JP2010164354A - Autocollimator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an autocollimator capable of suppressing attenuation of radiation light and return light and performing accurate measurement and positioning of a measuring object, even if the object has low reflectivity. <P>SOLUTION: The autocollimator, irradiating the measuring object 20 with radiation light to measure the inclination of the measuring object 20 on the basis of return light reflected and made to return from the measuring object 20, includes a light source 11, a radiation-light forming means 12 which causes part of light emitted from the light source 11 to pass and uses it as the radiation light, and an objective lens 13 for converting the radiation light into parallel light and converting the return light into converged light. The light source 11 and the radiation-light forming means 12 are so arranged that the optical axis of the radiation light and the optical axis of the return light pass positions which are different from each other and deviate from the center of the objective lens 13, when the measuring object 20 is opposed to the objective lens 13 at a predetermined angle. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an autocollimator.

  The autocollimator is a device for irradiating the object to be measured with parallel light and examining the minute inclination of the object to be measured based on the light beam reflected by the object to be measured. For example, a prism, mirror, lens, etc. It is used for adjusting the mounting angle of optical parts and inspecting the flatness and straightness of machined parts.

  FIG. 4 shows a schematic configuration of a conventional autocollimator 40. A beam splitter 43, a first slit plate 42, and a light source 41 are arranged on the main axis A ′ of the objective lens 44, and a second slit plate 45 and a detector are arranged on an axis orthogonal to the main axis A ′ and passing through the beam splitter 43. 46 is arranged.

  Light emitted from the light source 41 and passed through the slit hole 42a of the first slit plate 42 (referred to as “irradiation light”) is branched by the beam splitter 43, and one of the branched lights (passes through the beam splitter 43). Light) enters the objective lens 44. The light incident on the objective lens 44 is irradiated as a parallel light beam onto the object to be measured 50, and the light reflected on the surface of the object to be measured 50 (referred to as “return light”) enters the object lens 44. And condensed. The return light collected by the objective lens 44 is branched in two directions by the beam splitter 43, and one of the branched light (light reflected by the beam splitter 43) is irradiated onto the second slit plate 45. .

  As a result, an image of the first slit hole 42a (hereinafter referred to as a “slit image”) is projected onto the second slit plate 45. The image formation position of the slit image is the objective position. It changes in accordance with the angle formed by the main axis A ′ of the lens and the object 50 to be measured. For example, in the apparatus of FIG. 4, when the object to be measured 50 is arranged perpendicular to the main axis A ′ of the objective lens 44, the light reflected by the surface of the object to be measured 50 (return light) is It returns to the objective lens 44 by tracing back the same path as the irradiation light. At this time, the imaging position of the slit image coincides with the position of the second slit hole 45a. On the other hand, when the object to be measured 50 is inclined with respect to the main axis A ′ of the objective lens 44, the return light from the object to be measured 50 returns to the objective lens 44 through a path different from the irradiation light, and the slit image. Is projected to a position deviated from the second slit hole 45a.

  That is, the light amount detected by the detector 46 increases as the angle of the object 50 to be measured is closer to the principal axis A ′ of the objective lens 44, and the light amount detected by the detector 46 increases as the inclination of the object 50 increases. Becomes smaller. For this reason, for example, when the user adjusts the angle of the object to be measured 50 while checking the amount of light detected by the detector 46, the object to be measured 50 becomes a desired angle (here, perpendicular to the main axis A ′). Can be positioned as follows.

Japanese Patent No. 2748175

  As described above, in the conventional autocollimator, the beam splitter 43 is provided on the optical path between the light source 41 and the objective lens to guide the return light from the object to be measured 50 toward the detector 46. However, since the irradiation light and the return light are attenuated when passing or reflecting through the beam splitter 43, the slit image becomes dark when the reflectance of the object to be measured is low, and the like as described above. In some cases, it is difficult to evaluate and position the measured object.

  The present invention has been made in view of the above points, and its object is to suppress the attenuation of irradiation light and return light, and to accurately measure and position even a low-reflectance object to be measured. An object of the present invention is to provide an autocollimator capable of performing the above.

An autocollimator according to the present invention, which has been made to solve the above-described problems, irradiates an object to be measured with irradiation light and measures the inclination of the object to be measured based on return light reflected from the object to be measured. Autocollimator
a) a light source;
b) Irradiation light forming means that passes a part of the light emitted from the light source to be the irradiation light;
c) an objective lens that converts the irradiation light into parallel light and converts the return light into convergent light;
When the object to be measured is opposed to the objective lens at a predetermined angle, the optical axis of the irradiation light and the optical axis of the return light pass through different positions shifted from the center of the objective lens. As described above, the light source and the irradiation light forming means are arranged.

  In the above configuration, when the object to be measured is disposed so as to face the objective lens at a predetermined angle (hereinafter referred to as “reference state”), the irradiation light that has passed through the objective lens The light travels while being inclined with respect to the main axis, and is reflected so as to be folded in a V shape on the surface of the object to be measured. This reflected light (that is, return light) enters the objective lens again through a path different from that of the irradiation light, and is converged by the objective lens. Thus, according to the autocollimator according to the present invention, it is possible to separate the optical paths of the irradiation light and the return light without providing a beam splitter on the optical path. Note that when the object to be measured is tilted from the reference state, the path of the return light changes according to the tilt. For this reason, by providing a predetermined light receiving means on the optical path of the return light and confirming the irradiation position of the return light on the light receiving means, it is possible to evaluate the degree of inclination of the measured object from the reference state. .

The autocollimator according to the present invention is a first light shielding plate in which the irradiation light forming means has an opening of a predetermined shape,
Furthermore,
d) a second light shielding plate having an aperture through which the return light converged by the objective lens passes;
e) a detector for detecting light that has passed through the second light shielding plate;
It is desirable to provide.

  According to such a configuration, the return light that has passed through the objective lens is irradiated onto the second light shielding plate, so that an image of the opening of the first light shielding plate is projected onto the light shielding plate. . The image formation position of the aperture image changes according to the inclination of the object to be measured, and accordingly, the amount of return light passing through the opening of the second light shielding plate also changes. The inclination of the object to be measured can be evaluated based on the detection signal.

Moreover, the autocollimator according to the present invention is a transparent plate in which the irradiation light forming means has a mask portion having a predetermined shape,
Furthermore,
d) a screen having a predetermined mark,
The projection pattern of the mask portion may be projected onto or near the mark by causing the return light converged by the objective lens to be incident on the screen.

  According to such a configuration, it is possible to evaluate the inclination of the object to be measured based on the positional relationship between the projection pattern of the mask portion on the screen and the mark.

  As described above, according to the autocollimator of the present invention having the above-described configuration, it is not necessary to branch the optical path by a beam splitter as in the prior art, so that attenuation of irradiation light and return light can be suppressed. Accordingly, accurate measurement or positioning can be performed even when the reflectance of the object to be measured is low. Further, the autocollimator according to the present invention does not use a beam splitter, which is a relatively expensive optical component, and therefore can be manufactured at a lower cost than in the past.

1 is a schematic configuration diagram of an autocollimator according to an embodiment of the present invention. The schematic block diagram which shows another example of the structure of the light source and detector periphery of the autocollimator which concerns on the Example. The schematic block diagram of the autocollimator which concerns on the other Example of this invention. The schematic block diagram of the conventional autocollimator.

  Hereinafter, an embodiment (Example 1) of an autocollimator according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of an autocollimator according to the present embodiment. In the following description, the X axis in the figure is the left and right axis, the Y axis is the vertical axis, the Z axis is the front and rear axis, and the left side in the figure is the front.

  The autocollimator 10 according to the present embodiment is a so-called photoelectric autocollimator, and includes a light source 11, a first slit plate 12, an objective lens 13, a second slit plate 14, and a detector 15. As the light source 11, for example, a tungsten lamp or a semiconductor laser can be used. The first slit plate 12 and the second slit plate 14 are light shielding plates having slit holes (the first slit hole 12a and the second slit hole 14a) having substantially the same shape, and are located in front of the light source 11 and the detector 15, respectively. Is arranged. In addition, in FIG. 1, although the 1st slit board 12 and the 2nd slit board 14 are comprised integrally, you may comprise these as another body. The detector 15 detects light that has passed through the second slit hole 14a, and is composed of, for example, a photomultiplier tube. The output signal of the detector 15 is processed by predetermined processing means (not shown), and the result is presented to the user by predetermined display means (not shown). Although not shown here, a predetermined light shielding member is disposed between the light source 11 and the detector 15 so that the light from the light source 11 does not directly enter the detector 15.

  In the autocollimator of this embodiment, the first slit plate 12 corresponds to the first light shielding plate (that is, the irradiation light forming means) in the present invention, and the second slit plate 14 corresponds to the second light shielding plate in the present invention. To do. These slit plates 12 and 14 have a front surface (ie, a surface facing the objective lens 13) that is a focal plane of the objective lens 13 (ie, perpendicular to the principal axis A of the objective lens 13), and a focal point B of the objective lens 13. And the positions of the first slit hole 12a and the second slit hole 14a are point-symmetric with respect to the focal point B of the objective lens 13.

  In FIG. 1, the first slit holes 12a and the second slit holes 14a are arranged in a line along the Y axis (that is, the longitudinal axes of the slit holes 12a and 14a are aligned). As shown in FIG. 2, these slit holes 12a and 14a may be arranged in a line along the X axis (that is, the longitudinal axes of the slit holes 12a and 14a are parallel to each other).

  In the present embodiment, the light source 11 and the first slit plate 12 have an optical axis of light (hereinafter referred to as “irradiation light”) emitted from the light source 11 and passed through the first slit hole 12 a of the objective lens 13. The optical axis is inclined so that the optical axis passes through a position off the center of the objective lens 13. Further, the second slit plate 14 and the detector 15 are reflected by the measured object 20 in a state where the normal line of the measured object 20 coincides with the main axis A of the objective lens 13 (this state is referred to as “reference state”). The optical axis of the transmitted light (hereinafter referred to as “return light”) passes through the second slit hole 14 and the detector 15.

  Next, the operation of the autocollimator according to the present embodiment will be described. In the following description, using the autocollimator 10 according to the present embodiment, the inclination of the object to be measured 20 arranged at a predetermined distance from the objective lens 13 (that is, rotation around the Y axis) is measured. The size shall be evaluated.

  First, when the light source 11 is turned on, light generated from the light source 11 passes through the slit hole 12a of the first slit plate 12 and enters the objective lens 13 at a predetermined angle. At this time, the irradiation light that has entered the objective lens 13 passes slightly above the center of the objective lens 13, is converted into a parallel light beam, and is irradiated onto the object to be measured 20.

  The parallel light beam emitted from the objective lens 13 is incident on the object to be measured 20 obliquely from above and is reflected obliquely below (that is, the optical path of the irradiation light and the optical path of the return light are the surface of the object to be measured 20). V-shaped with the fold as a point). Therefore, the light (returned light) reflected by the object to be measured 20 returns to the objective lens 13 again through a path different from the irradiation light. At this time, the return light that has entered the objective lens 13 passes slightly below the center of the objective lens 13, is converted into convergent light, and is irradiated onto the second slit plate 14. Since the irradiation light described above is limited to a slit shape by the first slit plate 12, a slit image of the first slit hole 12a is projected on the second slit plate 14.

  Here, when the DUT 20 and the objective lens 13 are in the above-described reference state, the image position of the slit image coincides with the position of the second slit hole 14a. Therefore, the second slit plate 14 passes the projection image of the first slit hole 12a rearward as it is, and this enters the detector 15.

  On the other hand, when the normal line of the object to be measured 20 is shifted left and right from the main axis A of the objective lens 13 (that is, when the object to be measured 20 is rotated around the Y axis from the reference state), the second slit plate. The slit image projected onto 14 is shifted to the left and right from the position of the second slit hole 14a. As the deviation between the normal line and the principal axis A increases, the amount of light incident on the detector 15 decreases. Therefore, the inclination of the DUT 20 can be evaluated based on the detection signal from the detector 15.

  As described above, in the autocollimator according to the present embodiment, since the optical path of the irradiation light and the optical path of the return light are separated, it is not necessary to branch the optical path by a beam splitter as in the prior art. For this reason, there is no attenuation of the irradiation light and return light by a beam splitter, and even if the reflectance of a to-be-measured object is low, the inclination of the to-be-measured object can be evaluated reliably.

  Subsequently, an autocollimator according to another embodiment (embodiment 2) of the present invention will be described. FIG. 3 is an enlarged view showing a configuration around the light source 11 of the autocollimator according to the present embodiment. The configuration of the other parts is the same as that shown in FIG.

  The autocollimator according to the present embodiment is a so-called visual autocollimator that evaluates the inclination of the object to be measured 20 by the user's visual observation, and includes the first slit plate 12, the second slit plate 14, and the detection in the first embodiment. Instead of the container 15, a first transparent plate 16, a second transparent plate 17, and an eyepiece lens 18 are provided.

  Both the first transparent plate 16 and the second transparent plate 17 are made of a transparent glass plate, and the first transparent plate 16 is provided with a cross wire 16a, and the second transparent plate 17 is provided with a scale line 17a. In this embodiment, the first transparent plate 16 corresponds to the transparent plate (irradiation light forming means) in the present invention, and the second transparent plate 17 corresponds to the screen in the present invention. The transparent plates 16 and 17 have a front surface (that is, a surface facing the objective lens 13) located in the focal plane of the objective lens 13, and the intersection of the cross line 16a and the center of the scale line 17a is the objective lens. It is formed so as to come to a symmetrical position vertically (or left and right) with 13 focal points B as the center. In addition, although the example which formed the 1st transparent plate 16 and the 2nd transparent plate integrally is shown in FIG. 3, these may be comprised separately.

  In the present embodiment, the light emitted from the light source 11 passes through the first transparent plate 16, is converted into a parallel light beam by the objective lens 13 and is irradiated onto the object 20 to be measured, as in the first embodiment. The return light reflected from the DUT 20 is collected by the objective lens 13 and imaged on the second transparent plate 17 as in the first embodiment.

  As a result, an image of the cross line 16 a of the first transparent plate 16 is projected on the second transparent plate 17. This cross-line image overlaps the center of the scale line 17a of the second transparent plate 17 when the object to be measured 20 is in the above-described reference state, and when the object to be measured 20 is inclined to the left and right, the degree of the inclination. Accordingly, projection is performed at a position shifted from the center of the scale line 17a. Therefore, the user can know the degree of inclination of the DUT 20 by checking the crosshair image and the scale line 17a on the second transparent plate 17 through the eyepiece 18.

  The autocollimator according to the present invention has been described with reference to the embodiments. However, the present invention is not limited to the above-described embodiments, and appropriate modifications are allowed within the scope of the present invention. . For example, in the above embodiment, the second slit plate 14 and the detector 15 or the second transparent plate 17 and the eyepiece 18 are provided as a mechanism for confirming the amount of return light deviation. A one-dimensional or two-dimensional image sensor using a CCD or the like may be provided, and the imaging position of the slit image or crosshair image may be detected by receiving the return light by the image sensor.

DESCRIPTION OF SYMBOLS 10 ... Autocollimator 11 ... Light source 12 ... 1st slit plate 12a ... 1st slit hole 13 ... Objective lens 14 ... 2nd slit plate 14a ... 2nd slit hole 15 ... Detector 16 ... 1st transparent plate 16a ... Crosshair 17 2nd transparent plate 17a Scale line 18 Eyepiece 20 Object to be measured A Main axis of objective lens

Claims (3)

An autocollimator for irradiating a measurement object with irradiation light and measuring the inclination of the measurement object based on return light reflected from the measurement object,
a) a light source;
b) Irradiation light forming means that passes a part of the light emitted from the light source to be the irradiation light;
c) an objective lens that converts the irradiation light into parallel light and converts the return light into convergent light;
When the object to be measured is opposed to the objective lens at a predetermined angle, the optical axis of the irradiation light and the optical axis of the return light pass through different positions shifted from the center of the objective lens. As described above, an autocollimator in which the light source and the irradiation light forming means are arranged. The irradiation light forming means is a first light shielding plate having an opening of a predetermined shape,
Furthermore,
d) a second light shielding plate having an aperture through which the return light converged by the objective lens passes;
e) a detector for detecting light that has passed through the second light shielding plate;
The autocollimator according to claim 1, further comprising: The irradiation light forming means is a transparent plate having a mask portion having a predetermined shape,
Furthermore,
d) a screen having a predetermined mark,
The auto pattern according to claim 1, wherein the projection pattern of the mask portion is projected onto or near the mark by causing the return light converged by the objective lens to be incident on the screen. Collimator.

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