JPH02271208A - Measuring apparatus of three-dimensional shape - Google Patents

Abstract

PURPOSE:To improve the measuring accuracy by providing a shape measuring means for calculating the three-dimensional shape of an object to be measured on the basis of the phase distribution data from a phase distribution detecting means and a setting parameter from a setting parameter measuring means. CONSTITUTION:For a preparatory process in measuring the shape of an unknown object M1 to be measured, setting parameters of, for example, a light projecting means M4, a pick-up means M5 etc. are measured with the use of a known object. In other words, the means M4 radiates the light passing through a slit M2 and a lens M3 to the object M1, and the means M5 picks up the reflecting light. An electric signal from the means M5 is input to a phase distribution detecting means M6, so that the distribution data of the phase is obtained. The measuring result of the distribution of the phase is input to a setting parameter measuring means M7, where the setting parameters of the means M4 and M5 are obtained based on the known shape and positional data of the object M1. The obtained setting parameters are used to measure the shape of the object M1.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a three-dimensional shape measuring device that measures the shape of an object to be measured based on the reflected light by irradiating light through a slit. .

[Prior art and its problems] Conventionally, as this type of three-dimensional shape measuring device, the
The one published in No. 4402 is known.

That is, as shown in FIG. 10, the light that has passed through the slit 3 of the projector 1 is irradiated onto the three-dimensional object to be measured 7 through the lens 5, and the reflected light is reflected by the camera at a position separated by a predetermined angle. 9, the imaged striped pattern is converted into an electrical signal, and based on this signal, the signal processing device 13 determines the three-dimensional shape of the object to be measured 7,
This is displayed on the surface shape display device 15.

In this device, when measuring the shape of the object to be measured 7 (
Various installation parameters such as the distance between the projector 1 and the object to be measured 7 and the distance between the object to be measured 7 and the camera 9 must be determined in advance. The methods used to determine these installation parameters include manual measurement or installation of the projector 1 and camera 9 at preset positions. The problem of the present invention is that it is difficult to determine the installation parameters, which causes errors in the measurement results of the shape of the object to be measured 7.The present invention aims to solve the problems of the conventional technology described above, and It is an object of the present invention to provide a three-dimensional shape measuring device that can accurately measure the shape of an object to be measured by adding a function to measure the installation parameters of the device.

[Means for Solving the Problems] The present invention has been made to solve the above problems (as shown in Fig. 1 above, light passing through a slit M2 is irradiated onto an object to be measured M1 through a lens M3 a light irradiation means M4 that captures an image of the reflected light from the object to be measured M1 at a position having a predetermined incident angle θ; and a phase distribution of the reflected light from the object M1 that is detected based on the electrical signal from the image capture means M5. The light irradiation means M based on the phase distribution detection means M6, the data of the object to be measured M1 having a known shape or the installation data of the object to be measured M], and the phase distribution data from the phase distribution detection means M6.
4 and an installation parameter measuring means M7 for measuring the installation parameters of the imaging means M5, and a three-dimensional shape of the object to be measured based on the phase distribution data from the phase distribution detecting means M6 and the installation parameters from the installation parameter measuring means M7. The present invention is characterized by comprising a shape calculation means M8 that calculates the shape through calculation processing.

[Operation] First, as a preliminary process for measuring the shape of the unknown object to be measured M1, the installation parameters of the light irradiation means M4, the imaging means M5, etc. are measured using the known object to be measured M1. That is, the light irradiation means M4 directs the light that has passed through the slit M2 and the lens M3 onto the object to be measured M1.
The reflected light from the irradiated tongue is imaged by the imaging means M5. The electrical signal from the imaging means M5 (upper) is input to the phase distribution detection means M6, and its phase distribution data is determined.

The measurement results of this phase distribution are inputted to the installation parameter measuring means M7, where the installation parameters of the light irradiation means M4 and the imaging means M5 are determined based on the known shape of the object to be measured M1, its position data, etc.

The installation parameters thus determined (are used to measure the shape of the unknown object to be measured M1).

That is, the phase distribution detection means M6 obtained by the unknown measured object Mi through the same process as the known measured object M1.
The phase distribution data [upper] is input to the shape calculation means M8.In addition, the installation parameters determined by the installation parameter setting means M7 are also input to the shape calculation means M8, and these data are used to determine the shape of the object to be measured. The dimensional shape is measured.

Therefore, since the installation parameters required for measuring the three-dimensional shape of the object to be measured M1 are measured based on the signal of the phase distribution detection means M6 and the data of the known object to be measured M1, unlike the conventional technology, Accuracy and workability are improved compared to manual measurement.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

The three-dimensional shape measuring device according to this embodiment (as shown in FIG. 2 above, a projector) 00, a camera 20°O1 signal processing device 300, a surface shape display device 400, and a stage control device 600 are comprised.

A mercury arc lamp 101 is provided on the projector 1001,
The light passes through the condensing lens 102 and further through the slit 10
3 (Fig. 3). slit 1
03 +i Alternating opaque parts] 03a and transparent parts 1
03b, and is set at a predetermined lattice interval.

The lattice fringes created in this way are projected onto the projection lens 104.
The image is projected onto the object to be measured 700 (see FIG. 4).

A camera 20' is used to capture an image 702 of an object to be measured 700 as shown in FIG. 5 on an imaging plane 204 through an objective lens 202, and is composed of an ordinary low-speed scanning television camera, COD, etc. .

Signal processing device 300 + & A/D converter 3 that converts analog signals from camera 200 into digital signals]
1, a phase distribution detection section 3 which detects the phase based on the signal level of the checkered image; a shape calculation section 313 that calculates the surface shape of the surface (see Figure 6); an installation parameter measurement section 320 that calculates installation parameters based on the phase distribution detection section 312 and preset data;
The stage controller 330 receives the 20 command signals and outputs a drive signal to the stage controller 600.

Stage control device 600 Table f A stage moving device 602 that moves a stage having a reference plane 601;
The stage driving device 603 drives this stage moving device 602, and the reference plane 601 of the stage moving device 602 is moved in Z direction according to the command signal from the stage control section 330 as much as instructed by the installation parameter measuring section 320.
direction.

Next, in explaining the operation of the above embodiment, we will first explain the basic principle of this technology and the principle of arithmetic processing of installation parameters, which is a characteristic effect of this embodiment, and then explain a series of operations of the above embodiment. I will explain about it.

(1) Basic principle As shown in FIG. 6, the grid 103 of the projector 100
A number of regular stripes are projected onto the surface of the object to be measured 700 as a checkered pattern image 701 (FIG. 4). When this checkered image 701 is captured by the camera 200 from an angle different from that of the projector 100, a checkered image 702 as shown in FIG. 5, which is deformed according to the shape of the surface, is obtained. This image 702 ii is signal-processed by the signal processing device 300, and the shape of the object to be measured 700 is finally displayed as a set of points (X, Y, Zl) on the surface shape display device 400. ,this(
T.

This is based on the results of the calculations below.

That is, in the relationship between the surface shape of the object to be measured 700 and the image 702 of the checkered image, let the arbitrary point P0 of the grid 103 be (XO+Vo) a, l, and the corresponding point P on the object to be measured 700 be ( x, y, z) 882, any point Po (xol y.

) 881 and point P (X, Y,
Z) 8.2 The relationship is expressed by the following equations (3) and (4).

Q...distance between the grating and the projection lens...distance θ between the projection lens and the coordinate origin...angle between the projector and camera, and point p (x, y, z) 1112 is camera 20
Point P0 (xol Va)s on the most image plane 204 of 0
If the image is focused on at, the point P(X, Y, Z
)9112 and the point (Xor "Jo)81]3 is expressed by the following equations (5) and (6).

X = X0 (12z), /Q2 ・'・Formula (5
)Y:V, (L2 z> /a2...Formula (
6) Q2...Distance L2 between the coordinate origin and the objective lens...
- By substituting equation (5) into distance equation (3) between the objective lens and the imaging surface and rearranging, equation (7) is obtained.

Therefore, as is clear from equation (7), the object to be measured 7
00 upper (7) point P (X, Y, Z) el12
<7) Z coordinate (point Po (xol
y,) [xo of 1111 and point P0 on the imaging plane 204
(×.+ yo) eat×. It turns out that it can be expressed as

On the other hand, the grating 103 has sinusoidal shading at equal intervals as shown in FIG. 3, and when the pitch is So, it is represented by patent (8) characterized by a checkered pattern lft, a, b.

1=a+bcos(2πxo/So) +++Equation (8) If the phase term in Equation (8) is set as Φ, Equation (9) is obtained.

Φ" 27r X o/S o "'
Equation (9) Here, by substituting Equation (9) into Equation (7) and transforming it, Equation (10) is obtained.

A = −Hcosθ B=Q2cosθ C knee S i nθ D=-H122sinθ E = -HL 2cosθ F=Q2 L.

G knee 12 sin θ H=2π12+/S.

This equation (10) is a function of Xe+Φ, and therefore, the point P o (xc+ ya
) *The phase Φ of the checkered image reflected in az is separated (point P (X, Y, Z) on the object to be measured 700 *
7 coordinates of a□ (obtained from the above formula (10). Also,
Using this Z coordinate, point P (X,
Y, Z) 9@2 (7) The X coordinate and -Y coordinate can also be determined from equations (5) and (6).

Therefore, the distribution of the phase Φ (xo+Van Φ) on the imaging surface 204 of the camera 200 is determined, and the surface shape (X, Y, Z) of the measured object 7000 can be determined.

(2) Principle of calculation of installation parameters However, the above formula (10), formula (5), (6)
When calculating the shape of the object to be measured 700 using , the installation parameters of the optical system (Ll, L2. (11,
Q2. θ) must be determined in advance by some method, but in this example, instead of the conventional manual measurement, it is calculated from the known surface shape and the phase distribution of the imaged lattice fringe image, as explained below. Determine the above installation parameters.

That is, for equation (10), equation (5) 1 equation (6), the installation parameters of the optical system (L, , L2.Ql, Q2
．． 0) as a variable and expressed as a function f,, f,,, f2, formula (II) is obtained.

Equations (12) and (13) are obtained.

Z=f, (Φ,×.r'II' 2r Q II
Q2+θ)...(11)X:f2(xc,
Z, L2. (22) =l12)
Y= f s (x,, Z, L2. Q 2
) - (13) In these equations, the measured object 700 whose surface shape (X, Y, Zl is known)
The lattice pattern image on the surface of
! /a+ Φ) is detected and the surface shape (x, y,
z) and phase distribution (xo.

By substituting yo, Φ) into Equations (11), Equations (12), and Equations (13), the installation parameters of the optical system (Ll,
L2+Q,, Q2. An equation with θ) as a variable is created.

In other words, the phase Φ of the lattice fringe image of several points P (X, Y, Z) on the known surface and their image formation point Pa (Xc, ya) are separated, and the equation can be solved,
Optical system installation parameters (LL, L2. Ql,
Q2°θ) can be obtained.

For example] f, If the reference plane 601 of the stage is used as a known surface shape and the reference plane 601 is moved in two axial directions, the unknown position Z0, the amount of movement ΔZ, and the phase distribution (×., yo, Φ) (When expressed using equation (11) above, the relationship (13 Z =
f + (Φ, xc, LH, L2, 12, +Q2r
θ)-7O...Equation (14) Therefore, as shown in FIG.
By substituting Xc, Φ) into equation (14) and solving the simultaneous equations, the installation parameters of the optical system (LL,
12. 121. Q2. θ) can be obtained.

And this installation parameter (Ll, L2.12
+.

Q2r θ) is substituted into equations (1, (5), and (6)), and the unknown measured object 700 is placed on the reference plane 601 of the stage moving device 602, and the phase distribution fxc+y
. , Φ) (2) Surface shape (X, Y,
Z) can be found.

(2) Signal Processing]: The operation of the signal processing device 300 shown in FIG. 2, which obtains the surface shape of the object to be measured 700 using such a principle, will be described.

The video signal of the checkered image from the camera 200 is converted from an analog signal to a digital signal by the A/D converter 311, and then sent to the phase distribution detector 312 to determine the phase distribution I It will be done. In other words, the phase distribution detection unit 312 rotates the image 702 of the lattice stripe image shown in FIG. 5 in the X0 direction to obtain a one-dimensional waveform in the X0 direction as shown in FIG. Since the peak of each stripe is expressed by 2nπ (n is an integer) from this one-dimensional waveform (Equation (8)), the phase Φ of each peak and its position P6 (XOlVo) can be found. Therefore, The phase distribution (Xo+Ve+Φ) on the imaging surface 204 is determined. Based on this phase distribution (X6+'/O+Φ), the shape calculation unit 3]3 calculates the following equations:
The surface shape (X, Y.

2) is calculated, and at this time, the device parameters (Ll,
L2. Ql, Q2. θ) is used.

The calculation result of the shape calculation unit 313 is displayed on the surface shape display mounting 400.
is output by

The surface shape is determined by such signal processing, and the above-mentioned installation parameters (L, , L2+ (
! The setting of I+Qfh θ) is performed by the installation parameter measurement unit 320, the stage control unit 330, the stage control device 600, and the like.

First, when the reference plane 6° 1 of the stage control device 600 is at an unknown position Zo, the stage control unit 330 moves the reference plane 601 as much as instructed by the installation parameter measurement unit 320.
and move it in the Z direction via the stage drive device 603. The moving distance is assumed to be 72. Reference plane 60 at this time
A checkered pattern image on 1 is captured by a camera 200. After the video signal from the camera 200 is A/D converted by the A/D converter 31], the phase distribution detector 312
The phase distribution of the image of the checkered pattern image (X1llll You
Φ) is detected.

Here, the unknown position Zo of the reference plane 601 and the amount of movement ΔZ
Relationship between and phase distribution (Xa, Yc, Φ)
), so by changing /Z several times and substituting a total of six or more sets of (ΔZ, xc, Φ) into equation (14),
By solving the simultaneous equations, the installation parameters of the optical system (Ll, L2. Ql, (!2.
θ) is calculated. These calculations are performed by the installation parameter measuring section 320.

Shape calculation unit 3]3 whose installation parameters are as described above.
It is used when measuring an unknown shape when measuring an object to be measured with an unknown shape.

Therefore, the installation parameters required to measure the three-dimensional shape of the object to be measured 700 are determined by the signal of the phase distribution detection unit 312 and the known object to be measured 700 (reference plane 60).
]), the accuracy and workability are improved compared to conventional manual measurements.

Note that the following aspects can be considered as modifications of the above embodiment.

■ One table to determine installation parameters A total of six sets of simultaneous equations must be solved for the above equation (11), and the solution method is complicated, but there are the following methods to solve this problem. First, a checkered pattern image having a peak at the position x0=0 appears on the imaging surface 204 of the camera 200. Adjust the position of the reference plane 601 so that it comes to =O. That is, the reference plane 607 is moved to the position where 2=0. Then, a checkered image is captured and the phase distribution (X O+ y 01
Φ) is detected. A function between the surface shape at this time and the image 702 of the lattice fringe image (expressed by equation (15) by substituting Z20 into equation (10) above).

Ex, 10FΦ10Gx0Φ=0...Equation (15) Also,
Move the reference plane 60 by the specified distance in the Z direction,
The camera 20 captures the lattice fringe image with a peak at the position x0=O.
The position (Xo, Vo) on the imaging surface 204 of 0 is detected. Image 70 of the surface shape and checkered pattern image at this time
2 (represented by equation (16) by substituting x.20 (Φ=0) into equation (10) above.

By including in the simultaneous equations, the solution method becomes simple.

■ In the above embodiment, the stage reference surface 601 is
is being moved in the Z-axis direction, but the stage moving device 602
may be moved manually, and the hidden moving distance/Z may be input into the installation parameter measuring section 320 using a keyboard or the like. In this case, setting the amount of movement of the moving device 602 (or
Unlike the measurement of installation parameters, it can be measured relatively accurately, so there is no problem with accuracy.

■ In addition, in the above embodiment, the stage control device 600 that is movable is used, but in order to determine the installation parameters, it is sufficient to measure the reference plane 60 associated with the amount of movement △2, as shown in FIG. Yo (:.

It is also possible to use a shape having a stepped reference plane 601A and a known distance corresponding to the movement amount ΔZ, and input this value to the setting parameter measurement unit 320.

[Effects of the Invention] As explained above, 1. According to the present invention, the installation parameters required to measure the three-dimensional shape of the object to be measured can be set using known data of the object to be measured, the imaging means, and the phase distribution. Since the measurement is performed based on data based on the detection means, etc., accuracy and workability are improved compared to conventional manual measurement.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing the configuration of the three-dimensional shape device of the present invention.
FIG. 2 is a configuration diagram of a three-dimensional shape measuring device using a projector, camera, etc. according to an embodiment of the present invention. FIG. 3 is an explanation showing a slit. FIG. Figure 5 shows the grid pattern on the imaging surface of the camera. Figure 6 shows the positional relationship between the projector, camera, and object to be measured in a coordinate system. Figure 7 shows the state of the object being measured in coordinates. Figure 8 shows the waveform of the camera signal in the X0 direction, which is obtained by dividing the checkered image image in the y0 direction, and Figure 9 shows an example of an object to be measured with a known shape. A configuration diagram of a three-dimensional shape measuring device using a projector and a camera according to the technology is shown. Ml...Object to be measured M2...Slit M3...
・Lens M4...Light irradiation means M5...Imaging means M6...Phase distribution detection means Ml...Installation parameter measurement means M8...Shape calculation means 10
0...Projector 200...Camera 30
0-...Signal processing device 400...Surface shape display device 600...Stage control device 700...
Object to be measured

Claims (1)

[Scope of Claims] Light irradiation means for irradiating the object to be measured with light that has passed through a slit through a lens, and imaging means for taking an image of the reflected light from the object to be measured at a position with a predetermined angle of incidence. , a phase distribution detection means for detecting the phase distribution of the electrical signal from the imaging means, data of the object to be measured of a known shape or installation position data of the object to be measured, and phase distribution data from the phase distribution detection means. an installation parameter measuring means for measuring installation parameters of the light irradiation means and the imaging means based on the above-mentioned phase distribution detection means, and a three-dimensional shape of the object to be measured based on the phase distribution data from the phase distribution detection means and the installation parameters from the installation parameter measuring means. A three-dimensional shape measuring device comprising: a shape calculation means for determining a shape by calculation processing; and a three-dimensional shape measuring device.