JP2009097883A - Eccentricity measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an eccentricity measuring device capable of suppressing an influence of misalignment between an optical axis of the eccentricity measuring device and an optical axis of an imaging optical system, on measurement of an eccentricity amount. <P>SOLUTION: This eccentricity measuring device 1 has the imaging optical system 5 having a prescribed focal distance; a corner cube 8 for reflecting entering light after being transmitted through the imaging optical system 5 so as to enter a specimen S; a plane mirror 11 for reflecting entering light after passing the specimen S so as to enter the imaging optical system 5; and a position sensor 13 for condensing reflected light by the plane mirror 11 transmitted through the imaging optical system 5, and observing the position of the light quantity center of the condensed light. The corner cube 8 rotates entering light by 180 degrees with respect to the optical axis and reflects the light along the incident direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an eccentricity measuring apparatus.

2. Description of the Related Art Conventionally, as an eccentricity measuring apparatus, an apparatus including a high-precision rotating shaft (spindle) that can rotate at a high speed with a rotationally symmetric subject attached is known (for example, see Patent Document 1). In such an eccentricity measuring apparatus, the amount of eccentricity of the subject is measured by measuring the shake of the image of the light reflected by the subject's test surface. In the decentration measuring apparatus described in Patent Document 1 for measurement, in order to measure decentration using a parallel light beam, an imaging optical system is inserted into the optical path of the measuring apparatus, and light is transmitted through the imaging optical system. Is incident on the subject, and the reflected light from the subject is made incident on the eccentricity detection sensor via the imaging optical system.
JP-A-11-287742

  When the imaging optical system is inserted into the optical path of the eccentricity measuring device, if the optical axis of the imaging optical system and the optical axis of the eccentricity measuring device are misaligned, accurately measure the eccentricity. It is difficult.

  An object of the present invention is to provide an eccentricity measuring device capable of suppressing the influence of the deviation between the optical axis of the eccentricity measuring device and the optical axis of the imaging optical system on the measurement of the eccentricity. .

  According to an embodiment illustrating the present invention, an apparatus for measuring the amount of eccentricity of a subject, the imaging optical system having a predetermined focal length, and the light incident after passing through the imaging optical system are applied to the subject. A first reflecting member that reflects so as to be incident; a second reflecting member that reflects light incident after passing through the subject so as to enter the imaging optical system; and an imaging optical system with respect to the optical axis of the apparatus And an inclination detecting means for detecting the inclination of the reflected light from the second reflecting member via one of the first and second reflecting members, and the incident light is 180 degrees with respect to the optical axis. An eccentricity measuring device is provided, which is a reflecting member that rotates and reflects along an incident direction, the other being a plane mirror.

  According to the embodiment illustrating the present invention, the light incident on either one of the first and second reflecting members is rotated by 180 degrees with respect to the optical axis and reflected along the incident direction. Therefore, when the optical axis of the imaging optical system is deviated from the optical axis of the eccentricity measuring device, the reflected light from the subject is returned to the imaging optical system along the optical axis of the imaging optical system. In addition, the reflected light from the subject that has passed through the imaging optical system can be a parallel light beam. Thereby, according to the aspect illustrating the present invention, even when the optical axis of the imaging optical system and the optical axis of the eccentricity measuring device are shifted, the eccentricity amount of the subject is accurately measured. It becomes possible.

  ADVANTAGE OF THE INVENTION According to this invention, the eccentricity measuring apparatus which can suppress the influence which the shift | offset | difference of the optical axis of an eccentricity measuring apparatus and the optical axis of an imaging optical system has on the measurement of eccentricity can be provided. .

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted.

(First embodiment)
With reference to FIG.1 and FIG.2, the structure of the eccentricity measuring apparatus 1 which concerns on 1st Embodiment is demonstrated. FIG. 1 is a configuration diagram of an eccentricity measuring apparatus according to the first embodiment. FIG. 2 is a perspective view of a corner cube included in the eccentricity measuring apparatus according to the first embodiment.

  An eccentricity measuring apparatus 1 shown in FIG. 1 includes a light source 2, a collimator lens 3, a polarizing beam splitter 4, an imaging optical system 5, a polarizing beam splitter (light reflecting / transmitting member) 6, and a quarter wavelength plate. 7, 9, 10, a corner cube (first reflecting member) 8, a plane mirror (second reflecting member) 11, a condensing optical system 12, and a position sensor 13. The eccentricity measuring apparatus 1 causes the light L output from the light source 2 to enter the subject S via the imaging optical system 5 and the corner cube 8, and the light L reflected by the subject surface of the subject S is used. This is an apparatus for measuring the eccentricity of the subject S by being incident on the position sensor 13 via the plane mirror 11 and the imaging optical system 5.

  The light source 2 is a laser device, for example, and makes the light L incident on the collimator lens 3. The collimator lens 3 converts the light L output from the light source 2 into a parallel light beam and makes it incident on the polarization beam splitter 4. The polarization beam splitter 4 reflects the light L that has passed through the collimator lens 3 and causes the light L to enter the imaging optical system 5. The polarization beam splitter 4 also transmits the light L that has passed through the imaging optical system 5.

  The imaging optical system 5 is a focusing optical system having a finite focal length. The imaging optical system 5 is also a variable focal length optical system that can change the focal length. The imaging optical system 5 is disposed at a position away from the center of curvature of the test surface of the subject S along the optical axis Ax of the eccentricity measuring apparatus 1 by the focal length. The light L that has passed through the imaging optical system 5 from the light source 2 side enters the polarization beam splitter 6. On the other hand, the light L transmitted through the imaging optical system 5 from the subject S side enters the polarization beam splitter 4.

  The polarization beam splitter 6 reflects the light L transmitted through the imaging optical system 5 and makes it incident on the quarter-wave plate 7. The polarization beam splitter 6 also transmits the light L reflected by the corner cube 8 and transmitted through the quarter-wave plate 7 to be incident on the quarter-wave plate 9 and the subject S. The polarization beam splitter 6 also reflects the light L reflected by the test surface Sm of the subject S and transmitted through the quarter-wave plate 9 to enter the quarter-wave plate 10 and the plane mirror 11. The polarization beam splitter 6 also transmits the light L reflected by the plane mirror 11 and transmitted through the quarter-wave plate 10 to enter the imaging optical system 5.

  The quarter-wave plates 7, 9, 10 are circularly polarized when the incident light L is linearly polarized, and are linearly polarized when the incident light L is circularly polarized. And

  The corner cube 8 transmits the light L incident through the polarizing beam splitter 6 and the quarter-wave plate 7 after passing through the imaging optical system 5 through the polarizing beam splitter 6 and the quarter-wave plates 7 and 9. Reflected to enter the subject S. FIG. 2 shows a perspective view of the corner cube 8. As shown in FIG. 2, the corner cube 8 has three reflecting surfaces 8a, 8b, and 8c orthogonal to each other, and reflects the incident light L in the direction of the incident optical axis. Due to these characteristics of the corner cube 8, the light L is reflected in a direction along the incident optical path direction. The corner cube 8 reflects the incident light L along the incident direction by rotating 180 degrees with respect to the optical axis of the corner cube 8 itself, in this embodiment, the optical axis Ax of the apparatus 1.

  Returning to FIG. 1 again, the description of the eccentricity measuring apparatus 1 will be continued. The plane mirror 11 couples the light L incident on the polarization beam splitter 6 and the quarter wavelength plates 9 and 10 after being reflected by the subject S via the polarization beam splitter 6 and the quarter wavelength plate 10. Reflected to enter the image optical system 5. The plane mirror 11 is disposed so that the reflection surface and the optical axis Ax are orthogonal to each other, and reflects the light L in a direction along the incident optical path direction.

  The condensing optical system 12 condenses the reflected light L from the plane mirror 11 that has passed through the imaging optical system 5 on the position sensor 13. The position sensor 13 observes the position of the center of the light amount of the light L collected by the condensing optical system 12. The position sensor 13 may be composed of, for example, a screen and a CCD camera. In this case, the CCD camera images spot light collected on the screen. Or the position sensor 13 may be an optical position sensor (Position Sensitive Detector; PSD), for example. Or the position sensor 13 is a screen, for example, Comprising: You may observe the position of the spot light condensed on the screen by surveying.

  The position sensor 13 further detects the inclination of the reflected light L at the plane mirror 11 that has passed through the condensing optical system 12 with respect to the optical axis Ax, based on the position of the center of light quantity of the reflected light L that has been observed. Thus, the condensing optical system 12 and the position sensor 13 function as tilt detection means.

  The imaging optical system 5, the collimator lens 3, and the condensing optical system 12 are represented by one optical lens in FIG. 1, but may actually be configured by a plurality of optical lenses.

  Next, a method for measuring the eccentricity of the subject S using the eccentricity measuring apparatus 1 will be described. First, the light L emitted from the light source 2 passes through the collimator lens 3 to become a parallel light beam and is reflected by the polarization beam splitter 4. The imaging optical system 5 changes the focal length so as to focus on the center of curvature of the test surface Sm of the subject S. The light L reflected by the polarization beam splitter 4 passes through the imaging optical system 5 and is reflected by the polarization beam splitter 6. The light L reflected by the polarization beam splitter 6 passes through the quarter wavelength plate 7 and is reflected by the corner cube 8. The light reflected by the corner cube 8 is again transmitted through the quarter-wave plate 7 and the polarization beam splitter 6, and further passes through the quarter-wave plate 9, and then enters the test surface Sm of the subject S. The light L reflected by the test surface Sm passes through the quarter-wave plate 9 again and is then reflected by the polarization beam splitter 6. The light L reflected by the polarization beam splitter 6 passes through the quarter wavelength plate 10, then reflects by the plane mirror 11, passes through the quarter wavelength plate 10 again, and passes through the polarization beam splitter 6. The light L further passes through the imaging optical system 5, passes through the polarization beam splitter 4, and is then condensed on the position sensor 13 via the condensing optical system 12. From the position of the spot on the position sensor 13, the inclination of the reflected light L at the plane mirror 11 that has passed through the condensing optical system 12 with respect to the optical axis Ax is detected. Then, the amount of eccentricity of the test surface Sm of the subject S can be detected.

  Next, the principle of suppressing the influence of the deviation between the optical axis of the imaging optical system 5 and the optical axis Ax of the eccentricity measuring apparatus 1 on the measurement of the eccentricity will be described with reference to FIG. In the decentration measuring apparatus 1, when the imaging optical system 5 is arranged with its optical axis 5a shifted from the optical axis Ax of the decentering measuring apparatus 1, the light L passing through the imaging optical system 5 is connected to the apparatus. The optical axis 5a of the image optical system 5 proceeds as the optical axis of the apparatus. Therefore, the optical axis after the imaging optical system 5 is deviated from the optical axis Ax of the original apparatus. For this reason, the light L is condensed at the point A deviated from the center of curvature O of the test surface Sm after being reflected by the corner cube 8. Here, if the test surface Sm is not decentered, the image point of the light reflected by the test surface Sm is a point B1 that is point-symmetric with respect to the point A with respect to the center of curvature O. Accordingly, the light L reflected by the test surface Sm travels like light emitted from the point B1. The light L reflected by the test surface Sm is reflected by the polarization beam splitter 6 and the plane mirror 11. The image point of the light reflected by the polarizing beam splitter 6 and the plane mirror 11 is a point B2. In the eccentricity measuring apparatus 1, the image point B2 is on an extension line of the optical axis 5a of the imaging optical system 5, as shown in FIG. Therefore, when the test surface Sm has no eccentricity, the light reflected by the plane mirror 11 and then transmitted through the imaging optical system 5 becomes a parallel light beam parallel to the optical axis Ax of the eccentricity measuring apparatus 1. On the other hand, when the test surface Sm is decentered, the light reflected by the plane mirror 11 and then transmitted through the imaging optical system 5 is the optical axis Ax of the decentering measuring apparatus 1 as in the normal measurement. The position of the light quantity center of the spot on the position sensor 13 changes.

  In the eccentricity measuring apparatus 1, the light L incident on the corner cube 8 is rotated by 180 degrees with respect to the optical axis Ax and reflected along the incident direction. Therefore, as shown in FIG. 3, when the optical axis 5a of the imaging optical system 5 and the optical axis Ax of the eccentricity measuring device are shifted, the reflected light L on the test surface Sm of the subject S is reflected. Is returned to the imaging optical system 5 with the optical axis 5a of the imaging optical system 5 as the optical axis. Therefore, the reflected light L from the test surface Sm of the subject S that has passed through the imaging optical system 5 can be a parallel light beam. Thereby, in the eccentricity measuring apparatus 1, even when the optical axis 5a of the imaging optical system 5 and the optical axis Ax of the eccentricity measuring apparatus 1 are shifted, the eccentricity amount of the subject is accurately measured. It becomes possible to do.

  Further, in the eccentricity measuring apparatus 1, even if the optical axis 5a of the imaging optical system 5 is deviated from the optical axis Ax of the eccentricity measuring apparatus 1 as described above, the influence of the deviation is suppressed and the eccentricity is measured. Is possible.

  In addition, since a turntable is not required for measuring eccentricity, measurement time can be shortened and costs can be reduced. Furthermore, the posture of the subject S is not limited by the installation of the turntable, and measurement can be performed in various arrangements.

  Further, the eccentricity measuring apparatus 1 includes a polarization beam splitter 6 that reflects or transmits incident light. The corner cube 8 reflects the light incident through the polarization beam splitter 6 after passing through the imaging optical system 5 so as to enter the subject S through the polarization beam splitter 6. The plane mirror 11 reflects the light incident through the polarization beam splitter 6 after being reflected by the subject S so as to enter the imaging optical system 5 through the polarization beam splitter 6. Thus, since the eccentricity measuring apparatus 1 uses the polarization beam splitter 6, it is possible to reduce the size of the apparatus.

  The imaging optical system 5 is a variable focal length optical system that can change the focal length. Therefore, even if the subject S is replaced and the position of the center of curvature of the subject surface Sm changes, the focal length of the imaging optical system 5 can be changed to change the position of the condensing point. As a result, the eccentricity measuring apparatus 1 can accurately measure the eccentricity amounts of subjects having various shapes.

  FIG. 4 shows an eccentricity measuring apparatus 1 </ b> A according to a modification of the eccentricity measuring apparatus 1. The eccentricity measuring apparatus 1A is different in that the arrangement of the corner cube 8 and the arrangement of the plane mirror 11 are opposite. That is, the plane mirror 11 functions as a first reflecting member, and the corner cube 8 functions as a second reflecting member.

  In the eccentricity measuring apparatus 1 </ b> A, the light L emitted from the light source 2 passes through the imaging optical system 5, is reflected by the polarization beam splitter 6, passes through the quarter wavelength plate 7, and is reflected by the plane mirror 11. The light reflected by the plane mirror 11 passes through the quarter-wave plate 7 and the polarizing beam splitter 6 again, passes through the quarter-wave plate 9, and enters the test surface Sm of the subject S. The light L reflected by the test surface Sm passes through the quarter-wave plate 9 again and is then reflected by the polarization beam splitter 6. The light L reflected by the polarizing beam splitter 6 is transmitted through the quarter wavelength plate 10, then reflected by the corner cube 8, is again transmitted through the quarter wavelength plate 10, and passes through the polarizing beam splitter 6. The light L further passes through the imaging optical system 5, passes through the polarization beam splitter 4, and is then condensed on the position sensor 13 via the condensing optical system 12.

  In the eccentricity measuring apparatus 1A, similarly to the eccentricity measuring apparatus 1, even when the optical axis of the imaging optical system 5 and the optical axis of the eccentricity measuring apparatus 1 are deviated, the amount of eccentricity of the subject is measured. Can be measured with high accuracy.

  FIG. 6 shows an eccentricity measuring device 1 </ b> B according to another modification of the eccentricity measuring device 1. The eccentricity measuring apparatus 1B is different from the eccentricity measuring apparatus 1 according to the first embodiment in that it further includes first and second masks 14 and 15.

  The first mask 14 is disposed at a position where light enters the subject S after passing through the first mask 14, more specifically, between the collimator lens 3 and the polarization beam splitter 4. The second mask 15 is disposed at a position where light is incident on the second mask 15 after being reflected by the subject S, more specifically, between the polarization beam splitter 4 and the condensing optical system 12.

  The first mask 14 having a circular shape has a pattern including three shielding portions 14a that shield light and three passage portions 14b that allow light to pass therethrough. The shielding parts 14a and the passing parts 14b are alternately arranged in the circumferential direction. Each of the shielding part 14a and the passage part 14b has a fan shape with a central angle of 60 degrees extending radially from the center of the circle. In the pattern of the first mask 14, the position of the shielding part 14a and the position of the passage part 14b are reversed by rotating 180 degrees around the optical axis Ax.

  The second mask 15 having a circular shape has a pattern including three shielding portions 15a that shield light and three passage portions 15b that allow light to pass therethrough. The shielding parts 15a and the passing parts 15b are alternately arranged in the circumferential direction. Each of the shielding portion 15a and the passage portion 15b has a fan shape having a central angle of 60 degrees extending radially from the center of the circle. In the pattern of the second mask 15, the position of the shielding part 15a and the position of the passage part 15b are reversed by rotating 180 degrees around the optical axis Ax. In FIG. 6, the shielding portions 14 a and 15 a are hatched for easy viewing.

  The first and second masks 14 and 15 are arranged such that the patterns are inverted by 180 degrees with respect to the optical axis Ax. In other words, the shielding part 14a of the first mask 14 and the passage part 15b of the second mask are located at the same position with respect to the optical axis Ax, and the passage part 14b of the first mask 14 and the second mask pass through the second mask. The shielding part 15a is disposed at the same position with respect to the optical axis Ax.

  When the subject S is composed of a plurality of optical systems, for example, as shown in FIG. 7, one surface Sx of the plurality of optical systems of the subject S is the center of curvature or paraxial of the subject surface Sm. The light reflected from the surface Sx is also imaged on the position sensor 13 when the focal point is near the point X. And the light reflected by the surface Sx may reduce the measurement accuracy of the eccentric amount of the subject S as noise light.

  On the other hand, in the eccentricity measuring apparatus 1B, the first and second masks 14 and 15 are arranged so that the patterns are inverted by 180 degrees. Therefore, when the light that has passed through the passage portion 14b of the first mask 14 is reflected by the test surface Sm, the light passes through the passage portion 15b of the second mask 15, but passes through the passage portion 14b of the first mask 14. When the transmitted light is reflected by the surface Sx, the light reaches the shielding portion 15a of the second mask 15. This is because, as shown in FIG. 7, the light reflected by the test surface Sm is reflected in the same optical path direction as the incident light, whereas at the point X that is the center of curvature of the test surface Sm or the paraxial focus. This is because the light reflected by the surface Sx at a close position is reflected in the optical path direction symmetric with respect to the optical axis Ax with respect to the optical path of the incident light. As a result, in the eccentricity measuring apparatus 1B, only the measurement light reflected by the test surface Sm passes through the second mask 14 and reaches the position sensor 13. Then, the measurement light reflected by the test surface Sm and the noise light reflected by the surface Sx cannot be distinguished, and the noise light reflected by the surface Sx is suppressed from affecting the measurement.

  The first and second masks 14 and 15 are not limited to patterns in which three shielding portions 14a and 15a and three passage portions 14b and 15b are alternately arranged as shown in FIG. . The first and second masks 14 and 15 may be any patterns that can be reversed by rotating the masks 180 degrees.

  Specifically, for example, as shown in FIG. 8 and FIG. 9, an odd number of shielding portions and the same number of passage portions and fan shapes having equal central angles are alternately arranged and arranged alternately. It may be a pattern. That is, as shown in FIG. 8, the first and second masks 14 and 15 may each have a pattern formed by one shielding portion 14a and 15a and one passage portion 14b and 15b. In this case, the shielding portions 14a and 15a and the passing portions 14b and 15b all have a semicircular shape. Or as FIG. 9 shows, the 1st and 2nd masks 14 and 15 may exhibit the pattern formed by the five shielding parts 14a and 15a and the five passage parts 14b and 15b, respectively. In this case, the shielding portions 14a and 15a and the passing portions 14b and 15b all have a fan shape with a central angle of 36 degrees.

(Second Embodiment)
With reference to FIG. 5, the structure of the eccentricity measuring apparatus 21 which concerns on 2nd Embodiment is demonstrated. The eccentricity measuring apparatus 21 according to the second embodiment is different from the first embodiment in that the optical path of light incident on the test surface Sm of the subject S is different from the optical path of light reflected by the test surface Sm. This is different from the eccentricity measuring apparatus. FIG. 5 is a configuration diagram of the eccentricity measuring apparatus according to the second embodiment.

  5 includes a light source 22, a collimator lens 23, an imaging optical system 24, a planar reflecting mirror 25, a corner cube (first reflecting member) 26, and a polarizing beam splitter (light). (Reflection / transmission member) 27, quarter-wave plates 28 and 29, plane mirror (second reflection member) 30, imaging optical system 31, optical systems 32 and 34, spatial filter 33, and analyzing plate ( (Polarizing plate) 35, a condensing optical system 36, and a position sensor 37. The eccentricity measuring device 21 causes the light L output from the light source 22 to enter the subject S via the imaging optical system 24 and the corner cube 26, and the light L reflected by the subject surface Sm of the subject S. Is incident on the position sensor 37 through the plane mirror 30 and the imaging optical system 31 to measure the amount of eccentricity of the subject S.

  The light source 22 makes the light L incident on the collimator lens 23. The collimator lens 23 converts the light L output from the light source 22 into a parallel light flux and enters the imaging optical system 24. The imaging optical system 24 is a focusing optical system having a finite focal length. The imaging optical system 24 is arranged at a position away from the center of curvature of the test surface of the subject S by the focal length along the optical axis Ax of the eccentricity measuring device 21 via the corner cube 26. . The plane reflecting mirror 25 reflects the light L that has passed through the imaging optical system 24 and causes the light to enter the corner cube 26.

  The corner cube 26 reflects the light L reflected by the planar reflecting mirror 25 after passing through the imaging optical system 24 so as to enter the subject S via the polarization beam splitter 27. The corner cube 26 reflects the incident light L along the incident direction by rotating 180 degrees with respect to the optical axis of the corner cube 26 itself, in this embodiment, the optical axis Ax of the apparatus 1.

  The polarization beam splitter 27 transmits the light L reflected by the planar reflecting mirror 25 and makes it incident on the quarter-wave plate 28. The polarization beam splitter 27 also reflects the light L reflected by the test surface Sm of the subject S and transmitted through the quarter-wave plate 28 to enter the quarter-wave plate 29 and the plane mirror 30. The polarization beam splitter 27 also transmits the light L reflected by the plane mirror 30 and transmitted through the quarter-wave plate 29 to enter the imaging optical system 31.

  The imaging optical system 31 is arranged at a position away from the center of curvature of the test surface of the subject S by the focal length along the optical axis Ax of the eccentricity measuring device 21 via the plane mirror 30. In the eccentricity measuring device 21, the imaging optical system 24 and the imaging optical system 31 are arranged at a position away from the center of curvature of the test surface Sm of the subject S by the focal length along the optical axis Ax. It functions as one imaging optical unit F.

  The condensing optical system 36 condenses the light L that has passed through the optical system 32, the spatial filter 33, the optical system 34, and the light detection plate 35 on the position sensor 37 after passing through the imaging optical system 31. The position sensor 37 observes the position of the center of the light amount of the light L collected by the condensing optical system 36, and thereby the inclination of the reflected light L at the plane mirror 30 transmitted through the imaging optical system 36 with respect to the optical axis Ax. To detect.

  The imaging optical systems 24 and 31, the collimator lens 23, the optical systems 32 and 34, and the condensing optical system 36 are represented by one optical lens in FIG. 5, but actually a plurality of optical lenses. It may be constituted by.

  Next, a method for measuring the eccentricity of the subject S by the eccentricity measuring device 21 will be described. First, the light L emitted from the light source 22 is converted into a parallel light beam through the collimator lens 23 and enters the imaging optical system 24. After passing through the imaging optical system 24, the light L reflected by the plane reflecting mirror 25 is reflected by the corner cube 26. The light L reflected by the corner cube 26 enters the test surface Sm of the subject S through the polarization beam splitter 27 and the quarter wavelength plate 28. The light L reflected by the test surface Sm passes through the quarter-wave plate 28 again and is then reflected by the polarization beam splitter 27. The light L reflected by the polarization beam splitter 27 passes through the quarter wavelength plate 29, is reflected by the plane mirror 30, passes through the quarter wavelength plate 29 again, and passes through the polarization beam splitter 27. The light L further passes through the imaging optical system 31, passes through the spatial filter 33 and the light detection plate 35, and is then condensed on the position sensor 37 via the condensing optical system 36. From the position of the spot on the position sensor 37, the eccentricity amount of the test surface Sm of the subject S can be detected.

  In the eccentricity measuring device 21, the light L incident on the corner cube 26 is rotated by 180 degrees with respect to the optical axis Ax and reflected along the incident direction. Therefore, when the optical axis of the imaging optical unit F is deviated from the optical axis Ax of the eccentricity measuring device, the reflected light L from the test surface Sm of the subject S is reflected by the optical axis of the imaging optical unit F. Is returned to the imaging optical system 31 as an optical axis. Therefore, the reflected light L from the test surface Sm of the subject S that has passed through the imaging optical system 31 can be a parallel light beam. Thereby, in the eccentricity measuring apparatus 21, even when the optical axis of the imaging optical unit F and the optical axis Ax of the eccentricity measuring apparatus 21 are shifted, the eccentricity amount of the subject is accurately measured. It becomes possible.

  Further, in the eccentricity measuring device 21, even when the optical axis of the imaging optical unit F is deviated from the optical axis Ax of the eccentricity measuring device 21 as described above, the decentration amount is measured while suppressing the influence of the deviation. Therefore, it is possible to increase the measurement speed and reduce the cost. Furthermore, the subject S can be measured in various arrangements.

  The eccentricity measuring device 21 includes a polarization beam splitter 27 that reflects or transmits incident light. The corner cube 26 reflects the light incident through the plane reflecting mirror 25 after passing through the imaging optical system 24 so as to enter the subject S through the polarization beam splitter 27. The plane mirror 30 reflects the light incident through the polarization beam splitter 27 after being reflected by the subject S so as to enter the imaging optical system 31 through the polarization beam splitter 27. Thus, since the eccentricity measuring device 21 uses the polarization beam splitter 27, it is possible to reduce the size of the device.

  The eccentricity measuring device 21 includes a spatial filter 33 and a light detection plate 35. For this reason, the light directly reflected by the test surface Sm can be cut by the spatial filter 33 and the light detection plate 35. As a result, the measurement accuracy can be further improved.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, A various deformation | transformation is possible. For example, a corner reflector may be used as the first or second reflecting member. Further, the imaging optical systems 5, 24, and 31 may be optical systems that cannot change the focal length and have a fixed focal length.

It is a block diagram of the eccentricity measuring apparatus which concerns on 1st Embodiment. It is a perspective view of a corner cube. It is a figure for demonstrating the principle of the measuring method by the eccentricity measuring apparatus which concerns on 1st Embodiment. It is a block diagram of the eccentricity measuring apparatus which concerns on the modification of 1st Embodiment. It is a block diagram of the eccentricity measuring apparatus which concerns on 2nd Embodiment. It is a block diagram of the eccentricity measuring apparatus which concerns on the modification of 1st Embodiment. It is a figure which shows the optical path direction in which the light reflected by a subject advances. It is a top view of the 1st and 2nd mask. It is a top view of the 1st and 2nd mask.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 21 ... Eccentricity measuring apparatus 2, 22, ... Light source 3, 23 ... Collimator lens 4, 6, 27 ... Polarizing beam splitter 5, 24, 31 ... Imaging optical system 7, 9, 10, 28 , 29 ... 1/4 wavelength plate, 8, 26 ... Corner cube, 11, 30 ... Plane mirror, 12, 36 ... Condensing optical system, 13, 37 ... Position sensor, 14 ... First mask, 15 ... Second Mask, 25... Plane reflecting mirror, 33... Spatial filter, 35.

Claims (9)

An apparatus for measuring the amount of eccentricity of a subject,
An imaging optical system having a predetermined focal length;
A first reflecting member that reflects the light incident after passing through the imaging optical system so as to be incident on the subject;
A second reflecting member that reflects the light incident after passing through the subject so as to be incident on the imaging optical system;
Tilt detecting means for detecting the tilt of reflected light at the second reflecting member via the imaging optical system with respect to the optical axis of the device,
One of the first and second reflecting members is a reflecting member that rotates incident light by 180 degrees with respect to the optical axis and reflects the incident light along the incident direction, and the other is a plane mirror. An eccentricity measuring device. A light reflection / transmission member that reflects or transmits incident light;
The first reflecting member reflects light incident after passing through the imaging optical system so as to enter the subject through the light reflecting / transmitting member,
The second reflecting member reflects the light incident through the light reflecting / transmitting member after passing through the subject so as to enter the imaging optical system through the light reflecting / transmitting member. The eccentricity measuring apparatus according to claim 1.   Of the first and second reflecting members, the reflecting member that rotates incident light by 180 degrees with respect to the optical axis and reflects the incident light along the incident direction has three reflecting surfaces orthogonal to each other. The eccentricity measuring apparatus according to claim 1 or 2.   The reflective member that rotates incident light by 180 degrees with respect to the optical axis and reflects the incident light along the incident direction among the first and second reflective members is a corner cube. The eccentricity measuring apparatus as described in any one of -3.   The reflection member that rotates incident light 180 degrees with respect to the optical axis and reflects the incident light along the incident direction among the first and second reflecting members is a corner reflector. The eccentricity measuring apparatus as described in any one of -3.   The decentering measurement apparatus according to claim 1, wherein the imaging optical system can change the focal length.   7. The imaging optical system according to claim 1, wherein the imaging optical system has a finite focal length, and is disposed at a position away from the center of curvature of the subject along the optical axis by the focal length. The eccentricity measuring apparatus as described in any one of Claims.   The tilt detection means condenses the reflected light from the second reflecting member that has passed through the imaging optical system, and observes the position of the center of gravity of the collected light, whereby the optical axis of the apparatus The eccentricity measuring apparatus according to claim 1, wherein an inclination of reflected light from the second reflecting member that has passed through the imaging optical system is detected. A first portion having a pattern in which the position of the shielding portion and the position of the passage portion are reversed by rotating 180 degrees around the optical axis. A mask and a second mask;
The first mask is disposed at a position where light enters the subject after passing through the first mask,
The second mask is disposed at a position where light enters the second mask after passing through the subject,
The eccentric measurement apparatus according to any one of claims 1 to 8, wherein the first and second masks are arranged so that the patterns are inverted by 180 degrees from each other.

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