JP4407433B2 - Tilt angle measuring device - Google Patents

Description

  The present invention relates to an inclination angle measuring apparatus capable of measuring the inclination of a plane mirror provided on a measurement object.

  Conventionally, an autocollimator is known as an apparatus for measuring the inclination of a measurement target. In an autocollimator, a point light source is arranged at the focal position of the objective optical system, collimates the light emitted from the light source with the objective optical system, and then irradiates the collimated light onto a flat mirror provided for the measurement target. To do. The light reflected by the mirror enters the objective optical system again and is collected by the objective optical system.

  A beam splitter is disposed between the objective optical system and the light source, and the light condensed by the objective optical system is reflected by the beam splitter and detected by the light spot position detector. This detection position varies depending on the tilt of the plane mirror, that is, the tilt of the measurement target. Therefore, the inclination of the measurement target can be estimated by calculation from the deviation between the position to be measured when the inclination is zero and the actually measured position.

Japanese Patent No. 2748175

  However, in the conventional autocollimator, when the plane mirror provided on the measurement object is far away from the objective optical system, the reflected light beam reflected by the tilted plane mirror is separated from the objective optical system, and the tilt angle is measured. There was a problem that could not be.

The invention of claim 1 is an inclination angle measuring device for irradiating a plane mirror fixed to a measuring object with light, detecting reflected light from the plane mirror and measuring the inclination of the plane mirror, An objective optical system that condenses the reflected light, an optical position measuring means that receives the light collected by the objective optical system, and measures the light receiving position, and is disposed inside or in the vicinity of the objective optical system. An aperture stop that restricts light incident on the optical position measurement means via the objective optical system, and divergent light is emitted from the position of the aperture stop on or near the optical axis of the objective optical system toward the plane mirror And diverging light generating means.
According to a second aspect of the present invention, in the tilt angle measuring apparatus according to the first aspect, the divergent light generating means includes a light source that generates divergent light and an optical axis of the objective optical system, and the position of the aperture stop or the vicinity thereof. And an imaging optical system for forming an image of the light source.

  According to the present invention, divergent light is emitted toward the plane mirror from the position of the aperture stop at or near the optical axis of the objective optical system, so that the distance between the aperture stop and the plane mirror is large. Even if they are separated from each other, part of the reflected light of the plane mirror can pass through the aperture stop, and the tilt angle of the plane mirror can be measured.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an embodiment of a tilt angle change measuring apparatus according to the present invention. Reference numeral 1 denotes a light source that generates divergent light. For example, an LED chip without a sealing lens, a laser diode (LD), or the like is used. The relay optical system 2 is a refractive optical system having a positive power as a whole, and although shown as one lens in FIG. 1, it may be composed of a plurality of lenses. The relay optical system 2 collects the light of the light source 1 in cooperation with the objective optical system 4 described later, and the image of the light source 1 (secondary light source) on the optical axis J of the objective optical system 4 and at the position of the aperture stop 5. Image).

  The light source light emitted from the relay optical system 2 enters the beam splitter 3. The beam splitter 3 is formed by joining the inclined surfaces of two right-angle prisms, and the light that has passed through the beam splitter 3 enters the objective optical system 4 and forms an image at the position of the aperture stop 5 as described above. The aperture stop 5 may be provided separately from the objective optical system 4, and the lens frame of the objective optical system 4 may serve as the aperture stop 5. The objective optical system 4 is an optical system having a positive power as a whole. However, when the objective optical system 4 is composed of a plurality of lenses, the position of the aperture stop 5 may be located in the objective optical system 4.

  The light source light is emitted to the right side in the figure so as to diverge from the image forming position at the intersection with the optical axis on the aperture stop 5 diaphragm surface, and is incident on the plane mirror 6 fixed to the measurement object in advance. In the case of a measurement target to which the apparatus of the present embodiment is applied, the distance between the aperture stop 5 and the plane mirror 6 is a distance of several meters. For example, when used to measure the bending of a tank barrel, the apparatus main body provided with the aperture stop 5 is provided in the turret, and the flat mirror 6 is fixed to the tip of the gun barrel.

  The light source light emitted so as to diverge from the imaging position of the aperture stop 5 enters the region R2 of the plane mirror 6 and is reflected leftward in the drawing. Since the light source light is diverging light, the reflected light reflected by the flat mirror 6 also spreads as it travels to the left in the figure. For this reason, the reflected light is applied to a range larger than the opening of the aperture stop 5. Further, only the light reflected by the region R1 among the reflected light reflected by the region R2 can pass through the aperture stop 5. In the example shown in FIG. 1, the plane mirror 6 is arranged so that its mirror surface is perpendicular to the optical axis J of the objective optical system 4. Therefore, the region 1 is a region centered on the optical axis J.

  The reflected light that has passed through the aperture stop 5 is collected by the objective optical system 4, and the collected reflected light is reflected upward by the beam splitter 3 to the PSD (Position Sensitive Detector) 7 that is an optical position measuring means. Incident. The PSD 7 is an optical sensor that can detect the position of the spot-like light, and can obtain the position of the center of gravity of the received light amount. Therefore, accurate position data can be obtained when the spot light is uniformly spread even if it is out of focus. Reference numeral 8 denotes a driver for the PSD 7, and reference numeral 9 denotes an arithmetic unit that calculates the inclination of the plane mirror 6 based on the position data obtained by the PSD 7. The PSD 7 is an example of an optical position measuring unit, and other sensors may be used.

<Description of operation>
In FIG. 1 described above, the case where the mirror surface of the plane mirror 6 is perpendicular to the optical axis J of the objective optical system 4 is shown. FIG. 2 shows a case where the upper end of the flat mirror 6 is inclined by an angle θ so that it is shifted to the left side. In FIG. 2, the driver 8 and the arithmetic unit 9 are not shown. FIG. 3 is a diagram for explaining a light beam reflected by the plane mirror 6 and passing through the aperture stop 5. FIG. 3A shows a case where the plane mirror 6 is perpendicular to the optical axis J, and FIG. A case where the mirror 6 is tilted from the vertical by an angle θ is shown.

  As shown in FIG. 3A, the light source light is emitted so as to diverge from the secondary light source image P formed at the position of the aperture stop 5. Therefore, when considering the spherical surface S1 that contacts the reflecting surface of the plane mirror 6 with the point P as the center, assuming that the spherical surface S1 is a reflecting surface, all the light reflected by the spherical surface S1 returns to the point P. On the other hand, in the case of reflection by the vertically arranged flat mirror 6, the divergent light emitted from the point P is reflected in the left direction in the figure as if it diverged from the point Q1. The point Q1 is a point at a target position with respect to the point P with respect to the reflection surface, and is on the optical axis J.

  When the plane mirror 6 is inclined by an angle θ as shown in FIG. 3B, the spherical surface S2 in contact with the reflection surface of the plane mirror 6 has a smaller radius than the above-described spherical surface S1, and is a position away from the optical axis J upward. And is in contact with the reflecting surface of the plane mirror 6. Also in this case, assuming that the spherical surface S2 is a reflecting surface, all the light reflected by the spherical surface S2 returns to the point P. On the other hand, when the light is reflected by the inclined flat mirror 6, the divergent light emitted from the point P is diverged from the point Q2 that is symmetric with respect to the point P with respect to the reflection surface, as in the case of FIG. Like the light to be reflected, it is reflected in the diagonally lower left direction in the figure. In the case of FIG. 3B, the position where the divergent light emitted from the point P is perpendicularly incident on the reflecting surface is above the optical axis J, so the point Q2 is also above the optical axis J. It will be.

  Thus, in the present embodiment, since the light source light applied to the plane mirror 6 is emitted so as to diverge from the position of the aperture stop 5 on the optical axis J, the plane mirror 6 is inclined. However, there is always light incident vertically. As shown in FIGS. 3A and 3B, the reflected light of the vertically incident light passes through the point P, and the reflected light of the light incident near the vertical incident position passes through the opening of the aperture stop 5. It will be. In the example shown in FIG. 1, the light reflected by the region R <b> 1 of the plane mirror 6 passes through the aperture stop 5, and in the example shown in FIG. 2, the light reflected by the region R <b> 3 of the plane mirror 6 passes through the aperture stop 5.

  As described above, the reflected light that has passed through the aperture stop 5 passes through the objective optical system 4, is reflected by the beam splitter 3, and enters the PSD 7. FIG. 4 is a view of the PSD 7 as viewed from the direction of the beam splitter 3, and shows the incident position on the light receiving surface of the PSD 7. The PSD 7 is arranged so that light on the optical axis is incident on the center of the PSD 7.

  FIG. 4A shows an incident position in the case of FIG. 1 in which the plane mirror 6 is not inclined. In this case, as shown in FIG. 3A, the reflected light looks like divergent light emitted from the point Q1 on the optical axis J, and is collected on the optical axis J by the objective optical system 4. Lighted. Therefore, the spot light 70 enters the center of the PSD 7 as shown in FIG.

  On the other hand, FIG. 4B shows the incident position in the case of FIG. 2 in which the plane mirror 6 is inclined by the angle θ. In this case, as shown in FIG. 3B, the reflected light looks like divergent light emitted from a point Q2 above the optical axis J in the drawing. In FIGS. 1 and 2, the optical path of the reflected light is reflected by the beam splitter 3 and is bent by 90 degrees. However, FIG. 5 illustrates the optical path of the reflected light as a straight optical path. PSD7 is indicated by a two-dot chain line on the optical axis J. The divergent light emitted from the point Q2 in FIG. 3B is condensed at the lower side of the drawing with respect to the optical axis J as shown in FIG. This corresponds to the right side of the figure from the center on the light receiving surface of the PSD 7 shown in FIG. As a result, the spot light 70 is incident on the right side from the center of the PSD 7 by a distance Δd.

When the PSD 7 is disposed at a position as shown in FIG. 5, the interval Δd is given by the following equation (1).
Δd = (f + ΔL) · tan θ (1)
In Expression (1), f is the focal length of the objective optical system 4, ΔL is the distance between the focal position and the PSD 7, and L = f + ΔL. The sign of ΔL is (−) when the PSD surface is in front of the focal position and (+) when in the rear of the focal position. f and ΔL are stored in advance on a scale provided in the calculation unit 9, and the inclination θ of the plane mirror 6 can be calculated using Δd and the equation (1) that are measured. In the present embodiment, the PSD 7 is disposed at a position that is separated by ΔL from the focal point, but may be disposed at a position that is separated from the objective optical system 4 by the focal length f.

  FIG. 6 shows a schematic configuration of a general autocollimator as a comparative example, and the same components as those in FIG. 2 are denoted by the same reference numerals. As can be seen from FIG. 6, the difference from FIG. 2 is whether or not the relay optical system 2 that forms the secondary light source image of the light source 1 at the position of the aperture stop 5 is provided. In the case of the apparatus of FIG. 6, the light source 1 is disposed at the focal position of the objective optical system 4, and the light from the light source 1 is collimated by the objective optical system 4. The light source light converted into parallel light by the objective optical system 4 passes through the aperture stop 5 and is reflected by the plane mirror 6.

  In FIG. 6, the plane mirror 6 is tilted, and the incident light is reflected obliquely downward to the left, and a part of the reflected light passes through the aperture stop 5 and then passes through the objective optical system 4 and the beam splitter 3 to the PSD 7. Incident. In this case, the light is incident on the right side of the figure with a deviation from the center of the incident surface. However, when the distance from the aperture stop 5 increases as in the case of the flat mirror 6 ′, the reflected light reflected obliquely downward to the left is shifted downward from the aperture of the aperture stop 5. As a result, the PSD 7 cannot be reached, and it becomes impossible to measure the inclination of the plane mirror 6 '.

  On the other hand, in the present embodiment, since the light source light is emitted so as to diverge from the position of the aperture stop 5 on the optical axis J, as described in FIG. 3, a part of the light reflected by the plane mirror 6 The region R1 in FIG. 1 and the region R3 in FIG. 2 are reflected toward the aperture of the aperture stop 5. For this reason, even if the distance between the aperture stop 5 and the flat mirror 6 is increased, the reflected light does not deviate from the aperture of the aperture stop 5 as shown in FIG.

  Of course, if the plane mirror 6 in FIG. 2 is too small to obtain the region R3, the reflected light incident on the aperture stop 5 cannot be formed, so the distance from the aperture stop 5 to the plane mirror 6 and the inclination of the plane mirror 6 It is necessary to set the size of the plane mirror 6 according to the angle range and the like.

  In the embodiment described above, the light from the light source 1 is condensed by the relay optical system 2 to form the secondary light source image at the position of the aperture stop 5 as shown in FIG. If it is the structure which irradiates light to the plane mirror 6, it will not restrict to the structure mentioned above. For example, LED light may be incident on an optical fiber, and the output end of the optical fiber may be disposed at the position of point P in FIG.

  Further, the light source may be arranged at the position of the point P as long as the light source can be made small enough not to affect the measurement of the PSD 7. Thus, when the light source is arranged at the position of the point P, the relay optical system 2 and the beam splitter 3 can be omitted, and the PSD 7 can be arranged on the optical axis J behind the objective optical system 4. In addition, the present invention is not limited to the above embodiment as long as the characteristics of the present invention are not impaired.

  In the correspondence between the embodiment described above and the elements of the claims, PSD 7 constitutes an optical position measuring means, and relay optical system 2 constitutes an imaging optical system.

It is a figure which shows one Embodiment of the inclination angle measuring apparatus by this invention. It is a figure which shows the case where the plane mirror 6 inclines by angle (theta). It is a figure explaining the light beam which is reflected by the plane mirror 6, and passes the aperture stop 5, (a) is when the plane mirror 6 is perpendicular | vertical to the optical axis J, (b) is only the angle (theta) from the plane mirror 6 perpendicular | vertical. This is the case when tilted. It is a figure which shows the position of the incident light in PSD7, (a) is a case where the plane mirror 6 is perpendicular | vertical to an optical axis, (b) is a case where the plane mirror 6 inclines from perpendicular | vertical. It is a figure explaining (DELTA) d. It is a figure explaining the conventional autocollimator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 2 Relay optical system 3 Beam splitter 4 Objective optical system 5 Aperture stop 6,6 'Plane mirror 7 PSD
8 Driver 9 Calculation unit

Claims (2)

A tilt angle measuring device that irradiates a plane mirror fixed to a measurement object with light, detects reflected light from the plane mirror, and measures the tilt of the plane mirror,
An objective optical system for condensing the reflected light from the plane mirror;
A light position measuring means for receiving the light collected by the objective optical system and measuring the light receiving position;
An aperture stop that is disposed inside or in the vicinity of the objective optical system and restricts light incident on the optical position measurement means via the objective optical system;
A tilt angle measuring device comprising divergent light generating means for emitting divergent light toward the plane mirror from the position of the aperture stop or the vicinity thereof on the optical axis of the objective optical system. In the inclination angle measuring device according to claim 1,
The divergent light generating means includes a light source that generates divergent light, and an imaging optical system that forms an image of the light source on or near the aperture stop on the optical axis of the objective optical system. An inclination angle measuring device characterized by that.

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