JP5298619B2 - Eccentricity measuring method and eccentricity measuring device - Google Patents

Eccentricity measuring method and eccentricity measuring device Download PDF

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JP5298619B2
JP5298619B2 JP2008118042A JP2008118042A JP5298619B2 JP 5298619 B2 JP5298619 B2 JP 5298619B2 JP 2008118042 A JP2008118042 A JP 2008118042A JP 2008118042 A JP2008118042 A JP 2008118042A JP 5298619 B2 JP5298619 B2 JP 5298619B2
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義憲 井手
俊一郎 吉田
昭俊 野崎
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Konica Minolta Inc
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<P>PROBLEM TO BE SOLVED: To easily and accurately measure an eccentricity. <P>SOLUTION: The eccentricity measuring device 1 for measuring an eccentricity of an optical element K includes white interferometers 3 and 4 for measuring intensity distributions of interference fringes for only partial areas R1 and R2 of optical surfaces K1 and K2 of the optical element K; a holding member 2 which is interposed between the white interferometers 3 and 4 to hold the optical element K in a plurality of points over the circumferential direction of the optical element K while matching the outer shape center of the optical element K to the center of the holding member 2; a movement means 25 for substantially matching optical axes L1 and L2 of illuminating lights emitted to the optical surfaces K1 and K2 from the white interferometers 3 and 4 by moving the holding member 2 to the central axis of the holding member 2; and an arithmetic processing part 5 which calculates the optical center of each optical surface K1, K2 based on the intensity distributions of interference fringes measured by the white interferometers 3 and 4, and determines the eccentricity of the optical element K based on these optical central positions. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

本発明は、光学素子の偏心測定方法及び偏心測定装置に関する。   The present invention relates to an optical element eccentricity measuring method and an eccentricity measuring apparatus.

従来、撮像レンズ等の光学素子では、製造誤差などによって表裏の光学面で光学中心がずれる、つまり偏心することがあり、このような偏心の度合い（以下、偏心度とする）を測定する方法として、例えば以下２つの方法が提案されている。   Conventionally, in an optical element such as an imaging lens, the optical center may be shifted on the front and back optical surfaces due to manufacturing errors, that is, decentered. As a method of measuring the degree of decentering (hereinafter referred to as decentration). For example, the following two methods have been proposed.

すなわち１つ目の方法では、接触式のプローブによって光学面形状を測定し、この測定結果から偏心度を算出するようになっている（例えば、特許文献１参照）。   That is, in the first method, the optical surface shape is measured by a contact-type probe, and the eccentricity is calculated from the measurement result (see, for example, Patent Document 1).

また、２つ目の方法では、参照面の反射光と測定面の反射光との位相ずれを干渉縞で測定し、この測定結果から偏心度及び光学面形状を算出するようになっている（例えば、特許文献２，３参照）。
特開平８−２３３６８７号公報 特開平８−２３３６８８号公報 特開２００３−２６９９０８号公報 In the second method, the phase shift between the reflected light on the reference surface and the reflected light on the measurement surface is measured with interference fringes, and the eccentricity and the optical surface shape are calculated from the measurement results ( For example, see Patent Documents 2 and 3).
JP-A-8-233687 JP-A-8-233688 JP 2003-269908 A

しかしながら、上記１つ目の方法では、光学面にプローブを直接接触させて光学面形状を測定するため、高精度の測定を行うには接触圧を厳密に管理する必要があり、制御が困難である。また、光学面がプローブによって傷ついてしまう場合がある。   However, in the first method, since the shape of the optical surface is measured by bringing the probe directly into contact with the optical surface, it is necessary to strictly control the contact pressure in order to perform high-precision measurement, and control is difficult. is there. In addition, the optical surface may be damaged by the probe.

また、上記２つ目の方法では、光学面全体の干渉縞の測定結果に基づいて偏心度を算出するため、計算量が多く、操作ステップが煩雑である。   In the second method, since the eccentricity is calculated based on the measurement result of the interference fringes on the entire optical surface, the calculation amount is large and the operation steps are complicated.

本発明の課題は、簡易かつ高精度に偏心度を測定することのできる偏心測定方法及び偏心測定装置を提供することである。   An object of the present invention is to provide an eccentricity measuring method and an eccentricity measuring apparatus capable of measuring an eccentricity easily and with high accuracy.

本発明の第１の側面によれば、光学素子の偏心度を測定する偏心測定方法において、
前記光学素子の周方向に亘って複数点で当該光学素子を保持する保持部材を介在させて第１の白色干渉計及び第２の白色干渉計を互いに対向した状態とし、前記第１の白色干渉計から前記光学素子の一方の光学面に照射される照射光の光軸と、前記第２の白色干渉計から前記光学素子の他方の光学面に照射される照射光の光軸と、前記保持部材の中心軸とをほぼ一致させる第１工程と、
前記保持部材に前記光学素子を保持させることにより、当該保持部材の中心と、前記光学素子の外形中心とを一致させる第２工程と、
前記第１の白色干渉計の光源から前記光学素子に白色光を照射して前記一方の光学面のうち、一部の領域のみの干渉縞の強度分布を測定することにより、当該一方の光学面の光学中心位置を算出するとともに、前記第２の白色干渉計の光源から前記光学素子に白色光を照射して前記他方の光学面のうち、一部の領域のみの干渉縞の強度分布を測定することにより、当該他方の光学面の光学中心位置を算出する第３工程と、
各光学面の光学中心位置に基づいて前記光学素子の偏心度を求める第４工程と、を備え、
前記保持部材として、
前記光学素子の外周部全体を下方から支持する被載置部と、前記光学素子の周方向に亘って複数点で前記光学素子に外周側から当接する位置合わせ部とを有する保持部材であって、前記位置合わせ部は、前記光学素子の外形に沿って環状に形成されるとともに、厚み方向に沿って一方の側から他方の側に向かって内周縁部が狭まるように傾斜しており、かつ、当該位置合わせ部の内周面の直径が、厚み方向の一端部では前記光学素子の直径より大きく、他端部では前記光学素子の直径より小さくなっているものを用いることを特徴とする。 According to the first aspect of the present invention, in the eccentricity measuring method for measuring the eccentricity of the optical element,
The first white interferometer and the second white interferometer are opposed to each other by interposing holding members that hold the optical element at a plurality of points along the circumferential direction of the optical element. The optical axis of the irradiation light irradiated on one optical surface of the optical element from the meter, the optical axis of the irradiation light irradiated on the other optical surface of the optical element from the second white interferometer, and the holding A first step of substantially matching the central axis of the member;
A second step of causing the holding member to hold the optical element to match the center of the holding member with the outer shape center of the optical element;
By irradiating the optical element with white light from the light source of the first white interferometer and measuring the intensity distribution of interference fringes in only a part of the one optical surface, the one optical surface And calculating the intensity distribution of interference fringes in only a part of the other optical surface by irradiating the optical element with white light from the light source of the second white interferometer. A third step of calculating the optical center position of the other optical surface,
A fourth step of determining the degree of eccentricity of the optical element based on the optical center position of each optical surface ,
As the holding member,
A holding member having a placement portion that supports the entire outer peripheral portion of the optical element from below, and a positioning portion that contacts the optical element from the outer peripheral side at a plurality of points in the circumferential direction of the optical element. The alignment portion is formed in an annular shape along the outer shape of the optical element, and is inclined so that the inner peripheral edge narrows from one side to the other side along the thickness direction, and The diameter of the inner peripheral surface of the alignment portion is such that one end in the thickness direction is larger than the diameter of the optical element and the other end is smaller than the diameter of the optical element .

この偏心測定方法においては、
前記第３工程では、
前記第１の白色干渉計の光源から前記光学素子における前記一方の光学面のうち、前記一部の領域のみに白色光を照射して干渉縞の強度分布を測定するとともに、
前記第２の白色干渉計の光源から前記光学素子における前記他方の光学面のうち、前記一部の領域のみに白色光を照射して干渉縞の強度分布を測定することが好ましい。 In this eccentricity measurement method,
In the third step,
While measuring the intensity distribution of interference fringes by irradiating only a part of the one optical surface of the optical element from the light source of the first white interferometer with white light,
It is preferable that the intensity distribution of the interference fringes is measured by irradiating only the partial area of the other optical surface of the optical element from the light source of the second white interferometer with white light.

また、この偏心測定方法においては、
前記一方の光学面における前記一部の領域として、当該一方の光学面の有効径内の面積に対し、５〜１０％の面積を有する領域を用い、
前記他方の光学面における前記一部の領域として、当該他方の光学面の有効径内の面積に対し、５〜１０％の面積を有する領域を用いることが好ましい。 In this eccentricity measuring method,
As the partial region on the one optical surface, a region having an area of 5 to 10% with respect to the area within the effective diameter of the one optical surface is used.
As the partial region on the other optical surface, a region having an area of 5 to 10% with respect to the area within the effective diameter of the other optical surface is preferably used.

また、この偏心測定方法においては、
前記第３工程では、
前記第１の白色干渉計の光源から前記光学素子に白色光を照射して前記一方の光学面のうち、一部の領域のみの干渉縞画像を取得し、干渉縞画像を二値化して干渉縞のエッジを検出した後、当該エッジの曲率に対応する規定円を干渉縞画像に重ね合わせることにより、干渉縞の中心位置に規定円の中心を配置して、当該一方の光学面の光学中心位置を算出するとともに、前記第２の白色干渉計の光源から前記光学素子に白色光を照射して前記他方の光学面のうち、一部の領域のみの干渉縞画像を取得し、干渉縞画像を二値化して干渉縞のエッジを検出した後、当該エッジの曲率に対応する規定円を干渉縞画像に重ね合わせることにより、干渉縞の中心位置に規定円の中心を配置して、当該他方の光学面の光学中心位置を算出することが好ましい。 In this eccentricity measuring method,
In the third step,
The optical element is irradiated with white light from the light source of the first white interferometer to obtain an interference fringe image of only a part of the one optical surface, and the interference fringe image is binarized to cause interference. After detecting the fringe edge, the center of the prescribed circle is placed at the center position of the interference fringe by overlaying the prescribed circle corresponding to the curvature of the edge on the interference fringe image, and the optical center of the one optical surface While calculating the position, the optical element is irradiated with white light from the light source of the second white interferometer to obtain an interference fringe image of only a part of the other optical surface, and the interference fringe image After detecting the edge of the interference fringe by binarizing, the center of the prescribed circle is placed at the center position of the interference fringe by superimposing the prescribed circle corresponding to the curvature of the edge on the interference fringe image, and the other preferably it is possible to calculate the optical center position of the optical surface of the .

本発明の第２の側面によれば、光学素子の偏心度を測定する偏心測定装置において、
前記光学素子の一方の光学面のうち、一部の領域のみについて干渉縞の強度分布を測定する第１の白色干渉計と、
前記光学素子の他方の光学面のうち、一部の領域のみについて干渉縞の強度分布を測定する第２の白色干渉計と、
前記第１の白色干渉計及び前記第２の白色干渉計の間に介在し、前記光学素子の周方向に亘って複数点で当該光学素子を保持するとともに、中心に前記光学素子の外形中心を一致させる保持部材と、
前記第１の白色干渉計、前記第２の白色干渉計及び前記保持部材のうち、少なくとも１つを移動させることによって、前記第１の白色干渉計から前記一方の光学面に照射される照射光の光軸と、前記第２の白色干渉計から前記他方の光学面に照射される照射光の光軸と、前記保持部材の中心軸と、をほぼ一致させる移動手段と、
前記第１の白色干渉計及び前記第２の白色干渉計により測定された干渉縞の強度分布に基づいて各光学面の光学中心を算出し、これらの光学中心位置に基づいて前記光学素子の偏心度を求める演算処理部とを備え、
前記保持部材は、
前記光学素子の外周部全体を下方から支持する被載置部と、前記光学素子の周方向に亘って複数点で前記光学素子に外周側から当接する位置合わせ部とを有し、前記位置合わせ部は、前記光学素子の外形に沿って環状に形成されるとともに、厚み方向に沿って一方の側から他方の側に向かって内周縁部が狭まるように傾斜しており、かつ、当該位置合わせ部の内周面の直径が、厚み方向の一端部では前記光学素子の直径より大きく、他端部では前記光学素子の直径より小さくなっていることを特徴とする。 According to the second aspect of the present invention, in the eccentricity measuring apparatus for measuring the eccentricity of the optical element,
A first white interferometer that measures the intensity distribution of interference fringes for only a part of one of the optical surfaces of the optical element;
A second white light interferometer that measures the intensity distribution of interference fringes only for a part of the other optical surface of the optical element;
Said first interposed between the white light interferometer and the second white light interferometer holds the optical element at a plurality of points over the circumferential direction the optical element, outline center of the optical element, centered Holding members to match,
Irradiation light irradiated on the one optical surface from the first white interferometer by moving at least one of the first white interferometer, the second white interferometer, and the holding member. Moving means for substantially matching the optical axis of the second white interferometer with the optical axis of the irradiation light applied to the other optical surface, and the central axis of the holding member;
The optical center of each optical surface is calculated based on the intensity distribution of interference fringes measured by the first white interferometer and the second white interferometer, and the eccentricity of the optical element is calculated based on these optical center positions. An arithmetic processing unit for obtaining the degree ,
The holding member is
A mounting portion that supports the entire outer peripheral portion of the optical element from below; and an alignment portion that contacts the optical element from the outer peripheral side at a plurality of points along the circumferential direction of the optical element. The portion is formed in an annular shape along the outer shape of the optical element, is inclined so that the inner peripheral edge narrows from one side to the other side along the thickness direction, and the alignment is performed. The diameter of the inner peripheral surface of the part is larger than the diameter of the optical element at one end in the thickness direction, and smaller than the diameter of the optical element at the other end .

この偏心測定装置においては、
前記第１の白色干渉計は、光源から前記光学素子における前記一方の光学面のうち、前記一部の領域のみに白色光を照射して干渉縞の強度分布を測定し、
前記第２の白色干渉計は、光源から前記光学素子における前記他方の光学面のうち、前記一部の領域のみに白色光を照射して干渉縞の強度分布を測定することが好ましい。 In this eccentricity measuring device,
The first white interferometer measures the intensity distribution of interference fringes by irradiating only a part of the one optical surface of the optical element from a light source with white light.
The second white interferometer preferably measures the intensity distribution of interference fringes by irradiating only a part of the other optical surface of the optical element from the light source with white light.

また、この偏心測定装置においては、
前記一方の光学面における前記一部の領域は、当該一方の光学面の有効径内の面積に対し、５〜１０％の面積を有する領域であり、
前記他方の光学面における前記一部の領域は、当該他方の光学面の有効径内の面積に対し、５〜１０％の面積を有する領域であることが好ましい。 In this eccentricity measuring device,
The partial region in the one optical surface is a region having an area of 5 to 10% with respect to the area within the effective diameter of the one optical surface,
The partial region on the other optical surface is preferably a region having an area of 5 to 10% with respect to the area within the effective diameter of the other optical surface.

また、この偏心測定装置においては、
前記演算処理部は、
前記第１の白色干渉計の光源から前記光学素子に白色光を照射して得られる前記一方の光学面の一部の領域のみの干渉縞画像を二値化して干渉縞のエッジを検出した後、当該エッジの曲率に対応する規定円を干渉縞画像に重ね合わせることにより、干渉縞の中心位置に規定円の中心を配置して、当該一方の光学面の光学中心位置を算出するとともに、前記第２の白色干渉計の光源から前記光学素子に白色光を照射して得られる前記他方の光学面の一部の領域のみの干渉縞画像を二値化して干渉縞のエッジを検出した後、当該エッジの曲率に対応する規定円を干渉縞画像に重ね合わせることにより、干渉縞の中心位置に規定円の中心を配置して、当該他方の光学面の光学中心位置を算出することが好ましい。
In this eccentricity measuring device,
The arithmetic processing unit includes:
After detecting an interference fringe edge by binarizing an interference fringe image of only a partial region of the one optical surface obtained by irradiating the optical element with white light from the light source of the first white interferometer The center of the prescribed circle is arranged at the center position of the interference fringe by superimposing the prescribed circle corresponding to the curvature of the edge on the interference fringe image, and the optical center position of the one optical surface is calculated, and After binarizing the interference fringe image of only a partial region of the other optical surface obtained by irradiating the optical element with white light from the light source of the second white interferometer, and detecting the edge of the interference fringe, It is preferable to calculate the optical center position of the other optical surface by placing the center of the defined circle at the center position of the interference fringe by superimposing the defined circle corresponding to the curvature of the edge on the interference fringe image .

本発明によれば、光学素子の周方向に亘って複数点で当該光学素子を保持する保持部材を介在させて第１の白色干渉計及び第２の白色干渉計を互いに対向した状態とし、第１の白色干渉計から光学素子の一方の光学面に照射される照射光の光軸と、第２の白色干渉計から光学素子の他方の光学面に照射される照射光の光軸と、保持部材の中心軸とをほぼ一致させ、保持部材に光学素子を保持させることで当該保持部材の中心と、光学素子の外形中心とを一致させるので、第１，第２の白色干渉計からの照射光の光軸に対し、光学素子の外形中心がほぼ一致することとなる。従って、第１の白色干渉計の光源から白色光を照射して光学素子の一方の光学面のうち、一部の領域のみの干渉縞の強度分布を測定することによって当該一方の光学面の光学中心位置を算出する場合であっても、この一部の領域には一方の光学面の光学中心が含まれているため、正確な光学中心位置を算出することができる。同様に、第２の白色干渉計の光源から白色光を照射して光学素子の他方の光学面のうち、一部の領域のみの干渉縞の強度分布を測定することによって当該他方の光学面の光学中心位置を算出する場合であっても、この一部の領域には他方の光学面の光学中心が含まれているため、正確な光学中心位置を算出することができる。よって、このように各光学面について正確な光学中心位置を算出することができるため、正確な偏心度を測定することができる。
以上より、光学面の一部のみでの干渉縞の強度分布から正確な光学中心位置を算出できるので、光学面全体の干渉縞の強度分布から光学中心位置を算出する場合と比較して、簡易に光学中心位置、ひいては偏心度を測定することができる。
また、偏心度を測定するのに白色干渉計を用いており、白色干渉計で照射される白色光は可干渉距離が短いという性質を有するので、他の干渉計を用いる場合と比較して、高精度に偏心度を測定することができる。 According to the present invention, the first white interferometer and the second white interferometer are opposed to each other with the holding member holding the optical element at a plurality of points in the circumferential direction of the optical element. The optical axis of the irradiation light irradiated on one optical surface of the optical element from one white interferometer, and the optical axis of the irradiation light irradiated on the other optical surface of the optical element from the second white interferometer Since the center axis of the member is substantially coincident and the center of the holding member is made coincident with the center of the optical element by holding the optical element on the holding member, irradiation from the first and second white interferometers is performed. The outer center of the optical element substantially coincides with the optical axis of the light. Therefore, by irradiating white light from the light source of the first white interferometer and measuring the intensity distribution of interference fringes only on a part of one optical surface of the optical element, the optical of the one optical surface is measured. Even in the case of calculating the center position, the optical center position of one optical surface is included in this partial region, so that an accurate optical center position can be calculated. Similarly, by irradiating white light from the light source of the second white interferometer and measuring the intensity distribution of interference fringes on only a part of the other optical surface of the optical element, Even in the case of calculating the optical center position, the optical center position of the other optical surface is included in this partial region, so that an accurate optical center position can be calculated. Therefore, since an accurate optical center position can be calculated for each optical surface in this way, an accurate eccentricity can be measured.
From the above, it is possible to calculate the exact optical center position from the interference fringe intensity distribution on only a part of the optical surface, which is easier than calculating the optical center position from the interference fringe intensity distribution on the entire optical surface. In addition, the optical center position and thus the eccentricity can be measured.
In addition, a white interferometer is used to measure the degree of eccentricity, and the white light emitted by the white interferometer has the property that the coherence distance is short, so compared to the case of using another interferometer, Eccentricity can be measured with high accuracy.

以下、図面を参照しながら本発明の好ましい実施形態について説明する。
図１は、本発明に係る偏心測定装置１の概略構成を示す図である。 Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a schematic configuration of an eccentricity measuring apparatus 1 according to the present invention.

この図に示すように、偏心測定装置１は、測定対象の光学素子Ｋを保持する保持部材２と、この保持部材２を介在させて対向する２つの白色干渉計３，４と、各白色干渉計３，４に接続された演算処理部５とを備えている。   As shown in this figure, an eccentricity measuring apparatus 1 includes a holding member 2 that holds an optical element K to be measured, two white interferometers 3 and 4 that face each other with the holding member 2 interposed therebetween, and each white light interference. And an arithmetic processing unit 5 connected to a total of 3 and 4.

ここで、本実施の形態においては、測定対象の光学素子Ｋは円盤状に形成されているが、他の形状であっても構わない。このような光学素子Ｋとしては、数μｍ程度の偏心精度が求められる撮像レンズなどを用いることが好ましい。また、光学素子Ｋの外形中心に対し、各光学面Ｋ１，Ｋ２の光学中心が概ね一致する光学素子を用いるのが好ましい。   Here, in the present embodiment, the optical element K to be measured is formed in a disc shape, but may have another shape. As such an optical element K, it is preferable to use an imaging lens or the like that requires an eccentricity accuracy of about several μm. Further, it is preferable to use an optical element in which the optical centers of the optical surfaces K1 and K2 substantially coincide with the outer center of the optical element K.

保持部材２は、光学素子Ｋの周方向に亘って複数点で当該光学素子Ｋを下方から支持して保持するようになっており、本実施の形態においては、光学素子Ｋの外周部に対し全周に亘って当接している。より詳細には、図２（ａ）に示すように、保持部材２は、光学素子Ｋの円盤形状に対応して同心円の環状に形成された被載置部２０及び位置合わせ部２１を有している。   The holding member 2 is configured to support and hold the optical element K from below at a plurality of points along the circumferential direction of the optical element K. In the present embodiment, the holding member 2 is supported with respect to the outer peripheral portion of the optical element K. It abuts over the entire circumference. More specifically, as shown in FIG. 2A, the holding member 2 includes a placement portion 20 and an alignment portion 21 that are formed in a concentric annular shape corresponding to the disk shape of the optical element K. ing.

このうち、被載置部２０は、光学素子Ｋの外周部全体を下方から支持するようになっている。
また、位置合わせ部２１は、周方向に亘って複数点で光学素子Ｋに外周側から当接するようになっており、これによって保持部材２の中心と、光学素子Ｋの外形中心とを一致させて光学素子Ｋを固定するようになっている。より詳細には、位置合わせ部２１は、光学素子Ｋの外形に沿って環状に形成されるとともに、厚み方向（図中の上下方向）に沿って一方の側（図中の上側）から他方の側（図中の下側）に向かって内周縁部が狭まるように傾斜している。そして、この位置合わせ部２１の内周面の直径は、厚み方向の一端部（広く開口した側の部分）では光学素子Ｋの直径より大きく、他端部（狭く開口した側の部分）では光学素子Ｋの直径より小さくなっている。 Among these, the placement part 20 supports the entire outer peripheral part of the optical element K from below.
Further, the alignment portion 21 comes into contact with the optical element K from the outer peripheral side at a plurality of points in the circumferential direction, whereby the center of the holding member 2 and the outer center of the optical element K are made to coincide. Thus, the optical element K is fixed. More specifically, the alignment portion 21 is formed in an annular shape along the outer shape of the optical element K, and from the one side (the upper side in the drawing) to the other side along the thickness direction (the vertical direction in the drawing). It inclines so that an inner peripheral part may narrow toward the side (lower side in a figure). The diameter of the inner peripheral surface of the alignment portion 21 is larger than the diameter of the optical element K at one end in the thickness direction (a portion on the wide opening side) and optical at the other end (the portion on the narrow opening side). It is smaller than the diameter of the element K.

以上の保持部材２には、図１に示すように、当該保持部材２を中心軸の直交方向に移動させる移動手段２５が接続されている。なお、このような移動手段２５としては、従来より公知の装置を用いることができる。   As shown in FIG. 1, moving means 25 for moving the holding member 2 in the direction perpendicular to the central axis is connected to the holding member 2 described above. As such moving means 25, a conventionally known device can be used.

白色干渉計３，４は、光学素子Ｋにおける一方の光学面Ｋ１，他方の光学面Ｋ２について、干渉縞の強度分布を測定するものであり、本実施の形態においては、光学素子Ｋを介在させて対称に配設されている。これら白色干渉計３，４は、図３に示すように、それぞれ白色光源１０と、コリメータレンズ１１と、ビームスプリッタ１２と、対物レンズ１５と、参照面１３とを、この順に備えるとともに、ビームスプリッタ１２に対して光学素子Ｋの側に対物レンズ１６を、光学素子Ｋと反対の側に集光レンズ１７及び撮像素子１４を備えている。   The white interferometers 3 and 4 measure the intensity distribution of interference fringes on one optical surface K1 and the other optical surface K2 of the optical element K. In the present embodiment, the optical element K is interposed. Are arranged symmetrically. As shown in FIG. 3, each of the white interferometers 3 and 4 includes a white light source 10, a collimator lens 11, a beam splitter 12, an objective lens 15, and a reference surface 13 in this order. 12, the objective lens 16 is provided on the optical element K side, and the condenser lens 17 and the image sensor 14 are provided on the side opposite to the optical element K.

このうち、白色光源１０は、コリメータレンズ１１に向かって白色光を照射するものである。なお、このような白色光源１０としては、従来より公知の白色干渉計における光源を用いることができる。
コリメータレンズ１１は、白色光源１０から照射された白色光を平行光化するものである。 Among these, the white light source 10 emits white light toward the collimator lens 11. In addition, as such a white light source 10, the light source in a conventionally well-known white interferometer can be used.
The collimator lens 11 converts the white light emitted from the white light source 10 into parallel light.

ビームスプリッタ１２は、コリメータレンズ１１を透過した光束を２方向へ分割するものであり、分割した一方の光束をそのまま透過させて対物レンズ１５及び参照面１３の側（図中、右側）へ案内するとともに、他方の光束を対物レンズ１６及び光学素子Ｋの側（図中、下側）へ案内するようになっている。また、このビームスプリッタ１２は、参照面１３及び光学素子Ｋからの反射光を重畳させて撮像素子１４の側（図中、上側）へ案内するようになっている。   The beam splitter 12 divides the light beam transmitted through the collimator lens 11 in two directions, and transmits the divided one light beam as it is and guides it to the objective lens 15 and the reference surface 13 side (right side in the drawing). At the same time, the other light beam is guided to the objective lens 16 and the optical element K side (lower side in the figure). Further, the beam splitter 12 superimposes the reflected light from the reference surface 13 and the optical element K and guides it to the image sensor 14 side (upper side in the figure).

対物レンズ１５は、ビームスプリッタ１２からの平行光を参照面１３に対して集光するようになっている。
対物レンズ１６は、ビームスプリッタ１２からの平行光を光学素子Ｋに対して集光するようになっており、より詳細には、光学素子Ｋにおける光学面Ｋ１，Ｋ２のうち、一部の領域Ｒ１，Ｒ２のみに白色光を集光して照射するようになっている。なお、本実施の形態においては、対物レンズ１５，１６の倍率は１００倍となっているが、他の倍率としても良い。 The objective lens 15 condenses the parallel light from the beam splitter 12 with respect to the reference surface 13.
The objective lens 16 condenses the parallel light from the beam splitter 12 on the optical element K, and more specifically, a partial region R1 of the optical surfaces K1 and K2 of the optical element K. , R2 is focused and irradiated with white light. In the present embodiment, the magnification of the objective lenses 15 and 16 is 100 times, but other magnifications may be used.

参照面１３は、高精度に研磨されて平面となっている。このような参照面１３としては、従来より公知のものを用いることができる。
集光レンズ１７は、参照面１３及び光学素子Ｋから反射されて重畳された光を撮像素子１４の表面に集光するようになっている。 The reference surface 13 is polished with high accuracy to be a flat surface. As such a reference surface 13, a conventionally known surface can be used.
The condensing lens 17 condenses the light reflected and superimposed from the reference surface 13 and the optical element K on the surface of the imaging element 14.

撮像素子１４は、参照面１３及び光学素子Ｋから反射されて重畳された光を撮像するものであり、当該重畳光で発生する干渉縞を撮像してその強度分布を測定するようになっている。ここで、この干渉縞は光学面Ｋ１（またはＫ２）の凹凸によって等高線状に生じるものである。なお、本実施の形態においては、撮像素子１４としてＣＣＤが用いられており、このＣＣＤのサイズは１／３インチ（＝４．８ｍｍ×３．６ｍｍ）、画素数はＶＧＡ（６４０pixel×４８０pixel）となっている。   The image pickup device 14 picks up the light reflected and superimposed from the reference surface 13 and the optical element K, and picks up an interference fringe generated by the superposed light and measures its intensity distribution. . Here, the interference fringes are generated in contour lines by the unevenness of the optical surface K1 (or K2). In the present embodiment, a CCD is used as the image sensor 14. The size of the CCD is 1/3 inch (= 4.8 mm × 3.6 mm), and the number of pixels is VGA (640 pixels × 480 pixels). It has become.

以上の白色干渉計３，４は、本実施の形態においては光学素子Ｋの光学面Ｋ１に照射される照射光のＬ１と、光学素子Ｋの光学面Ｋ２に照射される照射光の光軸Ｌ２とが一致するよう、予め配設され固定されている。   In the present embodiment, the white interferometers 3 and 4 described above have the light L1 irradiated to the optical surface K1 of the optical element K and the optical axis L2 of the light irradiated to the optical surface K2 of the optical element K. Are arranged and fixed in advance so as to match.

演算処理部５は、干渉縞の強度分布に基づいて光学面の光学中心を算出し、これらの光学中心位置に基づいて光学素子Ｋの偏心度を求めるものであり、各白色干渉計３，４の撮像素子１４に接続されている。なお、本発明において偏心度とは、光学面Ｋ１，Ｋ２の光学中心位置のずれ量をいい、より詳細には、光学面Ｋ１，Ｋ２の光学中心を光軸方向に沿って通過する２本の直線間の距離をいう。   The arithmetic processing unit 5 calculates the optical center of the optical surface based on the intensity distribution of the interference fringes, and obtains the eccentricity of the optical element K based on these optical center positions. Connected to the image sensor 14. In the present invention, the degree of eccentricity refers to the amount of deviation of the optical center positions of the optical surfaces K1 and K2, and more specifically, two optical paths passing through the optical centers of the optical surfaces K1 and K2 along the optical axis direction. The distance between straight lines.

続いて、偏心測定装置１を用いた偏心測定方法について説明する。
まず、保持部材２を介在させて白色干渉計３，４が互いに対向した状態から、移動手段２５によって保持部材２を移動させることにより、白色干渉計３の白色光源１０から光学素子Ｋの光学面Ｋ１に照射される照射光の光軸Ｌ１と、白色干渉計４の白色光源１０から光学素子Ｋの光学面Ｋ２に照射される照射光の光軸Ｌ２とに対し、保持部材２の中心軸をほぼ一致させる（第１工程）。 Subsequently, an eccentricity measuring method using the eccentricity measuring apparatus 1 will be described.
First, from the state in which the white interferometers 3 and 4 are opposed to each other with the holding member 2 interposed therebetween, the holding member 2 is moved by the moving means 25, whereby the optical surface of the optical element K from the white light source 10 of the white interferometer 3. The central axis of the holding member 2 is set with respect to the optical axis L1 of the irradiation light irradiated to K1 and the optical axis L2 of the irradiation light irradiated to the optical surface K2 of the optical element K from the white light source 10 of the white interferometer 4. Almost match (first step).

ここで、光軸Ｌ１，Ｌ２に対して保持部材２の中心軸を「ほぼ一致させる」とは、例えば、光学面Ｋ１，Ｋ２に対する撮像素子１４の撮像領域内に保持部材２の中心軸を配置することをいい、具体的には、撮像素子１４におけるＣＣＤのサイズ（４．８ｍｍ×３．６ｍｍ）を対物レンズ１５，１６の倍率（１００倍）で割った４８μｍ×３６μｍの撮像領域内に保持部材２の中心軸を配置することをいう。但し、「ほぼ一致させる」とは、例えば、光学面Ｋ１，Ｋ２の有効径内の面積を１００％とした場合に、光軸Ｌ１，Ｌ２を中心として５〜１０％の面積を有する領域内に、保持部材２の中心軸を配置することとしても良い。なお、保持部材２の中心軸は、後述の第２工程で光学素子Ｋの外形中心と一致することとなるものである。   Here, “to make the central axis of the holding member 2 substantially coincide with the optical axes L1 and L2” means, for example, that the central axis of the holding member 2 is disposed in the imaging region of the imaging device 14 with respect to the optical surfaces K1 and K2. Specifically, the CCD size (4.8 mm × 3.6 mm) in the image sensor 14 is held within an imaging area of 48 μm × 36 μm divided by the magnification (100 times) of the objective lenses 15 and 16. Arrangement of the central axis of the member 2. However, “substantially match” means, for example, in a region having an area of 5 to 10% around the optical axes L1 and L2 when the area within the effective diameter of the optical surfaces K1 and K2 is 100%. The central axis of the holding member 2 may be disposed. Note that the central axis of the holding member 2 coincides with the center of the outer shape of the optical element K in the second step described later.

次に、保持部材２に光学素子Ｋを載置して保持させる。このとき、保持部材２は周方向に亘って複数点で光学素子Ｋに外周側から当接することで、当該光学素子Ｋの外形中心を保持部材２の中心に一致させるので、保持部材２の中心と、光学素子Ｋの外形中心とが一致する結果、白色干渉計３，４からの照射光の光軸Ｌ１，Ｌ２に対し、光学素子Ｋの外形中心がほぼ一致することとなる（第２工程）。   Next, the optical element K is placed and held on the holding member 2. At this time, the holding member 2 abuts the optical element K from the outer peripheral side at a plurality of points in the circumferential direction so that the outer center of the optical element K coincides with the center of the holding member 2. And the outer center of the optical element K coincide with each other, so that the outer center of the optical element K substantially coincides with the optical axes L1 and L2 of the irradiation light from the white interferometers 3 and 4 (second step). ).

次に、白色干渉計３，４が白色光源１０から光学面Ｋ１，Ｋ２のうち、一部の領域Ｒ１，Ｒ２のみに白色光を照射させて干渉縞画像を撮影して、干渉縞の強度分布を測定する。ここで、光学面Ｋ１，Ｋ２の一部の領域Ｒ１，Ｒ２とは、当該光学面Ｋ１，Ｋ２の有効径内の面積に対し、５〜１０％の面積を有する領域である。   Next, the white interferometers 3 and 4 irradiate only a part of the regions R1 and R2 of the optical surfaces K1 and K2 with the white light from the white light source 10 to capture the interference fringe image, and the interference fringe intensity distribution Measure. Here, the partial regions R1 and R2 of the optical surfaces K1 and K2 are regions having an area of 5 to 10% with respect to the area within the effective diameter of the optical surfaces K1 and K2.

次に、演算処理部５が、干渉縞画像を二値化して干渉縞のエッヂを検出した後、このエッジの曲率に対応する規定円を干渉縞画像に重ね合わせる（フィッティングする）ことにより、干渉縞の中心位置に規定円の中心を配置して、干渉縞の中心位置、つまり光学面Ｋ１，Ｋ２の光学中心位置を算出する（第３工程）。   Next, the arithmetic processing unit 5 binarizes the interference fringe image and detects the edge of the interference fringe, and then superimposes (fittings) a prescribed circle corresponding to the curvature of the edge on the interference fringe image, thereby causing interference. The center of the prescribed circle is arranged at the center position of the fringe, and the center position of the interference fringe, that is, the optical center position of the optical surfaces K1 and K2 is calculated (third step).

そして、演算処理部５は、各光学面Ｋ１，Ｋ２の光学中心位置に基づいて光学素子Ｋの偏心度を求める（第４工程）。なお、このとき、演算処理部５は、算出された偏心度と、光学素子Ｋについて予め設定された偏心度の許容範囲とを比較し、算出された偏心度が許容範囲に収まるか否かの判定結果を操作者に報知することが好ましい。   And the arithmetic processing part 5 calculates | requires the eccentricity of the optical element K based on the optical center position of each optical surface K1, K2 (4th process). At this time, the arithmetic processing unit 5 compares the calculated eccentricity with an allowable range of eccentricity set in advance for the optical element K, and determines whether or not the calculated eccentricity falls within the allowable range. It is preferable to notify the operator of the determination result.

以上の偏心測定装置１によれば、白色干渉計３から光学素子Ｋの光学面Ｋ１に照射される照射光の光軸Ｌ１と、白色干渉計４から光学素子Ｋの光学面Ｋ２に照射される照射光の光軸Ｌ２と、保持部材２の中心軸とをほぼ一致させ、保持部材２に光学素子Ｋを保持させることで当該保持部材２の中心と、光学素子Ｋの外形中心とを一致させるので、白色干渉計３，４からの照射光の光軸Ｌ１，Ｌ２に対し、光学素子Ｋの外形中心がほぼ一致することとなる。従って、白色干渉計３の白色光源１０から白色光を照射して光学素子Ｋの光学面Ｋ１のうち、一部の領域Ｒ１のみの干渉縞の強度分布を測定することによって当該光学面Ｋ１の光学中心位置を算出する場合であっても、この一部の領域Ｒ１には光学面Ｋ１の光学中心が含まれているため、正確な光学中心位置を算出することができる。同様に、白色干渉計４の白色光源１０から白色光を照射して光学素子Ｋの光学面Ｋ２のうち、一部の領域Ｒ２のみの干渉縞の強度分布を測定することによって当該光学面Ｋ２の光学中心位置を算出する場合であっても、この一部の領域Ｒ２には光学面Ｋ２の光学中心が含まれているため、正確な光学中心位置を算出することができる。よって、このように各光学面Ｋ１，Ｋ２について正確な光学中心位置を算出することができるため、正確な偏心度を測定することができる。
以上より、光学面Ｋ１，Ｋ２の一部のみでの干渉縞の強度分布から正確な光学中心位置を算出できるので、光学面Ｋ１，Ｋ２全体の干渉縞の強度分布から光学中心位置を算出する場合と比較して、簡易に光学中心位置、ひいては偏心度を測定することができる。 According to the eccentricity measuring apparatus 1 described above, the optical axis L1 of the irradiation light irradiated from the white interferometer 3 to the optical surface K1 of the optical element K, and the optical surface K2 of the optical element K from the white interferometer 4 are irradiated. The optical axis L2 of the irradiation light and the central axis of the holding member 2 are made to substantially coincide with each other, and the optical element K is held by the holding member 2 so that the center of the holding member 2 coincides with the outer shape center of the optical element K. Therefore, the outer center of the optical element K substantially coincides with the optical axes L1 and L2 of the irradiation light from the white interferometers 3 and 4. Therefore, by irradiating white light from the white light source 10 of the white interferometer 3 and measuring the intensity distribution of the interference fringes of only a part of the region R1 in the optical surface K1 of the optical element K, the optical surface K1 is optical. Even in the case of calculating the center position, the optical center position of the optical surface K1 is included in the partial region R1, so that an accurate optical center position can be calculated. Similarly, by irradiating white light from the white light source 10 of the white interferometer 4 and measuring the intensity distribution of interference fringes only in a part of the region R2 of the optical surface K2 of the optical element K, the optical surface K2 of the optical surface K2 is measured. Even in the case of calculating the optical center position, the optical center position of the optical surface K2 is included in the partial region R2, and thus the accurate optical center position can be calculated. Therefore, since the accurate optical center position can be calculated for each of the optical surfaces K1 and K2 in this way, an accurate eccentricity can be measured.
As described above, since the accurate optical center position can be calculated from the intensity distribution of the interference fringes on only a part of the optical surfaces K1 and K2, the optical center position is calculated from the intensity distribution of the interference fringes on the entire optical surfaces K1 and K2. As compared with the above, it is possible to easily measure the optical center position and thus the degree of eccentricity.

また、偏心度を測定するのに白色干渉計を用いており、白色干渉計で照射される白色光は可干渉距離が短いという性質を有するので、他の干渉計を用いる場合と比較して、高精度に偏心度を測定することができる。   In addition, a white interferometer is used to measure the degree of eccentricity, and the white light emitted by the white interferometer has the property that the coherence distance is short, so compared to the case of using another interferometer, Eccentricity can be measured with high accuracy.

また、光学素子Ｋにおける光学面Ｋ１，Ｋ２のうち、一部の領域Ｒ１，Ｒ２のみに白色光を照射して干渉縞の強度分布を測定するので、光学面Ｋ１，Ｋ２の全体に白色光を照射する場合と比較して、照射光を有効に利用し、鮮明な撮影画像を得ることができる。従って、より正確に光学中心位置を算出し、正確な偏心度を測定することができる。   In addition, since the intensity distribution of the interference fringes is measured by irradiating only the partial areas R1 and R2 of the optical surfaces K1 and K2 of the optical element K with white light, the white light is applied to the entire optical surfaces K1 and K2. Compared with the case of irradiation, it is possible to effectively use the irradiation light and obtain a clear photographed image. Accordingly, it is possible to calculate the optical center position more accurately and to measure the accurate eccentricity.

また、光学面Ｋ１における一部の領域Ｒ１として、当該光学面Ｋ１の有効径内の面積に対し５〜１０％の面積を有する領域を用い、光学面Ｋ２における前記一部の領域Ｒ２として、当該光学面Ｋ２の有効径内の面積に対し５〜１０％の面積を有する領域を用いるので、これら一部の領域Ｒ１，Ｒ２に各光学面Ｋ１，Ｋ２の光学中心を確実に含ませることができる。   Further, as the partial region R1 in the optical surface K1, a region having an area of 5 to 10% with respect to the area within the effective diameter of the optical surface K1 is used, and as the partial region R2 in the optical surface K2, Since a region having an area of 5 to 10% with respect to the area within the effective diameter of the optical surface K2 is used, the optical centers of the optical surfaces K1 and K2 can be surely included in these partial regions R1 and R2. .

また、保持部材２として、周方向に亘って複数点で光学素子Ｋに外周側から当接することで当該保持部材２の中心に光学素子Ｋの外形中心を一致させるものを用いるので、保持部材２に光学素子Ｋを保持させることによって、保持部材２の中心と光学素子Ｋの外形中心とを一致させることができる。従って、偏心度の測定を容易化することができる。   Further, as the holding member 2, a member that makes the optical element K coincide with the center of the holding member 2 by contacting the optical element K from the outer peripheral side at a plurality of points in the circumferential direction is used. By holding the optical element K, the center of the holding member 2 can coincide with the outer center of the optical element K. Therefore, the measurement of the eccentricity can be facilitated.

また、演算処理部５は白色光を照射して得られる干渉縞画像を２値化した２値化画像から光学中心位置を算出するので、より簡易に偏心度を測定することができる。   Further, since the arithmetic processing unit 5 calculates the optical center position from the binarized image obtained by binarizing the interference fringe image obtained by irradiating the white light, the degree of eccentricity can be measured more easily.

なお、本発明は上記実施の形態に限定して解釈されるべきではなく、適宜変更・改良が可能であることはもちろんである。   It should be noted that the present invention should not be construed as being limited to the above-described embodiment, and of course can be modified or improved as appropriate.

例えば、上記実施の形態においては、光学素子Ｋの光学面Ｋ１に照射される照射光の光軸Ｌ１と、光学素子Ｋの光学面Ｋ２に照射される照射光の光軸Ｌ２とが一致するよう、白色干渉計３，４が予め配設され固定されており、保持部材２を移動させることでこれらの２つの光軸Ｌ１，Ｌ２に対し保持部材２の中心軸をほぼ一致させることとして説明したが、２つの光軸Ｌ１，Ｌ２と保持部材２の中心軸とをほぼ一致させることが可能な限りにおいて、白色干渉計３，４及び保持部材２の２つ以上が移動可能となっていても良い。   For example, in the above-described embodiment, the optical axis L1 of the irradiation light irradiated on the optical surface K1 of the optical element K and the optical axis L2 of the irradiation light irradiated on the optical surface K2 of the optical element K match. The white interferometers 3 and 4 are arranged and fixed in advance, and the center axis of the holding member 2 is substantially aligned with the two optical axes L1 and L2 by moving the holding member 2. However, as long as the two optical axes L1 and L2 and the central axis of the holding member 2 can be substantially matched, two or more of the white interferometers 3 and 4 and the holding member 2 can be moved. good.

また、白色干渉計３，４は、光学面Ｋ１，Ｋ２の一部の領域Ｒ１，Ｒ２のみに白色光を集光し照射することで干渉縞画像を撮像することとして説明したが、光学面Ｋ１，Ｋ２の全体に照射し、一部の領域Ｒ１，Ｒ２のみの干渉縞画像を撮影することとしても良い。   The white interferometers 3 and 4 have been described as capturing the interference fringe image by condensing and irradiating only the partial areas R1 and R2 of the optical surfaces K1 and K2, but the optical surface K1. , K2 and the interference fringe image of only some of the regions R1 and R2 may be taken.

また、演算処理部５は干渉縞の曲率に対応する規定円を干渉縞画像にフィッティングする、いわゆる簡易偏心計測法によって光学面Ｋ１，Ｋ２の中心位置を測定することとして説明したが、形状測定法（垂直走査計測法）によって測定することとしてもよい。ここで、形状測定法によって中心位置を測定するには、まず、光学素子Ｋの光学面Ｋ１，Ｋ２に照射される照射光の光軸方向に沿って白色干渉計３，４を移動可能に設けておく。次に、白色干渉計３，４を当該光軸方向に一定速度で走査し、各箇所について干渉縞の強度の変動からピークを探すことで、当該箇所の高さ（光軸方向への相対的高さ、厚み）を算出する。そして、算出された各箇所の高さから光学面Ｋ１，Ｋ２の形状、中心位置を求める。なお、図４に示すように、干渉縞の強度は、ビームスプリッタ１２から参照面１３までの光路と、ビームスプリッタ１２から光学面Ｋ１，Ｋ２内の測定箇所までの光路とが等しくなるときに、最も大きくなる。   In addition, the arithmetic processing unit 5 has been described as measuring the center positions of the optical surfaces K1 and K2 by a so-called simple eccentricity measurement method, in which a prescribed circle corresponding to the curvature of the interference fringes is fitted to the interference fringe image. It is good also as measuring by (vertical scanning measuring method). Here, in order to measure the center position by the shape measuring method, first, the white interferometers 3 and 4 are provided so as to be movable along the optical axis direction of the irradiation light irradiated on the optical surfaces K1 and K2 of the optical element K. Keep it. Next, the white interferometers 3 and 4 are scanned in the optical axis direction at a constant speed, and the peak of each part is searched for from the fluctuation of the intensity of the interference fringes, so that the height of the part (relative to the optical axis direction). (Height, thickness) is calculated. Then, the shapes and center positions of the optical surfaces K1 and K2 are obtained from the calculated heights of the respective portions. As shown in FIG. 4, the intensity of the interference fringes is such that the optical path from the beam splitter 12 to the reference surface 13 is equal to the optical path from the beam splitter 12 to the measurement location in the optical surfaces K1 and K2. Become the largest.

また、保持部材２は、光学素子Ｋの外周部全体を下方から支持する被載置部２０と、保持部材２の中心に光学素子Ｋの外形中心を一致させて当該光学素子Ｋを固定する位置合わせ部２１とを有することとして説明したが、保持部材２の中心に光学素子Ｋの外形中心を一致させつつ光学素子Ｋを保持することが可能な限りにおいて、例えば、光学素子Ｋの外形に沿って環状に形成され、当該光学素子Ｋと嵌合する部材のみを有することとしても良い。更に、図２（ｂ）に示すように、光学素子Ｋａの外周部にフランジ部Ｋ３が設けられている場合には、このフランジ部Ｋ３の下面に保持部材２ａを当接させつつ、光学素子Ｋａと保持部材２ａとを嵌合させることが好ましい。また、被載置部２０は光学素子Ｋを下方から支持することとして説明したが、真空吸着によって上方から支持することとしても良い。   In addition, the holding member 2 is a position where the optical element K is fixed by aligning the outer center of the optical element K with the placement portion 20 that supports the entire outer peripheral portion of the optical element K from below and the center of the holding member 2. However, as long as it is possible to hold the optical element K while aligning the center of the outer shape of the optical element K with the center of the holding member 2, for example, along the outer shape of the optical element K. It is good also as having only a member formed in the shape of a ring and fitting with the optical element K concerned. Further, as shown in FIG. 2B, when the flange portion K3 is provided on the outer peripheral portion of the optical element Ka, the optical element Ka is brought into contact with the lower surface of the flange portion K3 while the holding member 2a is brought into contact therewith. And the holding member 2a are preferably fitted. In addition, although the placement unit 20 has been described as supporting the optical element K from below, it may be supported from above by vacuum suction.

また、保持部材２は光学素子Ｋの外周部に対し全周に亘って当接することとして説明したが、光学素子Ｋの周方向に亘って複数点、例えば３点などで当接することとしても良い。   In addition, the holding member 2 has been described as being in contact with the outer peripheral portion of the optical element K over the entire circumference. However, the holding member 2 may be in contact with the optical element K at a plurality of points, for example, three points in the circumferential direction. .

本発明に係る偏心測定装置１の概略構成を示す概念図である。It is a conceptual diagram which shows schematic structure of the eccentricity measuring apparatus 1 which concerns on this invention. 光学素子の保持部材を示す断面図である。It is sectional drawing which shows the holding member of an optical element. 白色干渉計の構成を示す概念図である。It is a conceptual diagram which shows the structure of a white interferometer. 白色干渉計におけるビームスプリッタから参照面，光学面までの光路を説明するための図である。It is a figure for demonstrating the optical path from the beam splitter in a white interferometer to a reference surface and an optical surface.

符号の説明Explanation of symbols

１ 偏心測定装置
２ 保持部材
３ 白色干渉計（第１の白色干渉計）
４ 白色干渉計（第２の白色干渉計）
５ 演算処理部
２５ 移動手段
１０ 白色光源（光源）
Ｋ 光学素子
Ｋ１ 光学面（一方の光学面）
Ｋ２ 光学面（他方の光学面）
Ｒ１，Ｒ２ 一部の領域 DESCRIPTION OF SYMBOLS 1 Eccentricity measuring apparatus 2 Holding member 3 White interferometer (1st white interferometer)
4 White interferometer (second white interferometer)
5 Arithmetic processing unit 25 Moving means 10 White light source (light source)
K optical element K1 optical surface (one optical surface)
K2 optical surface (the other optical surface)
R1, R2 Partial region

Claims (8)

光学素子の偏心度を測定する偏心測定方法において、
前記光学素子の周方向に亘って複数点で当該光学素子を保持する保持部材を介在させて第１の白色干渉計及び第２の白色干渉計を互いに対向した状態とし、前記第１の白色干渉計から前記光学素子の一方の光学面に照射される照射光の光軸と、前記第２の白色干渉計から前記光学素子の他方の光学面に照射される照射光の光軸と、前記保持部材の中心軸とをほぼ一致させる第１工程と、
前記保持部材に前記光学素子を保持させることにより、当該保持部材の中心と、前記光学素子の外形中心とを一致させる第２工程と、
前記第１の白色干渉計の光源から前記光学素子に白色光を照射して前記一方の光学面のうち、一部の領域のみの干渉縞の強度分布を測定することにより、当該一方の光学面の光学中心位置を算出するとともに、前記第２の白色干渉計の光源から前記光学素子に白色光を照射して前記他方の光学面のうち、一部の領域のみの干渉縞の強度分布を測定することにより、当該他方の光学面の光学中心位置を算出する第３工程と、
各光学面の光学中心位置に基づいて前記光学素子の偏心度を求める第４工程と、を備え、
前記保持部材として、
前記光学素子の外周部全体を下方から支持する被載置部と、前記光学素子の周方向に亘って複数点で前記光学素子に外周側から当接する位置合わせ部とを有する保持部材であって、前記位置合わせ部は、前記光学素子の外形に沿って環状に形成されるとともに、厚み方向に沿って一方の側から他方の側に向かって内周縁部が狭まるように傾斜しており、かつ、当該位置合わせ部の内周面の直径が、厚み方向の一端部では前記光学素子の直径より大きく、他端部では前記光学素子の直径より小さくなっているものを用いることを特徴とする偏心測定方法。 In the eccentricity measuring method for measuring the eccentricity of the optical element,
The first white interferometer and the second white interferometer are opposed to each other by interposing holding members that hold the optical element at a plurality of points along the circumferential direction of the optical element. The optical axis of the irradiation light irradiated on one optical surface of the optical element from the meter, the optical axis of the irradiation light irradiated on the other optical surface of the optical element from the second white interferometer, and the holding A first step of substantially matching the central axis of the member;
A second step of causing the holding member to hold the optical element to match the center of the holding member with the outer shape center of the optical element;
By irradiating the optical element with white light from the light source of the first white interferometer and measuring the intensity distribution of interference fringes in only a part of the one optical surface, the one optical surface And calculating the intensity distribution of interference fringes in only a part of the other optical surface by irradiating the optical element with white light from the light source of the second white interferometer. A third step of calculating the optical center position of the other optical surface,
A fourth step of determining the degree of eccentricity of the optical element based on the optical center position of each optical surface ,
As the holding member,
A holding member having a placement portion that supports the entire outer peripheral portion of the optical element from below, and a positioning portion that contacts the optical element from the outer peripheral side at a plurality of points in the circumferential direction of the optical element. The alignment portion is formed in an annular shape along the outer shape of the optical element, and is inclined so that the inner peripheral edge narrows from one side to the other side along the thickness direction, and The eccentricity is characterized in that the diameter of the inner peripheral surface of the alignment portion is larger than the diameter of the optical element at one end in the thickness direction and smaller than the diameter of the optical element at the other end. Measuring method. 請求項１記載の偏心測定方法において、
前記第３工程では、
前記第１の白色干渉計の光源から前記光学素子における前記一方の光学面のうち、前記一部の領域のみに白色光を照射して干渉縞の強度分布を測定するとともに、
前記第２の白色干渉計の光源から前記光学素子における前記他方の光学面のうち、前記一部の領域のみに白色光を照射して干渉縞の強度分布を測定することを特徴とする偏心測定方法。 The eccentricity measuring method according to claim 1,
In the third step,
While measuring the intensity distribution of interference fringes by irradiating only a part of the one optical surface of the optical element from the light source of the first white interferometer with white light,
Eccentricity measurement characterized in that the intensity distribution of interference fringes is measured by irradiating only a part of the other optical surface of the optical element from the light source of the second white interferometer with white light. Method. 請求項１または２記載の偏心測定方法において、
前記一方の光学面における前記一部の領域として、当該一方の光学面の有効径内の面積に対し、５〜１０％の面積を有する領域を用い、
前記他方の光学面における前記一部の領域として、当該他方の光学面の有効径内の面積に対し、５〜１０％の面積を有する領域を用いることを特徴とする偏心測定方法。 The eccentricity measuring method according to claim 1 or 2,
As the partial region on the one optical surface, a region having an area of 5 to 10% with respect to the area within the effective diameter of the one optical surface is used.
An eccentricity measuring method using an area having an area of 5 to 10% with respect to an area within an effective diameter of the other optical surface as the partial area on the other optical surface. 請求項１〜３の何れか一項に記載の偏心測定方法において、
前記第３工程では、
前記第１の白色干渉計の光源から前記光学素子に白色光を照射して前記一方の光学面のうち、一部の領域のみの干渉縞画像を取得し、干渉縞画像を二値化して干渉縞のエッジを検出した後、当該エッジの曲率に対応する規定円を干渉縞画像に重ね合わせることにより、干渉縞の中心位置に規定円の中心を配置して、当該一方の光学面の光学中心位置を算出するとともに、前記第２の白色干渉計の光源から前記光学素子に白色光を照射して前記他方の光学面のうち、一部の領域のみの干渉縞画像を取得し、干渉縞画像を二値化して干渉縞のエッジを検出した後、当該エッジの曲率に対応する規定円を干渉縞画像に重ね合わせることにより、干渉縞の中心位置に規定円の中心を配置して、当該他方の光学面の光学中心位置を算出することを特徴とする偏心測定方法。 In the eccentricity measuring method according to any one of claims 1 to 3 ,
In the third step,
The optical element is irradiated with white light from the light source of the first white interferometer to obtain an interference fringe image of only a part of the one optical surface, and the interference fringe image is binarized to cause interference. After detecting the fringe edge, the center of the prescribed circle is placed at the center position of the interference fringe by overlaying the prescribed circle corresponding to the curvature of the edge on the interference fringe image, and the optical center of the one optical surface While calculating the position, the optical element is irradiated with white light from the light source of the second white interferometer to obtain an interference fringe image of only a part of the other optical surface, and the interference fringe image After detecting the edge of the interference fringe by binarizing, the center of the prescribed circle is placed at the center position of the interference fringe by superimposing the prescribed circle corresponding to the curvature of the edge on the interference fringe image, and the other and characterized by calculating the optical center position of the optical surface of the Eccentricity measuring how. 光学素子の偏心度を測定する偏心測定装置において、
前記光学素子の一方の光学面のうち、一部の領域のみについて干渉縞の強度分布を測定する第１の白色干渉計と、
前記光学素子の他方の光学面のうち、一部の領域のみについて干渉縞の強度分布を測定する第２の白色干渉計と、
前記第１の白色干渉計及び前記第２の白色干渉計の間に介在し、前記光学素子の周方向に亘って複数点で当該光学素子を保持するとともに、中心に前記光学素子の外形中心を一致させる保持部材と、
前記第１の白色干渉計、前記第２の白色干渉計及び前記保持部材のうち、少なくとも１つを移動させることによって、前記第１の白色干渉計から前記一方の光学面に照射される照射光の光軸と、前記第２の白色干渉計から前記他方の光学面に照射される照射光の光軸と、前記保持部材の中心軸と、をほぼ一致させる移動手段と、
前記第１の白色干渉計及び前記第２の白色干渉計により測定された干渉縞の強度分布に基づいて各光学面の光学中心を算出し、これらの光学中心位置に基づいて前記光学素子の偏心度を求める演算処理部とを備え、
前記保持部材は、
前記光学素子の外周部全体を下方から支持する被載置部と、前記光学素子の周方向に亘って複数点で前記光学素子に外周側から当接する位置合わせ部とを有し、前記位置合わせ部は、前記光学素子の外形に沿って環状に形成されるとともに、厚み方向に沿って一方の側から他方の側に向かって内周縁部が狭まるように傾斜しており、かつ、当該位置合わせ部の内周面の直径が、厚み方向の一端部では前記光学素子の直径より大きく、他端部では前記光学素子の直径より小さくなっていることを特徴とする偏心測定装置。 In an eccentricity measuring device that measures the eccentricity of an optical element,
A first white interferometer that measures the intensity distribution of interference fringes for only a part of one of the optical surfaces of the optical element;
A second white light interferometer that measures the intensity distribution of interference fringes only for a part of the other optical surface of the optical element;
Said first interposed between the white light interferometer and the second white light interferometer holds the optical element at a plurality of points over the circumferential direction the optical element, outline center of the optical element, centered Holding members to match,
Irradiation light irradiated on the one optical surface from the first white interferometer by moving at least one of the first white interferometer, the second white interferometer, and the holding member. Moving means for substantially matching the optical axis of the second white interferometer with the optical axis of the irradiation light applied to the other optical surface, and the central axis of the holding member;
The optical center of each optical surface is calculated based on the intensity distribution of interference fringes measured by the first white interferometer and the second white interferometer, and the eccentricity of the optical element is calculated based on these optical center positions. An arithmetic processing unit for obtaining the degree ,
The holding member is
A mounting portion that supports the entire outer peripheral portion of the optical element from below; and an alignment portion that contacts the optical element from the outer peripheral side at a plurality of points along the circumferential direction of the optical element. The portion is formed in an annular shape along the outer shape of the optical element, and is inclined so that the inner peripheral edge narrows from one side to the other side along the thickness direction, and the alignment is performed. The diameter of the inner peripheral surface of the part is larger than the diameter of the optical element at one end in the thickness direction, and smaller than the diameter of the optical element at the other end . 請求項５記載の偏心測定装置において、
前記第１の白色干渉計は、光源から前記光学素子における前記一方の光学面のうち、前記一部の領域のみに白色光を照射して干渉縞の強度分布を測定し、
前記第２の白色干渉計は、光源から前記光学素子における前記他方の光学面のうち、前記一部の領域のみに白色光を照射して干渉縞の強度分布を測定することを特徴とする偏心測定装置。 The eccentricity measuring device according to claim 5 ,
The first white interferometer measures the intensity distribution of interference fringes by irradiating only a part of the one optical surface of the optical element from a light source with white light.
The second white interferometer measures the intensity distribution of interference fringes by irradiating only a part of the other optical surface of the optical element from a light source with white light. measuring device. 請求項５または６記載の偏心測定装置において、
前記一方の光学面における前記一部の領域は、当該一方の光学面の有効径内の面積に対し、５〜１０％の面積を有する領域であり、
前記他方の光学面における前記一部の領域は、当該他方の光学面の有効径内の面積に対し、５〜１０％の面積を有する領域であることを特徴とする偏心測定装置。 The eccentricity measuring device according to claim 5 or 6 ,
The partial region in the one optical surface is a region having an area of 5 to 10% with respect to the area within the effective diameter of the one optical surface,
The eccentric measurement apparatus, wherein the partial region of the other optical surface is a region having an area of 5 to 10% with respect to an area within an effective diameter of the other optical surface. 請求項５〜７の何れか一項に記載の偏心測定装置において、
前記演算処理部は、
前記第１の白色干渉計の光源から前記光学素子に白色光を照射して得られる前記一方の光学面の一部の領域のみの干渉縞画像を二値化して干渉縞のエッジを検出した後、当該エッジの曲率に対応する規定円を干渉縞画像に重ね合わせることにより、干渉縞の中心位置に規定円の中心を配置して、当該一方の光学面の光学中心位置を算出するとともに、前記第２の白色干渉計の光源から前記光学素子に白色光を照射して得られる前記他方の光学面の一部の領域のみの干渉縞画像を二値化して干渉縞のエッジを検出した後、当該エッジの曲率に対応する規定円を干渉縞画像に重ね合わせることにより、干渉縞の中心位置に規定円の中心を配置して、当該他方の光学面の光学中心位置を算出することを特徴とする偏心測定装置。 In the eccentricity measuring apparatus according to any one of claims 5-7,
The arithmetic processing unit includes:
After detecting an interference fringe edge by binarizing an interference fringe image of only a partial region of the one optical surface obtained by irradiating the optical element with white light from the light source of the first white interferometer The center of the prescribed circle is arranged at the center position of the interference fringe by superimposing the prescribed circle corresponding to the curvature of the edge on the interference fringe image, and the optical center position of the one optical surface is calculated, and After binarizing the interference fringe image of only a partial region of the other optical surface obtained by irradiating the optical element with white light from the light source of the second white interferometer, and detecting the edge of the interference fringe, The center of the prescribed circle is arranged at the center position of the interference fringe by superimposing the prescribed circle corresponding to the curvature of the edge on the interference fringe image, and the optical center position of the other optical surface is calculated. Eccentricity measuring device.
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