JPS5832103A - Noncontacting measuring device - Google Patents

Abstract

PURPOSE:To measure optical distances and surface shapes inexpensively with high accuracy in a large measuring range in a measuring device for optical distances and surface shapes by polarizing pulse light periodically and operating the optical distances or surface shapes from the detection positions and deflection angles of the reflected light from an object. CONSTITUTION:The pulse light of a constant period from a laser source 2 is deflected periodically with an optical deflector 3. A photodetector 4 is placed in the position of a known angle thetao, and an object 1 is placed in the direction of an unknown angle thetai. A photodetector group 5 is placed on the same plane as the front surface of the deflector. If the respective unit elements 51-5n detect only the vertical incident light, the scattered and reflected light at the point P on an object is detected by, for example, the element 5i. If the distance between the element 5i and the deflector is defined as D, the distance L between the point P and the element 5i is determined by L=D/tanthetai. Since thetai-thetao is determined from the difference Ti in the output pulse time of the photodetector 4 and the element 5i and the period of the deflector, the thetai is beforehand determined from the same.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a non-contact measuring device that can accurately measure the distance to a target object and the surface shape of the target object using an optical method.

Recently, automatic machines and robots have been developed, and in order to transport and process objects using these automatic machines and robots, it is extremely useful to measure the position and surface shape of objects with high precision. Various methods have been proposed. It is possible to perform measurements without contact.

Although it can be said that it is desirable because there are usually few movable subdivisions, high measurement accuracy, and few failures, conventional ones did not necessarily fully fulfill the above objectives. In other words, those using magnetism or capacitance are limited to relatively short distances, and become less accurate as the distance increases. Also, those that use ultrasonic waves have poor directivity and focusing, so they have poor accuracy against small objects and are prone to malfunction, and those that use optical interference have good accuracy but are very expensive. It is.

In view of the above points, the present invention provides a practical non-contact measuring device that is superior to conventional ones in terms of measurement distance range, accuracy, and formality.

The present invention will be explained below with reference to the drawings.

FIG. 1 is a diagram for explaining the measurement principle in the non-contact measuring device of the present invention. In the figure, 1 indicates the object to be measured;
Reference numeral 2 denotes a laser light source that repeatedly generates a narrow beam of light in the form of pulses, and this beam light enters the optical element 3 perpendicularly. The optical element 3 periodically deflects this light beam within one plane according to a deflection control signal, and can be an acousto-optic element 2 commonly called an optical deflector.

That is, the beam light emitted from the laser light source 2 is deflected at an angle θ with respect to the laser optical axis according to the deflection control signal. and the deflection angle θ. , the light directly enters the light receiving element 4 existing within this deflection plane. The light receiving element 4 emits a pulsed output corresponding to this pulsed beam light. This is shown in Figure 2 (A). Now, with the deflection 411Jm signal, a pulsed beam is emitted at the deflection angle θ, and that beam □
When light irradiates a minute portion P on the surface of an object, scattered light and specularly reflected light from P are generated. A light receiving element group 6 for receiving these lights is provided on a plane including the deflection surface.

and perpendicular to the beam light from the laser light source 2 and the optical element 3
Only a few unit light-receiving elements 51, 52 . Consists of ...5i, ...5n. Furthermore, it is assumed that all unit light receiving elements produce an output only for vertically incident frontal light. Furthermore, the distance between each unit light-receiving element and the optical element 3 (assuming that it is known to a rough degree).In this way, the scattered light and specular reflection from the minute portion P on the object (the distance between the light receiving element and the optical element 3 is assumed to be known). Only the beam whose optical path is parallel to the beam emitted from the laser light source 2 enters the element group 5 and produces an output, and in this case, it is the beam that enters the unit light-receiving element 6i.

The unit light receiving element 5i receives this and emits an output.

Since it also receives light and responds with output, these are also included in the layer 1.
: (See Figure 2 (b)). Now, the output pulse of the light receiving element 4 and the unit light receiving element 6. The distance from the unit light receiving element 6i to the point P is determined from the time difference Ti between the output pulses in the following manner. Now, if the distance of the deflected beam with the deflection angle θ is D, then the unit light receiving element 6. The distance from point P″i to point P″i is tan 01 . However, the deflection angle θ is a function of the polarization control signal, and from the time difference T of the output pulse, the difference in deflection angle (θ,
−〇. ) is determined, and θ. If is known, L can be found. In this way, the beam light is irradiated onto the object surface while being deflected by the optical element.

By detecting the front light toward the light-receiving element group among the scattered light, the distance to the object can be measured at intervals equal to the array pitch of the unit light-receiving elements, and the surface shape can be measured using an envelope. In order to perform these measurements with even greater precision, the following corrections can be made, namely, the beam deflected by the optical element.

When the deflection angle changes, the exit position of the deflected beam changes.

However, since this change can be measured in advance with respect to the deflection angle, it can be corrected during the geometrical calculation.

On the other hand, in order for the unit light-receiving elements constituting the light-receiving element group to output and respond only to the frontal light perpendicular to itself, as mentioned earlier, a long and narrow light guide path is provided in front of the unit light-receiving element, and all light other than the frontal light is directed toward the wall. This can be easily done by attenuating it by absorption of . The apparatus of the present invention as described above has the following effects.

(g) By using an optical measurement method, the measurement distance range is wide and there are no moving parts, so the measurement accuracy is high.

(iii) The device can be obtained with a very simple configuration and can be supplied at a lower cost than conventional optical precision measuring instruments.

OV) Since the scattered light of the object is used, it is possible to make a highly reliable measurement regardless of the influence of the surface condition or reflection coefficient.

(V) It can be easily used in mass production processes because it can be measured without adding marks, mirrors, etc. to the object to be measured.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the main parts of an embodiment of the non-contact measuring device according to the present invention, and FIG. 1...Object to be measured, 2...Laser light source, 3...Optical element, 4...Light receiving element,
6... Light receiving element group. Name of agent: Patent attorney Toshio Nakao and 1 other person lf
l figure

Claims (2)

[Claims] (1) A laser light source that generates a narrow beam of pulsed light by repeating it, an optical element that periodically deflects the front pulsed light within one plane, and a device that directly directs the polarized light from the optical element. A light-receiving element that receives and outputs light, a group of light-receiving elements that receives and outputs the light scattered by the object of the polarized light, and a polarization control signal for the output and front shoulder optics of these light-receiving elements and the group of light-receiving elements. and an electric circuit for obtaining a measurement signal from a non-contact measurement device, wherein the light receiving device group outputs an output response only to frontal light that is concentrated perpendicularly to the light receiving device group. (2) The laser light source, the light, the optical element, the light receiving element, and the light receiving element group have an elongated light guide path in front of the light receiving element group within a plane including the deflection plane by the optical element. A non-contact measuring device' according to claim (1).