JPH05215528A - Three-dimensional shape measuring apparatus - Google Patents

Abstract

PURPOSE:To reduce the errors caused by the inclination of a surface to be measured and the like and to make it possible to perform precise measurement by providing an apparatus, which uses the position of a light spot that is discriminated with an optical position detector as the data and operates a three- dimensional-shape signal. CONSTITUTION:The reflected light from the slant surface of a material to be measures repeats the reflection at the other surface. The diameter of a light spot, which is cast into an optical position detector CCD 3 becomes a<b<c. The shapes of the reflected spots from the vertical surface become approximately equal. The secondary reflected light has the long elliptical shape, and the spot diameter is increased. In an operating device, a discriminating- reference value for the spot shape to be detected is inputted as the value of (a) or less. The values (b) and (c) are removed from the data. Thus, the reflected light from the slant surface is removed, and the data are processed. In this way, the three-dimensional signal is operated based on only the detected data when the light is cast on the surface to be measured approximately vertically by the discrimination of the detected signal. Therefore, the shape can be measured in extremely high accuracy.

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.

[0002]

2. Description of the Related Art Conventionally, there has been known an optical non-contact method for measuring a three-dimensional shape, in which the spot position of reflected light is detected by PSD or the like to measure the displacement according to the principle of triangulation. There is. As shown in FIG. 3, when the measurement surface S ₁ is displaced, the PSD detection position is displaced. Detected position of the PSD, before the _{X 1,} the following and _{X 2.} If the PSD length is L and the distance between the detection position X and the _Ib output end is X, then I
The ratio of _a and _{I b} is _{I a / I b = X /} L-X ............ (1) On the other hand, B the distance between the illumination lens and the light receiving lens, the distance between the light receiving lens and the PSD F, the measuring surface If the distance to is R, then R = BF / X (2), and from equations (1) and (2), R = (1 + I _b / I
_a ) BF / L, and the distance R can be found by calculating the current ratio I _a / I _b with _a divider. Naturally, S ₁ → S
_When it changes to _2, it changes from X _{1 to} X _2, and it is detected that R increases because I _a / I _b decreases. However, according to the PSD sensor that detects such an analog current from the two electrodes, when the measurement surface is the inclined surface S ₃ , as shown in FIG. 4, the light secondarily reflected to the other surface S ₄ is simultaneously generated. Input will be made to the two positions X ₃ and X ₄ of the PSD. That is, the reflected light is detected at both positions X ₃ and X ₄ of the PSD, and the detection position on the sensor at this time is detected so as to be at the intermediate position between X ₃ and X ₄ , and the true position is detected. The position detection processing deviated from X ₃ is performed, which causes a measurement error.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the influence of the inclination of the measuring surface in the above-mentioned shape measurement and to enable the precision measurement with less measurement error.

[0004]

SUMMARY OF THE INVENTION The present invention discriminates a light spot shape detected by an optical position detector that detects reflected light by triangulation, and uses the discriminated light spot position as data to generate a three-dimensional shape signal. Is provided with an arithmetic processing unit for arithmetically processing

[0005]

As described above, the present invention discriminates among the detection signals of the optical position detector for detecting the reflected light by triangulation, the spot shape having a predetermined range is discriminated, and the discriminated optical spot position is used as the tertiary data. Since it is characterized by being provided with an arithmetic processing unit for arithmetically processing the original shape signal, a lot of reflected light is two-dimensionally reflected from points other than the light irradiation point on the measurement surface. Or, when the diameter becomes large, it is excluded from the detection data and processed, and the position of the light spot that has been valved in a predetermined range is treated as data, so that the three-dimensional shape signal is arithmetically processed.
A small error can be detected and precise measurement can be performed.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment of the drawings. In FIG. 1, reference numeral 1 is a semiconductor laser that oscillates a laser, and 2 is a laser beam irradiation lens, which constitutes an irradiation system. Reference numeral 3 is an optical position detector capable of measuring the spot shape of the reflected light, for example, a CCD is used. Reference numeral 4 denotes the light receiving lens, and 5 denotes a filter, which constitutes a light receiving system. The irradiation system and the light receiving system are provided on a biaxial optical axis having a predetermined angle, and the whole is housed in the measuring head 6.
7 is an object to be measured whose shape is measured in a non-contact manner, and is fixed to an X, Y feed table 8. 9, 10, 11 are the X axis and Y, respectively
Axes and Z-axis drive motors, 12 is an NC controller for automatically controlling each axis motor, and 13 is an arithmetic processing unit, which calculates a three-dimensional shape signal based on CCD detection data and position information of the NC controller 12. Reference numeral 14 is a printer for recording the calculation output.

In the above, the CCD 3 is an optical sensor in which a large number of pixels are arranged two-dimensionally in the vertical and horizontal directions at a fixed pitch, and the light input position can be determined by the pixel number. The laser beam oscillated by the semiconductor laser 1 is focused by the irradiation lens 2 and focused on one point of the DUT 7. Of the light reflected by the object to be measured 7 by this light irradiation, the reflected light in the direction of the light receiving axis provided at a required angle different from the irradiation axis is focused by the lens 4 and is incident on the CCD 3 as a light spot. C
The CD3 can be detected on the two-dimensional surface as described above, and the shape of the light spot can be detected.

For example, as shown in FIG. 2, when the surface to be measured is tilted, the light reflected by the tilted surface hits another surface and is repeatedly reflected, and the light reflected secondarily and thirdly is received by the light receiving lens. Since it is captured by 4, the light spot diameter incident on the CCD detection surface increases as a <b <c. In this case, the shape of the light spot reflected from the vertical surface is almost the same, but the light secondary-reflected becomes an elliptical shape, and the spot diameter increases. Therefore, the discrimination reference value of the spot shape to be detected is input to the arithmetic processing device 13, and for example, if only spot diameters of a or less are discriminated, b and c are excluded from the data. Data processing can be performed by excluding the reflected light from the inclined surface. As described above, the three-dimensional shape signal is calculated only by the detection data when the surface to be measured is irradiated with light substantially perpendicularly by the discrimination processing of the detection signal, and thus the shape measurement can be performed with extremely high accuracy.

Then, the signal detected by the CCD 3 is discriminated in the form of a light spot, and the discrimination is OK.
The light spot position on the CCD 3 is read as data from the generated signal, and data processing is performed by the arithmetic processing unit 13. The arithmetic processing unit 13 outputs the detection signal of the CCD 3 to A
-The D-converted digital signal is subjected to linear correction and averaging by the CPU, and the processed data is stored in the memory and the three-dimensional shape signal is stored together with the position information on the X and Y planes of the measurement points from the NC controller 12. Is calculated. The calculation output is printed out by the printer 14.

As described above, in the position measurement by the laser beam, since only the detection signal when the laser irradiation is performed substantially perpendicular to the measurement point is processed by the arithmetic processing unit 13, the laser beam having an acute angle on the inclined surface is used. It is possible to perform measurement with extremely high accuracy by reducing the measurement error due to irregular reflection such as secondary and tertiary reflection due to irradiation and position measurement. At the measurement point, the X-axis motor 9 and the Y-axis motor 10 are driven to sequentially move and scan the measurement point of the DUT 7, and the measurement is repeated. When the depth of the measurement point of the DUT 7 in the Z-axis direction changes, the CCD 3 By changing the light spot position on the surface, the Z-axis position is detected by the principle of triangulation,
The three-dimensional shape signal can be calculated and output by opening the line and the scanning positions on the X-axis and Y-axis planes. Further, while the moving scanning of the measuring point of the DUT 7 is performed, the measuring scanning is repeated,
By distinguishing the reflection spot shape, when it is within a certain range, that is, when the reflected wave is detected by irradiating light almost perpendicular to the measurement surface, data processing is performed as effective, and this measurement control is measured. The three-dimensional shape can be precisely measured by performing the operation processing of the effective data over the entire surface of the object 7.

The discrimination criterion of the light spot shape of the CCD 3 may be set to a small value when high accuracy is required, and may be set to a large value in the opposite case. For example, an inclined surface, a wall surface or an edge excluded by discrimination. For the part (1), the entire surface can be measured with high accuracy by performing the precise measurement again while changing the direction of the light irradiation axis after one scanning measurement. Also, filter 5
Is to allow light of a certain intensity or more to pass through and to be detected by the CCD 3. The outer peripheral edge of the light spot due to scattered light is cut, and only light in a predetermined intensity range is detected and data processing is performed to improve measurement accuracy. be able to. The spot diameter can be controlled by using an LC film for the filter. Further, a diaphragm mechanism can be used for spot control, and detection accuracy can be improved by performing detection while controlling the diaphragm. Further, as the light position detector for detecting the reflected light, a detector for detecting on the line such as PSD can be used in addition to the one for detecting the two-dimensional surface of CCD, and the length of the spot on the line can be used. The data can be selected by discriminating between the two.

[0010]

As described above, the present invention is provided with an optical position detector for detecting the reflected light by triangulation, discriminates the optical spot shape detected by the optical position detector, and discriminates the discriminated optical spot position. Is provided as an arithmetic processing device for arithmetically processing a three-dimensional shape signal,
Of the detection signals detected by the optical position detector, it is possible to remove spots other than those with a spot shape within a predetermined range, that is, light spots due to secondary and tertiary reflections from points other than the light irradiation point on the measurement surface. When the shape is deformed or the diameter becomes large, it is processed by excluding it from the detection data, and only the discriminated light spot in the predetermined range is taken out, and the three-dimensional shape signal is calculated using this spot position as data. Therefore, when the light irradiation point on the surface to be measured is tilted or at the edge part, it is not processed as detection measurement data, but only the data when the irradiation light hits the measurement point almost vertically is measured. By doing so, it is possible to obtain the effect that the measurement error can be reduced and the precise measurement can be performed.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of the present invention.

FIG. 3 is a block diagram of a conventional device.

FIG. 4 is a conventional explanatory view.

[Explanation of symbols]

 1 Laser Oscillator 2, 4 Lens 3 Optical Position Detector 5 Filter 6 Head 7 Object to be Measured 8 Table 9, 10, 11 Motor 12 NC Control Device 13 Arithmetic Processing Device

Claims (2)

[Claims] 1. An apparatus for detecting and measuring the reflected light when a three-dimensional shape is irradiated with a light beam such as a laser by using a triangulation method, and a light position where the spot shape of the reflected light by the triangulation can be measured. A detector is provided, and a light spot shape detected by the light position detector is discriminated and an arithmetic processing unit for arithmetically processing a three-dimensional shape signal is provided with the discriminated light spot position as data. Three-dimensional shape measuring device. 2. An arithmetic processing unit according to claim 1, which discriminates a light spot shape and a light amount detected by an optical position detector, and arithmetically processes a three-dimensional shape signal using the discriminated light spot position as data. A three-dimensional shape measuring device characterized by being provided with.