JPS6126812A - Detecting device for distance - Google Patents

Abstract

PURPOSE:To improve the detection sensitivity without increasing the size of the device by arranging the 2nd reflector at the other side of an observation lens, and reflecting light passed through the observation lens and forming its image at relatively close distance from the optical axis of the observation lens. CONSTITUTION:Two plane mirrors 8 are arranged at one side of one observation lens 5 in parallel to the optical axis and two plane mirrors 12 are arranged at the other side of the observation lens 5 in parallel to the optical axis. A light beam 13 is projected through the observation lens 5 of a body to be measured as to its shape, motion, and deformation to form a bright point T on the object body 3. Light from this bright point is reflected by the 1st reflector 8, and passed through the observation lens and reflected by the 2nd reflector 12 to form an image on an observation surface 9 eventually. Consequently, the size at right angles to the optical axis is reduced although the distance detection sensitivity is improved by using an enlargement optical system.

Description

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

When measuring the shape, motion, deformation, etc. of an object, distance (
The basic method is the measurement of length, position).

The present invention relates to a distance detection device used to measure such distances.

Conventional technology Distance detection methods used to measure the shape, motion, deformation, etc. of objects range from those using mechanical probes to those using light, sound waves,
Various measurement methods using various physical phenomena such as electricity and magnetism 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. 161088/1988).

This will be explained with reference to FIGS. 2 and 3.

In a measurement method based on the principle of triangulation, once one side and the angles at both ends of a triangle are determined, the triangle is uniquely determined, and the position of the vertex relative to the -side can be determined. An example of a distance measuring system based on this principle is shown in FIG. Two observation optical systems 1.2 are placed a certain distance apart and their optical axes are parallel. Then, Z is the distance from the two observation optical systems 1.2 to the point of interest T of the non-measurement object 3, and the image of the point of interest T is the distance from the two observation optical systems 1.2.
Assuming that the observation position is a distance A away from T and is detected at positions Xa and Xb from the respective optical axes, the distance Z to the point of interest T is determined by the following equation.

Z-AX L/ (Xa + Xb) However, in this distance measuring method, it is necessary to space the two observation optical systems a certain distance apart from each other in terms of measurement accuracy. The drawback is that the fruiting device as a whole becomes large, and cannot be applied to applications such as endoscopes where the overall size should be made as small as possible. In order to overcome this drawback, we proposed the configuration of the distance detection device shown in FIG. 3 (Japanese Patent Application No. 161088/1988). In Fig. 3, with respect to the observation lens 5 and the optical axis 6 of the observation lens, φ The angle of is tilted lol
A reflector 8 is placed on A7. Light from an arbitrary point T on the object to be measured 3 is reflected by the reflector 8 and passes through the observation lens 5.
An image 11 is formed on the observation surface 9. On the other hand, the object to be measured 3
Light from one point T above that is not reflected by the reflector is imaged by the observation lens onto To on the observation surface.

A virtual image T1ν 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 onto the observation surface 9. The formed image T and the image T are symmetrical to each other with respect to the line 7. The image T0 is observed through the observation lens 5, and T is equivalent to TIv observed through the virtual lens 10 placed in a mirror image relationship with the observation lens 5 with respect to the line 7. However, the signs of the detected coordinate values of T+, T, and v on the observation plane are opposite.

This is equivalent to the configuration in conventional triangulation using the observation lens 5 and the virtual lens 10, and the arrangement of φ-Q and d=L/2 in Fig. 3 is basically the arrangement shown in Fig. 2. are essentially the same. 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 a distance measurement detection device configured using the principle of triangulation using the observation lens and a virtual lens. I can do it. 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.

The coordinate values of To and T on the observation plane are now X,
. , Xi, the distance to the point T of interest and the X coordinate value are given by the following equation.

xlllo・Z In the example in Figure 3, one reflector is used, but two reflectors may be arranged parallel to the optical axis or spread out toward the observation lens, or one reflector may be used. Cylindrical or conical reflectors may also be used.

Problems to be Solved by the Invention Detection sensitivity for displacement (distance change △Z) of any one point on the object in the optical axis direction of the observation lens (displacement of a 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, if such a magnifying optical system is used, the image formation position on the observation surface will be far away from the optical axis of the observation lens, and the distance detection device will eventually have to be made larger. There was a problem in that it would cause problems (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. 1
a second reflector, and the light from an arbitrary point on the object to be measured is directly incident, and the light from the arbitrary point is reflected by the first reflector and is incident on the object. This is achieved by arranging an observation lens, and arranging a second reflector at a position where it reflects the light that 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 (Tl; T+'). In this case, the ratio of the change in imaging position to the change in distance is the same as in the case of imaging without reflection, so the detection sensitivity is increased without increasing the size of the distance sensing device.

The structure and operation of an embodiment of the present invention will be explained below with reference to FIG. 4.5.

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. A light beam 13 is projected through an observation lens 5 onto an object to be measured whose shape, motion, deformation, etc. are to be measured, and a bright spot T is created on the object 3 to be measured. 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 reaches the observation surface 9.
image on top.

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

All of the examples use a single 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. Furthermore, 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.

Effect As is clear from the soft soil, although the distance detection device according to 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. There isn't. 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 drawings]

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 one side of the distance detection device already proposed by the present inventor. FIG. 4 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... first reflector, 12... second reflector.

Claims (1)

[Claims] comprising one observation lens, at least one first reflector disposed on one side of the observation lens, and at least one second reflector disposed on the other side of the observation lens; The observation lens is arranged at a position where light from an arbitrary point is directly incident, and the light from the arbitrary point is reflected by the first reflector and then enters, and from the first reflector. A distance detection device characterized in that a second reflector is arranged at a position to reflect light that has been reflected and passed through an observation lens.