JPS61281906A - Angle and displacement measuring instrument - Google Patents

Abstract

PURPOSE:To eliminate influences of direction deviation of optical beams due to the variation of a light source by providing an optical element which inverts the passing position of one of two divided optical beams in the longitudinal direction. CONSTITUTION:One optical beam 8d divided by a beam splitter 2 passes an image rotator 3 and is irradiated to an object 6 to be examined together with the other optical beam 8c. If the beam 8a is varied by the variation of a light source 1 at this time, these optical beams are moved symmetrically with respect to an optical beam 8e and are moved symmetrically also on the light receiving face of a PSD (optical position detector) 9. Consequently, variation components of the light source in the division direction are eliminated. With respect to variation components of the light source in the direction orthogonal to said division direction, the fact that the passing position of the optical beam is inverted by the rotator 3 is used to invert the variation direction of an optical beam 8d', and this optical beam is shifted symmetrically to the optical beam which does not pass the rotator 3. Thus, horizontal and vertical variation components are compensated, and a certain output is obtained though the light source is varied in an optional direction.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is applicable to control of optical devices, installation and control of mechanical tools, analysis and monitoring of distortion and vibration of objects, optical axis alignment of laser devices, medical equipment, etc. Especially regarding angle/displacement measuring devices used in various fields.

The present invention relates to an angle/displacement measuring device using an optical position detector (hereinafter abbreviated as PSD).

[Prior Art] Conventionally, the high phase difference resolution, linearity, and reproducibility of PSD have been considered to be applied not only to optical devices but also to various fields.

FIG. 1O is a longitudinal cross-sectional view showing a structural example of a one-dimensional PSD. In FIG. 10, the one-dimensional PSD comprises a uniform resistance layer 102 of a P layer on the surface of a flat silicon 101,
Electrodes XI and X2 are provided on both sides, respectively, and a common electrode XI is provided on the N-layer resistance layer 103 on the back surface.

FIG. 11 is a schematic diagram showing the principle of operation.

The photo-generated charge corresponding to the incident position of the light Q reaches the resistance layer 102 as a photocurrent corresponding to the energy thereof,
The signal is divided in inverse proportion to the distance between the position P and the extraction electrodes XI and X2 at both ends, and is output from each electrode. If the photocurrent due to incident light is calculated (then, electrodes X + ,
The devices IXI and IX2, which are composed of I x+= I L ゛ RX2/
RX2) I X2= I L −RXI/ (RX
l+RX2), and the resistance between x and -x2 maintains a uniform distribution, so the resistance between Xl and X2 and the length L
The following equations hold true between .

RXI+RX2=L RX1=X RX1=L-x Therefore, the signals taken out from each electrode are represented by L and X.

IXI=IL・(L−x)/L I)B:II °x/L. In other words, the information on the incident position and light intensity of the light is x
1 and x2 electrodes. Furthermore, taking the sum and difference of Ix+ and IX2, and using this as calculation data for the position signal P, the following is obtained, and from x=0 to L, x=o,
Position signals independent of changes in light intensity can be obtained continuously, such as P=1, X=station, P=Ox=L, P=-1.

Although the above is a one-dimensional case, a two-dimensional position detector can be considered in the same way, and a position signal is obtained by the operation circuit shown in the block diagram of FIG. Here, according to the operating principle of the PSD, if there are two or more points of light incidence, position signals weighted in proportion to the respective light intensities are obtained. Furthermore, even when the light beam is spread out, a position signal of the center of gravity of the light intensity can be obtained.

FIG. 6 is a configuration diagram showing an example of a conventional remote angle/displacement measuring device to which the above-mentioned PSD is applied. In the same figure,
The measuring device uses a lens 84 to detect the beam light 82 from the laser light source 81 reflected by the test object B3.
The detection element surface 85 is focused, and the angle and displacement of the test object 83 are measured by changing the relative position of the spot.

[Problems to be Solved by the Invention] However, in measurements using such a PSD, fluctuations in the emission angle of the light source itself greatly affect the measurement accuracy, and in particular, in measurements using a gas laser, It was impossible to perform position detection with high precision.

The present invention eliminates the influence of such fluctuations in the light source itself,
Angle and
The purpose of the present invention is to provide a displacement measuring device.

[Means for Solving the Problem] The present invention guides the beam light emitted from the light source shown in FIG. 6 to the object to be measured, and detects the reflected light with an optical position detector, thereby determining the angle of the object to be measured. In an angle/displacement measurement device that measures either or both of the light beam and the displacement, the device includes a means for dividing a light beam emitted from a light source into two, and a means for dividing a light beam emitted from a light source into two, and a means for dividing a passing position of at least one of the two divided light beams in a longitudinal direction. an optical element that inverts the beam, a means for configuring two beams such that the directional components to be compensated for among beam fluctuations due to light source fluctuations are symmetrical to each other, and a means for configuring two beams such that the directional components to be compensated for among beam fluctuations due to light source fluctuations are symmetrical to each other; The invention is characterized by comprising means for matching the spots.

Among the above-mentioned means, the means for dividing the light beam into two is as follows:
A beam splitter or a half mirror may be used, and image raw data may be used as a means for vertically reversing the passing position of the light beam.

Further, as a means for forming the light beam into a desired course, a combination of a mirror and a half mirror can be used.

[Function] In the present invention, the light beam emitted from the light source is divided into two, and when the light source fluctuates, the amount of variation that appears in each of the two divided lights changes the average beam spot of the two divided lights. It is constructed so that when they match on the light receiving surface, they compensate for each other and become zero.As the principle of the PSD method, the PSD
The D output is designed to finally obtain a signal at the center of gravity of the light intensity distribution.

FIG. 7 is a coordinate diagram illustrating the principle of the compensation method according to the present invention. In FIG. 7(a), mutually orthogonal X-Y coordinate axes are set on a plane J2 perpendicular to the uniform emission direction of the light beam emitted from the light source, and the amount of deflection of the emitted light is indicated by the arrow 71. is shown. If the above coordinate axes are inverted using the required optical system, the projection will be as shown in Figure 7 (b).
), and the amount of deflection of the emitted light is also indicated by the arrow?
2. When these mutually inverted light beams are irradiated onto the target irradiation surface, their coordinates are shown in Figure 3 (
As shown in C), point symmetry (71a,
? 2a), and if the intensities of both light beams are equal, the center of gravity of the light beam energy always coincides with the origin O. Therefore, if an optical system that satisfies the above conditions is used, even if the light source fluctuates, the intensity center of the irradiation beam will not be affected, and the PSD output will not be affected due to the PSD principle.

FIG. 8 is a schematic configuration diagram of a basic device for one-dimensionally verifying the effect based on the above principle, in which a light beam 82 from a Ha-Ne laser light source 8I is amplitude-divided by an l\-humira-83, The divided light beams are each passed through a mirror 84.
A and 84b are used to illuminate the PSD 85 and record fluctuations in the light source 81.

FIG. 9 is a graph showing the verification results, in which the vertical axis shows the detection position P of the light beam, and the horizontal axis shows the time. 8th
In the figure, a half mirror 83 and a mirror 84a
, When the light beam is directly irradiated to the PSD without going through 84b, fluctuations are recorded as shown in (a), whereas when compensation is performed according to the principle of the present invention, fluctuations are recorded as shown in (b). This confirms that light source fluctuations have been removed.

[Example] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the angle/displacement measuring device according to the present invention, which is used to measure rotation and movement of a test object 6 in an arbitrary direction using a two-dimensional PSD. In the figure, a light beam 8a emitted from a light source 1 is split into two light beams 8C and 8d by a beam splitter 2. One light beam 8d passes through an image raw data 3, and the other light beam 8d passes through an image raw data 3. Together with the beam 8c, the two light beams pass through the mirror 4 and the half mirror 5 and become close to each other, and are irradiated onto the test object 6. At this time, if the light beam 8a fluctuates due to fluctuations in the light source, the light beam 8d will change to 8c', 8c', as shown in the partially enlarged view of FIG.
8d' and moves symmetrically around -88. Therefore, from now on, the light receiving surfaces of the PSD 9 will also move in mutually symmetrical directions centering on the position where there is no light source fluctuation.

On the other hand, FIG. 2 is a side view of the measurement system shown in FIG. 1, and shows the optical path of a light beam 8d that passes through the image raw data 3 out of the light beams split into two by the beam splitter 2. . The light source fluctuation component along the dividing direction of the beam splitter 2 is removed according to the principle explained in FIG. 7, but the light source fluctuation component in the direction orthogonal to it is removed by the second
As is clear from the figure, the light beam is not affected by the beam splitter 2, and therefore, as shown in the partially enlarged view of FIG. If the direction of variation of 8d' is reversed, it will move symmetrically with the light beam that does not pass through the image raw data 3. In this way, horizontal,
Each vertical variation component is compensated based on the principle of the present invention, so even if light source variation occurs in any direction,
A constant output can always be obtained.

FIG. 5 is a configuration diagram showing another embodiment of the angle/displacement measuring device according to the present invention. In this embodiment, a new reference surface 5 is added.
4, one of the light beams split into two by the beam splitter 52 is used as the reference surface 54, and the other 58d is used as the test object 5.
5, both are focused by lens 5B, and P
The light is irradiated onto the light receiving surface of the SD 57. In this case as well, the two light beams are P
The beams become mutually inverted on the SD, and the influence of fluctuations in the light source can be removed.

Note that the image raw data may be input into either optical path of the light beam split into two by the beam splitter.

Further, the angle of incidence on the test object can be set arbitrarily.

[Effect of the Invention J] As explained above, according to the present invention, it is possible to eliminate the influence of deviation in the light beam emission direction caused by fluctuations in the light source itself, and the measurement accuracy can be improved to the limit of the PSD resolution. It is possible to provide an angle/displacement measuring device that improves.

[Brief explanation of the drawing]

1, 2, and 5 are block diagrams showing each embodiment of the present invention, FIGS. 3 and 4 are explanatory diagrams of inverted beams, FIG. 6 is a block diagram of a conventional example, and FIG. 7 is a detailed explanatory diagram of the present invention, No. 8
The figure is a configuration diagram of the verification mechanism of the principle, FIG. 9 is a graph of the verification results, and FIGS. 10 to 12 are explanatory diagrams of the PSD. 1, 51.61.81...Light source. 2.52...Beam splitter, 3.53...Image raw data, 4.84...Mirror, 5.83...Half mirror-1
6,55,83...Test object, 7,58. E14...
·lens. 8, 58.82.82... light beam, 9.57...
-PSD (optical position detector), 54...reference plane.

Claims (1)

[Claims] (1) In an angle/displacement measuring device consisting of a light source, an object to be measured, and an optical position detector, there is a means for dividing the light beam emitted from the light source into two, and at least one of the two divided light beams. an optical element that vertically reverses the passing position of a book; a means for configuring two beams such that directional components to be compensated for among beam fluctuations due to light source fluctuations are symmetrical to each other; and a light receiving surface of an optical position detector. and means for matching the respective average beam spots.