JPH06129826A - Conversion factor determining method in three dimensional shape measurement - Google Patents

Abstract

PURPOSE:To provide a conversion factor determining method by which a cost can be lowered in three dimensional measurement requiring no special shape exclusive object. CONSTITUTION:As moving an object 6 in a Y-axis direction of three dimensional measuring coordinates, the picture of a light cutting line 8 formed on two slit light-irradiated planes S1, S2 of the object 6 is taken at five or more moving step positions by a television camera 9 so as to regression compute the formulae of two straight lines constituting the light cutting lines on screen coordinate. The crossing points of these plural straight lines are computed so as to regression compute arbitrary four straight lines from these crossing points coordinates. The conversion factors of coordinate conversion formulae are computed by using these four straight lines. By rotating the object 6 around the rotation center axis of an object to be measured intersecting with a slit light plane 7a at right angles, the crossing point of two straight lines constituting light cutting line images on the screen coordinates at plural rotating step positions. Thereby the position of the rotation center axis of the object to be measured is computed from the crossing point coordinates at plural rotating step positions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention uses a light-section method.
The present invention relates to a conversion coefficient determination method in three-dimensional shape measurement.

[0002]

2. Description of the Related Art Three-dimensional shape measurement using a light section method is usually performed as follows.

A slit light source device irradiates slit light to a workpiece to be measured fixed to a workpiece stage, and the slit light strikes the surface of the workpiece to form a light cutting line which is inclined with respect to the slit light surface. 2D image data of a light-section line image in the screen coordinate system of the 2D image pickup device by using a coordinate conversion formula, and 2D measurement coordinates by two orthogonal coordinate axes in the slit light plane. It is converted into two-dimensional shape data of the light cutting line in the system. Two-dimensional shape data is obtained from the above two-dimensional image data at each rotation step position by rotating the DUT stage a plurality of steps by a fixed step angle around a fixed rotation axis of the DUT orthogonal to the slit light surface. Is performed, and the cross-sectional shape data of the measured object on the slit light surface is synthesized from the plurality of two-dimensional shape data thus obtained. By moving the DUT stage in the direction of the central axis of rotation of the DUT by a plurality of steps with a constant step length, at each movement step position, the above-mentioned cross-sectional shape data is synthesized, and a plurality of thus obtained cross-sectional shape data are obtained. From the cross-sectional shape data, the three-dimensional shape data of the measured object in the three-dimensional measurement coordinate system having two orthogonal coordinate axes parallel to the slit light surface and one coordinate axis parallel to the rotation axis of the measured object is synthesized.

The conversion from the screen coordinate system to the two-dimensional measurement coordinate system when obtaining the two-dimensional shape data of the light section line as described above is generally called projective transformation and is widely used. Since the conversion coefficient of the coordinate conversion formula in this conversion changes depending on the installation condition of the two-dimensional imaging device and the state of the slit light surface,
This needs to be determined for each measuring device.

As a method for determining the conversion coefficient of the coordinate conversion formula in the projective conversion, a method for imaging and determining a specific pattern as described in Japanese Patent Laid-Open No. 61-205927, has been known. As disclosed in Japanese Patent No. 503121, there is proposed a method of making a determination using a test object of a specific shape processed with high accuracy.

[0006]

However, each of the conventional methods as described above requires a special test object having a special shape, which lacks general versatility and may increase the cost of the apparatus. is there.

The object of the present invention is to solve the above problems,
It is an object of the present invention to provide a conversion coefficient determination method in three-dimensional shape measurement that can reduce costs without requiring a special test object having a special shape.

[0008]

According to a first aspect of the present invention, there is provided a conversion coefficient determining method for three-dimensional shape measurement, wherein a slit light source device irradiates slit light to a measured object, and the slit light strikes the surface of the measured object to form the slit light. The two-dimensional image data of the light-section line image in the screen coordinate system of the two-dimensional image pickup device is imaged by the two-dimensional image pickup device from the direction inclined with respect to the slit light surface using the coordinate conversion formula. , Is converted into two-dimensional shape data of the light cutting line in the two-dimensional measurement coordinate system with two orthogonal coordinate axes in the slit light plane, and the measured object is centered around a constant rotation center axis of the measured object orthogonal to the slit light plane. Rotate multiple steps by a fixed step angle,
At each rotation step position, the above two-dimensional image data is converted into two-dimensional shape data, and from the plurality of two-dimensional shape data thus obtained, the cross-sectional shape data of the object to be measured on the slit light surface is obtained. By synthesizing and moving the object to be measured in the direction of the rotation axis of the object to be measured by a plurality of steps by a constant step length, at each moving step position, the above-mentioned cross-sectional shape data is combined, and thus obtained. The three-dimensional shape data of the measured object in the three-dimensional measurement coordinate system with two orthogonal coordinate axes parallel to the slit light surface and one coordinate axis parallel to the rotational axis of the measured object is synthesized from the plurality of sectional shape data 3 A method for determining a conversion coefficient of the above coordinate conversion formula when measuring a three-dimensional shape, which comprises using an object to be inspected having two slit light irradiation planes orthogonal to each other. The two slit light irradiation planes are orthogonal to the slit light surface, and the slit light is irradiated onto the two slit light irradiation planes, and the surface that divides the angle formed by the two slit light irradiation planes into two equal parts is a two-dimensional measurement coordinate system. The object to be measured which is to be irradiated with the slit light is moved by moving the object to be measured in a predetermined coordinate axis direction of the three-dimensional measurement coordinate system in a state where the object to be measured is parallel to one of the coordinate axes. The positions of the two slit light irradiation planes are moved in the above-mentioned one coordinate axis direction of the two-dimensional measurement coordinate system by a plurality of steps with a constant step length, and at two or more moving step positions, 2
A plurality of light-cutting lines formed in this way are obtained by imaging the light-cutting lines formed on one slit light irradiation plane with a two-dimensional image pickup device and performing a regression operation on two straight line formulas that constitute the light-cutting line image in the screen coordinate system. The intersection points of the straight lines are calculated, and using these intersection coordinates as sampling data, four arbitrary straight lines are regression calculated, and the conversion coefficient is calculated using these four straight lines to determine the rotation axis of the DUT. The object to be measured is rotated around the center at a constant step angle, and at a plurality of rotation step positions, the intersections of two straight lines forming the optical cutting line image in the screen coordinate system are calculated, and the intersections at the plurality of rotation step positions are calculated. The position of the rotation axis of the DUT is calculated from the coordinates of.

The conversion coefficient determining method in the three-dimensional shape measurement according to the second invention uses an object having two slit light irradiation planes orthogonal to each other, and the two slit light irradiation planes of the object are slit light surfaces. So that the slit light is radiated onto the two slit light irradiation planes, and the plane that bisects the angle formed by the two slit light irradiation planes is substantially parallel to one coordinate axis of the two-dimensional measurement coordinate system. By moving the measured object in the predetermined coordinate axis direction of the three-dimensional measurement coordinate system with the measured object positioned, the positions of the two slit light irradiation planes of the measured object to which slit light is irradiated are set to two positions.
A two-dimensional image pickup device is configured to move a plurality of steps in a predetermined step length in one of the coordinate axis directions of the dimensional measurement coordinate system to form light cutting lines formed on two slit light irradiation planes at five or more moving step positions. Image is taken, and the equations of two straight lines forming the light section line image in the screen coordinate system are regressively calculated, the intersections of the plurality of straight lines thus obtained are calculated, and the coordinates of these intersections are used as sampling data. Then, regression calculation of any 4 straight lines from these
Calculate the conversion coefficient using the coefficient of the equation that expresses the two straight lines and the installation angle deviation of the test object, and change the installation angle deviation of the test object in fixed steps to obtain each installation angle deviation. For the amount, calculate the conversion coefficient using the above formula, rotate the DUT around the rotation axis of the DUT at multiple fixed steps, and at multiple rotation step positions, in the screen coordinate system. The intersection point of two straight lines forming the light-section line image is calculated, and the rotation axis of the DUT is calculated using the conversion coefficient calculated as described above from the coordinates of the intersection point at a plurality of rotation step positions for each installation angle deviation amount. A plurality of calculated values of the position of, the installation angle deviation amount when the deviation of the plurality of calculated values of the measured object rotation center axis obtained in this way is the installation angle deviation amount of the measured object, and That It is characterized in making the Kino transform coefficient transform coefficients.

For example, by using a test object having a pair of two slit light irradiation planes orthogonal to each other, the slit light is irradiated by moving the test object in the one coordinate axis direction of the two-dimensional measurement coordinate system. The positions of the two slit light irradiation planes of the object to be inspected are moved in the one coordinate axis direction of the two-dimensional measurement coordinate system.

Further, for example, a test object having a plurality of sets of two slit light irradiation planes which are orthogonal to each other and whose positions in the above-mentioned one coordinate axis direction of the two-dimensional measurement coordinate system are orthogonal to each other is used, By moving the test object in the direction of the center axis of rotation of the test object, the positions of the two slit light irradiation planes of the test object irradiated with the slit light are moved in the one coordinate axis direction of the two-dimensional measurement coordinate system. .

[0012]

By using a test object having two slit light irradiation planes that are orthogonal to each other, the two slit light irradiation planes are orthogonal to the slit light surface and the two slit light irradiation planes are irradiated with the slit light. Also, the object to be measured is three-dimensionally measured while the object to be measured is positioned so that the plane that bisects the angle formed by the two slit light irradiation planes is parallel to one coordinate axis of the two-dimensional measurement coordinate system. By moving in the predetermined coordinate axis direction of the coordinate system, the positions of the two slit light irradiation planes of the test object irradiated with the slit light are moved in the one coordinate axis direction of the two-dimensional measurement coordinate system by a constant step length. By moving a plurality of steps, the light cutting lines formed on the two slit light irradiation planes are imaged by a two-dimensional imaging device at five or more moving step positions, and a light cutting line image is formed in the screen coordinate system. One Regression is performed on the equation of the straight line, intersections of the plurality of straight lines thus obtained are calculated, and arbitrary four straight lines are regressed from these using the coordinates of these intersections as sampling data. The conversion coefficient is calculated by using the two, and the object to be measured is rotated about the rotation axis of the object to be measured at a constant step angle to form two optical cutting line images in the screen coordinate system at a plurality of rotation step positions. The intersection of straight lines is calculated, and the position of the rotation axis of the DUT is calculated from the coordinates of the intersection at a plurality of rotation step positions. The conversion coefficient can be determined to the same degree as the conventional one in a short time.

Particularly, in the case of the second invention, the conversion coefficient can be accurately determined even if the installation angle of the object to be inspected is deviated.

The object to be inspected may be one having two slit light irradiation planes orthogonal to each other, and it is not necessary to prepare an exclusive object to be inspected having a special shape. Further, the feeding mechanism and the rotating mechanism of the object to be measured are necessary for the three-dimensional shape measurement and do not directly increase the cost. Furthermore, since four straight lines obtained by regression are used, it is possible to avoid the influence of the feed accuracy of the DUT on the determination of the conversion coefficient.

By using a test object having two sets of slit light irradiation planes orthogonal to each other, by moving the test object in the one coordinate axis direction of the two-dimensional measurement coordinate system, the test object irradiated with the slit light is illuminated. When the positions of the two slit light irradiation planes of the test object are moved in the one coordinate axis direction of the two-dimensional measurement coordinate system, the shape of the test object is extremely simple.

Further, using a test object having a plurality of sets of two slit light irradiation planes which are orthogonal to each other and whose positions in the one coordinate axis direction of the two-dimensional measurement coordinate system are different from each other, the test object is measured. When the positions of the two slit light irradiation planes of the test object irradiated with the slit light are moved in the one coordinate axis direction of the two-dimensional measurement coordinate system by moving the test object in the object rotation center axis direction, It is not always necessary to provide a feeding mechanism that moves the object to be tested in the coordinate axis direction of the two-dimensional measurement coordinate system.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show the overall schematic structure of a three-dimensional shape measuring apparatus. This apparatus comprises an object stage (1) to be measured, a slit light source device (2), a two-dimensional image pickup device (3),
A data storage device (4) and a data processing device (5) are provided.

The slit light source device (2) is an LD (not shown).
This is for irradiating the object to be measured or the object to be measured (6) fixed on the stage (1) with the slit light (7) using a (laser diode), a cylindrical lens or the like. In this case, the slit light surface (7a) is horizontal and
In (7a), a two-dimensional measurement coordinate system having an X axis and a Y axis orthogonal to each other is set. X-axis and Y-axis intersect 2
The vertical axis that passes through the origin (O) of the dimensional measurement coordinate system and is orthogonal to these is the Z axis, and the coordinate system based on the X, Y, and Z axes is called the three-dimensional measurement coordinate system.

An object to be measured or an object to be inspected (6) is fixed on the upper surface of the stage (1). The stage (1) is rotated by a suitable driving means (not shown) around a constant vertical axis of rotation of the DUT in the vicinity of the Z-axis and is moved in the Z-axis direction (vertical direction). Has become.
The stage (1) may be moved in the X-axis direction and the Y-axis direction, but even in such a case, the position of the rotation axis of the DUT in the measurement coordinate system should be constant. Has been done.

The two-dimensional image pickup device (3) picks up an image of a light cutting line (8) formed by the slit light (7) striking the surface of the object to be measured or the object (6) to obtain the two-dimensional image data. It is for outputting to the data processing device (5) and is equipped with a television camera (9) having a two-dimensional image pickup device. Figure 3
Fig. 8 shows a television image (optical cutting line image) (10) of the optical cutting line (8) taken by the television camera (9). Light section line image
The two-dimensional image data of (10) is expressed using a screen coordinate system composed of an x-axis and a y-axis which are orthogonal to each other on the television screen (two-dimensional image sensor).

The data storage device (4) is for storing a coordinate conversion formula for converting the two-dimensional image data in the screen coordinate system into the two-dimensional shape data in the two-dimensional measurement coordinate system and its conversion coefficient. , For example, is composed of a memory of a microcomputer. The conversion coefficient is calculated before the three-dimensional shape measurement of the measured object.
Obtained by calibration.

The data processor (5) controls the rotation and movement of the stage (1), processes the two-dimensional image data, etc. to determine the conversion coefficient and the position of the center axis of rotation of the object to be measured, and also three-dimensionally. For synthesizing three-dimensional shape data of the object to be measured in the measurement coordinate system,
For example, it is composed of a microcomputer.

In the above-mentioned three-dimensional shape measuring apparatus, prior to measurement, calibration is performed as follows,
The conversion coefficient and the position of the rotation center axis are determined, and these are stored in the data storage device (4).

The coordinates in the two-dimensional measurement coordinate system are (X,
Y) and the coordinates in the screen coordinate system are (x, y),
The coordinate conversion formula is expressed as follows.

X = {c _x · (x−x _o ) + d _x · (y−
y _o )} / {m ₁ · (x−x _o ) + m ₂ · (y−y _o )
+ M ₃ } (1) Y = { _cy · (x− _xo ) + _dy · (y− _yo )} /
_{{M 1 · (x-x} o) + m 2 · (y-y o) + m 3} ...
(2) (x _o , y _o ) is the coordinate of the origin (o) in the screen coordinate system.

Rewriting equations (1) and (2) gives the following:

X = (a _x · y−x + b _x ) / (n ₁ · x)
_{+ N 2 · y + n 3} ) ... (3) Y = r · (a y · x-y + b y) / (n 1 · x + n 2 ·
y + n ₃ ) (4) (r ≠ 0) In the above three-dimensional shape measuring apparatus, the above equations (3) and (4) are used as coordinate transformation equations, and the transformation coefficients r, a
_{x, b x, a y,} b y, n 1, n 2, n 3 are determined by the calibration.

When performing the calibration, first, as shown in FIGS. 1 and 2, the object (6) is placed on the stage (1).
Fixed on. The object to be inspected (6) has one set of two slit light irradiation planes (S1) (S2) orthogonal to each other,
The planes (S1) (S2) and the ridgeline (E) between them are the slit light plane (7
It is fixed to the stage (1) so that it is orthogonal to a). Then, slit light (7) is applied to the two planes (S1) (S2) of the object (6).
Is irradiated, and the stage (1) is positioned so that the plane that divides the angle formed by the two planes (S1) and (S2) into two equal parts is substantially parallel to the Y axis.

The test object (6) is fixed to the stage (1),
Once the stage (1) has been positioned, the stage
With the rotation of (1) stopped, move the stage in the Y-axis direction.
(1) is moved in multiple steps with a constant step length stp, and two planes are set in five or more movement step positions.
The optical section line (8) formed on (S1) and (S2) is the TV camera (9).
Is imaged by. A light-section line image (10) taken at one step position is shown in FIG. 3, which has a V-shape in which two right and left straight line portions (10a) and (10b) intersect at an intersection point (10c). The left straight part (10a) is the part of the light section line (8) formed on the left side plane (S1), and the right straight part (10b) is the light section line (S2) formed on the right side surface (S2). The intersection (10c) corresponds to the portion of the optical cutting line (8) formed on the ridge (E) in the portion of 8). Then, at each movement step position, an equation of two straight lines including the two straight line portions (10a) and (10b) is obtained by regression calculation. The straight lines on the screen coordinate system at the plurality of movement step positions thus obtained are shown in FIG. The number of straight lines at this time is twice the number of movement step positions. Further, straight lines on the two-dimensional measurement coordinate system corresponding to the straight lines on the screen coordinate system are shown in FIG.

Next, on the screen coordinate system, the intersections of a plurality of straight lines obtained as described above are calculated, and the coordinates of these intersections are used as sampling data, and from these, arbitrary four straight lines l _o and l ₁ are calculated. , L ₂ and l ₃ are obtained by regression calculation. These straight lines l _o , l ₁ , l ₂ , l _3
Are four straight lines L _o , L ₁ , on the two-dimensional measurement coordinate system,
It corresponds to L ₂ and L ₃ , respectively.

A straight line L _o on the two-dimensional measurement coordinate system is expressed by the following equation.
In the formula (5), the straight line L ₁ is expressed by the formula (6), the straight line L ₂ is expressed by the formula (7), and the straight line L ₃ is expressed by the formula (8).

X = 0 ... (5) Y = X · tan 2θ ... (6) X = k · cos 2θ ... (7) Y = X · tan 2θ + k ... (8) θ is the value of the object to be inspected (6). This is the deviation angle of the installation angle.

A straight line l _o on the screen coordinate system is expressed by the following equation (9):
The straight line l ₁ is expressed by the formula (10), the straight line l ₂ is expressed by the formula (11), and the straight line l ₃ is expressed by the formula (12).

[0035] _{x = a xo · y + b} xo ... (9) y = a yo · x + b yo ... (10) x = a xk · y + b xk ... (11) y = a yk · y + b yk ... (12) and, these Coefficients of a _xo , b _xo , a _yo , b _yo , a _xk ,
b _xk , a _yk , and b _yk are obtained by the above regression calculation. Next, these coefficients a _xo , b _xo , a _yo , b _yo ,
_{a xk, b xk, a yk} , b yk and the expressions using the offset angle θ of the object (6) (3), the coefficient of (4), i.e., transform coefficients r, a _x, b _x, a _y, seek _{b y, n 1, n 2} , n 3 calculates the equation. These equations are expressed as:

[0036] _{a x = a xo ... (13} ) b x = b xo ... (14) a y = a yo + (a xo · a yo -1) · tan 2θ / r ... (15) b y = b yo ＋ (a _xo・ b _yo ＋ b _xo ) ・ tan 2θ / r… (1
6) r = R / cos 2θ−a _xo · tan 2θ (17) R = {− b _yk · (a _xo −a _xk ) − (a _xo · b _xk −b _xo ·
a _xk ) ・_{ay k} − (b _xo −b _xk )} / {(a _yo · by _k −b
_yo・ a _yk ) ・ a _xk ＋ (a _yo −a _yk ) ・ by _k ＋ (b _yo −b
_yk )} (17-1) n ₁ = N ₁ / k · cos 2θ (18) N ₁ = {(a _yo −a _yk ) · (b _xo −b _xk ) + (a _yo · b
_yk −b _yo · a _yk ) · (a _xo −a _xk )} / {(a _yo · by _k
−b _yo・ a _yk ) ・ a _xk ＋ (a _yo −a _yk ) ・ b _xk ＋ (b _yo
−b _yk )} (18-1) n ₂ = N ₂ / k · cos 2θ (19) N ₂ = {(a _xo −a _xk ) · (b _yo −b _yk ) + (a _xo · b
_xk −b _xo · a _xk ) · (a _yo −a _yk )} / {(a _yo · by _k
−b _yo・ a _yk ) ・ a _xk ＋ (a _yo −a _yk ) ・ b _xk ＋ (b _yo
−b _yk )} (19-1) n ₃ = N ₃ / k · cos 2θ (20) N ₃ = {(b _xo −b _xk ) · (b _yo −b _yk ) − (a _xo · b
_xk- b _xo・ a _xk ) ・ (a _yo・_byk −b _yo・ a _yk )} /
_{{(A yo · b yk -b} yo · a yk) · a xk + (a yo -a yk)
· B _xk + In _{(b yo -b yk)} ...} (20-1) above equation (17) to (20), the coefficient _{a xo, b xo, a yo} ,
Since b _yo , a _xk , b _xk , a _yk , and b _yk have already been obtained, if the shift angle θ is obtained, the conversion coefficients r, a _x , b _x ,
_{a y, b y, n 1} , n 2, n 3 is obtained. Therefore,
Next, in order to obtain the deviation angle θ, the deviation angle θ is changed by a fixed amount within a predetermined range, and for each value of the deviation angle θ, using the equations (17) to (20), a tentative conversion is performed. Coefficient r,
_{a x, b x, a y} , b y, the n _1, n _2, n ₃ is calculated,
Remember these. For example, the deviation angle θ is -5 °
The value is changed by 0.01 ° in the range of ˜5 °.

Next, the stage (1) is rotated at a constant step angle φ (for example, 10 °) about the center axis of rotation of the object under test.
By step rotation, at three rotation step positions, the light section line (8) formed on the two planes (S1) and (S2) is imaged by the television camera (9), and the light section line image (in the screen coordinate system ( The coordinates of the intersection (10c) of 10) are obtained. Then, at each value of the displacement angle changed as described above,
The conversion coefficient at that value is used to convert the coordinates of the intersection (10c) of the light cutting line image (10) in the screen coordinate system into the coordinates in the two-dimensional measurement coordinate system. The coordinates in this two-dimensional measurement coordinate system represent the coordinates of the intersection of the light cutting line (8) in the two-dimensional measurement coordinate system. 3 obtained in this way
The coordinates of the intersections of the light section lines (8) on the two-dimensional measurement coordinate system at one rotation step position are (X ₁ , Y ₁ ), (X ₂ , Y
₂ ) and (X ₃ , Y ₃ ). Next, these coordinates (X
_1, Y _1), determine the _{(X 2, Y 2),} (X 3, Y 3) with the coordinates of the object to be measured rotation center axis in the two-dimensional coordinate system for measurement (X _c, Y _c). Three coordinates (X ₁ ,
From Y ₁ ), (X ₂ , Y ₂ ), and (X ₃ , Y ₃ ), the following three calculated values (X _c1 , Y _c1 ), (X _c2 , Y _c2 ) and (X _c3 , Y _c3 ) are obtained.

X _c1 = {X ₁ + X ₂ + (Y ₁ -Y ₂ ) .si
nφ / (1-cosφ)} / 2 (21) Y _c1 = {Y ₁ + Y ₂ − (X ₁ −X ₂ ) · sin φ / (1−
cos φ)} / 2 (22) X _c2 = {X ₂ + X ₃ + (Y ₂ −Y ₃ ) · sin φ / (1-
cos φ)} / 2 ... (23) Y _c2 = {Y ₂ + Y ₃ − (X ₂ −X ₃ ) · sin φ / (1−
cos φ)} / 2 (24) X _c3 = {X ₁ + X ₃ + (Y ₁ −Y ₃ ) ・ sin 2 φ / (1
−cos 2φ)} / 2 (25) Y _c3 = {Y ₁ + Y ₃ − (X ₁ −X ₃ ) · sin 2φ / (1
−cos 2φ)} / 2 (26) For all values of the deviation angle θ, 3 of the measured object rotation center axis
If one coordinate calculation value is obtained, three coordinate calculation values (X _c1 , Y _c1 ), (X _c2 , Y
The deviation between _c2 ) and ( _Xc3 , _Yc3 ) is determined. Then, the value of the deviation angle θ when this deviation becomes the smallest is set as the deviation angle θ of the object (6), and the conversion coefficients r, a _x , b _x , a _{y at} the deviation angle θ are b _y ,
Let n ₁ , n ₂ , and n ₃ be conversion coefficients.

In the case of the above embodiment, the conversion coefficient is determined by using a test object (6) having an extremely simple shape having only one pair of two slit light irradiation planes (S1) (S2) orthogonal to each other. You can

In the above-mentioned embodiment, the case where the installation angle of the test object (6) is deviated is shown. However, when there is no such deviation, the conversion coefficient can be obtained a little more easily.
In this case, basically, the calculation is performed using the equations obtained by removing the deviation angle θ from the above equations.

FIG. 6 shows an example of a conversion coefficient determination method using a test object different from the above.

In this case, the test object (16) is constructed as follows. The structure of the object (16) is the stage (1).
The state of being fixed to will be described. The test object (16) has two or more sets of two slit light irradiation planes (S1) (S2) orthogonal to each other in the Z-axis direction. The object to be inspected (16) is a cube or a rectangular parallelepiped in which two adjacent side surfaces are formed in steps, and for example, five sets of irradiation planes (S1) (S2) are formed in the steps. . Irradiation plane is code (S1) (S
When it is necessary to collectively refer to each other in 2) and to distinguish them, the first irradiation plane (S1a) (S2a), the second irradiation plane (S1b) (S2
b), third irradiation plane (S1c) (S2c), fourth irradiation plane (S1d) (S2
d) and the fifth irradiation plane (S1e) (S2e). Also,
The ridgeline between the two first irradiation planes (S1a) and (S2a) is (Ea), the ridgeline between the two second irradiation planes (S1b) and (S2b) is (Eb), and the two third irradiation planes (S1c) ) (S2c) is the ridgeline between (Ec), 2nd irradiation planes (S1d) (S2d) is the ridgeline between (Ed), 2nd irradiation planes (S1e) (S2e) is the ridgeline between Is defined as (Ee), and these ridges are collectively referred to by the symbol (E). The corresponding five irradiation planes (S1a) (S1b) (S1c) (S1d) (S1e) of each set are parallel to each other, and their vertical and horizontal pitches (distances) are constant. The other 5 irradiation planes (S2a) (S2
b) (S2c) (S2d) (S2e) are also parallel to each other, and their vertical and horizontal pitches are equal to the above pitches, respectively. That is, the second to fifth irradiation planes (S1b) (S2b) to (S1e)
(S2e) is a combination of the first irradiation plane (S1a) and (S2a) with two irradiation planes.
It is a parallel translation of a fixed amount in sequence in the horizontal direction in the plane that divides the angle formed by (S1) and (S2) into two equal parts.

Also in this case, the object to be inspected (16) is the irradiation plane (S1).
(S2) and ridge (E) are fixed to the stage (1) so that they are orthogonal to the slit light surface (7a), and either set of irradiation planes (S1) (S
The stage (1) is positioned such that the slit light (7) is irradiated on the surface (2) and the plane that bisects the two irradiation planes (S1) (S2) is substantially parallel to the Y axis. When determining the conversion coefficient, the stage in the above embodiment is used.
Instead of moving (1) in the Y-axis direction, the stage (1) is moved in the Z-axis direction. More specifically, first, the stage (1) is positioned so that the slit light (7) is irradiated to the first irradiation plane (S1a) (S2a), and then the irradiation plane (S1) (S2)
The stage (1) is moved downward by one pitch in the Z-axis direction. Thereby, from the first irradiation plane (S1a) (S2a) to the second, third, fourth and fifth irradiation planes (S1b) (S2b), (S1c) (S2
c), (S1d) (S2d), (S1e) (S2e) are sequentially irradiated with slit light (7), and the second to fifth irradiation planes (S1b) (S2b) to (S1e) (S2e) are irradiated with the first irradiation. Since the planes (S1a) and (S2a) are sequentially translated in a direction substantially parallel to the Y axis by a fixed amount, the same as when moving the stage (1) in the Y axis direction by a fixed amount in the above embodiment. The result is obtained.

Others are the same as those in the above-mentioned embodiment, and the same portions are denoted by the same reference numerals.

When an object (16) as shown in FIG. 6 is used,
When determining the conversion coefficient, the stage (1) need only be moved in the Z-axis direction, and need not be moved in the Y-axis direction.
Therefore, a feed mechanism for moving the stage (1) in the X-axis direction and the Y-axis direction is not always necessary.

[0046]

According to the method of the present invention, as described above, the conversion coefficient can be easily determined without preparing a special test object having a special shape, and the cost can be reduced.

In particular, according to the method of the second invention, the conversion coefficient can be accurately determined even if the installation angle of the object to be inspected is deviated.

By using an object having one set of two slit light irradiation planes orthogonal to each other, by moving the object in the direction of the one coordinate axis of the two-dimensional measurement coordinate system, the object irradiated with the slit light is irradiated. By moving the positions of the two slit light irradiation planes of the inspection object in the direction of one of the coordinate axes of the two-dimensional measurement coordinate system, the shape of the inspection object can be made extremely simple, further reducing the cost. Will be possible.

Further, using a test object having a plurality of sets of two slit light irradiation planes which are orthogonal to each other and whose positions in the one coordinate axis direction of the two-dimensional measurement coordinate system are different from each other, the test object is measured. By moving the test object in the central axis direction of the object rotation, the positions of the two slit light irradiation planes of the test object irradiated with the slit light are moved in the one coordinate axis direction of the two-dimensional measurement coordinate system. Then, the feeding mechanism for moving the object to be examined in the coordinate axis direction of the two-dimensional measurement coordinate system is not necessarily required, and the cost can be further reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a three-dimensional shape measuring apparatus showing an embodiment of the present invention.

FIG. 2 is a plan view of the three-dimensional shape measuring apparatus of FIG.

FIG. 3 is an explanatory diagram showing an example of a television image of an optical cutting line of a test object.

FIG. 4 is an explanatory diagram showing a plurality of straight lines of a light cutting line image at a plurality of movement step positions on a screen coordinate system.

FIG. 5 is an explanatory diagram showing a plurality of straight lines of light cutting lines at a plurality of step positions on a measurement coordinate system.

FIG. 6 is a schematic configuration diagram of a main part of a three-dimensional shape measuring apparatus showing another embodiment of the present invention.

[Explanation of symbols]

 (2) Slit light source device (3) Two-dimensional imaging device (4) Data storage device (5) Data processing device (6) Test object (7) Slit light (7a) Slit light surface (8) Light cutting line (9 ) TV camera (10) Light section line image (16) Test object (S1) (S2) Slit light irradiation plane

Claims (4)

[Claims] 1. A two-dimensional image pickup device from a direction in which a slit light source device irradiates slit light to a measured object, and the slit light strikes the surface of the measured object to form a light cutting line inclined with respect to the slit light surface. The two-dimensional image data of the light-section line image in the screen coordinate system of the two-dimensional image pickup device is captured by the coordinate conversion formula and the light-section line in the two-dimensional measurement coordinate system by the two orthogonal coordinate axes in the slit light plane. 2D shape data, and the object to be measured is rotated a plurality of steps by a constant step angle around a constant axis of rotation of the object to be measured orthogonal to the slit light surface, and at each rotation step position, the above-mentioned 2 The three-dimensional image data is converted into two-dimensional shape data, and the plurality of two-dimensional shape data thus obtained is combined with the cross-sectional shape data of the object to be measured on the slit light surface, Serial to the object to be measured by multi-step movement by a predetermined step length to the measurement object rotation center axis,
At each movement step position, the above-mentioned cross-sectional shape data is combined, and from the plurality of cross-sectional shape data obtained in this way, two orthogonal coordinate axes parallel to the slit light surface and the rotation center axis of the DUT are parallel. A method for determining a conversion coefficient of the above coordinate conversion formula when performing three-dimensional shape measurement for synthesizing three-dimensional shape data of an object to be measured in a three-dimensional measurement coordinate system with one coordinate axis, and two slits orthogonal to each other. Using a test object having a light irradiation plane, the two slit light irradiation planes of the test object are orthogonal to the slit light surface, the slit light is irradiated to the two slit light irradiation planes, and the two slit light irradiation planes are The object to be measured is placed in such a manner that the plane that divides the angle formed into two is parallel to one coordinate axis of the two-dimensional measurement coordinate system, and the object to be measured is in the predetermined coordinate axis direction of the three-dimensional measurement coordinate system. By moving the two slit light irradiation planes of the test object irradiated with the slit light in the above-mentioned one coordinate axis direction of the two-dimensional measurement coordinate system by a plurality of steps with a constant step length. At two or more movement step positions, the two-dimensional image pickup device images the light cutting lines formed on the two slit light irradiation planes, and a regression calculation is performed on the equations of the two straight lines forming the light cutting line images in the screen coordinate system. Then, the intersections of the plurality of straight lines thus obtained are calculated, the intersection coordinates of these are used as sampling data, and arbitrary four straight lines are regression calculated from these, and the conversion coefficient is calculated using these four straight lines. Then, the object to be measured is rotated around the rotation axis of the object to be measured at a constant step angle, and at two or more rotation step positions, two linear images forming an optical cutting line image in the screen coordinate system are formed. Conversion factor determination method in the three-dimensional shape measurement, characterized in that the intersection is calculated, and calculates the position of the object to be measured rotation axis from the intersection of the coordinates in a plurality of rotational step position. 2. A test object having two slit light irradiation planes that are orthogonal to each other is used, and two slit light irradiation planes of the test object are orthogonal to the slit light plane, and slit light is projected onto the two slit light irradiation planes. The object to be measured is positioned with the object to be measured positioned such that the plane that illuminates and that divides the angle formed by the two slit light irradiation planes into two equal parts is substantially parallel to one coordinate axis of the two-dimensional measurement coordinate system. By moving in the predetermined coordinate axis direction of the three-dimensional measurement coordinate system, the positions of the two slit light irradiation planes of the test object irradiated with the slit light are moved in a predetermined step in the one coordinate axis direction of the two-dimensional measurement coordinate system. A plurality of steps are moved by the length, and at two or more moving step positions, the two-dimensional image pickup device images the light cutting lines formed on the two slit light irradiation planes, and the light cutting line image is displayed in the screen coordinate system. Constitution The regression equation of the two straight lines is calculated, the intersections of the plurality of straight lines thus obtained are calculated, and the arbitrary four straight lines are regression calculated from these by using the coordinates of these intersections as sampling data. Calculate the conversion coefficient using the coefficient of the equation that expresses the two straight lines and the installation angle deviation of the test object, and change the installation angle deviation of the test object in fixed steps to obtain each installation angle deviation. For the amount, calculate the conversion coefficient using the above formula, rotate the DUT around the rotation axis of the DUT at multiple fixed steps, and at multiple rotation step positions, in the screen coordinate system. The intersection point of two straight lines forming the optical cutting line image is calculated, and the measurement is performed using the conversion coefficient calculated as described above from the coordinates of the intersection point at a plurality of rotation step positions for each installation angle deviation amount. Obtain a plurality of calculated values of the position of the rotation center axis, and determine the installation angle deviation amount when the deviation of the calculated values of the rotation center axis of the DUT obtained in this way is the smallest as the installation angle deviation amount of the DUT. The conversion coefficient determining method in the three-dimensional shape measurement according to claim 1, wherein the conversion coefficient at that time is used as the conversion coefficient. 3. A slit light is irradiated by using a test object having one set of two slit light irradiation planes orthogonal to each other and moving the test object in the one coordinate axis direction of the two-dimensional measurement coordinate system. The method for determining the conversion coefficient in the three-dimensional shape measurement according to claim 1 or 2, wherein the positions of the two slit light irradiation planes of the test object are moved in the one coordinate axis direction of the two-dimensional measurement coordinate system. 4. An object to be measured having a plurality of sets of two slit light irradiation planes which are orthogonal to each other and have different positions in the direction of one of the coordinate axes of the two-dimensional measurement coordinate system in the direction of the axis of rotation of the object to be measured. By moving the test object in the central axis direction of the object rotation, the positions of the two slit light irradiation planes of the test object irradiated with the slit light are moved in the one coordinate axis direction of the two-dimensional measurement coordinate system. Claim 1 characterized by
Alternatively, the conversion coefficient determination method in the three-dimensional shape measurement of 2.