JPH0567198A - Three-dimensional shape measuring instrument - Google Patents

Abstract

PURPOSE:To provide a three-dimensional shape measuring instrument which has a high resolution and has excellent characteristics by resolving the problem that the measurement resolving power is limited by the width of photodetectors constituting an array type position detecting element at the time of using the array type position detecting element. CONSTITUTION:This instrument is provided with a first array type position detecting element 105, a semitransparent mirror 108, a second array type position detecting element 111, a first three-dimensional shape calculating means 106, and a second three-dimensional shape calculating means 112, and the first three- dimensional shape calculating means 106 acquires height information of a high resolution in the X-axis direction by the output signal of the first array type position detecting element 105, and the second three-dimensional shape calculating means 112 acquires height information of a high resolution in the Y-axis direction by the output signal of the second array type position detecting element 111, and two height information are interpolated to obtain height information of high resolution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional shape measuring device for measuring the three-dimensional shape of an object to be measured without contact,
In particular, the present invention relates to a three-dimensional shape measuring apparatus that measures the shape of an object to be measured using the light section method.

[0002]

2. Description of the Related Art Conventionally, as a method for measuring a three-dimensional shape, there are a light section method, a stereo vision method, a moire topography method, etc., and a non-contact type three-dimensional measuring apparatus using these methods has been put into practical use. Have begun. Among these methods, the light-section method is particularly widely used because it is excellent in measurement accuracy, processing speed, data processing amount, and easiness of making a device. In the normal optical cutting method, CC is used as an image pickup device.
Since a scanning image pickup device such as a D camera is used, the time for inputting one slit image is one field (1/60
Second) or 1 frame (1/30 second). Therefore, it takes several seconds to obtain the shape data of the entire DUT.
It takes 10 seconds or more, and there is a problem that it cannot be used for applications requiring high speed. In order to solve this problem, a shape measuring apparatus using a non-scanning type image pickup device has been devised and a patent has already been applied (Japanese Patent Laid-Open No. 64-46605). The present invention is a method of using an image pickup device in which a plurality of one-dimensional position detection elements are arranged in the image pickup device in the optical cutting method. Since each device can perform signal processing and position calculation in parallel, the image pickup device is connected to the image pickup surface. The position of the imaged slit image can be detected almost in real time. Therefore, the above invention (Japanese Patent Laid-Open No. 64-4)
6605), the measurement time can be drastically shortened. Therefore, a moving object or a moving body that cannot be measured by a conventional shape measurement device using a scanning imaging device can be measured. It is possible to measure shapes such as.

FIG. 5 is a diagram showing an example of block connection of the three-dimensional shape measuring apparatus of the present invention using a conventional non-scanning type image pickup device. In FIG. 5, 501 is an object to be measured, 502 is a slit light scanning mechanism, 503 is slit light, 504 is an image pickup device, 505 is an array type position detection element arranged on the image pickup surface of the image pickup device, and 506.
Is a three-dimensional shape calculation means for calculating a three-dimensional shape from the output signal of the array-type position detecting element, 515 is a symbol indicating the coordinate axes of the present measurement system, P is a measurement point of the object to be measured, and P'is an array of measurement points P. An image on the mold position detecting element, R _O is the projection center, and S _O is the slit light emitting point. The slit light 503 is parallel to the Y axis and X
Scanned along the axis. In such a three-dimensional shape measuring apparatus, the slit light 503 is projected on the object 501 to be measured, and an image of the diffuse reflection light thereof is formed on the array type position detection element 505 arranged on the image pickup surface of the image pickup apparatus 504. In this case, the image on the array-type position detection element corresponding to the measurement point P of the measured object is P ′.
Therefore, the baseline length (distance between the projection center R _O and the slit light emitting point S _O ) and the slit projection angle α are known, and the angle θ between the straight line connecting the projection center and the measurement point and the baseline is defined as the object to be measured. By obtaining from the image P ′ of the measuring point P on the array type position detecting element, the triangle S _O PR _O is determined, and the coordinate value of the measuring point P of the measured object can be calculated by the principle of triangulation. The entire shape of the DUT is sequentially scanned with slit light 503 in the X-axis direction,
It can be obtained by sequentially obtaining the coordinate values of the points corresponding to the measured object from the captured image. FIG. 6 is a diagram showing a detailed configuration of the array-type position detection element 505 and the three-dimensional shape calculation means 506 in FIG. In FIG. 6, 601 is an array type position detecting element in which N one-dimensional position detecting elements are arranged in an array, 602 is an image of slit light reflected light of the object to be measured, and 603 is I /
V converter, 604 is position calculation circuit, 605 is coordinate calculation circuit, 60
6 is a three-dimensional shape calculation means, and three-dimensional shape calculation means 606
Is an I / V converter 603, a position calculation circuit 604, and a coordinate calculation circuit 60.
It is composed of 5. The output from the one-dimensional position detecting element 601-1 is a current indicating the position of the incident light spot for each element, and one one-dimensional position detecting element 601-1 has two outputs. Therefore, N one-dimensional position detecting elements 601-
In case of I, 2N outputs are required. I / V converter 603
Is for converting the current output from the one-dimensional position detecting element 601-I into a voltage, which is usually converted using an operational amplifier. The position calculation circuit 604 is a calculation circuit that calculates the position of the light spot incident on the one-dimensional position detection element 601-I, and the two currents I ₁ and I ₂ output from each one-dimensional position detection element 601-I.
Is converted into a voltage, the calculation shown in the equation (1) is performed using V ₁ and V ₂ , and the light spot position P ′ is obtained for each one-dimensional position detecting element 601-I.

P ′ = (V ₁ −V ₂ ) / (V ₁ + V ₂ ) ───────────── (1) This calculation can be performed using an analog divider. /
It is also possible to perform D conversion and digital processing. The coordinate calculation circuit 605 is a mechanism that calculates the three-dimensional coordinates of the object to be measured from the position of the slit image on the one-dimensional position detection element 601-I calculated by the position calculation circuit 604, and performs the calculation based on the above-described triangulation principle. Has been realized. As described above, the light cutting method is a method of projecting slit light onto the object to be measured and measuring the shape of the object to be measured from the reflection slit image, so that the operation and processing method of the image data is simple, and the device It is also relatively easy to implement.

[0005]

However, in the above conventional structure, the image resolution of the image of the slit light reflected light is determined by the width in the short side direction of the one-dimensional position detecting element.
The resolution of the measurement result in the Y-axis direction is also determined by the width in the short side direction of the one-dimensional position detecting element. The width of the one-dimensional position detecting element in the short side direction is about 100 μm at the current technical level due to restrictions such as electrical characteristics. On the other hand, the resolution in the X-axis direction depends on the scanning control accuracy of slit light and the detection accuracy of the light position.
It can be realized up to about 10 μm. For the above reasons, the conventional three-dimensional shape measuring apparatus using the non-scanning image pickup device has a problem that the resolution of the acquired data differs depending on the scanning direction.

The present invention solves the above-mentioned problems of the prior art, and an object of the present invention is to provide a three-dimensional shape measuring apparatus capable of obtaining high-resolution three-dimensional information independent of the scanning direction.

[0007]

In order to achieve this object, the present invention provides a first type having an array type position detecting element on an image pickup surface.
Between the first image pickup device and the object to be measured, and a first slit light scanning mechanism that is orthogonal to the longitudinal direction of the array-type position detection elements of the first image pickup device and scans the object to be measured. Arranged semi-transmissive reflecting mirror, a second imaging device having an array type position detection element on an imaging surface for imaging an object to be measured through the semi-transmissive reflecting mirror, and an array of the second imaging device A second slit light scanning mechanism that is orthogonal to the longitudinal direction of the die position detection element and scans the object to be measured, and a first three-dimensional shape that calculates three-dimensional shape information from the output signal of the position detection element of the first imaging device. Shape calculating means, second three-dimensional shape calculating means for calculating three-dimensional shape information from the output signal of the position detecting element of the second image pickup device, first three-dimensional shape information and second three-dimensional shape information A measuring accuracy improving means for further interpolating each other to improve the measuring accuracy; The imaging device and the first slit light scanning mechanism and the second imaging device and the second slit light scanning mechanism first
The three-dimensional shape calculating means, the second three-dimensional shape calculating means and the measurement accuracy improving means are synchronized with the overall control means.

[0008]

According to the present invention, according to the above construction, the three-dimensional shape information is obtained by the first three-dimensional shape calculation means from the output signal obtained by the first image pickup device, and the scanning directions are arranged so as to be orthogonal to each other. The three-dimensional shape information is obtained by the second three-dimensional shape calculation means from the output signal obtained by the second imaging device, and the two pieces of three-dimensional shape information are interpolated by the measurement accuracy improving means to obtain high-resolution three-dimensional shape information. Can be obtained.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block connection diagram of a three-dimensional shape measuring apparatus according to an embodiment of the present invention. In FIG. 1, 10
1 is the object to be measured, 102 is the first slit light scanning mechanism, 103 is the first slit light, 104 is the first image pickup device, and 105 is the first image pickup surface of the first image pickup device 104. An array-type position detection element, 106 is a first three-dimensional shape calculation means for calculating a three-dimensional shape from the output signal of the first image pickup apparatus, and 107 is a semi-circle disposed between the object to be measured and the first image pickup apparatus. Transmissive mirror,
Reference numeral 108 denotes a second slit light scanning mechanism that scans orthogonally to the first slit light scanning mechanism 102, 109 denotes a second slit light scanning mechanism, 1
Reference numeral 10 is a second image pickup device for picking up an image by the semi-transmissive reflecting mirror 107, 111 is a second array type position detecting element arranged on the image pickup surface of the second image pickup device 104, and 112 is a second image pickup device. Second three-dimensional shape calculating means for calculating a three-dimensional shape from the output signal of the reference numeral 113, reference numeral 113 denotes the three-dimensional shape acquired by the first three-dimensional shape calculating means and the three-dimensional shape acquired by the second three-dimensional shape calculating means. Measurement accuracy improving means for interpolating each other to improve calculation accuracy, 114 is overall control means for controlling synchronization of the entire operation, 115 is a symbol indicating the coordinate axis of the main measurement system, P is a measurement point of the object to be measured, P ′ is an image of the measurement point P on the first array type position detecting element, R _O is a projection center of the first image pickup device, and S _O is a slit light emitting point of the first slit light scanning mechanism.

In such a three-dimensional shape measuring apparatus, the first
The slit light 103 of the first is projected on the DUT 101, and the image of the diffuse reflection light is arranged on the image pickup surface of the first image pickup device 104.
An image is formed on the array type position detection element 105 of. in this case,
The image on the first array type position detecting element 105 corresponding to the measurement point P of the object to be measured becomes P ′, and the base line length (distance between the projection center R _O and the slit light emitting point S _O ) and the slit projection angle α are It is known and the angle θ formed by the straight line connecting the projection center and the measurement point and the base line
Is the first array type position detecting element 105 at the measuring point P of the object to be measured.
The triangle S _O PR _O is determined by obtaining it from the above image P ′,
The coordinate value of the point P on the object to be measured can be calculated by the first three-dimensional shape calculation means 106 by the principle of triangulation.
The entire shape of the object to be measured can be acquired by sequentially scanning the first slit light 103 in the X-axis direction and sequentially obtaining the coordinate values of the corresponding points of the object to be measured from the captured image.

Similarly, the second slit light 109 is projected on the object 101 to be measured, and the image of the diffuse reflection light thereof is passed through the semi-transmissive reflecting mirror and is placed on the image pickup surface of the second image pickup device 110.
An image is formed on the array type position detection element 111 of. in this case,
The base line length (distance between the projection center (not shown) and the slit light emitting point (not shown)) and the slit projection angle (not shown) are known, and the straight line connecting the projection center and the measurement point forms the base line. The angle (not shown) is obtained from the image (not shown) of the measuring point P of the object to be measured on the second array position detecting device, so that the coordinates of the measuring point P of the object to be measured are coordinated by the principle of triangulation. The value can be calculated by the second three-dimensional shape calculation means 112. The entire shape of the object to be measured can be acquired by sequentially scanning the second slit light 109 in the Y-axis direction and sequentially obtaining the coordinate values of the corresponding points from the imaged image. Note that the first slit light 103 and the second slit light 109 are not simultaneously irradiated, and the first three-dimensional shape calculation means 106 obtains a three-dimensional shape based on the irradiation of the first slit light 103. Then, the overall control means 1 so that the second three-dimensional shape calculation means 112 acquires the three-dimensional shape based on the irradiation of the second slit light 109.
It is controlled by 14.

The structure and operation of the first three-dimensional shape calculating means 106 and the second three-dimensional shape calculating means 112 are the same as those of the conventional three-dimensional shape calculating means 506, and therefore their explanations are omitted here.

Next, the operation of the measurement accuracy improving means 113 will be described with reference to FIGS. 2, 3, and 4. FIG. 2 and FIG. 3 are schematic diagrams showing the image pickup state in the first array type position detecting element and the second array type position detecting element. 21-1 and 21- in Figure 2
2, 21-3, 21-4, ..., 21-N are individual one-dimensional position detecting elements of the first array type position detecting element, 22 is an image of one slit reflected light, and 23 is a one-dimensional position. A region in which the detection element 21-I shares an imaging area with the J-th one-dimensional position detection element of the second array type position detection element, 31-1, 31-2, 31-3, 31- in FIG.
4, ..., 31-N are individual one-dimensional position detecting elements of the second array type position detecting element, 32 is an image of one slit reflected light,
Reference numeral 33 denotes an area in which the one-dimensional position detecting element 31-J shares an imaging area with the I-th one-dimensional position detecting element of the first array type position detecting element. By controlling the movement of the slit light 103 in the X-axis direction with sufficient accuracy, the measurement resolution in the X-axis direction can be increased. Further, by controlling the movement of the slit light beam 109 in the Y-axis direction with sufficient accuracy, the measurement resolution in the Y-axis direction can be increased. FIG. 4 is a more detailed view of the shared imaging area. As shown in FIG. 4A, a plurality of reflected light images 401-j of the slit light 103 are generated in this area within a certain time, and an image 402-i of the reflected light of the slit light 109 is also generated within the certain time. Multiple occurrences. The coordinate value of the measurement point obtained by using the first array-type position detecting element 105 from the image 401-j of the reflected light of the slit light 103 is 403-j in FIG.
The coordinate values of the measurement points obtained by using the second array type position detecting element 111 from the image 402-i of the reflected light of the slit light 109 are shown in FIG.
It becomes 404-i in (c). A point p obtained by dividing the shared imaging area by the measurement accuracy improving means 113 into a predetermined fineness.
The measured value in the Z-axis direction with respect to (x, y) is calculated as follows. That is, y _i <y ≤ y _{i + 1} ──────────────────── (2) The first array type for y _i , y _{i + 1} Position detection element 105
Z (y _i ), z is the measured value in the Z-axis direction obtained by using
(Y _{i + 1} ), measurement value z in the Z-axis direction with respect to y
(Y)

[0015]

[Equation 1]

X _j <x ≤ x _{j + 1} ──────────────────── (4) The second array for x _j and x _{j + 1} Mold position detection element 109
Z (x _j ), z is the measured value in the Z-axis direction obtained by using
When (x _{j + 1} ), the measured value z in the Z-axis direction with respect to x
(X)

[0017]

[Equation 2]

And the measured value z (x, y) in the Z-axis direction with respect to the point p (x, y)

[0019]

[Equation 3]

By setting the above, the measured value is interpolated. In the present embodiment, the interpolation calculation by the measurement accuracy improving means 113 is realized by using a microcomputer.

As described above, in the present embodiment, the first array-type position detecting element obtains a measurement value in the Z-axis direction with fine resolution in the X-axis direction, and the second array-type position detecting element acquires the Y-axis. It is possible to obtain high-resolution three-dimensional shape information by acquiring measurement values in the Z-axis direction with fine resolution in the direction and interpolating these two measurement values with each other.

[0022]

As described above, according to the present invention, the first image pickup apparatus having the array type position detecting element on the image pickup surface, and the array type position detecting element of the first image pickup apparatus are orthogonal to the longitudinal direction and are measured. A first slit light scanning mechanism for scanning an object, a semi-transmissive reflecting mirror disposed between the first imaging device and the object to be measured, and an image of the object to be measured is imaged through the semi-transmissive reflecting mirror. A second imaging device having an array-type position detection element on the imaging surface; and a second slit light scanning mechanism that is orthogonal to the longitudinal direction of the array-type position detection element of the second imaging device and scans an object to be measured. First
The first three-dimensional shape calculation means for calculating the three-dimensional shape information from the output signal of the position detection element of the second image pickup device, and the second three-dimensional shape information from the output signal of the position detection element of the second image pickup device. The three-dimensional shape calculation means, the measurement accuracy improving means for interpolating the first three-dimensional shape information and the second three-dimensional shape information with each other to improve the measurement accuracy, the first slit light scanning mechanism and the second By providing the slit light scanning mechanism, the first three-dimensional shape calculation means, the second three-dimensional shape calculation means, and the overall control means for synchronizing the operations of the measurement accuracy improving means, the short side of the one-dimensional position detecting element It is possible to realize a three-dimensional shape measuring apparatus with excellent resolution that is not limited by the width of the direction.

[Brief description of drawings]

FIG. 1 is a block connection diagram of a three-dimensional shape measuring apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing an imaging state of a first array type position detection element, which is a main part of the three-dimensional shape measuring apparatus in the embodiment.

FIG. 3 is a diagram showing an imaging state of a second array-type position detection element, which is a main part of the three-dimensional shape measuring apparatus in the embodiment.

FIG. 4 is a diagram showing an interpolation algorithm in the Z direction in a shared area of the three-dimensional shape measuring apparatus according to the same embodiment.

FIG. 5 is a block connection diagram of a conventional three-dimensional shape measuring device.

FIG. 6 is a detailed block connection diagram of an array-type position detecting element and a three-dimensional shape calculating means in a conventional three-dimensional shape measuring apparatus.

[Explanation of symbols]

 101 Object to be Measured 102 First Slit Light Scanning Mechanism 103 First Slit Light 104 First Imaging Device 105 First Array Type Position Detecting Element 106 First Three-Dimensional Shape Calculating Means 107 Semi-Transmissive Reflecting Mirror 108 2 slit light scanning mechanism 109 2nd slit light 110 2nd imaging device 111 2nd array type position detection element 112 2nd three-dimensional shape calculation means 113 measurement accuracy improvement means 114 overall control means 115 Symbols indicating coordinate axes

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mutsuko Gomi 3-10-1 Higashisanda, Tama-ku, Kawasaki City, Kanagawa Prefecture Matsushita Giken Co., Ltd.

Claims (1)

[Claims] 1. A first imaging device having an array-type position detection element on an imaging surface, and a first slit orthogonal to a longitudinal direction of the array-type position detection element of the first imaging device and scanning an object to be measured. An optical scanning mechanism, a semi-transmissive reflecting mirror arranged between the first imaging device and the object to be measured, and an array type position detecting element on an imaging surface for picking up an image of the object to be measured through the semi-transmissive reflecting mirror. And a second image pickup device having a second scanning device that scans an object under measurement orthogonal to the longitudinal direction of the array-type position detection element of the second image pickup device.
From the slit light scanning mechanism, the first three-dimensional shape calculation means for calculating three-dimensional shape information from the output signal of the position detecting element of the first image pickup device, and the output signal of the position detecting element of the second image pickup device. A second three-dimensional shape calculation means for calculating the three-dimensional shape information; a measurement accuracy improving means for interpolating the first three-dimensional shape information and the second three-dimensional shape information with each other to improve the measurement accuracy; A first slit light scanning mechanism, a second slit light scanning mechanism, a first three-dimensional shape calculation means, a second three-dimensional shape calculation means, and an overall control means for synchronizing the operations of the measurement accuracy improving means. A characteristic three-dimensional shape measuring device.