JPH0521165B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a compact distance sensing device using the principle of triangulation.

Measurement of distance (length, position) is fundamental in measuring the shape, movement, deformation, etc. of objects. The present invention relates to a distance detection device used to measure such distances.

Conventional technology There are various distance detection methods used to measure the shape, motion, deformation, etc. of objects, from those using mechanical stylus to those using various physical phenomena such as light, sound waves, electricity, and magnetism. measurement methods have been devised and used. However, the mechanical stylus method is still widely used for shape measurement in the mechanical industry. There is a strong desire for a non-contact distance sensor to replace the mechanical stylus method, in order to measure objects that are deformed or in motion using the stylus method, and to improve measurement speed. There is. Using an optical method, it is possible to measure distance without touching the object.

The present inventor proposed an optical distance detection device using the principle of triangulation (Japanese Patent Application No. 58-161088).
This will be explained with reference to FIGS. 2 and 3. In the measurement method based on the principle of triangulation, 3
When one side and the angles at both ends of the triangle are determined, the triangle is uniquely determined, and the position of the vertex relative to that side can be determined. An example of a distance measuring system based on this principle is shown in FIG. Two observation optical systems 1 and 2 are arranged so that they are separated by a certain distance L and their optical axes are parallel. And 2
The distance from the two observation optical systems 1 and 2 to the point of interest T of the non-measurement object 3 is Z, and the image of the point of interest T is at the observation position separated by the distance A from the two observation optical systems 1 and 2, and the respective optical axes are Assuming that the detection is performed at the positions Xa and Xb, respectively, the distance Z to the point of interest T is determined by the following equation.

Z=A×L/(Xa+Xb) However, in this distance measuring method, the distance L between the two observation optical systems must be set apart by a certain distance from the viewpoint of measurement accuracy. As a result, the device as a whole becomes large, and if you want to make it as small as possible, such as with an endoscope,
The drawback was that it could not be applied. To overcome this drawback, we proposed the configuration of the distance detection device shown in Fig. 3 (Japanese Patent Application No. 161088/1988). In Figure 3,
With respect to the observation lens 5 and the optical axis 6 of the observation lens, a line 7 that passes through a point distanced by a distance d from the optical axis 6 at the node 0 of the observation lens and is inclined at an angle of φ with respect to a line parallel to the optical axis of the observation lens. A reflector 8 is placed above. Light from an arbitrary point T on the object to be measured 3 is reflected by the reflector 8 and focused on T ₁ on the observation surface 9 by the observation lens 5 . On the other hand, light from one point T on the object to be measured 3 that is not reflected by the reflector is imaged by the observation lens at T ₀ on the observation surface.

A virtual image T ₁ v of T created on a virtual observation surface 11 by a virtual lens 10 placed at a position symmetrical to the observation lens 5 with respect to the reflector is reflected by the reflector 8 and is reflected by the observation surface 9. Image of T formed above
T ₁ and each other have a symmetrical relationship with respect to line 7. Statue T ₀
is observed through the observation lens 5,
Further, T ₁ is equivalent to T ₁ v observed through a virtual lens 10 placed in a mirror image position with respect to the observation lens 5 with respect to the line 7 . However, on the observation plane, T ₁ and
The sign of the detected coordinate value is opposite to that of T ₁ v.

This is equivalent to the configuration in conventional triangulation using the observation lens 5 and the virtual lens 10,
The arrangement in which φ=0 and d=L/2 in FIG. 3 is basically the same as the arrangement shown in FIG. Therefore, by arranging the reflector 8 and the observation lens 5 as shown in Fig. 3, it is possible to obtain the same effect as that of a distance measurement detection device based on the principle of triangulation using the observation lens and a virtual lens. Obtainable. Moreover, its size is about half that of the distance detection device shown in FIG. 2, which uses two lenses, so the entire device can be miniaturized. In the arrangement of FIG. 3, the formula for calculating the distance is slightly more complex than in the case of FIG.

Now, let the coordinate values of T ₀ and T ₁ on the observation plane be respectively,
Assuming X _n0 and X _n1 , the distance and x-coordinate value to a point T of interest are given by the following equation.

Z=ad(x _n1・sin2φ−2acos ^2φ )/a(asi
n2φ＋x _n1・cos2φ)−x _n0・(acos2φ−x _n1・sin2φ)
x=-x _n0・Z/a In the example in Figure 3, one reflector is used,
Two reflectors may be arranged parallel to the optical axis or divergent toward the observation lens, or a single cylindrical or conical reflector may be used.

Problems to be solved by the invention Detection sensitivity for displacement (distance change △Z) of any point on the object in the optical axis direction of the observation lens (observation surface for displacement △Z of the point on the object in the optical axis direction) In order to increase the ratio of the position change △Y of the upper image (△Y/△Z), the distance a from the observation lens 5 to the observation surface 9 is compared to the distance Z from the observation lens 5 to a point on the object. However, with such a magnifying optical system, the image formation position on the observation plane will be far away from the optical axis of the observation lens, and in the end, the distance detection device will have to be made larger. There was a problem with storage (see Figure 1).

An object of the present invention is to provide a distance detection device with improved detection sensitivity without increasing the size of the distance detection device.

Means for Solving the Problem This object, according to the invention, comprises an observation lens, at least one first reflector arranged on one side of said observation lens, and at least one first reflector arranged on the other side of said observation lens. at least one second reflector,
Light from an arbitrary point on the object to be measured is directly incident, and light from the arbitrary point is directly incident on the object to be measured, and the light from the arbitrary point is directly incident on the object to be measured.
This is achieved by arranging the observation lens at a position where the light is reflected by the reflector and entering the observation lens, and by arranging the second reflector at a position where the light is reflected from the first reflector and passes through the observation lens. (See broken line in Figure 1). That is, by arranging the second reflector 12 on the other side of the observation lens 5, the light reflected from the first reflector 8 and passed through the observation lens 5 is reflected and focused at a relatively short distance from the optical axis of the observation lens 5. image (T ₁ ; T ₁ ′). In this case, the ratio of the change in the imaging position to the change in distance is the same as in the case of imaging without reflection, and therefore the detection sensitivity is increased without increasing the size of the distance detection device.

The structure and operation of an embodiment of the present invention will be explained below with reference to FIGS. 4 and 5.

Please refer to FIG. In FIG. 4, two plane mirrors 8 are arranged parallel to the optical axis on one side of one observation lens 5, and another two plane mirrors 12 are arranged parallel to the optical axis on the other side of the observation lens 5. shape, movement,
A light beam 13 is projected onto the object to be measured whose deformation or the like is to be measured through the observation lens 5, creating a bright spot T on the object to be measured 3. The light from this bright spot is reflected by the first reflector 8, passes through the observation lens, is reflected by the second reflector 12, and finally forms an image on the observation surface 9.

Figure 5 shows the case where a cylindrical reflector is used. When the beam is projected along the optical axis of the observation lens 5, the image of the bright spot T on the object to be measured becomes annular on the observation surface. The distance to any point on the object to be measured can be measured as a direct function of the radius of this ring.

All of the examples use only one second reflector, but if the magnification (a/z) is large, it may be necessary to reflect multiple times on the other side of the observation lens. A corresponding number of second reflectors are used. Further, by arranging the second reflector so as to diverge toward the optical axis, the dimension in the direction perpendicular to the optical axis can be further reduced than when the second reflector is arranged parallel to the optical axis.

Effects As is clear from the description, although the distance detection device of the present invention uses a magnifying optical system to increase the distance detection sensitivity, the dimension in the direction perpendicular to the optical axis is increased. Never. Furthermore, when a cylindrical or conical mirror is used as the second reflector, the S/N ratio of the image obtained on the observation surface is increased.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a comparison between a configuration in which a magnifying optical system is employed in the distance detection device shown in FIG. 3 and a configuration of the present invention. FIG. 2 is an explanatory diagram of the conventional distance measurement method. FIG. 3 is an explanatory diagram showing an example of a distance detection device already proposed by the present inventor. Fourth
The figure is a perspective view showing an embodiment of the distance detection device of the present invention. FIG. 5 is a perspective view showing another embodiment of the invention. In the figure; 3...object to be measured, 5...observation lens, 8...
1st reflector, 12...2nd reflector.

Claims (1)

[Claims] 1 one observation lens and at least one first perfect reflector disposed on one side of the observation lens;
at least one disposed on the other side of the observation lens;
a position where light from an arbitrary point on the object to be measured directly enters, and where light from the arbitrary point is reflected by the first perfect reflector and enters the object; A distance detecting device characterized in that the above-mentioned observation lens is disposed at a position, and a second perfect reflector is disposed at a position to reflect the light reflected from the first perfect reflector and passed through the observation lens.