JPH0690031B2 - Configuration of non-contact optical distance detection probe - Google Patents

Description

The present invention relates to the configuration of an optical non-contact distance detector,
In particular, the present invention relates to a configuration of a non-contact optical distance detection probe for a three-dimensional shape measuring device, which is small and lightweight and suitable for measuring an edge or a hole of an object and tracking a surface.

(Prior Art) As a measuring probe for a three-dimensional shape measuring instrument, a mechanical contact type is widely used. In order to measure an object that is deformed by the contact method or to improve the measurement speed, a light beam is projected onto the object to generate a bright spot,
Attempts have been made to develop an optical probe stylus that detects the image position and detects the distance in the light beam projection direction based on the principle of triangulation.

FIG. 5 shows a conceptual diagram of the structure of this conventional general optical probe. In this conventional general optical non-contact probe, the image position of the bright spot T generated on the object O by the light beam B from the light beam projecting means B _P is used as the gauge direction detecting means.
The image position detecting element S in D _S detects the distance, and the distance with respect to the projection direction of the light beam B can be detected point by point according to the principle of triangulation. When measuring the shape of a surface or detecting a ridge, it is necessary to mechanically move this probe and detect a distance corresponding to each point a number of times.
When tracking ridges or edges (steps), the measurement speed is significantly reduced. In order to improve this, a non-contact probe based on the optical cutting method whose conceptual diagram is shown in FIG. 6 has been devised. Slit light projection means instead of light beam
The band-like light B _L is projected by B _LP to generate a bright line T _L on the object O, and the image of the bright line is detected by the image detection element S _i in the gauge direction detection means D _i , and the principle of three surveying is measured. Gives the distance of points along the bright line. Therefore, by projecting and measuring the band-shaped light so as to cross the ridgeline or the stepped portion, this can be easily detected without mechanical movement of the probe, and the measurement speed can be improved. However, when the direction of the ridgeline or the step changes, it is necessary to mechanically rotate the probe accordingly. In addition, a two-dimensional image detection element is required for detecting the bright line image, and generally, the image position detection accuracy of the two-dimensional image detection element is several times higher than that of the one-dimensional image detection element ( Since it is 4 to 5 times lower), the distance detection accuracy cannot be sufficiently improved. Although the measurement speed is higher than that of point measurement, the improvement is still insufficient.

(Problems to be Solved by the Invention) As described above, the point-measuring optical distance detecting probe is
It is necessary to move the probe mechanically point by point,
It is difficult to improve the measurement speed and detect the ridges and edges of objects and the outline of holes.

In addition, the conventional light-section method using band-shaped light is insufficient in size and weight reduction of the apparatus as described above, and the resolution of the two-dimensional image detection element used for slit image detection is low. It is difficult to improve the detection accuracy, and it is easy to detect the edges and ridges of objects that intersect the slit light, but it is difficult to detect the edges and ridges of almost parallel objects. These edges, ridges,
It was necessary to mechanically rotate the device so that it was approximately perpendicular to the outline of the hole, etc.

(Means for Solving the Problems) In order to solve the above problems, in the present invention, a light beam is deflected and scanned in two or more specific directions or two-dimensionally to scan an object surface. To produce a bright spot on the surface of the object, and to form a mirror image of the bright spot formed by the mirror arranged between the object and the one-dimensional gauge orientation detector, rather than the two-dimensional image position detecting element. To detect the three-dimensional position of the bright spot generated on the surface of the object by detecting using a plurality of one-dimensional gauge position azimuth detectors configured by using a one-dimensional image position detecting element with high position detection accuracy. It is characterized by having done.

(Operation and effect) With the mirror arranged between the object and the one-dimensional gauge orientation detector, the one-dimensional gauge orientation detector is arranged at a position where it has a mirror image relationship with respect to this mirror. The same effect as can be obtained. Therefore, the width of the device can be made significantly narrower than the equivalent baseline length in triangulation, and the entire device can be made smaller and lighter. The deflection scanning of the light beam makes it possible to detect the distance within a certain area without mechanical movement of the distance detector.

Therefore, when used as a non-contact probe for a three-dimensional shape measuring machine, the mechanical movement of the probe can be minimized and the measurement speed can be improved. Also, the ridgeline of the object,
This makes it easy to detect the outlines of edges and holes, and facilitates the automation of ridge lines, edges, hole outlines, and object surface traces that could not be realized by conventional point measuring probes.

The detection accuracy can be improved by adopting a one-dimensional gauge orientation detector using a one-dimensional image position detecting element as the image position detecting element.

(Examples) It is the present invention to improve the above-mentioned drawbacks and further improve the performance, and a non-contact optical distance detection probe configured based on the present invention in FIGS. 1a and 1b is used. A conceptual diagram is shown. Light beam deflection projection means arranged on the axis of the device
The light beam B is projected onto the target surface by B _S , and the bright spot T
(T ') is generated. The light beam deflection projection means B _S is configured so that the light beam can be deflected and scanned over the entire area of the distance detection space R _S. The light from the bright spot T (T ') is reflected by the mirrors M ₁ , M ₂ , M ₃ , M ₄ arranged axially around the device axis, and then, around the light beam deflection projection means. One-dimensional gauge orientation detector corresponding to each mirror placed in
The one-dimensional image position detection element S is incident on D _S1 , D _S2 , D _S3 , and D _S4.
Thus, the position of the bright spot image I (I ′) is detected. The one-dimensional gauge orientation detector arranged around the light beam deflecting means B _S is a virtual one-dimensional gauge orientation detector arranged at a position having a mirror image relationship with the corresponding mirror. D
_S1V , D _S2V , D _S3V , and D _S4V have exactly the same imaging relationship as that of observing the bright point _IV ( _{IV '} ), and eventually, these three-dimensional triangulation is performed by the virtual one-dimensional gauge azimuth detector. Is exactly equivalent to The mirrors M ₁ , M ₂ , M ₃ and M ₄ fold these virtual one-dimensional gauge orientation detectors inward, which means that the width of the device is equivalent to the equivalent baseline length of triangulation. Can be significantly narrowed, which is extremely effective for downsizing the non-contact optical distance detection probe.

Typical deflection scanning modes of the light beam of the light beam deflection projection means used in the non-contact optical distance detecting probe according to the present invention are shown in FIGS. 2a, 2b and 2c. FIG. 2a shows a structure in which a light beam is scanned in a cross shape, and a laser beam B is directed by an optical deflector B _S1 (rotating mirror, vibrating mirror, ultrasonic deflector, etc.) in the x direction or the y direction. Can be realized with a bias. In this figure, L _f is a lens for projecting a light beam, which has an angle with respect to the axis of the optical system and goes away, in a direction parallel to the axis of the optical system. There is no problem even if the projection direction of the light beam has an angle with respect to the axis of the optical system, but since the condition for illuminating the object is constant, it is more preferable to project the light beam in a direction parallel to the axis of the optical system. In Fig. 2b, a light source E _D capable of scanning bright spots like an emitting diode array is used as a light source, and one-dimensional scanning is performed by the light source E _D , and the bright spots are projected by a projection means R _T including an image rotator. It is configured such that the image is rotated and projected, and the scanning direction (angle) θ of the bright spot is rotated about the axis of the optical system to perform line scanning in an arbitrary direction. Rotation in the scanning direction is performed by rotating an image rotation prism or the like, or by rotating the light source itself, or changing the scanning direction of the electron beam by using a cathode ray tube or a laser diode array capable of issuing control by an electron beam for the light source. It can also be realized by a method such as FIG. 2c shows that the light beam B is deflected by a two-dimensional deflecting means (rotation, vibrating mirror, ultrasonic deflection element, etc.) B _S2 .
It is a dimensional scanning type. As the light source, as in the case of FIG. 2b described above, a two-dimensional emitting diode array or one using a cathode ray is used, and a type in which it is projected is also considered. In both cases of Figures 2b and 2c,
As in the case of FIG. 2a, it is possible to combine means for making the projection direction of the light beam B parallel to the axis of the optical system,
This is more desirable because the illumination conditions can be kept constant.
The one in which the light beam can be freely projected in two dimensions in Fig. 2c enables the most flexible measurement, but as a distance detection probe for a three-dimensional shape measuring machine, Two-direction (cross) scans in the figure or line scan rotations in Figure 2b are sufficient. That is, even when tracking the steps or ridges, measuring holes, etc., even if the direction changes,
Cross-direction scanning or line scanning and rotation are sufficient.

FIG. 3 is a structural example of a general one-dimensional gauge orientation detector. It is composed of a combination of a cylindrical lens L and a one-dimensional image position detecting element S. Due to the cylindrical lens L, the bright spot T is
It is projected as a line image I. By detecting the position of this line image by the one-dimensional image position detecting element S, the angle θ of the plane where the bright spot exists can be determined. Therefore, if three or more one-dimensional gauge orientation detectors are used, the three-dimensional position of the bright spot can be determined as the intersection of the planes defined by the detectors. If the light beam projection method is known, the three-dimensional position of the bright spot can be determined as the intersection of the plane defined by the one-dimensional gauge orientation detector and the straight line indicating the beam projection direction. By using the one-dimensional image position detecting element having high position detection accuracy, the detection accuracy can be improved as compared with the two-dimensional one.

FIGS. 4a and 4b show a method of constructing an optical system of the one-dimensional gauge orientation detector used in the present invention. Two mirrors facing each other between the cylindrical lens L and the one-dimensional image position detecting element S
It has a structure in which M ₁ and M ₂ are arranged. In the normal configuration (configuration in FIG. 3), when the bright spot T moves in the y direction in FIGS. 4a and 4b, the line image I _V deviates from the one-dimensional image position detecting element S and becomes undetectable. In order to avoid this, it is necessary to extend the axial length of the cylindrical lens L, and there is a drawback that the one-dimensional gauge orientation detector becomes large. With the configuration shown in FIGS. 4a and 4b, the light incident on the cylindrical lens L is repeatedly reflected by the mirrors M ₁ and M ₂ and is projected onto the image position detecting element S. Therefore, the limit of the detectable range in the y direction is virtually eliminated, and the width of the one-dimensional gauge orientation detector can be significantly narrowed. By adopting the one-dimensional gauge orientation detector of this method, the non-contact optical distance detecting probe according to the present invention can be further reduced in size and weight.

[Brief description of drawings]

1a and 1b are respectively a side view and a plan view of an embodiment of an optical non-contact probe according to the present invention, and FIGS. 2a, 2b and 2c are light beams used in the present invention. Fig. 3 is a conceptual diagram showing an example of a deflection scanning mode, Fig. 3 is a conceptual diagram of a configuration example of a cylindrical lens and a one-dimensional image position detecting element of a one-dimensional gauge direction detector, and Figs. 4a and 4b are parallel mirror optics, respectively. Perspective view and side view of an optical system configuration for downsizing a one-dimensional gauge orientation detector by a system, FIG. 5 is a conceptual diagram of a conventional general optical non-contact probe, and FIG. 6 is a conventional optical disconnection. Schematic diagram of the optical non-contact probe by the method. (Explanation of symbols) B _P ...... light beam projection means, B ...... light beam, T, T '...... bright spot, O, O' ...... object, D _S ...... gage point direction detection means, S ...... Image position detection element, I, I '... Bright spot image, B _LP ...... Slit light projection means, B _L ...... Slit light, T _L ...... Bright spot, D ₁ ...... Image detection means, S _I ... ... Image detection element, I _L ... image of bright line, B _S ... light beam deflection scanning means, D _S1 , D _S2 , D _S3 , D _S4 ... one-dimensional gauge orientation detection means, D _S1V , D _S2V , D _S3V , D _{S4V ・ ・ ・} Virtual one-dimensional gauge orientation detecting means, S _{V ・ ・ ・} Virtual image position detecting element, I _V , I _{V ′} …… Virtual image of bright spot, R _S …… Detection space, M ₁ , M ₂ , M ₃ , M ₄ …… Plane mirror, L _f …… Lens, B _S1 …… Light beam deflection projection means, E _D …… Light emitting diode array, R _T …… Image rotation projection means, B _S2 …… Light Beam two-dimensional deflection projection means.

Claims (1)

[Claims] 1. A light beam deflecting and projecting means for scanning an object surface with a bright spot, a mirror surface for returning and reflecting light from the bright spot generated on the object surface by the light beam projection, and reflected by this mirror surface. A cylindrical lens that condenses light, a one-dimensional image position detecting element that detects the image position of the bright spot condensed by the cylindrical lens, and the cylinder between the cylindrical lens and the one-dimensional image position detecting element A structure of a non-contact optical distance detection probe, characterized in that a plane mirror is provided facing each other in the axial direction of the lens.