JPH11118419A - Displacement gauge and three-dimensional shape measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a displacement gange which can freely switch between regular reflection and reverse reflection and to provide a three-dimensional measuring apparatus of simple structurely using such a displacement gange. SOLUTION: When the center of a convex lens 23 is moved onto a light emitting shaft H21, a laser beam emitted from a light emitting part 21 passes through the convex lens 23 and is reflected by a face to be measured of an article to be measured 1, and this reflection light is refracted by the convex lens 23 and receiving by a light receiving part 22 and operates as a displacement gange of a irregular reflection type. When the center of the convex lens 23 is moved onto the center lines of the light emitting shaft H21 and a light receiving shaft H22, the laser beam emitted from the light emitting part 21 is refracted by the convex lens 23 and reflected by the face to be measured of the article to be measured 1, and this reflection light is refracted by the convex lens 23 and received by the light receiving part 22 and operates as the displacement measuring device of the regular reflection type. When the convex lens 23 is moved on the two-dimensional plane in the direction vertical to the light emitting shaft H21 and the light receiving shaft H22, three-dimensional shape of the article to be measured 1 can be measured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a displacement meter such as a laser displacement meter for measuring a displacement (distance) of a measurement surface of an object to be measured using a triangulation method, and a two-dimensional optical axis of the displacement meter. The present invention relates to a three-dimensional shape measuring device that scans (in a planar manner) and measures a three-dimensional shape of a measurement surface of an object to be measured.

[0002]

2. Description of the Related Art Conventionally, as a technique of this kind of displacement meter,
For example, there is one described in the following literature. Literature: "Sensor Device and Instrument Handbook '92"
June 1992 Special issue of sensor technology, published by Information Research Committee, 83-85 As described in the above document, among the displacement meters of the triangulation method, for example, a laser displacement meter projects a laser beam onto an object to be measured, and reflects reflected light from the object in an oblique direction. Since the angle of the reflected light changes depending on the distance (displacement) between the measured object and the displacement meter when observing from, the measuring instrument measures the displacement of the measured object. The laser displacement meter includes a sensor unit having a light projecting unit that projects laser light onto the object to be measured, and a light receiving unit that detects a light receiving position of reflected light from the object to be measured, and a circuit unit is provided in the sensor unit. It is connected. The circuit unit has a function of supplying power to the sensor unit, obtaining a displacement amount of the measured object from an output signal of a light receiving unit in the sensor unit, and the like. Laser displacement meters include a specular reflection type and a diffuse reflection type (also referred to as a vertical type) depending on the arrangement of a light projecting unit and a light receiving unit constituting the sensor unit.

FIG. 2 is a schematic structural view showing a sensor portion of a conventional irregular reflection type displacement meter described in the above-mentioned document. The sensor unit 10 of the irregular reflection type displacement meter emits a laser beam to the projection axis H11.
A light projecting unit 11 for projecting the object to be measured 1 along the
A light receiving unit 12 for detecting a light receiving position of reflected light reflected by the measurement surface of the measurement object 1 and transmitted along the light receiving axis H12. The light projecting unit 11 includes a light source such as a laser diode that generates laser light, and a condenser lens that projects the laser light toward the device under test 1. Light receiving section 12
Is a light receiving lens 12 for condensing reflected light on a light receiving axis H12.
a, and a light receiving element 12b that receives reflected light condensed by the light receiving lens 12a and detects a light receiving position. The light receiving element 12b is constituted by, for example, a CCD (Charge Coupled Device) line sensor which is a digital line sensor.

In this irregular reflection type displacement meter, the light projecting axis H11 is set perpendicular to the DUT 1 (ie, the light projecting axis H1).
1 is placed on the axis H10 of the sensor unit 10), and the light receiving axis H1
2 is set at an angle. And the light emitting unit 1
The measurement surface of the DUT 1 is illuminated with the laser light projected from 1 and the reflected light is collected on the light receiving element 12b by the light receiving lens 12a on the light receiving axis H12. Here, the axis of the reflected light depends on the displacement of the measurement surface of the DUT 1 and the light receiving lens 1
Since the angle changes about the center 2a, the angle changes when the light receiving position on the light receiving element 12b is displaced. Light receiving element 1
The circuit 2b converts the voltage into a displacement amount by a circuit unit in order to output a different voltage depending on the light receiving position.

For example, when a laser beam is irradiated from the light projecting unit 11 to the measurement surface of the DUT 1, the irradiated portion becomes a luminance (spot) and is reflected at that point. Assuming that a spot when the DUT 1 is at the position 1-3 farthest from the sensor unit 10 is s3, the reflected light at the spot s3 is condensed by the light receiving lens 12a and forms an image at a point n3 of the light receiving element 12b. Is done. As the DUT 1 approaches the sensor section 10, the position changes from 1-3 → 1-2 → 1-1, and the spot also moves from s3 → s2 → s1. At the same time, the position of the imaging point on the light receiving element 12b also moves from n3 to n2 to n1,
The displacement W of the measurement surface of the DUT 1 is replaced with the displacement w of the positions n3 to n1 on the light receiving element 12b. Light receiving element 1
The CCD line sensor constituting 2b has a structure in which a large number of semiconductor photodetectors are arranged on a straight line, and has an image forming point (ie,
A signal can be extracted from the light detection element at the point where light is irradiated).
The extracted signal is processed by the circuit unit, and the address of that portion is read, whereby the displacement of the DUT 1 can be measured. This type of irregular reflection type displacement meter can measure a vertical change at a certain point on the plane of the DUT 1, but has a characteristic that it cannot be measured unless the surface is irregularly reflected.

FIG. 3 is a schematic structural view showing a sensor section of the conventional regular reflection type displacement meter described in the above-mentioned document.
Elements common to those in the middle are denoted by common reference numerals. In the sensor unit 10A of the regular reflection type displacement meter, the light projecting axis H1 of the light projecting unit 11 with respect to the axis H10A of the sensor unit 10A.
1 and the light receiving axis H12 of the light receiving unit 12 are set to be inclined at the same angle. This regular reflection type displacement meter can also measure the displacement amount of the DUT 1 by the same operation principle as the irregular reflection type displacement meter of FIG. In the regular reflection type, the DUT 1 is positioned at position 1-1.
In the case of a vertical change as in 1-3, the measurement point on the plane moves, so a change at a certain point cannot be measured (that is, a change within a certain area). It is possible to measure even the DUT 1 as described above.

Conventionally, a three-dimensional shape measuring instrument for measuring the three-dimensional shape of the DUT 1 using the displacement meter shown in FIG. 2 or FIG. 3 has the following two types (a) and (b). One configuration example is generally employed. (A) Sensor units 10, 1 of the displacement meter of FIG. 2 or FIG.
OA is moved two-dimensionally (two-dimensionally), and the displacement due to this movement position is measured to measure the three-dimensional shape of the DUT 1. (B) FIG. 4 is a schematic structural view showing a sensor unit of a conventional three-dimensional shape measuring instrument constituted by using the displacement meter of FIG. 2 or FIG. The sensor unit of the three-dimensional shape measuring device includes a light projecting unit 11 and a light receiving unit 12, and a mirror 13 disposed so as to straddle the light projecting axis H11 of the light projecting unit 11 and the light receiving axis H12 of the light receiving unit 12. It is composed of And
With respect to the measurement surface of the DUT 1 (that is, the scan range),
Projection axis H11 and reception axis H by shaking mirror 13
With the change of 12, the one-dimensional portion in the X-axis direction (mirror scan direction) and the remaining one-dimensional portion move the entire sensor unit including the mirror 13, the light projecting portion 11 and the light receiving portion 12 in the Y-axis direction (unit moving direction). By doing so, the measurement surface of the DUT 1 is two-dimensionally scanned, and the three-dimensional shape of the measurement surface of the DUT 1 is measured.

[0008]

However, the conventional displacement meter and the three-dimensional shape measuring instrument using the same have the following problems (i) and (ii). (I) Problems of the Displacement Meter When the measurement surface of the DUT 1 is perpendicular to the axes H10 and H10A of the sensor units 10 and 10A of the displacement meter, the regular reflection type displacement meter of FIG. Since the angle of incidence and the angle of reflection of light to the light are almost the same, in principle,
However, reflected light can be obtained, and displacement can be measured. On the other hand, in the diffuse reflection type displacement meter of FIG. 2, since the incident angle and the reflection angle of the DUT 1 with respect to the measurement surface are different, reflected light cannot be obtained unless the light incident on the measurement surface is diffusely reflected to some extent. Cannot measure. However, in an actual displacement meter, the light receiving element 12b for detecting the light receiving position, which detects the amount of displacement as a light receiving position difference, cannot detect the light receiving position if the reflected light is too strong or too weak. For example, when the reflected light is too strong in the regular reflection type or the reflected light is too weak in the irregular reflection type, the displacement of the DUT 1 cannot be measured. Therefore, in the displacement meter, it is usually necessary to use the reflection type and the irregular reflection type depending on the light reflection characteristics of the measurement surface of the DUT 1, which is inconvenient in use. (Ii) Problems of the three-dimensional shape measuring device In the conventional three-dimensional shape measuring device using the displacement meter, the sensor unit must be moved in any of the above configurations (a) and (b). However, there are problems such as an increase in size and difficulty in high-speed scanning. The present invention solves the problems of the prior art, and provides a displacement meter capable of freely switching between a regular reflection type and a diffuse reflection type, and a three-dimensional structure having a simple structure using such a displacement meter. An object of the present invention is to provide a shape measuring instrument.

[0009]

According to a first aspect of the present invention, there is provided a displacement meter for measuring a displacement of a measurement surface of an object to be measured by using a triangulation method. A light projecting unit having a light projecting axis in a direction perpendicular to the object to be measured, and irradiating light to a measurement surface of the object to be measured along the light projecting axis; and a light receiving part parallel to the light projecting axis. A light receiving portion for detecting a light receiving position of reflected light reflected by the measurement surface and sent along the light receiving axis, and having a lens diameter large enough to straddle the light projecting axis and the light receiving axis. And has an optical axis parallel to the light projecting axis and the light receiving axis, and is disposed between the light projecting part and the light receiving part and the object to be measured, with respect to the light projecting axis and the light receiving axis. A vertically movable objective lens, wherein the center of the objective lens is positioned on the light projecting axis and on a center line of the light projecting axis and the light receiving axis. It is to place a movable structure.
By adopting such a configuration, when the center of the objective lens is moved on the light projecting axis of the light projecting part, the light emitted from the light projecting part passes through the center part of the objective lens, and Is reflected on the measurement surface, and the reflected light on the measurement surface is refracted by the objective lens toward the light receiving portion, and is received by the light receiving portion.
Thereby, it functions as a diffuse reflection type displacement meter. When the center of the objective lens is moved on the center lines of the light projecting axis and the light receiving axis, the light emitted from the light projecting portion is refracted by the objective lens in the direction of the object to be measured and is irradiated on the measurement surface. This reflected light is bent by the objective lens in the direction of the light receiving section, and then received by the light receiving section. Thereby, it functions as a regular reflection type displacement meter.

According to a second aspect of the present invention, there is provided a three-dimensional shape measuring instrument for measuring a three-dimensional shape of a measurement surface of an object to be measured by using a triangulation method. A light projecting unit that irradiates light to the measurement surface of the device under measurement along the light projecting axis, and a light receiving axis that is parallel to the light projecting axis.
A light-receiving portion for detecting a light-receiving position of reflected light reflected by the measurement surface and sent along the light-receiving axis, a lens aperture having a size across the light-projecting axis and the light-receiving axis, and Axis, and an optical axis parallel to the light-receiving axis, disposed between the light-emitting section and the light-receiving section and the device under test, and two-dimensional in a direction perpendicular to the light-emitting axis and the light-receiving axis. And a movable objective lens. By adopting such a configuration, if the objective lens is moved two-dimensionally with respect to the measurement surface of the measurement object, the measurement surface can be two-dimensionally scanned.
By measuring the displacement of the measurement surface at each scan position, the three-dimensional shape of the measured object can be measured.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment FIGS. 1A and 1B are schematic diagrams of a sensor unit of a regular reflection type / diffuse reflection type switchable displacement meter according to a first embodiment of the present invention. FIG. The displacement meter according to the first embodiment uses a triangular ranging method, irradiates a laser beam to a measurement surface of the DUT 1, receives the reflected light, and detects the light receiving position to detect the light reception position. A sensor unit for measuring the amount of displacement of the object, and a sensor unit for irradiating and receiving laser light, and a circuit unit for calculating the displacement of the measurement surface of the DUT 1 based on a detection signal of a light receiving position received by the sensor unit It is composed of The sensor unit projects a laser beam toward the DUT 1 and receives a reflected light from the DUT 1, and is disposed between the sensor unit 20 and the DUT 1. Objective lens (eg convex lens)
23.

The sensor unit 20 has an axis H2 of the sensor unit 20.
0, a light projecting unit 21 that projects a laser beam along the light projecting axis H21, and a light receiving axis H22 that is parallel to the light projecting axis H21 at a fixed distance. Light receiving axis H22
And a light receiving section 22 for detecting the light receiving position of the reflected light sent along the line. The light projecting unit 21 includes a light source such as a laser diode that emits a laser beam, and a light receiving lens that converts the laser beam into a parallel beam and projects the beam in the direction of the projection axis H21. The light receiving section 22 includes a light receiving lens 22a for collecting the reflected light sent along the light receiving axis H22, and a light receiving element 22b for detecting a light receiving position from the reflected light collected by the light receiving lens 22a. Have been. The light receiving element 22b is, for example, a digital line sensor CC
It is composed of a D-line sensor, and a circuit section is connected to this output side. The convex lens 23 disposed between the sensor unit 20 and the DUT 1 has a lens diameter large enough to straddle the light projecting axis H21 and the light receiving axis H22, and is parallel to the light projecting axis H21 and the light receiving axis H22. An optical axis H23;
21 and the light receiving axis H22. The moving range of the center of the convex lens 23 is a range from the light projecting axis H21 to the center line of the light projecting axis H21 and the light receiving axis H22, and has a structure that can be switched by a moving means such as a manual lever or a motor. . next,
(I) the diffuse reflection type operation of FIG. 1 (a) and (ii) FIG.
The operation of the specular reflection type shown in FIG.

(I) Diffuse reflection type operation of FIG. 1A When the displacement meter is used as a diffuse reflection type, as shown in FIG. 1A, the center of the convex lens 23 is moved on the light projecting axis H21 by the moving means. Moving. When the laser beam is projected from the light projecting unit 21 in the direction of the light projecting axis H21, the laser beam passes through the center of the convex lens 23 and irradiates the measurement surface of the DUT 1, and the irradiated portion becomes a spot. Reflect at that point. The position 1-3 at which the DUT 1 is farthest from the convex lens 23
Let s3 be the spot when there is
3 is reflected by the convex lens 23 into the light receiving lens 22a.
After being refracted in the direction, the light is condensed by the light receiving lens 22a and is imaged at a point n3 on the light receiving element 22b. As the DUT 1 approaches the convex lens 23, its position is changed from 1-3 → 1-
2 → 1-1, and the spot also moves from s3 → s2 → s1. At the same time, the position of the imaging point on the light receiving element 22b also moves from n3 to n2 to n1, and the displacement W of the measurement surface of the DUT 1 is replaced with the displacement w of n3 to n1 on the light receiving element 22b. Can be Since the light receiving element 22b is composed of, for example, a CCD line sensor in which a large number of semiconductor light detecting elements are arranged in a straight line, the light receiving element 22b receives a signal from the light detecting element at the image forming point (that is, the point irradiated with light). I can put it out. By processing this signal in the circuit section and reading out the address of that portion, the displacement of the DUT 1 can be measured. The method of using such a displacement meter is almost the same as the structure of the conventional diffuse reflection type displacement meter of FIG. 2 in which the convex lens 23 is inserted on the light projecting axis H11. Therefore, the displacement meter of the present embodiment has almost the same displacement detection characteristics as the conventional diffuse reflection type displacement meter of FIG. (Ii) Specular reflection type operation of FIG. 1B When the displacement meter is used as a specular reflection type, as shown in FIG. 1B, the center of the convex lens 23 is moved by the moving means to the light projecting axis H21 and the light receiving axis. In the direction perpendicular to the axis H22, the parallel movement is performed to the center line of the light projecting axis H21 and the light receiving axis H22. Then, the laser light projected from the light projecting unit 21 is refracted by the convex lens 23 in the direction of the optical axis H23 of the convex lens 23, and is irradiated on the measurement surface of the DUT 1. The reflected light is refracted in the direction of the light receiving lens 22a by the convex lens 23, and is condensed on the light receiving element 22b by the light receiving lens 22a. In such a usage method, the laser light from the light projecting unit 21 is refracted by the convex lens 23 in the direction of the optical axis H23 of the convex lens 23, and the light reflected by the measurement surface of the DUT 1 changes accordingly. The light receiving position on the light receiving element 22b with respect to the positions 1-1, 1-2, and 1-3 on the measurement surface of the DUT 1 hardly changes. Therefore, the angle relationship between the light projection and the light reception becomes a regular reflection type, and the displacement of the DUT 1 can be accurately measured. As described above, in the displacement meter of the first embodiment, it is possible to freely switch between the regular reflection type and the irregular reflection type only by moving the convex lens 23 in parallel.
In addition, the displacement detection characteristic at this time hardly changes.
Therefore, it is possible to realize a displacement meter that can arbitrarily select the regular reflection type or the irregular reflection type depending on the received light intensity or the like.

Second Embodiment FIGS. 5A and 5B are schematic structural views of a sensor unit of a three-dimensional shape measuring instrument according to a second embodiment of the present invention. 1 are denoted by the same reference numerals as those in FIG. This three-dimensional shape measuring instrument differs from the displacement meter in FIG. 1 in the structure of the moving means of the convex lens 23 and in the configuration of the circuit for processing the light receiving position detection signal of the light receiving element 22b. That is, the moving means of the convex lens 23 in this three-dimensional shape measuring instrument is
The convex lens 23 is moved by a motor or the like on a two-dimensional plane including the X-axis direction and the Y-axis direction perpendicular to the light projecting axis H21 and the light receiving axis H22. Further, the circuit unit for inputting the output signal of the sensor unit 20 is configured to detect the position of the DUT 1 based on the light receiving position detection signal of the light receiving element 22b.
The three-dimensional shape of the measurement surface is calculated by calculation.

FIG. 6 is a diagram for explaining the operation of FIG. When measuring the three-dimensional shape of the measurement surface of the DUT 1, FIG.
As shown in (a) and (b), the convex lens 23 is moved in the X-axis direction by the moving means. For example, FIG.
At the position of the convex lens 23 shown in FIG.
Since the optical axis 21 coincides with the optical axis H23 of the convex lens 23, the laser light emitted from the light projecting section 21 passes through the central portion of the convex lens 23 and irradiates the measurement surface of the DUT 1. The reflected light is reflected by the convex lens 23 into the light receiving lens 2.
After being refracted in the 2a direction, the light is condensed on the light receiving element 22b by the light receiving lens 22a. When the convex lens 23 is moved in parallel from this state to the position shown in FIG. 5B, the laser light emitted from the light projecting unit 21 is refracted by the convex lens 23 in the direction of the optical axis H23 of the convex lens 23. The reflected light from the measurement surface of the object 1 is also refracted by the convex lens 23 in the direction of the light receiving lens 22a in accordance with the refraction of the emitted laser light and changes. For this reason, the light receiving unit 20 can receive the reflected light from the measurement surface of the DUT 1 without being affected by the movement of the convex lens 23.

After the convex lens 23 is moved in the X-axis direction in FIG. 6, the convex lens 23 is moved in the Y-axis direction by a predetermined pitch, and is moved in the X-axis direction in the same manner as described above. As described above, only the convex lens 23 is moved in a zigzag manner in the X-axis direction and the Y-axis direction by the moving means, and the light receiving position detection signal of the light receiving element 22b at each of these moving positions is arithmetically processed by the circuit unit. DUT 1 at moving position
The height of the measurement surface can be measured. As described above, this second
In the embodiment, the measurement surface of the DUT 1 is two-dimensionally scanned by moving the convex lens 23 only on a two-dimensional surface including the X-axis direction and the Y-axis direction without moving the sensor unit 20. Then, the three-dimensional shape of the measurement surface can be measured by continuously detecting the displacement of the measurement surface at each scanning position at a high speed. As a result, the moving means of the convex lens 23 can be reduced in size and high-speed scanning can be performed. Note that the present invention is not limited to the above-described embodiment. For example, the light projecting unit 21 and the light receiving unit 2
Various modifications are possible, such as 2 having another structure or arrangement shape.

[0017]

As described above in detail, according to the first aspect, the center of the objective lens can be switched and moved between the projection axis and the center lines of the projection axis and the light receiving axis. Therefore, one displacement meter can be freely switched between a specular reflection type and a diffuse reflection type. In addition, since the displacement amount detection characteristic at this time hardly changes, a displacement meter that can arbitrarily select the regular reflection type or the irregular reflection type depending on the received light intensity or the like can be realized. Second
According to the invention, the optical axis of the objective lens is two-dimensionally moved along the measurement surface of the object to be measured only by moving the objective lens two-dimensionally and without moving other parts of the displacement meter. By scanning and measuring the displacement at each scanning position, the three-dimensional shape of the measured object can be measured. Therefore, the means for moving the objective lens can be miniaturized,
A three-dimensional shape measuring instrument capable of high-speed scanning can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic structural diagram of a sensor unit of a displacement meter according to a first embodiment of the present invention.

FIG. 2 is a schematic structural diagram showing a sensor unit of a conventional irregular reflection type displacement meter.

FIG. 3 is a schematic structural view showing a sensor unit of a conventional regular reflection type displacement meter.

FIG. 4 is a schematic structural view showing a sensor unit of a conventional three-dimensional shape measuring instrument.

FIG. 5 is a schematic structural diagram of a sensor unit of a three-dimensional shape measuring instrument according to a second embodiment of the present invention.

FIG. 6 is an operation explanatory diagram of FIG. 5;

[Explanation of symbols]

 Reference Signs List 1 object to be measured 20 sensor unit 21 light emitting unit 22 light receiving unit 22a light receiving lens 22b light receiving element 23 convex lens

Claims (2)

[Claims] 1. A displacement meter for measuring a displacement amount of a measurement surface of an object to be measured by using a triangular distance measuring method, comprising: a light projecting axis perpendicular to the object to be measured; A light projecting unit for irradiating the measurement surface of the object with light along the light receiving axis, and a reflected light reflected from the measurement surface and sent along the light receiving axis, having a light receiving axis parallel to the light projecting axis. A light receiving unit that detects the light receiving position of the light receiving unit, having a lens diameter large enough to straddle the light projecting axis and the light receiving axis, and having an optical axis parallel to the light projecting axis and the light receiving axis;
An objective lens disposed between the light projecting unit and the light receiving unit and the object to be measured, the objective lens being movable in a direction perpendicular to the light projecting axis and the light receiving axis. A displacement meter having a structure capable of switching and moving on the light projecting axis and on the center line of the light projecting axis and the light receiving axis. 2. A three-dimensional shape measuring device for measuring a three-dimensional shape of a measurement surface of an object to be measured by using a triangular distance measuring method, comprising: a light projecting axis perpendicular to the object to be measured; A light projecting unit that irradiates light onto the measurement surface of the DUT along the light projection axis, and a light receiving axis that is parallel to the light projection axis, and is reflected along the measurement surface and sent along the light receiving axis. A light receiving unit for detecting a light receiving position of the reflected light coming, having a lens aperture having a size across the light projecting axis and the light receiving axis, and having an optical axis parallel to the light projecting axis and the light receiving axis,
An objective lens disposed between the light projecting unit and the light receiving unit and the object to be measured, and movable two-dimensionally in a direction perpendicular to the light projecting axis and the light receiving axis. 3D shape measuring instrument.