on a straight line where the at least five light sources are arranged. The X axis is the X axis, the straight line of the light transmission region is the Y axis, and the normal direction of the grating plane of the grating plate is the Z axis, and the Z axis from the origin of the light source array to the surface of the object to be measured The distance in the direction is z, the distance in the Z-axis direction from the origin of the light source array to the lattice plane is d, the distance from the origin to the center of the camera lens is v, and the distance from the origin to the reference plane is Z. The axial distance is z _R , the interval between the one-dimensional gratings is p, and the phase of the projected one-dimensional grating at the distance x in the X-axis direction from the origin to the surface of the measurement target object is Φ _S , The distance x A straight line passing through the center of the measurement object surface position and the lens, when the phase of the one-dimensional lattice which is the projection of the intersection between the reference plane and the [Phi _R,

  In the shape measuring apparatus of the present invention, the control unit uses the reference flat plate for three-dimensional coordinates composed of x, y coordinates of the X axis and Y axis determined by the pixel position of the camera and z coordinates of the Z axis. A table that associates the relationship between the phase and the x and y coordinates and the relationship between the phase shift amount and the x and y coordinates is created and stored in the memory for each z coordinate measured at a predetermined interval. And means for deriving three-dimensional coordinates relating to the measurement target object from the phase of the one-dimensional grating calculated for the measurement target object and the phase shift amount with reference to a table held in the memory. It is characterized by.

  Furthermore, the shape measuring method of the present invention provides a light source region in which at least five light sources are arranged in a straight line at equal intervals, and a light transmission region consisting of a straight line perpendicular to the straight line in which the at least five light sources are arranged. A lattice plate having a lattice plane of a one-dimensional lattice arranged at equal intervals with respect to the shielding area, and a camera for photographing a measurement target object onto which the one-dimensional lattice is projected by sequentially turning on the at least five light sources; , A shape measuring method for measuring the shape of the object to be measured by a shape measuring device comprising a control unit, wherein the processing of the control unit comprises at least four light sources adjacently arranged among the at least five light sources. A step of setting two sets of light sources, and a step of controlling the light source array so as to sequentially turn on each light source in the two sets of light sources. Illuminating each light source sequentially and controlling the camera to photograph a one-dimensional lattice projected onto the measurement target object, respectively, and projecting onto the measurement target object by the two sets of light sources A step of calculating the phase of the one-dimensional grating, and a difference between the calculated two phases as a phase shift amount, based on a predetermined conversion formula for determining a distance from the phase shift amount, Obtaining a height coordinate.

  According to the present invention, since the phase shift can be performed at high speed by sequentially turning on at least five light sources, the shape of the measurement target object can be measured at high speed and with high accuracy.

It is a figure which shows the structure of the shape measuring apparatus of 1st Embodiment by this invention, and its operation principle. (A), (B) is a figure which shows the example of arrangement | positioning of the light source array and grating | lattice plate in the shape measuring device of 1st Embodiment (and 2nd Embodiment) by this invention. It is a block diagram of the control unit in the shape measuring apparatus of 1st Embodiment (and 2nd Embodiment) by this invention. It is a figure which shows the relationship between the phase shift amount and the brightness | luminance in the optical stepping method which concerns on this invention. It is a figure which shows an example of the operation | movement flow of the shape measuring apparatus of 1st Embodiment by this invention. It is a figure which shows the example of the three-dimensional coordinate table by the shape measuring apparatus of 1st Embodiment by this invention. It is a figure which shows the structure and operating principle of the shape measuring apparatus of 2nd Embodiment by this invention. It is a figure which shows the example of the three-dimensional coordinate table by the shape measuring apparatus of 2nd Embodiment by this invention. It is a figure which shows the example of the relationship between the cosine of the phase shift amount and height which concern on this invention. It is a figure which shows the example of the relationship between the tangent of a phase which concerns on this invention, and height. It is a figure which shows the relationship between the difference of the phase on the measurement object which concerns on this invention, and the phase on a reference plane, and height.

  Hereinafter, a shape measuring device according to a first embodiment and a second embodiment of the present invention will be described with reference to the drawings. In addition, the shape measuring apparatus 1 of 1st Embodiment is an aspect which measures the shape of a measurement target object, without using a reference plane, and the shape measurement apparatus 2 of 2nd Embodiment is a measurement target object using a reference plane. It is the aspect which measures the shape of.

[First Embodiment]
First, the shape measuring apparatus 1 of 1st Embodiment by this invention is demonstrated. FIG. 1 is a diagram showing the configuration of the shape measuring apparatus 1 according to the first embodiment of the present invention and its operating principle. Shape measuring apparatus 1 of this embodiment, measuring a device for measuring a three-dimensional shape of the target object 21, equally spaced and six arranged in a row of the light source _{L -2, L -1, L 0} , L 1, A light source array 11 composed of L ₂ and L ₃ , a lattice plate 12 having a lattice plane composed of a one-dimensional lattice, a camera 13, and a control unit 50 are provided.

X-axis, Y-axis and made of Z-axis coordinate points x, y, in order to define the three-dimensional space by z, 6 single light source _L -2 constituting the light source array _{11, L -1, L 0,} L 1, The position of one of the light sources L ₂ and L ₃ (the position of L _{0 in} the example shown in FIG. 1) is the origin O (ie, x = 0, y = 0, z = 0), and the grating plate 12 The arrangement direction of the respective light transmission regions 12b is defined as the X axis, the straight line of the light transmission region 12b is defined as the Y axis, and the normal direction of the lattice plane of the lattice plate 12 is defined as the Z axis. The measurement target object 21 is arranged in the Z-axis direction. The position of the origin O can also be defined as the center position between the light sources at both ends in the light source array 11, but here, any one of the six light sources is defined as the origin O.

Light source array 11, six light sources _{L -2,} L _-1, has a configuration that is linearly arranged to L _0, L 1, _{L 2} and _{L 3} at equal intervals. In FIG. 1, an example of six light sources arranged at equal intervals in the X-axis direction will be representatively described as the light source array 11, but the light source array 11 may be configured to include five light sources or seven or more light sources. it can. Moreover, the light emitting diode (LED) is used as a light source, and each LED can be comprised as a line light source or a point light source. That is, since the output of the LED chip is small, a plurality of LED chips are arranged in the Y-axis direction to form a line light source that is parallel to the Y-axis, and each of these line light sources is arranged at equal intervals in the X-axis direction. _{-2, L -1,} it is possible to configure the L _0, L 1, _{L 2} and _{L 3.} Furthermore, a plurality of LED chips can be integrated into a single point light source. For example, as shown in FIG. 2A, each light source can be configured as a linear light source by arranging a plurality of LED chips 11c in the Y-axis direction and providing a directional lens 11d as necessary. Further, as shown in FIG. 2B, each light source can be configured as a single point light source by integrating a plurality of LED chips. The interval between the six light sources is l. Hereinafter, six light sources _{L -2, L -1, L 0} , L 1, L 2 and _{L 3} the plane of z = 0 comprising (consisting of X-axis and Y-axis X, parallel to the Y-axis plane z = 0 Is referred to as a “light source surface”. That is, the distance in the Z-axis direction from the light source array 11 to the surface of the measurement target object 21 is set to z (in other words, the position in the Z-axis direction from the light source surface is a coordinate point z representing “height”). it can.

Grid plates 12, six light sources _{L -2,} L _-1, (in the example shown in FIGS. 1 and 2, X-axis _{direction) L 0, L 1, L} 2 and _{L 3} having an array direction perpendicular to the It has a lattice plane of a one-dimensional lattice formed by arranging light transmission regions 12b composed of straight lines in the direction (that is, the Y-axis direction) at equal intervals with respect to the light shielding region 12a. For example, the grating plate 12 can be configured by printing a black one-dimensional grating surface on a transparent glass or plastic surface, and a slit (light shielding region 12a) with a slit ( A light transmission region 12b) may be provided. The grating plate 12 is configured such that a light irradiated from the light source array 11 passes through the grating plate 12 so that a one-dimensional grating is projected onto the measurement target object 21. The lattice spacing of each light transmission region 12b constituting the one-dimensional lattice is p. In the embodiment illustrated in FIG. 1, the light source surface and the lattice surface are parallel, and the distance between the light source surface and the lattice surface is d. Further, of the central positions of the light transmission regions 12b constituting the one-dimensional lattice, the shortest distance from the Z axis is defined as a reference point E (Φ = 0), and the intersection of the lattice plane of the lattice plate 12 and the Z axis. Is C. Note that the luminance distribution of the projected one-dimensional grating needs to be a cosine wave. For this reason, even if the luminance distribution (transmittance distribution) on the grid plate 12 is a rectangular wave shape, it is projected onto the measurement target object 21 by the light emitted from the light source of the light source array 11 provided at the position of the distance d. The dimensional lattice has a substantially cosine wave shape on the image captured by the camera 13. It does not have to be strictly a cosine wave. In particular, the error can be canceled by using the all-space table forming method described later.

In the present embodiment, as shown in FIG. 2, it is arranged at equal intervals on each light source in the X-axis direction 6 of the light source _{L -2,} constituting _{L -1, L 0, L 1} , L 2 and _{L 3} The light source array 11 and the grating plate 12 are arranged in the Z-axis direction so as to be parallel in the X and Y axis planes. However, the light source array 11 can be arranged in the X and Y axis planes with z = 0 and inclined with respect to the X axis with the origin O as the center. That is, the light source array 11 does not have to be parallel to the X axis. In this case, as the interval l between the six light sources in the above description, the interval between the light sources in the X-axis direction (that is, the direction perpendicular to the straight line of the light transmission region 12b constituting the one-dimensional grating) (that is, six X-axis direction component of the interval between the light sources) is used. Although it is difficult to physically reduce the interval between the light sources, the interval between the light sources in the X-axis direction can be easily reduced by tilting the light source array 11 with respect to the X-axis as described above. Become. The grating plate 12 only needs to have a straight line of the light transmission region 12b parallel to the Y axis.

As shown in FIG. 2, in the present embodiment, six light sources _{L -2, L -1, L 0} , L 1, of the _{L 2} and _{L 3,} the light source sets of five light sources adjacently arranged two pairs Set. Specifically, five light sources _{L -2,} L _-1, the L 0, _{L 1} and _{L 2} and the first light source assembly 11a, five light sources _{L -1,} L _0, L 1, _{L 2} and L ₃ is a second light source set 11b. As will be described in detail later, each light source is sequentially turned on in each light source set, a one-dimensional lattice projected on the measurement target object 21 is photographed, and the phase of the one-dimensional lattice by each light source set is calculated. This is because the height coordinate z is obtained using the phase difference between the obtained two one-dimensional gratings as a phase shift amount. Even when the number of light source sets including five light sources arranged adjacent to each other is set to three or more, the phase shift amount can be accurately obtained by using a light source set including a light source having a predetermined origin O. For example, when three light source sets are set as the first, second, and third light source sets, the phase shift amount by the first and second light source sets, the phase shift amount by the second and third light source sets, and The amount of phase shift by the first and third light source sets can be obtained respectively. Therefore, even when the number of light source sets including five light sources arranged adjacent to each other is three or more, the height coordinate z is obtained by setting two light source sets for obtaining the phase shift amount among the three or more light source sets. Can do.

Referring to FIG. 1, the camera 13, six light sources _{L -2, L -1, L 0} , L 1, the measurement object one-dimensional lattice, each projected by one lighting of _{L 2} and _{L 3} The object 21 is photographed. As the camera 13, a CCD sensor, a CMOS sensor, or the like can be used. For the x and y coordinates, for example, the phase in the X-axis direction and the Y-axis direction are obtained by the Fourier transform grid method, and the phase connection is further performed to obtain the x-coordinate and y-coordinate at each point ( For example, see Japanese Patent No. 3281918).

  In addition, a member for enlarging or reducing an image such as a lens may be disposed between the light source and the grating plate 12 or between the grating plate 12 and the measurement target object 21.

  As shown in FIG. 3, the control unit 50 supplies a light source switching control signal for sequentially turning on the respective light sources in the respective light source sets 11a and 11b to the light source array 11 and measures the lighting of the respective light sources in turn. A camera control signal for photographing a one-dimensional lattice projected on the target object 21 is supplied to the camera 13 and an image signal obtained by photographing the one-dimensional lattice from the camera 13 is acquired. Further, the control unit 50 calculates the phase of the one-dimensional grating projected on the measurement target object 21 by each light source set 11a, 11b based on the luminance value for each pixel obtained from the captured image signal, A difference in phase between the two projected one-dimensional gratings calculated is determined as a phase shift amount, and a height coordinate related to the measurement target object 21 is obtained based on a predetermined conversion formula for determining a distance from the phase shift amount. More specifically, the control unit 50 includes a control unit 51 and a memory 52. The control unit 51 includes a light source determination unit 511, a camera photographing processing unit 512, a pixel-by-pixel luminance calculation unit 513, a phase / phase shift amount calculation unit 514, and a three-dimensional coordinate calculation unit 515.

  The light source determination unit 511 supplies the light source array 11 with a light source switching control signal for sequentially lighting each light source in each of the light source groups 11a and 11b.

  The camera photographing processing unit 512 supplies the camera 13 with a camera control signal for photographing a one-dimensional lattice projected on the measurement target object 21 by sequentially turning on each light source, and images of the images photographed from the camera 13. Get the signal.

  The pixel-specific luminance calculation unit 513 calculates a luminance value at each pixel position from the acquired image signal.

  The phase / phase shift amount calculation unit 514 calculates the phase of the one-dimensional grating by each of the light source groups 11a and 11b based on the luminance value for each pixel obtained from the image signal of the captured image, and obtains the obtained two one-dimensional values. A phase shift amount that is a difference in phase of the grating is calculated. Hereinafter, the process of obtaining the phase Φ and the phase shift amount Ψ is referred to as “phase analysis process”. Further, for example, x and y coordinates are obtained for each pixel from this phase by phase analysis using a Fourier transform lattice method.

  The three-dimensional coordinate calculation unit 515 obtains the height coordinate z from the phase shift amount obtained for each pixel in the measurement target object 21 based on a predetermined conversion formula, and stores the three-dimensional coordinate data of the measurement target object 21 in the memory. 52.

  In this phase analysis process, a table that associates the phase of the one-dimensional lattice with the spatial coordinates is created in advance for each pixel, and the spatial coordinates (from the phase of the one-dimensional lattice obtained from each pixel are referred to by referring to the table. That is, it is also possible to apply a whole space table formation method for obtaining the coordinates of the point S on the measurement target object 21). More specifically, as a function of the three-dimensional coordinate calculation unit 515 in the control unit 50, a three-dimensional coordinate composed of the x and y coordinates of the X axis and the Y axis determined by the pixel position of the camera 13 and the z coordinate of the Z axis. The relationship between the phase and the x and y coordinates, and the relationship between the phase shift amount and the x and y coordinates, for each z coordinate at a constant interval measured using a predetermined reference flat plate as disclosed in Patent Document 1. Are created and held in the memory 52, and the measurement target object 21 is referred to with reference to these tables held in the memory 52 from the phase and phase shift amount of the one-dimensional grating calculated for the measurement target object 21. What is necessary is just to comprise so that the three-dimensional coordinate regarding may be derived | led-out.

  That is, the control unit 50 calculates “the phase of the one-dimensional grating by the respective light source sets 11a and 11b” from the “brightness” of each pixel position obtained from the captured image of the camera 13, and “the respective light source sets 11a and 11b”. The phase shift amount, which is the phase difference between the two one-dimensional gratings obtained by the above, is calculated, and the “height coordinate z” in the measurement target object 21 is calculated from the phase shift amount based on a predetermined conversion formula. The x and y coordinates can be obtained from phase analysis by the Fourier transform lattice method, for example. Therefore, the z coordinate is obtained for each pixel of the camera 13, and the x and y coordinates are also obtained.

  Hereinafter, the measurement principle will be described more specifically with reference to FIG.

In the following description, (directional characteristics of the light-emitting) six light sources _{L -2, L -1, L 0} , each light emission luminance distribution of L 1, _{L 2} and _{L 3} are assumed to be equal and uniform in the observation range To do. If it is not uniform, the luminance value obtained from the captured image may be corrected using the distribution as a coefficient. An example in which the light source surface and the lattice surface are arranged in parallel will be described. Here, when the light source surface and the lattice surface are not parallel, the distance d between the light source surface and the lattice surface is a distance in the Z-axis direction from the origin O of the light source array 11 to the lattice surface of the lattice plate 12. The non-uniformity of the light emission luminance distribution (light emission directivity) of each light source may be corrected similarly.

First, the five light sources L _n sequentially lit in the light source assembly 11a, given that one-dimensional lattice is projected onto the measuring symmetric object 21. Here, n is given as -2, -1, 0, 1, 2 indicating the position of the light source with the origin O as 0. In this case, the transmittance distribution of the one-dimensional lattice in the z = d has become a cosine wave, the luminance distribution of the shadow of the one-dimensional grating which is illuminated by the light source L _n is expressed by the following equation.

Where Φ is the phase of the one-dimensional lattice, a _g is the amplitude, b _g is the background luminance, x _g is the x coordinate on the lattice plane, and e is between the reference point E (Φ = 0) and the point C on the lattice plane. Is the distance. Of the central positions of the light transmission regions 12b constituting the one-dimensional lattice of the lattice plate 12, the shortest distance from the Z axis is defined as a reference point E (Φ = 0), and the lattice plane of the lattice plate 12 and Z The intersection with the axis is C.

First, the five light sources _{L -2, L -1, L 0} , L 1 and of _{L 2,} the position S (x on the measurement object 21 to the one-dimensional grating is projected by the lighting of the light source _{L 0,} y, The luminance I ₀ in z) is approximately expressed by the following equation.

  Here, it is considered that the luminance at an arbitrary point is inversely proportional to the square of the distance from the light source. As shown in FIG. 1, a shadow of point G of the one-dimensional lattice on the lattice plane in FIG.

  At this time, there is a relationship of the following expression rather than a geometric relationship.

Next, when the light source is switched from L ₀ to L ₁ , the shadow of the point G is projected toward the point A on the (x, y) plane of the coordinate point z. At this time, a shadow of point F of the one-dimensional lattice is projected onto point S, and a phase shift occurs. Therefore, the point S has a different luminance value due to the phase shift amount caused by switching the light source.

Position S by the light source _{L 1 (x, y, z} ) between the luminance and the amount of phase shift Ψ in can be formulated as follows. That is, by switching the light source from L ₀ to L ₁ , the phase (unwrapped phase) of the one-dimensional grating projected onto the measurement target object 21 is shifted by an amount given by the following equation (4). . Note that unwrapping refers to a state in which phase characteristics are continuously connected to a phenomenon (wrapping) in which the obtained phase distribution is folded into a limited range.

This phase shift amount Ψ is obtained as follows. That is, a triangle composed of points L ₀ , L ₁ , G in FIG. 1 (hereinafter such triangle is represented as “ΔL ₀ L ₁ G”) and ΔSAG composed of points S, A, G are similar. Therefore, the following equation is obtained.

Further, since the point S, A, and becomes △ SAL ₁ from _{L 1,} point F, G, consists of _{L 1} △ FGL ₁ and is similar to, the following equation.

  From the equations (5) and (6), the following equation is obtained.

  Moreover, the following equation is obtained from the equations (4) and (7).

In this way, the value of the phase shift amount ψ of the one-dimensional grating projected onto the measurement target object 21 when the light source is switched from L ₀ to L ₁ can be formulated. It can be seen that this phase shift amount Ψ depends on z.

Similarly, by switching from the light source L ₀ to the light source L _n , the phase is shifted by n · Ψ as compared with the equation (2). Therefore, the luminance In at the position S (x, y, z) is _expressed by the following equation: Become. Note that n is given as -2, -1, 0, 1, 2 indicating the position of the light source with the origin O as 0.

  When this formula (9) is replaced using formula (8) and formulas (10) to (12), formula (13) is obtained.

Thus, when the light source was on L _n, the position S (x, y, z) the relationship between the luminance I _n and the phase Φ and the phase shift amount Ψ in can be formulated.

  When the reflectance r of the measurement target object 21 is taken into consideration, a and b in the equation (13) may be multiplied by the reflectance r, but are omitted here for the sake of simplicity.

  Therefore, in order to obtain the height coordinate z to the measurement target object 21, it is sufficient to know the phase shift amount Ψ or the phase Φ. The relationship between the height z and the phase shift amount ψ is obtained from the equation (8) as follows.

  Here, the distance in the Z-axis direction from the origin O of the light source array 11 to the surface of the measurement target object 21 is z, the interval between each light source of the light source array 11 is l, and the lattice plane of the lattice plate 12 from the origin O of the light source array 11 The distance in the Z-axis direction until is d, the phase shift amount is ψ, and the one-dimensional grating interval of the grating plate 12 is p. Thereby, the height z can be obtained. In this case, the isophase lines are contour lines.

  When the phase Φ is obtained, the following equation is obtained from the equation (12).

  Here, the distance in the Z-axis direction from the origin O of the light source array 11 to the surface of the measurement target object 21 is z, the distance in the Z-axis direction from the origin O of the light source array 11 to the lattice plane of the lattice plate 12 is d, and the lattice The phase of the one-dimensional grating of the plate 12 is Φ, the interval of the one-dimensional grating of the grating plate 12 is p, the distance in the X-axis direction from the origin O to the surface of the measurement target object 21 is x, and the one-dimensional grating of the grating plate 12 is The shortest distance from the Z-axis among the central positions of the respective light transmission regions 12b is e. Accordingly, when the phase Φ is obtained, the height z is obtained. In this case, the isophase line is a function of x and does not become a contour line.

Thus, five light _L in the light source assembly 11a _-2, L _-1, L 0, _{L 1} and _{L 2} only sequentially lit, it is possible to obtain the phase shift amount Ψ or phase [Phi, phase shift amount If Ψ or phase Φ can be obtained, the height z can be obtained from Expression (14) or Expression (15) regardless of the position of the camera 13. Similarly, the phase shift amount Ψ or the phase Φ can be obtained only by sequentially lighting the five light sources L ₋₁ , L ₀ , L ₁ , L ₂ and L ₃ in the light source set 11b, and the height z is set to Can be sought. However, in the present embodiment, the phase shift amount Ψ to further high accuracy, five light _L in the light source assembly 11a _-2, L _-1, L 0, _{L 1} and _{L 2} is sequentially turned that the The difference between the obtained phase Φ ₁ and the phase Φ ₂ obtained by sequentially lighting the five light sources L ₋₁ , L ₀ , L ₁ , L ₂ and L ₃ in the light source set 11 b is defined as a phase shift amount Ψ. . Before explaining the reason for achieving high accuracy by setting the phase shift amount Ψ by the difference of the phase Φ obtained by each light source set, a specific calculation method of the phase Φ and the phase shift amount Ψ by phase analysis and its problem The point will be described. This is because the problem due to the phase analysis can be improved by setting the phase shift amount Ψ by the difference of the phase Φ obtained in each light source group.

  Therefore, a method for obtaining the phase Φ and the phase shift amount ψ necessary for obtaining the height z will be described. As described above, the conventional phase shift method shifts the phase by 2π / N at every position by dividing the phase 2π by the integer N by directly moving the grating plate 12 of FIG. On the other hand, in the phase shift method according to the present invention, by sequentially selecting and lighting five light sources, the phase of the one-dimensional grating projected onto the measurement target object 21 is changed to the phase shift amount represented by the equation (8). The phase is shifted five times (including the initial position) at equal intervals by Ψ. This phase shift amount ψ is different from the conventional method because it is not normally obtained by dividing 2π into five equal parts. Further, as is clear from the equation (8), the phase shift amount Ψ varies depending on the value of z. Such a light source switching type phase shift method according to the present invention is referred to as an “optical stepping method” because the phase is stepped at equal intervals by light source switching.

FIG. 4 shows the relationship between the luminance of the sample point and the phase shift amount when the phase of the one-dimensional grating whose luminance changes like a cosine wave is phase-shifted at equal intervals by the phase shift amount ψ. In the optical stepping method, the phase Φ in the luminance I ₀ of the light source L ₀ located at the origin O is a phase to be obtained, and the phase is shifted by Ψ every time the light source L _n is switched and sequentially turned on. At this time, the luminance is expressed by the above equation (13), and when all n are written, equations (16) to (20) are obtained.

  Here, there are four unknowns, Φ, ψ, a, and b. From these equations, the wrapped value φ of the phase Φ and the wrapped value ψ of the phase shift amount ψ are respectively expressed by the following equations (21 ) And (22).

  By using these equations (21) and (22), the wrapped phase φ and the phase shift amount ψ can be easily obtained. In order to solve equation (13), five equations of equations (16) to (20) were used, but since the number of unknowns is four, if four of these five equations are used, Needless to say, four unknowns can be obtained. That is, in the present invention, for the light source array 11 in which at least five light sources are arranged at equal intervals and in a line, at least two light source sets composed of at least four light sources adjacent to each other are set. The light source is sequentially turned on and a one-dimensional grid projected on the measurement target object 21 is photographed by the camera 13 to obtain a luminance value. Accordingly, the phase φ and the phase shift amount ψ that are phase-shifted by sequentially lighting the at least four light sources can be obtained.

Thus, five light _L in the light source assembly 11a _-2, L _-1, L 0, _{L 1} and _{L 2} only sequentially lit, it is possible to obtain the phase shift amount Ψ or phase [Phi, phase shift amount If Ψ or phase Φ can be obtained, the height z can be obtained from Expression (14) or Expression (15) regardless of the position of the camera 13. Similarly, the phase shift amount Ψ or the phase Φ can be obtained only by sequentially lighting the five light sources L ₋₁ , L ₀ , L ₁ , L ₂ and L ₃ in the light source set 11b, and the height z is set to Can be sought.

However, in the present embodiment, the phase Φ ₁ obtained by sequentially lighting the five light sources L ₋₂ , L ₋₁ , L ₀ , L ₁ and L ₂ in the light source set 11a and the five light sources in the light source set 11b. The height z is obtained by using the difference from the phase Φ ₂ obtained by sequentially lighting L ₋₁ , L ₀ , L ₁ , L ₂ and L ₃ as the phase shift amount Ψ.

  When the phase shift amount Ψ of the equation (22) is obtained by experiment, the error increases near the denominator being close to 0, and the variation is large over the entire range. In addition, since the phase shift amount Ψ in Expression (22) is obtained from cos Ψ, if there is an error, the right side of Expression (22) may exceed between −1 and 1, and in this case, Ψ cannot be obtained. . On the other hand, the phase Φ can be obtained with considerably high accuracy using the equation (21).

Therefore, in order to separately obtain the highly accurate phase shift amount ψ rather than obtaining the phase shift amount ψ with a single light source set, the five light sources L ₋₂ , L ₋₁ , L ₀ , L ₁ in the light source set 11 a are obtained. and a phase [Phi ₁ obtained by sequentially lighting the _{L 2,} 5 one light source _L -1 in the light source group _11b, and L _0, L 1, _{L 2} and phase [Phi ₂ obtained by sequentially lighting the _{L 3} Is the phase shift amount ψ.

  That is, the phase shift amount Ψ using two light source sets is obtained by the following equation.

Since both the phase Φ ₁ and the phase Φ ₂ can be obtained with high accuracy, the phase shift amount ψ obtained by the equation (23) can also be obtained with high accuracy.

By using the phase shift amount ψ shown by the equation (23), it is possible to improve the accuracy of the phase connection. That is, the relationship between cos ψ and z determined from Equation (14) and Equation (22) is a monovalent function of ψ over a wide range of z, as can be seen from FIG. Further, as can be seen from FIG. 10 described later, the relationship between tan φ and z determined from the equations (15) and (21) is a multivalent function of z, and can be treated as a monovalent function. Only a narrow range of z. Therefore, z in a wide range cannot be determined only by the phase φ. Therefore, z is obtained using the phase shift amount ψ, and fine and accurate z is obtained using the phase φ (that is, the phase φ ₁ and the phase φ ₂ ) from the relationship of the equation (15) near the z. Can do. Alternatively, _two z values can be obtained from the two data of the phase φ ₂ and the phase φ ₁ , so that taking the average increases the accuracy accordingly.

  Next, the operation of the shape measuring apparatus 1 of the present embodiment will be described with reference to FIG.

  First, the light source determination unit 511 of the control unit 50 selects one of the two light source sets 11a and 11b (step S1).

  Subsequently, the light source determination unit 511 of the control unit 50 turns on one of the five light sources constituting the selected light source set (for example, the light source set 11a) (step S2).

  Subsequently, the camera imaging processing unit 512 of the control unit 50 captures an image of the measurement target object 21 onto which the one-dimensional lattice is projected via the lattice plate 12 (step S3).

  Subsequently, the camera imaging processing unit 512 of the control unit 50 determines whether or not all five light sources constituting the selected light source set have been photographed (step S4). If all five light sources have been photographed (Y in step S4), the process proceeds to step S5. On the other hand, if all five light sources are not photographed (N in step S4), steps S2 and S3 are repeated until all five light sources are photographed. Thereby, it is possible to obtain an image signal obtained by photographing the measurement target object 21 while sequentially turning on the five light sources and shifting the phase of the one-dimensional grating projected onto the measurement target object 21. This image signal can be obtained as a luminance value for each pixel.

  That is, the pixel-by-pixel luminance calculation unit 513 of the control unit 50 determines each of the five types of luminance values for the selected light source set for each pixel of the camera (step S5).

  Subsequently, the phase / phase shift amount calculation unit 514 of the control unit 50 calculates the phase φ of the projected one-dimensional grating from the five types of luminance values (step S6).

  Furthermore, the light source determination unit 511 of the control unit 50 determines whether or not all light source groups have been selected (step S7). When all the light source groups have been selected (Y in step S7), the process proceeds to step S8. On the other hand, when all the light source groups are not selected (N in step S7), steps S1 to S6 are repeated until all the light source groups are selected. Thereby, the phase of the projected one-dimensional grating by each light source set is obtained.

Subsequently, the phase / phase shift amount calculation unit 514 of the control unit 50 calculates the phase shift amount ψ represented by the difference from the phases φ = Φ ₁ and Φ ₂ obtained from the two light source sets (step S8). .

  Subsequently, the three-dimensional coordinate calculation unit 515 of the control unit 50 calculates the height coordinate z from the calculated phase shift amount Ψ based on the equation (14), and determines the three-dimensional coordinate of the measurement target object 21 (step). S9). In this manner, the shape of the measurement target object 21 can be obtained by performing phase analysis processing on the captured image by the optical stepping method. In the operation flow shown in FIG. 5, the example in which the phase is calculated by imaging for each light source set has been described. However, after imaging with all the light sources, the operation may be performed to calculate the phase by setting the light source set. it can.

Accordingly, for example, as shown in FIG. 8, two phases Φ ₁ and Φ ₂ are calculated from the luminance values obtained by imaging with the respective light sources to calculate the phase shift amount Ψ, and the two phases Φ ₁ and Φ are calculated. _The three-dimensional coordinate table can be generated with high accuracy by calculating the height coordinate z using ₂ and the phase shift amount Ψ and obtaining the x and y coordinates from the phase analysis by the Fourier transform lattice method, for example.

  In FIG. 1, the arrangement of the components other than the light source array 11 is fixed in the three-dimensional space of the X axis, the Y axis, and the Z axis, and the light source array 11 is centered on the origin O in the plane of z = 0. And tilted with respect to the X axis. That is, the light source array 11 does not have to be parallel to the X axis. In this case, as the interval l between the six light sources, a component in the X-axis direction of the interval between the six light sources is used. Although it is difficult to physically reduce the interval between the light sources, the interval between the light sources in the X-axis direction can be easily reduced by tilting the light source array 11 with respect to the X-axis as described above. Become.

In FIG. 1, the light sources L constituting the light source array 11 in the plane of z = 0 in a state where the arrangement of the components other than the light source array 11 is all fixed in the three-dimensional space of the X axis, the Y axis, and the Z axis. ₋₂ , L ₋₁ , L ₀ , L ₁ , L _2, and L ₃ can be arranged at arbitrary positions in the Y-axis direction. That is, the light source _{L -2,} L _-1 constituting the light source array _{11, L 0, L 1,} L 2 and _{L 3,} it is sufficient equally spaced as the distance component in X-axis direction.

[Second Embodiment]
Next, the shape measuring apparatus according to the second embodiment using the reference surface according to the present invention will be described. FIG. 7 is a diagram showing the configuration and operating principle of the shape measuring apparatus 2 according to the second embodiment of the present invention. Components similar to those in FIG. 1 are denoted by the same reference numerals.

  In contrast to the configuration of the shape measuring apparatus 1 shown in FIG. 1, the shape measuring apparatus 2 of the second embodiment is a reference parallel to the grid plate 12 at a position away from the light source surface by a distance zR in the Z-axis direction. The difference is that a reference flat plate 14 having a surface 14a is further provided. The shape measuring apparatus 2 according to the second embodiment separates the grid plate 12 on the reference flat plate 14 on which the measurement target object 21 can be placed, in addition to projecting and shooting the one-dimensional grid of the grid plate 12 on the measurement target object 21. The phase difference between the measurement target object 21 and the reference plane 14a is measured by projecting and photographing the one-dimensional lattice of the above, and the height of the measurement target object 21 is calculated based on a predetermined conversion formula from this phase difference. The three-dimensional shape is measured by obtaining z.

  In the second embodiment, the center V of the lens of the camera 13 is disposed at a predetermined position (X = v) in the X-axis direction. That is, the distance in the X-axis direction from the origin O to the center V of the lens is v. Note that, as in the first embodiment, the measurement target object 21 is disposed between the lattice plate 12 and the reference flat plate 14. In FIG. 7, the state of the phase φ = 0 to 5π of the one-dimensional grating obtained from the origin O through the grating plate 12 is indicated by a dotted line, and the phase φ passing through the bright center of the grating on the grating surface is an even number π, The phase φ passing through the dark center of the lattice of the lattice plane is an odd number π.

In the shape measuring apparatus 2 in the second embodiment, first, a one-dimensional lattice by each light source of the light source set 11a is projected onto the reference plane 14a under the control of the light source determination unit 511 in the control unit 50, and the camera photographing processing unit 512 A one-dimensional grid formed by each light source projected onto the reference plane 14a is photographed under control, the luminance value of each pixel by each light source is calculated by the pixel-specific luminance calculation unit 513, and the phase Φ _R1 is calculated by the phase / phase shift calculation unit 514. The distribution is recorded in the memory 52. Next, the measurement target object 21 is arranged between the reference plane 14a and the grid plate 12, and 1 projected by the respective light sources of the light source set 11a at the point S on the measurement target object 21 as in the first embodiment. Determine the phase Φ _{S1 of the} dimensional grating. Subsequently, from the phase difference (Φ _S1 −Φ _R1 ) between the reference plane 14 a and the point S on the measurement target object 21 in each pixel of the camera 13, from the origin O in the light source set 11 a by the three-dimensional coordinate calculation unit 515. The height z in the Z-axis direction or the height h _S = z _R −z of the measurement target object 21 from the reference plane 14a is obtained. Similarly, from the phase difference (Φ _S2 −Φ _R2 ) with respect to the point S by each light source of the light source set 11b, the height z in the Z-axis direction from the origin O or the height of the measurement target object 21 from the reference plane 14a. H _S = z _R −z is obtained. Further, similarly to the first embodiment, from the phase shift amount (Φ _S2 −Φ _S1 ), the height z in the Z-axis direction from the origin O or the height h _S = z of the measurement target object 21 from the reference plane 14a. _R- z is obtained. A precise and accurate z can be obtained using the phase shift amount (Φ _S2 −Φ _S1 ), and two z can be obtained from the two data of the phase Φ _S2 and the phase Φ _S1. If the average is taken, the accuracy will increase accordingly.

  The principle will be described in detail below.

Now, one pixel U of the camera 13 arranges the measurement target object 21 at a point R on the reference plane 14a when the measurement target object 21 is not arranged between the grid plate 12 and the reference flat plate 14. Assume that the user is looking at a point S on the measurement target object 21 when he / she is performing. The phase at the point S of the one-dimensional grating projected onto the measurement target object 21 by any one of the light source groups 11a and 11b is Φ _S , and the phase at the point R is Φ _R. Let Q be the intersection of the straight lattice plane 12a connecting the point R and the origin O. At this time, the phases Φ _S and Φ _R are the same as the phases of the one-dimensional grating at the points G and Q, respectively, and the relationship of the following equation is obtained from the phase difference between them.

  Since ΔSPO consisting of points S, P, and O is similar to ΔGQO consisting of points G, Q, and O, the following equation is obtained.

  From the equations (24) and (25), the following equation is obtained.

  Further, since ΔSPR composed of points S, P, and R and ΔVOR composed of points V, O, and R are similar, the following equation is obtained.

  From the equations (26) and (27), the following equation is obtained.

  From this equation (28), the following equation is obtained for the height z.

Here, the distance in the Z-axis direction from the light source array 11 to the surface of the measurement target object 21 is z, the distance in the Z-axis direction from the origin O to the grating surface of the grating plate 12 is d, and the center V of the lens from the origin O The distance from the origin O to the reference surface 14a of the reference flat plate 14 in the Z-axis direction, z _R , the distance between the one-dimensional gratings of the grating plate 12, and the distance from the origin O to the surface of the measurement target object 21. The phase of the projected one-dimensional grating at the distance x in the X-axis direction is Φ _S , and the projection at the intersection of the reference plane 14a and a straight line passing through the surface position of the measurement target object 21 at the distance x and the center V of the lens. It has a phase of one-dimensional lattice which is a [Phi _R. Thus, based on equation (29), the phase [Phi _S phase [Phi _R and a point S on the measurement object 21 in the reference plane 14a of the pixels of the camera 13, the light source assembly 11a, of the point S in each of 11b The z coordinate can be determined. Further, the equiphase difference (Φ _S −Φ _R ) line is a contour line. Further, similarly to the first embodiment, z or the height h _S = z _R −z of the measurement target object 21 from the reference plane 14a can be obtained from the phase shift amount (Φ _S2 −Φ _S1 ).

  As for the x coordinate and the y coordinate, as in the case of the first embodiment, each phase is obtained by obtaining the phase in the X axis direction and the Y axis direction by, for example, the Fourier transform grid method, and further performing phase connection. X coordinate and y coordinate can be obtained respectively.

  As in the case of the first embodiment, in the second embodiment as well, the arrangement of the components other than the light source array 11 is fixed in the three-dimensional space of the X axis, the Y axis, and the Z axis, and the light source array 11 is used. In the plane of z = 0, and can be arranged inclined with respect to the X axis with the origin O as the center. That is, the light source array 11 does not have to be parallel to the X axis. In this case, as the interval l between the six light sources, a component in the X-axis direction of the interval between the six light sources is used. Although it is difficult to physically reduce the interval between the light sources, the interval between the light sources in the X-axis direction can be easily reduced by tilting the light source array 11 with respect to the X-axis as described above. Become.

In FIG. 1, the light sources L constituting the light source array 11 in the plane of z = 0 in a state where the arrangement of the components other than the light source array 11 is all fixed in the three-dimensional space of the X axis, the Y axis, and the Z axis. ₋₂ , L ₋₁ , L ₀ , L ₁ , L _2, and L ₃ can be arranged at arbitrary positions in the Y-axis direction. That is, the light source _{L -2,} L _-1 constituting the light source array _{11, L 0, L 1,} L 2 and _{L 3,} it is sufficient equally spaced as the distance component in X-axis direction.

Thus, the coordinates x, y, and z of the point S on the measurement target object 21 can be obtained, and the shape of the measurement target object 21 can be obtained. For example, as shown in FIG. 8, by controlling the control unit 50, two phases Φ _S1 and Φ _S2 are calculated from the luminance values of the pixels captured by the light sources of the two light source groups 11a and 11b, respectively. The phase shift amount Ψ = Φ _S2 −Φ _S1 is calculated, and the phase connection is made using the calculated phase shift amount Ψ and the phase difference (Φ _S1− Φ _R1 ) and (Φ _S2− Φ _R2 ), and the height coordinate z Can be generated and stored in the memory 53. Note that the control unit 50 is configured to display a three-dimensional image of the measurement target object 21 on a display device (not shown) connected to the shape measuring device 2 using the three-dimensional coordinate table. You can also.

Also in the second embodiment of the present invention, the shape measurement of the measurement target object 21 can be performed at a higher speed by applying the total space table formation method (see, for example, JP-A-2008-281491). That is, as shown in FIG. 7, a reference plate 14 having a reference surface 14a on which a two-dimensional lattice arranged parallel to the lattice surface 12a is drawn (or projected) is prepared. The reference plane 14a is photographed while being moved by a predetermined minute amount in the direction, and a phase analysis process is performed on the photographed image, whereby the x and y coordinates are determined for each pixel of the camera 13, and the phase is also determined. The relationship between the shift amount Ψ, the phase Φ, the phase difference (Φ _S −Φ _R ), and the height z is determined and stored in advance in the memory 52 as a table. At the time of measurement of the measurement object 21, the phase Φ is calculated from the luminance obtained for each pixel by referring to the table prepared in advance for each pixel, and the phase shift is performed based on the calculated phase Φ. The value of the height z can be obtained by calculating the quantity Ψ and the phase difference (Φ _S −Φ _R ).

  In this total space table formation method, it is only necessary to refer to a table for each pixel prepared in advance, and there is almost no need to perform geometric calculation used in triangulation or the like, so that the shape of the measurement target object 21 can be further increased. Can be sought.

(Specific verification of the relationship between z and Ψ, Φ, Φ _S, and Φ _R )
Here, the relationship between the height z and Ψ and Φ will be described more specifically. Expressions (14) and (15) described above represent the relationship between the phase Φ (and the phase shift amount Ψ) and the height z, and Ψ and Φ, or (Φ _S −Φ _R ) can be obtained. The height z can be obtained using any of these equations. However, in practice, determined tan represented by formula (21) and equation (22), cos, as tan _S and tan _R. These phases (and the amount of phase shift) are wrapped and output with being limited to 2mπ ≦ Φ ≦ 2 (m + 1) π or qπ ≦ ψ ≦ (q + 1) π. Here, m and q are integers. In general, it is limited when m = 0 and q = 0. Therefore, using tanΦ, cos Ψ, tanΦ _S, and tanΦ _R , the relationship between these and the height z was specifically obtained as follows.

As an example, consider the case where the light source array 11 is composed of five light sources, and consider the case where l = 0.5 mm, d = 10 mm, p = 0.5 mm, v = 50 mm, z _R = 500 mm and e = 0 mm. At this time, the relationship between z and cos Ψ obtained using equation (14) is as shown in FIG.

  On the other hand, z obtained using equation (15) is a function of x. Here, an equation of a straight line passing through the intersection point I between the reference plane 14a and the Z axis and a certain pixel of the camera 13 looking at the intersection point I is as follows.

  Substituting this equation (29) into equation (12) to eliminate x yields the following equation:

  FIG. 10 shows the relationship between z and tan Φ given by this equation (30).

For example, five light sources _L -2 in the light source assembly _11a, L _-1, by L 0, _{L 1} and sequential lighting for shooting the _{L 2,} can be carried out five times the phase shift at high speed, FIG. 9 and The phase of FIG. 10 is obtained.

Similarly, if the phase distribution of the reference surface 14a is obtained in advance, the phase indicating the relationship between z obtained using the equation (28) and (Φ _S −Φ _R ) wrapped in the range of 0 to 2π. A distribution is also obtained at the same time (see FIG. 11) and can be held in the memory 52.

  Therefore, the height z can be obtained by using any of the characteristics shown in FIGS. 9, 10 and 11 obtained in one preliminary experiment. However, the relationship between the height and the phase can be obtained only in a range where the correspondence between the height and the phase is 1: 1. That is, only the range of 2mπ ≦ Φ ≦ 2 (m + 1) π or qπ ≦ ψ ≦ (q + 1) π can be analyzed.

As described above, in FIG. 9, cos Ψ has a monotonically increasing or decreasing range over a wide range of z. Therefore, it can be said that the resolution is low, but the dynamic range is wide. On the other hand, in FIG. 10 or FIG. 11, since the range of z in which tan Φ or (Φ _S −Φ _R ) monotonously increases or decreases monotonically is narrow, the dynamic range is narrow, but it can be said that the resolution is high.

  Therefore, in the relationship between z and cos Ψ shown in FIG. 9, a height z having a slightly poor resolution is obtained in advance, and in the relationship of FIG. 10 or FIG. 11, a one-to-one correspondence in the vicinity of z obtained in advance is established. Find the value of z with high resolution in the range. Thereby, the height z can be obtained with high accuracy over a wide range. Furthermore, by using the phase shift amount Ψ of the equation (23) according to the present invention, the value of z can be obtained with higher accuracy.

Further, in the second embodiment, when the center V of the lens of the photographing apparatus 13 is the origin O, v = 0 and x = 0, and Φ = 0 from the equation (12), and the height z in FIG. In the relationship between tanΦ and tanΦ, the height z is indefinite and not determined. Thus, in FIG. 10, the relationship between the height z and the phase Φ varies greatly depending on the position, and the accuracy also varies greatly depending on the position. Therefore, the relationship between the height z and tan Φ shown in FIG. 10 is not used, the relationship between z and cos Ψ shown in FIG. 9 and the height z and phase difference (Φ _S −Φ _R ) shown in FIG. It is preferable to use a combination of these.

Further, similarly to the first embodiment, by obtaining z or the height h _S = z _R −z of the measurement target object 21 from the reference surface 14a from the phase shift amount (Φ _S2 −Φ _S1 ), it is possible to obtain a higher value. The accuracy z can be determined.

  In addition, it is conceivable that sufficient accuracy can be obtained with z obtained each time in Expression (14) or Expression (15), but Expression (14) or Expression (15) is directly used when the total space table formation method is used. It does not have to be.

  In this way, by sequentially calculating or holding the entire space table indicating the conversion formula between the phase Φ and the coordinates x, y, and z or the phase shift amount Ψ and the coordinates x, y, and z in advance, on the measurement target object 21 The coordinates x, y, and z are obtained from the phase Φ of the point S and the phase shift amount ψ, and the shape of the measurement target object 21 can be obtained.

  In the first embodiment and the second embodiment, various constraint conditions are provided for the arrangement of the light sources and the lattice planes. However, if there is some unevenness in the light emission luminance distribution of the six light sources, the point light source is completely If the area of the camera 13 is not constant and the spacing between the LEDs is not constant and slightly different, or if the lens position of the camera 13 is slightly off the light source surface, the components arranged in parallel are parallel. Even when the luminance distribution of the one-dimensional grating is slightly deviated from the cosine wave, there is a relationship between the measured phase Φ and the height z by the phase analysis using the reference plane 14a. As long as it changes monotonously and has a one-to-one correspondence, these errors can be canceled and the shape of the measurement target object 21 can be obtained with high accuracy.

More specifically, in creating the entire space table using the reference surface 14a, first, the phase Φ ₁ and the height z of the phase Φ ₁ and the height z are calculated using Equation (21) with five phase shifts by the first light source set 10a. Seeking a relationship. Next, the relationship between the phase Φ ₂ and the height z is obtained using Expression (21) with five phase shifts by the second light source set 10b. At the same time, the phase shift amount ψ = Φ ₂ −Φ ₁ is obtained, and the relationship between the phase shift amount ψ and the height z is obtained. While changing the position of the z coordinates of the reference surface 14a at regular intervals Repeat this procedure to store in search of relationship between the phase [Phi ₁ and height z as a table T ₁ into the memory 52. Similarly, the relationship between the phase Φ ₂ and the height z is obtained as a table T ₂ and stored in the memory 52. Further, the relationship between the phase shift amount ψ (= Φ ₂ −Φ ₁ ) and z is obtained as a table T ₃ and stored in the memory 52. Using the tables T ₁ , T ₂ , T ₃ , interpolation is performed to obtain tables having z values z ₁ , z _2, and z ₃ for the phases Φ ₁ , Φ ₂ and the phase shift amount Ψ at regular intervals. , Each table T ₁ ', T ₂ ' and T ₃ 'is generated. As can be seen from FIGS. 9, 10, or 11, for the range in which the relationship between Ψ and z is 1: 1, the relationship between Φ ₁ , Φ _2, and z is Φ ₁ , Φ with respect to z _{Since 2} is a multivalent function, it is preferable to generate these tables T ₁ ′, T ₂ ′, and T ₃ ′.

Then, when placing the measuring object 21, first, obtains a phase [Phi ₁ in five phase shift by the first light source group 10a, then, at five phase shift by the second light source group 10b The phase Φ ₂ is obtained, and the phase shift amount ψ is obtained from these differences. Then, the height z ₃ is obtained by referring to the table T ₃ ′. Even with this alone, the value of the height z can be obtained with considerably high accuracy. Further, among the tables T ₁ ′ and T ₂ ′, by using the phase Φ ₁ and the phase Φ ₂ in the range in which the relationship between the phases Φ ₁ and Φ ₂ near the height z ₃ and the height z is a monovalent function. , Heights z ₁ and z ₂ are uniquely determined. That is, the height z ₁ is obtained from the phase Φ ₁ with reference to the table T ₁ ′. Furthermore, the height z ₂ is obtained from the phase Φ ₂ with reference to the table T ₂ ′. Finally, the obtained z ₁ and z ₂ values are averaged to obtain the desired z value. Thereby, z can be obtained with high accuracy.

Further, based on the coordinate values x and y in the x and y directions, respectively, the entire space table forming method can be applied to the phases Φ ₁ and Φ ₂ and the phase shift amount Ψ, and the x, The three-dimensional coordinates of y and z can be obtained.

  That is, in the shape measuring apparatus 1 according to the first embodiment, the use of the total space table method improves the accuracy and increases the measurement speed. In the shape measuring apparatus 2 according to the second embodiment, when the reference flat plate 14 and the total space table forming method are used, not only the measurement speed is increased, but also the accuracy is improved. In the first embodiment and the second embodiment, the example using the predetermined reference flat plate (the reference flat plate 14 in the second embodiment) having the reference plane arranged in parallel to the lattice plane has been described. By using the spatial table formation method, the relationship between the phase of the projected one-dimensional grating and the three-dimensional coordinates can be tabulated and stored in the memory 52. Need not be arranged in parallel. For example, the X axis and the Y axis are taken on the reference flat plate 14, and the Z axis is taken in a direction perpendicular to the reference plane 14a. Even when a projector (not shown) that projects a two-dimensional lattice indicating coordinate values x and y onto the reference flat plate 14 by using this total space table forming method, the positions of the projector, the light source array 11 and the camera 13 are determined. It becomes possible to arrange freely. Therefore, when a predetermined reference flat plate is used in the shape measuring apparatus according to the present invention, it is effective to apply the total space table method in that the reference flat plate need not be arranged parallel to the lattice plane. .

  The control unit 50 in each embodiment can be configured as a computer. When the control unit 50 is configured as a computer, a program for causing the computer to realize each component of the control unit 50 is stored in a memory. 52. The central processing unit (CPU) provided in the computer reads a program or processing data in which processing contents for realizing the function of each component are described from the memory 52 as appropriate, and each component of the control unit 50 Can be realized on a computer. Here, it goes without saying that the function of each component may be realized by a part of hardware.

  According to the present invention, the phase shift can be performed at high speed by sequentially switching at least five light sources, and the shape of the measurement target object can be measured at high speed and with high accuracy. It is useful for medical, and applications such as stereoscopic observation and stereoscopic measurement of small organisms.

DESCRIPTION OF SYMBOLS 1, 2 Shape measuring device 11 Light source array 12 Grating plate 12a Grating light shielding area 12b Grating light transmission area 13 Camera 14 Reference flat plate 14a Reference plane 21 Measurement object 50 Control unit 51 Control part 52 Memory 511 Light source determination part 512 Camera Imaging processing unit 513 Pixel-specific luminance calculation unit 514 Phase / phase shift amount calculation unit 515 Three-dimensional coordinate calculation unit L ₋₂ , L ₋₁ , L ₀ , L ₁ , L ₂ , L ₃ Light source U Pixel V imaging of imaging device Device lens center

Claims (7)

A shape measuring device that measures the shape of an object to be measured without contact,
A light source array in which at least five light sources are arranged linearly at equal intervals;
A lattice plate having a lattice plane of a one-dimensional lattice configured by arranging light transmission regions composed of straight lines perpendicular to the straight line in which the at least five light sources are arranged at equal intervals with respect to the light shielding region;
A camera that captures a measurement target object onto which the one-dimensional grating is projected by sequentially turning on the at least five light sources;
Two sets of light sources composed of at least four light sources arranged adjacent to each other among the at least five light sources are set, and the light source array is controlled to sequentially turn on the light sources in the two sets of light sources. The camera is controlled so as to photograph one-dimensional gratings that are sequentially turned on and projected onto the measurement target object, and the phase of the one-dimensional grating projected onto the measurement target object by the two light source sets is determined. A control unit for calculating a height coordinate related to the measurement target object based on a predetermined conversion formula for determining a distance from the phase shift amount using a difference between the calculated two phases as a phase shift amount,
A shape measuring device comprising: The predetermined conversion formula for determining the distance from the phase shift amount is based on the arrangement direction of the respective light transmission regions of the lattice plate as the X axis, with one point on the straight line where the at least five light sources are arranged as the origin. A straight line of the light transmission region is defined as a Y-axis, a normal direction of a lattice plane of the lattice plate is defined as a Z-axis, a distance in the Z-axis direction from the origin of the light source array to the surface of the object to be measured is z, and the light source When the interval between the light sources of the array is l, the distance in the Z-axis direction from the origin of the light source array to the grating plane is d, the phase shift amount is ψ, and the interval of the one-dimensional grating is p,
The control unit has means for obtaining a height coordinate relating to the measurement target object based on a predetermined conversion formula for determining a distance from the phase of the projected one-dimensional grating, and arranging the at least five light sources With one point on the straight line as the origin, the arrangement direction of the light transmission regions of the lattice plate is the X axis, the straight line of the light transmission region is the Y axis, and the normal direction of the lattice plane of the lattice plate is the Z axis The distance in the Z-axis direction from the origin of the light source array to the surface of the object to be measured is z, the distance in the Z-axis direction from the origin of the light source array to the grating plane is d, and the phase of the one-dimensional grating Φ, the interval of the one-dimensional grating p, the distance in the X-axis direction from the origin to the surface of the object to be measured, x, and the Z of the center positions of the light transmission regions constituting the one-dimensional grating Shortest from axis When the release was e,
  The control unit further includes a reference plate having a reference surface arranged so that the one-dimensional grating is projected, and the control unit sets two sets of light sources composed of at least four light sources adjacent to each other among the at least five light sources. And controlling the light source array so that each light source in the two light source sets is sequentially turned on, and simultaneously turning on each light source and photographing the one-dimensional lattice projected on the reference plane. Means for controlling and calculating the phase of the one-dimensional grating projected on the reference plane by the two sets of light sources and holding them in the memory; and holding each of the two sets of light sources in the memory The difference between the phase of the one-dimensional grating projected on the reference plane and the phase of the one-dimensional grating projected on the measurement target object is calculated, and the distance is determined from the difference. Characterized in that it comprises a means for determining the height coordinates for the measurement target object based on a predetermined conversion formula, the shape measuring apparatus according to any one of claims 1 to 3. The predetermined conversion formula for determining the distance from the difference is that the arrangement direction of the respective light transmission regions of the lattice plate is the X axis, with one point on the straight line where the at least five light sources are arranged as the origin, and the light transmission. The straight line of the region is the Y axis, the normal direction of the lattice plane of the lattice plate is the Z axis, the distance from the origin of the light source array to the surface of the object to be measured is z, the distance of the light source array The distance in the Z-axis direction from the origin to the lattice plane is d, the distance from the origin to the center of the lens of the camera is v, the distance in the Z-axis direction from the origin to the reference plane is z _R , 1 The interval of the three-dimensional grating is p, the phase of the projected one-dimensional grating at the distance x in the X-axis direction from the origin to the surface of the measurement target object is Φ _S , and the surface of the measurement target object of the distance x The position and the label A straight line passing through the center of the figure, when the phase of the one-dimensional lattice which is the projection of the intersection between the reference plane and the [Phi _R,
  The control unit performs z-coordinates at regular intervals measured using the reference plate for three-dimensional coordinates composed of x- and y-coordinates of the X-axis and Y-axis determined by the pixel position of the camera and a z-coordinate of the Z axis. And a means for creating a table for associating the relationship between the phase and the x, y coordinates and the relationship between the phase shift amount and the x, y coordinates and storing the table in the memory, and calculating the measurement target object A means for deriving three-dimensional coordinates relating to the measurement target object from the phase of the one-dimensional grating and the phase shift amount with reference to a table held in the memory. The shape measuring device according to any one of the above. A light source array in which at least five light sources are arranged in a straight line at equal intervals, and a light transmission region composed of straight lines perpendicular to the straight line in which the at least five light sources are arranged are arranged at equal intervals with respect to the light shielding region. A shape measuring apparatus comprising: a lattice plate having a lattice plane of a one-dimensional lattice, a camera for photographing a measurement target object onto which the one-dimensional lattice is projected by sequentially turning on the at least five light sources, and a control unit. A shape measuring method for measuring the shape of the measurement target object by:
The processing of the control unit is as follows:
Setting two sets of light sources composed of at least four light sources arranged adjacent to each other among the at least five light sources;
Controlling the light source array to sequentially turn on each light source in the two light source sets;
Controlling the camera to illuminate each of the light sources sequentially and capture a one-dimensional grid projected onto the object to be measured;
Calculating each phase of the one-dimensional grating projected onto the measurement target object by the two sets of light sources;
Calculating a height coordinate related to the measurement target object based on a predetermined conversion formula for determining a distance from the phase shift amount, using the calculated difference between the two phases as a phase shift amount;
A shape measuring method comprising: