JPH0396802A - Position detecting method - Google Patents

Abstract

PURPOSE:To detect a position with high accuracy by fixing a pair of a light source and a reflecting member or image information reflection system on a movable body, positioning a real image formed by the image formation reflection system for a spot light on a photodetection surface, and detecting the position of a moving body from the real image position of a photodetection position detecting member. CONSTITUTION:A detecting element 12, a semiconductor laser 14, and a beam splitter 16 are put in measurement mode, the semiconductor laser light 14 is turned on to form a real image at a point P through a concave mirror 18, and the detecting element 12 detects the position of the point P. The position Q of a virtual light source and the position P of the real image are symmetrical about an optical axis passing the peak point B of the concave mirror 18, the position of the point Q is already determined, and the position of the movable body 10 is detected from the distance between the points P and Q. Consequently, the position of the moving body 10 can be detected with high accuracy.

Description

[Detailed description of the invention] [Industrial application fields] The present invention relates to a position detection method.

[Prior Art] In the assembly and precision machining of precision machines, extremely high-precision position adjustment is often required for assembled parts, machined parts, and the like.

For this reason, the positions of movable objects such as assembly parts and processed parts are being detected with high precision.

[Problems to be Solved by the Invention] The present invention also aims to provide a novel position detection method that can detect the position of a movable object with high precision.

[Means to solve the problem] The present invention will be explained below.

The present invention is a method for detecting the position of a movable object that can be displaced on a straight line or on a plane with respect to a reference position,
A point light source, an imaging reflection system, a reflection member, and a light receiving position detection member are used.

As a point light source, for example, a semiconductor laser can be used. The imaging reflection system is an optical system having a reflection function and an imaging function, and is, for example, a combination of a plane mirror and an imaging lens, or a concave mirror. As the reflecting member, a plane mirror, a half mirror, or a beam splitter can be used. In addition, the light receiving position detection member is
Any device capable of detecting the incident position of the light flux incident on the light receiving surface can be used, such as a line sensor, an area sensor, or a semiconductor position detection element.

For position detection, the light-receiving position detection member is held in a standard position, and either the point light source and reflection member set is fixed to the movable object, or the imaging reflection system is fixed to the movable object.

Then, the diverging light beam from the point light source is made incident on the imaging reflection system via the reflection member, and both the virtual image of the point light source by the reflection member and the real image of the point light source by the imaging reflection system are received. so as to be located on the light receiving surface of the position detection member.
The positional relationship between the point light source, the imaging reflection system, the reflection member, and the light receiving position detection member is determined.

Then, the point light source is caused to emit light, and the position of the movable object is detected based on the position detection of the real image by the light receiving position detection member.

[Action: "Virtual image position of point light source" and "real image by imaging reflection system" are
Both are located on the light receiving surface of the light receiving position detection member, and the position of the movable object and the real image position are in a corresponding relationship. Therefore, the position of the movable object can be detected based on the output of the light receiving position detection member.

[Example] Hereinafter, description will be given based on specific examples.

In the embodiment shown in FIG. 1, reference numeral 10 denotes a movable object;
2 is a semiconductor position detection element (hereinafter simply referred to as detection element 12) as a light receiving position detection member, 14 is a semiconductor laser as a point light source, 16 is a beam splitter as a reflection member, and 18 is an image forming reflection system. Each shows a concave mirror.

The movable object 10 is movable on a two-dimensional plane in the left-right direction of FIG. 1 and in a direction perpendicular to the drawing.

On the other hand, the detection element 12 is arranged with a plane parallel to the above-mentioned "two-dimensional plane" as a reference plane, and the light-receiving surface matches this reference plane, and the arrangement position is set at a fixed position. The attitude of the detection element 12 when it is deployed at this deployment position is referred to as a reference attitude.

A beam splitter] 6 is provided near the detection element 12, and a semiconductor laser 14 is provided on the side of the beam splitter 16.

In this embodiment, the detection element 12 and the beam splitter 1
6 and the semiconductor laser 14 are integrated so as to maintain the mutual positional relationship shown in the figure.

These three people collectively occupy the position shown in the figure, and are able to evacuate from this position. When the posture shown in the figure (referred to as the detection posture) is assumed, the detection element 12 automatically assumes the reference posture.

The light emitting portion of the semiconductor laser 14 is a point light source, and a diverging light beam is emitted from this point light source. A portion of this light beam is reflected by the beam splitter 16. At this time, the reflected light flux enters the concave surface [18] while diverging just like light from point Q.

The Q point is the position of the virtual image of the point light source created by the beam splitter l6. The position of this virtual image is uniquely determined depending on the positional relationship between the semiconductor laser 14 and the beam splitter 16. Then, as shown in the figure, the detection element 12,
The positional relationship between the semiconductor laser 14 and the beam splitter 16 is determined.

Further, as described above, since the positional relationship between these three is fixed, the position Q of the virtual image is a fixed position. Therefore, in this embodiment, the calculation means (
(not shown) is stored in advance.

The light beam reflected by the beam splitter 16 is incident on the concave surface [18] while diverging, and when reflected, it is imaged at point P by the imaging action of the concave mirror 18. This point P is therefore the position at which a real image is formed by the concave mirror 18, which is a point light source. concave mirror 1
The position of 8 is adjusted so that this point P is located on the light receiving surface of the detection element 12.

Now, detection of the position of the movable object 10 will be explained.

The movable object 10 is provided with a suitable mark (the end of the movable object or the like may be used). This landmark is indicated by the symbol A in the figure. Then, "detecting the position of the movable object 10" means determining how far the position of the landmark A is from the reference position Q mentioned above in the left-right direction of FIG. This is nothing but detecting the distance between the projection point projected onto the movable object 10 and the landmark A.

Position detection is performed as follows.

First, the detection element 12, semiconductor laser 14, and beam splitter 16 are evacuated as one from the state shown in FIG. In this state, the position B of the top of the concave mirror 16 is measured using a microscope. This microscope is called a spherometer. Since the light beam emitted from the center of curvature of the concave mirror is focused on the center of curvature, this is used to find the center of curvature of the concave mirror using a spherometer, and from this center of curvature, the position where the optical axis of the microscope hits the concave mirror 18 is determined by the movable object 10. The upwardly projected position is the above-mentioned "top" position B. From this state, the microscope is moved to the left in Figure 1 until the microscope captures the mark A on the optical axis, and the amount of displacement of the microscope during this time is measured on the scale of the microscope.

As a result, the distance L between the position B of the top of the concave surface R18 and the mark A is known, and this L is input into the above-mentioned calculation means.

Next, the detection element 12, the cow conductor laser l6, and the beam splitter 16 are returned to the measurement position (the position shown in FIG. 1). As a result, the detection element 12 assumes the reference position.

When the semiconductor laser 14 emits light, a real image formed by the concave mirror 18 is formed at point P. The position of this point P is detected by the detection element 12. Since the imaging magnification by the concave mirror 18 is equal to the same magnification, the position Q of the virtual light source and the position P of the real image are symmetrical with respect to the optical axis passing through the top point B of the concave mirror 18.

Since the position of point Q has already been determined, when the position of point P is detected by the detection element 12, the distance 2δ between points P and Q is known.

Then, it can be seen that the position of the mark A on the movable object 10 is separated from the reference position Q by (L + δ).

The position of the movable object is thus detected.

In this example, the reference position is set at point Q of the virtual image of the point light source, but the reference position is not limited to this, and can be set at any position on the light receiving surface of the detection element 12, such as the center position of the light receiving surface. can.

As shown in FIG. 2, the detection element 12 has a square light-receiving surface whose width is 2d in the X direction (horizontal direction in FIG. 2) and the Y direction (vertical direction in the same figure), and when a light spot is incident,
Depending on its incidence position, four outputs IXllIX21I
YllIY2 is output. These outputs are sent to amplifier 21
After being amplified by steps 27 to 27, the signals are input to position calculation sections 31 and 33. These position calculation units are X:d(Ixz−Ix+
)/(Ixz+Ix+)Y-d(Iy2-Iy+)/(
．． L2"Iy+) is performed to calculate the X and Y coordinates that give the position of the incident spot. However, the origin of the XY coordinates is the center of the light receiving surface.

The output of the position calculation section is sent to the calculation means 35.

Since the coordinates of the Q point and the distance L have already been input and stored in the calculation means 35, the position of the landmark point A can be detected based on these and the result of the position calculation of the P point.

When aligning the movable object 10, it is necessary to determine in which direction and by how much the movable object should be displaced in order for the position of point A obtained in this way to occupy a predetermined position. As can be seen, by executing the displacement, alignment can be achieved easily and precisely.

In the case of the embodiment described above, the position Q of the imaginary light source is located between the detection element 12, the beam splitter 16, and the semiconductor laser 1.
A value determined by design based on the positional relationship of 4 was used. However, in reality, it is considered that there is a deviation due to an error between the imaginary light source position Q determined by design and the actual imaginary light source position. This deviation becomes an error in position detection accuracy.

By accurately determining the positional relationship between the detection element 12, the beam splitter 16, and the semiconductor laser 14, the above-mentioned deviation can be sufficiently reduced, but if the actual imaginary light source position can be measured, the influence of the "deviation" can be eliminated.

To measure the actual imaginary light source position, do the following.

In FIG. 3, reference numeral 40 indicates a microscope 10 for positioning. When the point light source 41 emits light, the light is emitted through the half real mirror 43 and the objective lens 45, enters the light receiving surface of the detection element 12 through the beam splitter 16, and is reflected by the beam splitter 16, The light enters the half mirror 43 through the objective lens 45, is reflected by the half mirror 43, and then enters the screen 47. This incident state is observed through the eyepiece lens 49.

First, the entire microscope 40 is displaced in the direction of the optical axis of the objective lens 45, and a life-sized image of the point light source 41 is formed on the screen 47. At this time, the image is in the center of the target chart on the screen.

Next, when the semiconductor laser 14 is caused to emit light, an image of the actual imaginary light source position Q" can be observed on the screen 47. In this state, the microscope fi 40 is displaced in the direction perpendicular to the optical axis, and the image of the point light source 41 and the image of the point light source 41 can be observed. The images of point Q' are made to overlap.At this time, the light from the point light source 41 is focused on the actual virtual light source position Q'.

Therefore, the actual imaginary light source position Q' can be known from the output of the detection element 12 at this time.

The detection element 12 has a single light-receiving surface. In this case, if the position of the real image of the point light source 11 shifts slightly with respect to the light receiving surface, the spot on the light receiving surface will spread somewhat, but the detection element 1
In such a case, the output No. 2 is output according to the position of the center of gravity of the intensity distribution using the intensity distribution within the spot as a weight, so that the position of the real image can be accurately measured.

Another embodiment will be described below.

When the imaging reflection system is a concave mirror, a protective member 18 made of glass or the like may be provided on the concave surface M18A as shown in FIG.

In addition, as in the embodiment shown in FIG.
81 and an imaging lens 182 may be combined. However, in this case, the plane mirror 181 and the detection element 12
It is necessary to make the light-receiving surface parallel with high precision. Further, as shown in FIG. 5, a plane mirror 16A can be used as the reflecting member.

[Effects of the Invention] As described above, according to the present invention, a novel position detection method can be provided. Since the present invention is structured as described above, the position of a movable object can be detected easily and reliably.

[Brief explanation of drawings]

1 and 2 are diagrams for explaining one embodiment of the present invention, and FIGS. 3 to 5 are diagrams for explaining another embodiment. 10. ．． ．． Movable object, 12. ．． ．． Semiconductor position detection element as a light receiving position detection member, 14. ．． ．． Semiconductor laser as a point light source, 16. ．． ．． Beams 13 as a reflective member

Claims (1)

[Claims] A method for detecting the position of a movable object that can be displaced on a straight line or on a plane with respect to a reference position, the method comprising: a point light source, an imaging reflection system, a reflection member, and a light receiving position detection member. The light receiving position detecting member is held in a standard position, and the set of the point light source and the reflecting member is fixed to a movable object, or the image forming reflection system is fixed to a movable object, and The light-receiving surface of the light-receiving position detection member is arranged such that the diverging light flux is incident on the imaging reflection system via the reflection member, and the virtual image of the point light source by the reflection member and the real image of the point light source by the imaging reflection system are The positional relationship between the point light source, the imaging reflection system, the reflection member, and the light-receiving position detection member is determined so that the light-receiving position detection member emits light, and the point light source is movable based on the position detection of the real image by the light-reception position detection member. A position detection method characterized by detecting the position of an object.