JPH0672769B2 - Photoelectric detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application of the Invention The present invention relates to a displacement and an angle of a position / orientation control device used for various objects requiring position / orientation accuracy, such as a table of a semiconductor manufacturing device or a machine tool. The present invention relates to a photoelectric detection method for measurement.

[Conventional technology]

Conventionally, in order to measure the position / angle error of a moving body that moves straight ahead, a light source of a straight beam such as a laser is fixed at the base point, and then a beam irradiated in parallel to the direction of travel is installed on the moving body as is. A common method is to receive light from a plate and detect changes in position and angle based on changes in the light receiving point. 11 and 12 show the principle of this measuring method. In Figures 11 and 12
Reference numeral 20 is a laser light source, 21 is a linear stage body, 22 is a photoelectric plate mounted on the linear stage body, and 23 is a laser beam. In FIG. 11, the beam 23 emitted from the laser light source 20 is received by the photoelectric plate 22. When the stage main body 21 moves to the position indicated by the dotted line in the figure, if the beam is accompanied by a parallel displacement in the vertical direction, the displacement amount will be detected by the photoelectric plate 22. Similarly,
In FIG. 12, if the posture of the stage main body 21 changes during movement, the tilt angle is detected by the photoelectric plate 22.

In this method, the beam uses the emitted light as it is,
For this reason, the photoelectric plate has to be covered with photoelectric elements over the entire range in which the beam can move, which is economically and functionally wasteful, and beam position detection is divided by calculation from all photoelectric elements that detect light. It must be complicated.

[Object of the Invention]

An object of the present invention is to provide a photoelectric detection method having a simple structure capable of measuring the position and angle of an object that makes a rectilinear motion.

〔Example〕

FIG. 1 shows a first embodiment of the present invention. In FIG. 1, 1 is a laser oscillator as a light source, 4 is a parallel prism for converting a laser beam into two parallel beams, 5 is an optical element (axicon) for converting the cross-sectional shape of the laser beam into a ring shape, 6 And 7 are light receiving element substrates, 6a to 6d and 7a
Reference numerals 7d to 7d denote optical array sensors arranged on the light receiving element substrates 6 and 7, respectively, and 10 denotes a sensor housing that holds the sensor unit. Although not shown in the figure, the housing 10 includes a laser oscillator 1, a parallel prism 4, and an axicon 5 on a moving object.
Are installed on a fixed substrate. The moving body can move in the direction of the arrow.

In the above configuration, the laser beam oscillated by the laser light source 1 is divided into two laser beams by the parallel prism 4, and further divided into two laser beams having a ring-shaped cross section by the axicon 5. The optical array sensors 6a to 6d and 7a to 7d, which have been converted and are incident on the light receiving element substrates 6 and 7 respectively in the sensor housing 10 and arranged in a cross, detect the positions of the respective ring members in the longitudinal direction. The beam position on the substrate is detected.

Generally, when the object to be measured has coordinates as shown in FIG. 2 and the object to be measured is sent in the direction of the arrow in the figure, that is, in the x-axis direction, other movements of five degrees of freedom, that is, in the y-axis and z-axis directions are performed. Standing motion, x
Rotational movements about the axes, the y-axis and the z-axis, occur. In FIG. 2, the rotation directions around the x-axis, the y-axis, and the z-axis are ω _X ,
Represented by ω _Y and ω _Z.

FIG. 3 shows changes in the position of the ring-shaped laser light incident on the light receiving substrate when the object to be measured moves in the above five degrees of freedom in the configuration of FIG. In the figure, the broken line represents the ring position before the exercise, and the solid line represents the ring position after the exercise. As can be seen from the figure, the change patterns of the ring positions on the light receiving element substrates 6 and 7 are different for the displacements in the y and z directions and the rotations in the ω _Y and ω _Z directions. Therefore, by detecting the change pattern at the same time as the change of the ring position with the optical array sensor, it is possible to measure the change in which motion component direction and how much.

Since the array-shaped sensor in which the beam made into a ring with an axicon is arranged in a cross is detected, the beam center position can be easily calculated from the positions of the four intersections of the ring and the array sensor, and the output laser beam can be simply used as it is. The beam position can be detected with a smaller number of photoelectric elements than when incident on a photoelectric plate or the like. Since the thickness of the ring that substantially matches the arrangement direction of the optical array sensors can be made sufficiently small, the position detection accuracy of the optical array sensors can be sufficiently improved.

With the configuration of the embodiment of FIG. 1, the rotation direction ω around the x-axis
_It is difficult to detect the change in _X , and it may be possible that the same pattern as that of other motion component changes appears depending on the position of the detector and the center of rotation. This problem can be solved in the second embodiment shown in FIG.

In FIG. 4, the same members as those in FIG. 1 have the same reference symbols. Reference numeral 2 is a beam splitter for splitting the laser light into two directions. Reference numeral 3 is a beam bender for bending the traveling direction of the laser light. The beam splitter 2 and the beam bender 3 are arranged so as to produce two parallel laser lights. 4'is 4
Same parallel prism, 5'is the same axicon as 5, 8a ~
8d and 9a to 9d are optical array sensors corresponding to 6a to 6d and 7a to 7d, respectively, and 10 'is the same sensor housing as 10. Housing 10,10 'is a static pressure guide type linear stage body 11
It is installed in. 12 is a linear motor for driving the stage,
13, 13 'are hydrostatic bearing guides and 14, 14' are hydrostatic bearing pads.

In the above configuration, the laser light oscillated from the laser light source 1 is split into two directions by the beam splitter 2, and the transmitted light enters the axicon 5 through the parallel prism 4 and the cross section is converted into a ring shape, so that the sensor housing 10 The light is incident on the light receiving element substrates 6 and 7 inside and is detected by the optical array sensors 6a to 6d and 7a to 7d. Similarly, the reflected light is also reflected by the beam bender 3, passes through the parallel prism 4'and the axicon 5 ', and is detected by the optical array sensors 8a to 8d and 9a to 9d.

The sensor housings 10 and 10 'are installed on the stage main body so that they are symmetrically located in the driving direction of the linear stage. FIG. 5 shows an example of changes in the rings on the substrates 6, 7, 8 and 9 associated with the movement in five degrees of freedom other than the driving direction in this case.
As you can see from this figure, the displacements in the y and z directions, x, y,
The pattern of changes in the ring positions on the four substrates is different for each rotation around the z-axis. Therefore, it is possible to detect the amount of change and the change pattern at the same time, and measure the direction and amount of change at once.

FIG. 6 shows a third embodiment. In FIG. 1, FIG.
The same reference symbols are given to the same members as those in FIG. The sensor housings 10 and 10 'are installed in a bearing body 11' of a direct acting magnetic bearing guide. 15 is an electromagnet, 13
a is a guide.

The sensor housings 10 and 10 'are installed at vertically symmetrical positions on the bearing body 11', and the ring changes on the four substrates due to the movement of the five degrees of freedom are the same as those in the second embodiment.
The pattern is as shown. Therefore, the change direction change amount simultaneous measurement can be similarly performed.

FIG. 7 shows a fourth embodiment. In FIG. 1, FIG.
The same reference symbols are given to the same members as the members in FIGS. 4 and 6. 7'and 9'are photoelectric element substrates made of a transparent member, and 6a 'to 6d' and 8a 'to 8d' form an angle of 45 ° with the optical array sensors 7a 'to 7d' and 9a 'to 9d', respectively. The optical array sensors are arranged on the substrates 6'and 8 '.

The beam emitted from the laser oscillator 1 is split into two beams by the beam splitter 2, the transmitted light is unchanged, the reflected light is parallel to the transmitted light by the beam bender 3, passes through the axicon 5, 5 ', and the cross section is ringed. It is converted into a shape and enters the substrates 7'and 9 ', respectively. The part of the incident beam ring which hits the optical array sensors 7a'-7d ', 9a'-9d' is blocked, while the other parts pass through the transparent substrates 7 ', 9',
It is incident on the substrates 6'and 8 ', respectively.

Optical array sensors 6a'-6d, 8a'-8d 'on substrates 6', 8 '
Are optical array sensors 7a 'to 7d', 9a 'to 9d' and 45, respectively.
゜ They are arranged side by side. The ring portions shaded by the optical array sensors on the substrates 7'and 9'do not come on the optical array sensors 6a 'to 6d', 8a 'to 8d' within the range of possible movement of the stage 11 and always The optical array sensors facing each other are sufficiently spaced so that the ring portion passing through the substrates 7'and 9'can be detected.

Since the photoelectric elements are arranged in a cross shape having a center and the beams are formed in a ring shape, such light separation can be performed, and one beam can be simultaneously detected by two sets of optical sensors. The structure is simple and small as compared with the third embodiment. Further, in the second to third embodiments, since two substrates are installed in one housing while being displaced in the y direction or the z direction, when rotation in the ω _X direction is performed, the rings on the two substrates are moved. The amount of change takes different values, and the change pattern is complicated when motions in other directions are added. In the fourth embodiment, the two substrates in one housing have the same displacement in the y direction and the z direction, and even if the two substrates are rotated in the ω _X direction, the change amounts of the rings on the two substrates are equal. The change pattern when a motion in another direction is added is not complicated. FIG. 8 shows an example of changes in the rings on the substrates 6 ', 7', 8 ', 9'according to the movement of five degrees of freedom other than the driving direction in the fourth embodiment. Although the positions of the optical array sensors on the substrates 6'and 8'are different, the change pattern of the ring is the same as in FIG.

FIG. 9 shows a fifth embodiment. In FIG. 1, FIG.
The same symbols are given to the same members as those in FIGS. 4, 6 and 7. 17, 19 are light receiving element substrates installed in the housing with a tendency of 45 ° in the traveling direction of the stage 11, 16 and 18 are received at positions where the beams incident on the light receiving element substrates 17 and 19 in the figure are substantially reflected. Element boards 17, 19 and 4
It is a light receiving element substrate installed in the housing so as to form an angle of 5 °.

Half mirrors are installed on the surfaces of the substrates 17 and 19 in close contact with the substrates. The half mirror has a sufficiently small thickness so that incident light is not refracted as much as possible when transmitted. Boards 17, 19
The beams respectively incident on the upper half mirrors are divided into two beams, and the transmitted light is detected as it is by the optical array sensors 17a to 17d and 19a to 19d on the substrate which are in close contact with each other. On the other hand, the reflected light is incident on the substrates 16 and 18 which are inclined by 45 ° to the half mirrors and is received by the optical array sensors 16a to 16d and 18a to 18d. Substrates 16,17,18,1 associated with movement in five degrees of freedom other than the driving direction in this case
Fig. 10 shows an example of changes in the upper ring. Unlike FIG. 5, the positions of the rings on the substrates 17 and 19 do not change during rotation in the ω _Y direction and the ω _Z direction. However, since the change patterns of the positions of the rings on the four plates for each movement are different, the change direction change amount simultaneous measurement can be performed as in the second to fourth embodiments. In addition, the device can be made smaller than in the fourth embodiment without complicating the pattern when rotating in the ω _X direction, and the displacement and angle can be measured only in a small area on the stage.

Although the two substrates in the housing are displaced in the z direction in the drawings in the first to third embodiments, they may be displaced in the y direction. In the fourth embodiment, the deviation between the optical array sensor on the front substrate and the optical array sensor on the rear substrate as seen from the laser oscillator side is within the range of stage motion in which the shadow of the front optical array sensor can be considered. Any shape may be used as long as it does not come on the optical array sensor in the back. In the fifth embodiment, the substrate for receiving the reflected light of the half mirror inclined by 45 ° with respect to the traveling direction may be on the side surface or the bottom surface side of the housing. Further, the inclined substrate is formed by a total reflection mirror without attaching a half mirror, and the arrangement of the optical array sensors on the substrate that receives the reflected light is shifted from the arrangement of the optical array sensors on the inclined substrate as in the fourth embodiment. I don't care. The arrangement of the photoelectric elements on the substrate can be any shape such as an L-shape other than the cross shape as long as the effect of the present invention is not impaired. You may install a laser oscillator etc. and a light-receiving part in reverse.

〔The invention's effect〕

According to the present invention, it becomes possible to perform photoelectric detection with a simple configuration capable of measuring the position and the angle of the object that makes a rectilinear motion in the direction perpendicular to the traveling direction.

[Brief description of drawings]

FIG. 1 is a perspective view of a first embodiment of the present invention, FIG. 2 is a coordinate diagram showing a directional relationship of other 5 degrees of freedom with respect to a moving direction of a moving body, and FIG. 3 is the same as the first embodiment. FIG. 5 is a pattern diagram of the position change of the ring-shaped laser light incident on the light receiving element substrate when the movement of five degrees of freedom is performed, FIG. 4 is a perspective view of the second embodiment of the present invention, and FIG. Is a pattern diagram of the position change of the ring-shaped laser light incident on the light receiving element substrate when the movement of 5 degrees of freedom is performed in the second embodiment, and FIG. 6 is the third embodiment of the present invention. FIG. 7 is a perspective view of an example, FIG. 7 is a perspective view of a fourth embodiment of the present invention, and FIG.
FIG. 9 is a pattern diagram of the position change of the ring-shaped laser light incident on the light receiving element substrate when the movement of 5 degrees of freedom is performed in the fourth embodiment, and FIG. 9 is the fifth embodiment of the present invention. FIG. 11 is a perspective view of the embodiment, and FIG. 10 is a pattern diagram of the position change of the ring-shaped laser light incident on the light receiving element substrate when the movement of the five degrees of freedom is performed in the fifth embodiment. FIG. 12 and FIG. 12 are principle diagrams of the conventional position / angle detection method. In the figure; 1: laser oscillator, 2: beam splitter 3: beam bender, 4: parallel prism 5: axicon 6,7,8,9,6 ', 7', 8 ', 9': light receiving element substrate 6a ~ 6d, 7a to 7d, 8a to 8d, 9a to 9d, 6a 'to 6d', 7a 'to 7d',
8a 'to 8d', 9a 'to 9d': (Optical array sensor) 10, 10 ': Sensor housing 11: Linear stage body 12: Linear motor 13,13': Hydrostatic bearing guide 13a: Magnetic bearing guide 14,14 ′: Hydrostatic bearing pad, 15: Electromagnet 16,17,18,19: Photosensitive element substrate 16a to 16d, 17a to 17d, 18a to 18d, 19a to 19d: Optical array sensor 20: Laser oscillator 21: Linear stage body, 22: Photoelectric plate 23: Laser beam.

Claims (4)

[Claims] 1. A method of detecting a beam position with a plurality of light receiving elements, wherein the beam has a ring-shaped cross-section. 2. The photoelectric detection method according to claim 1, wherein the light receiving elements are arranged in a cross shape having a central portion. 3. The photoelectric detection method according to claim 2, wherein a plurality of light receiving element groups arranged in a cross shape having the central portion are provided. 4. The photoelectric detection method according to claim 3, wherein the light-receiving element arrays of the plurality of light-receiving element groups do not substantially overlap with each other when viewed from the traveling direction of the beam.