JPH11325848A - Aspherical surface shape measurement device - Google Patents
Aspherical surface shape measurement deviceInfo
- Publication number
- JPH11325848A JPH11325848A JP10153807A JP15380798A JPH11325848A JP H11325848 A JPH11325848 A JP H11325848A JP 10153807 A JP10153807 A JP 10153807A JP 15380798 A JP15380798 A JP 15380798A JP H11325848 A JPH11325848 A JP H11325848A
- Authority
- JP
- Japan
- Prior art keywords
- light
- optical element
- shape measuring
- measurement
- diffractive optical
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Landscapes
- Instruments For Measurement Of Length By Optical Means (AREA)
- Length Measuring Devices By Optical Means (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、レンズ、ミラー等
の光学素子の面形状を測定する面形状測定装置に関し、
特にこれらの面形状が非球面である場合の測定に適した
非球面形状測定装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface shape measuring device for measuring the surface shape of an optical element such as a lens or a mirror.
In particular, the present invention relates to an aspherical surface shape measuring apparatus suitable for measurement when the surface shape is an aspherical surface.
【０００２】[0002]
【従来の技術】近年、高精度の光学機器の需要に伴い、
その機器を構成するレンズやミラー等の光学素子は高精
度化する傾向にある。そのため、その光学素子の非球面
形状を測定する非球面形状測定装置にも、同じように、
高い精度が求められるようになっている。このような高
精度の非球面形状測定装置としては、フィゾー型干渉計
と呼ばれるものがある。フィゾー型干渉計は、参照面を
有するフィゾー部材と、フィゾー部材を透過する光を被
検面の理想形状（設計形状）に対応した波面に変換する
ヌル素子（波面形成手段）とを構成部材としてもつ。ま
た、ヌル素子としては、ゾーンプレート等の回折光学素
子を用いたものがある。2. Description of the Related Art In recent years, with the demand for high-precision optical instruments,
Optical elements such as lenses and mirrors that constitute such equipment tend to be highly accurate. Therefore, the same applies to an aspherical shape measuring device that measures the aspherical shape of the optical element,
High precision is required. As such a highly accurate aspherical shape measuring apparatus, there is a so-called Fizeau interferometer. The Fizeau-type interferometer includes a Fizeau member having a reference surface, and a null element (wavefront forming means) for converting light transmitted through the Fizeau member into a wavefront corresponding to an ideal shape (design shape) of a surface to be measured. Have. As the null element, there is an element using a diffractive optical element such as a zone plate.
【０００３】図９にて、非球面形状測定装置のヌル素子
の従来例を示す。ヌル素子６は、ゾーンプレート等の回
折面７ａ（格子形成面）を有する回折光学素子７と、球
面レンズ８とで形成されている。光源（不図示）から発
せられた後に、回折光学素子７に入射した光束は、回折
光学素子７を射出する際に、種々の次数の回折光とな
る。この回折光のうち、測定に用いられる回折次数の測
定光Ｌ1は、球面レンズ８を透過した後に、被検面１２
に入射する。ここで、回折光学素子７及び球面レンズ８
は、測定光Ｌ1が被検面１２の理想形状に対して同位相
で垂直入射するように設定されている。被検面１２で反
射した測定光Ｌ1は、球面レンズ８、回折光学素子７の
順に透過した後に、光軸ｚに対して、平行な光束となっ
て、２次元検出器（不図示）へと導かれる。この測定光
Ｌ1と、参照面（不図示）で反射する参照光との干渉に
よって形成される干渉縞を、２次元検出器で観察するこ
とにより、被検面１２の面形状を測定する。FIG. 9 shows a conventional example of a null element of an aspherical shape measuring device. The null element 6 is formed by a diffractive optical element 7 having a diffraction surface 7 a (grating forming surface) such as a zone plate and a spherical lens 8. Light emitted from a light source (not shown) and incident on the diffractive optical element 7 becomes diffracted light of various orders when exiting the diffractive optical element 7. Of the diffracted light, the measurement light L 1 of the diffraction order used for the measurement is transmitted through the spherical lens 8,
Incident on. Here, the diffractive optical element 7 and the spherical lens 8
The measurement light L 1 is set to normal incidence at the same phase relative to the ideal shape of the surface 12. The measurement light L 1 reflected by the test surface 12 is a spherical lens 8, after passing the order of the diffractive optical element 7 with respect to the optical axis z, become a parallel beam, two-dimensional detector to (not shown) It is led. This measurement light L 1, the interference fringes formed by interference between the reference beam reflected by the reference surface (not shown), by observing the two-dimensional detector measures the surface shape of the surface 12.
【０００４】[0004]
【発明が解決しようとする課題】上記の従来技術による
と、被検面１２で反射した回折光のうち、測定光Ｌ1と
は異なる次数の回折光であっても、その入射高さによっ
ては、ヌル素子６を往復透過した後に、測定光Ｌ1と同
様、光軸ｚに対してほぼ平行な光線Ｌ2となるおそれが
ある。この光軸ｚに平行にもどる測定光Ｌ1以外の光線
Ｌ2は、迷光と呼ばれ、測定光Ｌ1と共に２次元検出器に
入射する。この場合、非球面形状である被検面と理想非
球面形状との形状差を、正しく表すべき２次元検出器上
の干渉縞が、この迷光の影響により、それと異なる形状
の干渉縞となってしまう。すなわち、被検面の高精度な
面形状測定が困難となってしまう。したがって本発明
は、２次元検出器への迷光を極めて少なくして、非球面
形状の被検面の面形状を高精度に測定できる非球面測定
装置を提供することを課題とする。According to the above prior art [0005] Of the diffracted light reflected by the test surface 12, even the measurement light L 1 order diffracted lights different from, depending on its incident height , a null element 6 after reciprocating transmitted, similarly to the measurement light L 1, it may become light L 2 substantially parallel to the optical axis z. Light L 2 other than the measurement light L 1 to return to parallel to the optical axis z is called a stray incident on the two-dimensional detector with the measurement light L 1. In this case, the interference fringes on the two-dimensional detector, which should accurately represent the difference between the shape of the aspherical surface to be measured and the ideal aspherical shape, are changed into interference fringes due to the influence of the stray light. I will. That is, it becomes difficult to measure the surface shape of the test surface with high accuracy. Therefore, an object of the present invention is to provide an aspherical surface measuring apparatus capable of measuring stray light to an aspherical surface with high accuracy while minimizing stray light to a two-dimensional detector.
【０００５】[0005]
【課題を解決するための手段】本発明は上記課題を解決
するためになされたものであり、すなわち、添付図面に
符した符号をカッコ内に付記すると、本発明は、光源
（１）から射出した光（Ｌ）を分割する光分割手段（５
ａ）を備え、分割された一方の光を参照光として用い、
他方の光を回折光学素子（７）を含む波面形成手段
（６）を介して非球面形状の被検面（１２）に対応した
波面に変換した後に被検面（１２）に入射させ、被検面
（１２）で反射した測定光と参照光との干渉によって形
成される干渉縞を観察することにより被検面（１２）の
面形状を測定する非球面形状測定装置において、回折光
学素子（７）で形成される測定光、すなわち種々の次数
の回折光のうちで測定に使用する次数の回折光が、一旦
集光してから被検面（１２）に入射するように、波面形
成手段（６）を形成し、測定光の集光位置（Ｏ）の近傍
に絞り（１１）を配置したことを特徴とする非球面形状
測定装置である。SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem. That is, when the reference numerals in parentheses are added in parentheses, the present invention provides a light source (1) which emits light from a light source (1). Light splitting means (5) for splitting the split light (L)
a) using one of the divided lights as a reference light;
The other light is converted into a wavefront corresponding to the aspherical test surface (12) via the wavefront forming means (6) including the diffractive optical element (7), and then is incident on the test surface (12). In an aspherical shape measuring apparatus for measuring the surface shape of the test surface (12) by observing interference fringes formed by interference between the measurement light reflected by the test surface (12) and the reference light, a diffractive optical element ( Wavefront forming means such that the measurement light formed in step 7), that is, the diffracted light of the order used for measurement among the diffracted lights of various orders is once collected and then incident on the surface to be measured (12). An aspherical shape measuring apparatus characterized in that (6) is formed and an aperture (11) is arranged near the condensing position (O) of the measuring light.
【０００６】その際、回折光学素子（７）が平面基板に
形成され、回折光学素子（７）の回折面（７ａ）が光分
割手段（５ａ）を兼ねることができる。また、回折面
（７ａ）は、平面基板（７）の射出面に形成されてお
り、平面基板（７）の入射面は射出面に対して非平行で
あっても良い。以上の構成において、波面形成手段
（６）は、回折光学素子（７）と絞り（１１）との間に
配置された１又は複数枚のレンズ（８）を更に有するこ
とができる。また、波面形成手段（６）は、絞り（１
１）と被検面（１２）との間に配置された１又は複数枚
のレンズ（９、１０）を更に有することもできる。At this time, the diffractive optical element (7) is formed on a flat substrate, and the diffractive surface (7a) of the diffractive optical element (7) can also serve as the light splitting means (5a). Further, the diffraction surface (7a) is formed on the emission surface of the flat substrate (7), and the incidence surface of the flat substrate (7) may be non-parallel to the emission surface. In the above configuration, the wavefront forming means (6) may further include one or more lenses (8) disposed between the diffractive optical element (7) and the stop (11). The wavefront forming means (6) is provided with a diaphragm (1).
It may further include one or more lenses (9, 10) arranged between 1) and the surface to be inspected (12).
【０００７】[0007]
【発明の実施の形態】本発明の実施の形態を図面によっ
て説明する。図１及び図２にて、本発明による非球面形
状測定装置の第１実施例を示す。図１は、非球面形状測
定装置の概略を示す。光源ユニット１より射出した直線
偏光した光ビームＬは、コリメータレンズ２を透過した
後に平行光になって、偏光ビームスプリッター３に入射
する。偏光ビームスプリッター３に入射する光ビームＬ
は、ｓ偏光となるように調整されている。したがってｓ
偏光の光ビームＬは、偏光ビームスプリッター３の光束
分割面で反射して、１／４波長板４に入射する。ここで
偏光ビームスプリッター３の光束分割面の入射平面（図
１の紙面である。）と平行な方向に電気ベクトルが振動
する偏光をｐ偏光とし、入射平面に直交する方向に電気
ベクトルが振動する偏光をｓ偏光とする。１／４波長板
４を透過した光ビームＬは、フィゾー部材５の参照面５
ａに入射する。参照面５ａに入射した光ビームＬのう
ち、一部は参照面５ａを透過して測定光となり、他の部
分は参照面５ａで反射して参照光となる。Embodiments of the present invention will be described with reference to the drawings. 1 and 2 show a first embodiment of an aspherical surface shape measuring apparatus according to the present invention. FIG. 1 shows an outline of an aspherical shape measuring device. The linearly polarized light beam L emitted from the light source unit 1 passes through the collimator lens 2, becomes parallel light, and enters the polarization beam splitter 3. Light beam L incident on polarization beam splitter 3
Is adjusted to be s-polarized light. Therefore s
The polarized light beam L is reflected by the light beam splitting surface of the polarizing beam splitter 3 and enters the quarter-wave plate 4. Here, the polarized light whose electric vector oscillates in a direction parallel to the incident plane (the paper surface in FIG. 1) of the light beam splitting surface of the polarization beam splitter 3 is p-polarized light, and the electric vector oscillates in a direction perpendicular to the incident plane. The polarization is s-polarization. The light beam L transmitted through the 波長 wavelength plate 4 is applied to the reference surface 5 of the Fizeau member 5.
a. A part of the light beam L incident on the reference surface 5a is transmitted through the reference surface 5a to be measurement light, and the other portion is reflected by the reference surface 5a to be reference light.
【０００８】参照面５ａを透過した測定光は、ヌル素子
６に入射する。ヌル素子６を透過した測定光は、一旦集
光点Ｏで集光した後に、被検面１２に入射する。ここ
で、集光点Ｏの近傍には、絞り１１が設置されており、
迷光となる回折光を遮断している。また、ヌル素子６を
透過した測定光は、被検面１２の理想非球面形状に対し
て、同位相で垂直入射するように非球面波に変換されて
いる。被検面１２で反射した測定光は、絞り１１、ヌル
素子６、フィゾー部材５、１／４波長板４の順に通過し
た後、偏光ビームスプリッター３に入射する。ここで、
測定光は、１／４波長板４を往路と復路の２回通過して
いるため、その偏光面は９０度回転し、ｓ偏光からｐ偏
光に変換される。このｐ偏光の測定光は、偏光ビームス
プリッター３の光束分割面を透過する。偏光ビームスプ
リッター３を透過した測定光は、ビームエクスパンダー
１３によってビーム径が変換された後、２次元画像検出
器１４に入射する。The measurement light transmitted through the reference surface 5a enters the null element 6. The measurement light transmitted through the null element 6 is once focused at the focusing point O, and then enters the surface 12 to be measured. Here, an aperture stop 11 is installed near the focal point O,
It blocks the stray light that is diffracted. The measurement light transmitted through the null element 6 is converted into an aspherical wave so that the light is perpendicularly incident on the ideal aspherical shape of the test surface 12 in the same phase. The measurement light reflected by the test surface 12 passes through the stop 11, the null element 6, the Fizeau member 5, and the quarter-wave plate 4 in this order, and then enters the polarization beam splitter 3. here,
Since the measurement light has passed through the quarter-wave plate 4 twice, that is, the forward path and the return path, the plane of polarization is rotated by 90 degrees and converted from s-polarized light to p-polarized light. The p-polarized measurement light passes through the light beam splitting surface of the polarization beam splitter 3. The measurement light transmitted through the polarization beam splitter 3 is incident on the two-dimensional image detector 14 after the beam diameter is changed by the beam expander 13.
【０００９】一方、参照面５ａで反射した参照光は、１
／４波長板４を透過した後に、測定光と同様にｐ偏光の
光となって、偏光ビームスプリッター３に入射する。偏
光ビームスプリッター３の光束分割面を透過した参照光
は、ビームエクスパンダー１３によってビーム径が変換
された後、２次元画像検出器１４に入射する。ここで、
測定光と参照光は、参照面５ａからの光路中、互いに干
渉しながら２次元画像検出器１４に入射する。２次元画
像検出器１４では、この測定光と参照光の干渉による干
渉縞が観察される。この干渉縞を解析することにより、
測定光の被検面１２への入射波面と、被検面１２の形状
とのずれが計測され、被検面１２の面形状を測定するこ
とができる。On the other hand, the reference light reflected by the reference surface 5a is 1
After passing through the 波長 wavelength plate 4, it becomes p-polarized light similarly to the measurement light, and is incident on the polarization beam splitter 3. The reference light transmitted through the light beam splitting surface of the polarization beam splitter 3 is incident on the two-dimensional image detector 14 after the beam diameter is converted by the beam expander 13. here,
The measurement light and the reference light enter the two-dimensional image detector 14 while interfering with each other in the optical path from the reference surface 5a. In the two-dimensional image detector 14, interference fringes due to interference between the measurement light and the reference light are observed. By analyzing this interference fringe,
The deviation between the wavefront of the measurement light incident on the test surface 12 and the shape of the test surface 12 is measured, and the surface shape of the test surface 12 can be measured.
【００１０】図２は、本第１実施例の非球面形状測定装
置のヌル素子６の部分を、拡大して詳しく示した図であ
る。ヌル素子６は、回折光学素子７と、球面レンズ８と
で形成されている。そして、回折光学素子７の射出面に
は、回折面７ａが形成されている。回折光学素子７に入
射した測定光は、回折光学素子７を射出する際に、種々
の次数の回折光となる。この回折光のうち、測定に用い
られる回折次数の測定光Ｌ1は、球面レンズ８を透過し
て、絞り１１近傍で集光した後に、被検面１２に入射す
る。ここで、回折光学素子７及び球面レンズ８は、測定
光Ｌ1が被検面１２の理想形状に対して同位相で垂直入
射するように設定されている。被検面１２で反射した測
定光Ｌ1は、絞り１１、球面レンズ８、回折光学素子７
の順に透過した後に、光軸ｚに対して、平行な光束とな
る。FIG. 2 is an enlarged view showing a part of the null element 6 of the aspherical shape measuring apparatus of the first embodiment in detail. The null element 6 is formed by a diffractive optical element 7 and a spherical lens 8. A diffractive surface 7 a is formed on the exit surface of the diffractive optical element 7. The measurement light that has entered the diffractive optical element 7 becomes diffracted light of various orders when it exits the diffractive optical element 7. Of the diffracted light, the measurement light L 1 of the diffraction order used for measurement passes through the spherical lens 8, converges near the stop 11, and then enters the surface 12 to be measured. Here, the diffractive optical element 7 and the spherical lens 8, the measurement light L 1 is set to normal incidence at the same phase relative to the ideal shape of the surface 12. The measurement light L 1 reflected by the test surface 12, stop 11, a spherical lens 8, the diffractive optical element 7
, The light flux becomes parallel to the optical axis z.
【００１１】一方、被検面１２で反射した後にヌル素子
６を透過して、測定光Ｌ1と同様、光軸ｚに対して平行
となる迷光Ｌ2は、往路又は復路において絞り１１で遮
断される。以上のように、回折光学素子７を透過する種
々の次数の回折光のうち、測定に使用する次数以外の回
折光は絞り１１で遮断され、迷光は除去されるので、被
検面１２の面形状を高精度に測定することができる。On the other hand, stray light L 2 which is reflected on the surface 12 to be measured and then passes through the null element 6 and is parallel to the optical axis z, like the measurement light L 1 , is blocked by the stop 11 on the outward path or the return path. Is done. As described above, out of the diffracted lights of various orders transmitted through the diffractive optical element 7, the diffracted lights other than the order used for the measurement are blocked by the stop 11, and the stray light is removed. The shape can be measured with high accuracy.
【００１２】次に図３にて、本発明による非球面形状測
定装置のヌル素子の第２実施例を示す。本第２実施例と
前記第１実施例との違いは、絞り１１と被検面１２との
間に第２レンズ９を設置した点である。そして、回折光
学素子７、球面レンズ８、第２レンズ９で、全体のヌル
素子６が形成されている。本第２実施例は、図２に示す
ようなヌル素子６等の光学素子の配置では、ヌル素子６
と被検面１２との距離が長くなってしまう場合等に有効
である。すなわち、回折光学素子７と球面レンズ８との
構成だけで、ヌル素子６を透過した光束を、被検面１２
に対応した最適な波面に変換するのが困難となる場合が
ある。これに対して、本第２実施例では、第２レンズ９
を配置しており、ヌル素子６を透過した光束が、被検面
１２に最適な波面となるように設計することができる。
本第２実施例でも、集光点に絞り１１が配置されてお
り、第１実施例と同様に、絞り１１により迷光を遮断で
きる。Next, FIG. 3 shows a second embodiment of the null element of the aspherical shape measuring apparatus according to the present invention. The difference between the second embodiment and the first embodiment is that a second lens 9 is provided between the diaphragm 11 and the surface 12 to be measured. The entire null element 6 is formed by the diffractive optical element 7, the spherical lens 8, and the second lens 9. In the second embodiment, the arrangement of the optical element such as the null element 6 shown in FIG.
This is effective when the distance between the object and the test surface 12 becomes long. That is, only the configuration of the diffractive optical element 7 and the spherical lens 8 allows the light flux transmitted through the null
It may be difficult to convert the wavefront to an optimal wavefront corresponding to On the other hand, in the second embodiment, the second lens 9
Can be designed so that the light flux transmitted through the null element 6 becomes an optimal wavefront for the surface 12 to be measured.
Also in the second embodiment, the stop 11 is disposed at the light condensing point, and stray light can be blocked by the stop 11 as in the first embodiment.
【００１３】次に図４にて、本発明による非球面形状測
定装置のヌル素子の第３実施例を示す。被検面１２が凹
面になっている前記第１実施例に対して、本第３実施例
は、被検面１２が凸面になっている。この場合、ヌル素
子６を透過した測定光を、絞り１１を通過した後に、被
検面１２に垂直入射させるために、絞り１１と被検面１
２との間に第２レンズ１０を配置している。そして、回
折光学素子７、球面レンズ８、第２レンズ１０で、全体
のヌル素子６が形成されている。本第３実施例でも、集
光点に絞り１１が配置されており、第１実施例と同様
に、絞り１１により迷光を遮断できる。Next, FIG. 4 shows a third embodiment of the null element of the aspherical shape measuring apparatus according to the present invention. In contrast to the first embodiment in which the test surface 12 is concave, the third embodiment has a convex test surface 12. In this case, the stop 11 and the surface 1 to be measured are transmitted so that the measurement light transmitted through the null element 6 passes through the stop 11 and then enters the surface 12 to be measured perpendicularly.
2, the second lens 10 is arranged. The entire null element 6 is formed by the diffractive optical element 7, the spherical lens 8, and the second lens 10. Also in the third embodiment, the stop 11 is disposed at the condensing point, and the stray light can be blocked by the stop 11 as in the first embodiment.
【００１４】次に、図５及び図６にて、本発明による非
球面形状測定装置の第４実施例を示す。図５は非球面形
状測定装置の概略を示し、図６は非球面形状測定装置の
ヌル素子の部分を拡大して詳しく示した図である。図５
に示すように、本第４実施例では、前記第１実施例にお
けるフィゾー部材５が設置されていない。そして図６に
示すように、ヌル素子６は、回折光学素子７と球面レン
ズ８とで形成されている。そして、回折光学素子７の射
出面には、参照面５ａを兼ねた回折面７ａが形成されて
いる。回折面７ａを透過した光束は、種々の次数の回折
光となり、そのうちのある次数の回折光が測定光Ｌ1と
なる。一方、参照面５ａで反射した光束、すなわち回折
面７ａの反射０次光が参照光となる。Next, FIGS. 5 and 6 show a fourth embodiment of the aspherical shape measuring apparatus according to the present invention. FIG. 5 shows an outline of the aspherical shape measuring device, and FIG. 6 is an enlarged view showing a null element portion of the aspherical shape measuring device in detail. FIG.
As shown in FIG. 7, in the fourth embodiment, the Fizeau member 5 in the first embodiment is not provided. As shown in FIG. 6, the null element 6 is formed by a diffractive optical element 7 and a spherical lens 8. A diffractive surface 7a also serving as a reference surface 5a is formed on the exit surface of the diffractive optical element 7. The light beam which has passed through the diffractive surface 7a becomes the various orders of diffracted light, order diffracted light certain of its becomes measurement light L 1. On the other hand, the light beam reflected by the reference surface 5a, that is, the zero-order light reflected by the diffraction surface 7a becomes the reference light.
【００１５】光源ユニット１より射出した直線偏光した
光ビームＬは、前記第１実施例と同様に、１／４波長板
４に入射する。１／４波長板４を透過した光ビームＬ
は、ヌル素子６の参照面５ａに入射する。参照面５ａで
反射した参照光は、第１実施例と同様に、２次元画像検
出器１４に入射する。一方、回折面７ａを透過した測定
光Ｌ1は、第１実施例と同様に、球面レンズ８を透過し
て、絞り１１近傍で集光した後に、被検面１２に入射す
る。被検面１２で反射した測定光Ｌ1は、絞り１１、ヌ
ル素子６の順に透過した後に、光軸ｚに対して、平行な
光束となる。この測定光Ｌ1は、第１実施例と同様に、
２次元画像検出器１４に入射する。２次元画像検出器１
４では、第１実施例と同様に、測定光Ｌ1と参照光の干
渉による干渉縞が観察されて、被検面１２の面形状を測
定することができる。本第４実施例でも、集光点Ｏに絞
り１１が配置されており、第１実施例と同様に、絞り１
１により迷光を遮断できる。また本第４実施例では、フ
ィゾー部材が設置されていないため、非球面形状測定装
置を単純な構成にすることができる。The linearly polarized light beam L emitted from the light source unit 1 is incident on the quarter-wave plate 4 as in the first embodiment. Light beam L transmitted through quarter-wave plate 4
Are incident on the reference surface 5a of the null element 6. The reference light reflected on the reference surface 5a is incident on the two-dimensional image detector 14, as in the first embodiment. On the other hand, the diffractive surface 7a measurement light L 1 having passed through the, like the first embodiment, it is transmitted through the spherical lens 8, after condensed by the diaphragm 11 near incident on the test surface 12. The measurement light L 1 reflected by the test surface 12, aperture 11, after being transmitted in the order of the null element 6, with respect to the optical axis z, a parallel beam. The measurement light L 1 is similar to the first embodiment,
The light enters the two-dimensional image detector 14. Two-dimensional image detector 1
In 4, like the first embodiment, interference fringes due to the interference of the measurement light L 1 and the reference light is observed, it is possible to measure the surface shape of the surface 12. In the fourth embodiment as well, the stop 11 is arranged at the focal point O, and the stop 1
1 allows stray light to be blocked. In the fourth embodiment, since the Fizeau member is not provided, the aspherical shape measuring device can have a simple configuration.
【００１６】次に、図７及び図８にて、本発明による非
球面形状測定装置の第５実施例を示す。図７は非球面形
状測定装置の概略を示し、図８は非球面形状測定装置の
ヌル素子の部分を拡大して詳しく示した図である。本第
５実施例では、前記第４実施例の回折光学素子７が楔形
状になっている。すなわち、回折光学素子７の射出面は
光軸ｚに対して垂直に配置され、回折光学素子７の入射
面は射出面に対して非平行となっている。そして、絞り
１１と被検面１２は、回折光学素子７の楔形状に対応し
た角度にて配置されている。このように回折光学素子７
を楔形状とすることで、回折光学素子７の入射面に入射
する光束のうち、入射面で反射する光束、いわゆる戻り
光Ｌ3を、入射光路と異なる光路に進めることができ
る。したがって、２次元画像検出器１４上で観察される
測定光と参照光の干渉縞に対する、戻り光Ｌ3の影響を
除くことができる。Next, FIGS. 7 and 8 show a fifth embodiment of the aspherical shape measuring apparatus according to the present invention. FIG. 7 shows an outline of the aspherical surface shape measuring device, and FIG. 8 is an enlarged view showing a null element portion of the aspherical surface shape measuring device in detail. In the fifth embodiment, the diffractive optical element 7 of the fourth embodiment has a wedge shape. That is, the exit surface of the diffractive optical element 7 is arranged perpendicular to the optical axis z, and the incident surface of the diffractive optical element 7 is not parallel to the exit surface. The stop 11 and the test surface 12 are arranged at an angle corresponding to the wedge shape of the diffractive optical element 7. Thus, the diffractive optical element 7
The by a wedge shape, of the light beam incident on the incident surface of the diffractive optical element 7, the light beam reflected by the incident surface, the so-called return light L 3, it is possible to proceed in different light path the incident light path. Therefore, to interference fringes of the measuring light and the reference light to be observed on the two-dimensional image detector 14, it is possible to eliminate the influence of the return light L 3.
【００１７】更に、本第５実施例でも、集光点Ｏに絞り
１１が配置されており、第１実施例と同様に、絞り１１
により迷光を遮断できる。また本第５実施例では、フィ
ゾー部材が設置されていないため、非球面形状測定装置
を単純な構成にすることができる。なお、本第５実施例
では、第４実施例における回折光学素子７を楔形状とし
たが、第１〜３実施例における回折光学素子７を楔形状
としても良い。Further, also in the fifth embodiment, the stop 11 is disposed at the light condensing point O, and the stop 11 is disposed similarly to the first embodiment.
Can block stray light. Further, in the fifth embodiment, since no Fizeau member is provided, the aspherical shape measuring device can have a simple configuration. In the fifth embodiment, the diffractive optical element 7 in the fourth embodiment has a wedge shape. However, the diffractive optical element 7 in the first to third embodiments may have a wedge shape.
【００１８】[0018]
【発明の効果】以上のように本発明によれば、回折光学
素子からの測定光が一旦集光してから被検面に入射する
構成としており、更にその集光位置近傍に絞りを配置し
ているので、迷光が有効に除去されて、非球面形状の被
検面の面形状を高精度に測定できる非球面測定装置を提
供することができる。As described above, according to the present invention, the measuring light from the diffractive optical element is once condensed and then incident on the surface to be measured, and a stop is arranged near the condensing position. Therefore, it is possible to provide an aspherical surface measuring apparatus capable of effectively removing stray light and measuring the surface shape of the aspherical surface to be measured with high accuracy.
【図１】本発明の第１実施例による非球面形状測定装置
を示す図である。FIG. 1 is a view showing an aspherical surface shape measuring apparatus according to a first embodiment of the present invention.
【図２】本発明の第１実施例による非球面形状測定装置
のヌル素子を示す拡大図である。FIG. 2 is an enlarged view showing a null element of the aspherical shape measuring device according to the first embodiment of the present invention.
【図３】本発明の第２実施例による非球面形状測定装置
のヌル素子を示す図である。FIG. 3 is a view showing a null element of an aspherical shape measuring apparatus according to a second embodiment of the present invention.
【図４】本発明の第３実施例による非球面形状測定装置
のヌル素子を示す図である。FIG. 4 is a view showing a null element of an aspherical shape measuring apparatus according to a third embodiment of the present invention.
【図５】本発明の第４実施例による非球面形状測定装置
を示す図である。FIG. 5 is a view illustrating an aspherical surface shape measuring apparatus according to a fourth embodiment of the present invention.
【図６】本発明の第４実施例による非球面形状測定装置
のヌル素子を示す図である。FIG. 6 is a view showing a null element of an aspherical shape measuring apparatus according to a fourth embodiment of the present invention.
【図７】本発明の第５実施例による非球面形状測定装置
を示す図である。FIG. 7 is a view showing an aspherical surface shape measuring apparatus according to a fifth embodiment of the present invention.
【図８】本発明の第５実施例による非球面形状測定装置
のヌル素子を示す図である。FIG. 8 is a view showing a null element of an aspherical surface shape measuring apparatus according to a fifth embodiment of the present invention.
【図９】非球面形状測定装置のヌル素子の従来例を示す
図である。FIG. 9 is a diagram showing a conventional example of a null element of the aspherical shape measuring device.
１…光源ユニット ２…コリメータレンズ ３…偏光ビームスプリッター ４…１／４波長板 ５…フィゾー部材 ５ａ…参照面 ６…ヌル素子 ７…回折光学素子 ７ａ…回折面 ８…球面レンズ ９、１０…第２レンズ １１…絞り １２…被検面 １３…ビームエクスパンダー １４…２次元画像検出器 DESCRIPTION OF SYMBOLS 1 ... Light source unit 2 ... Collimator lens 3 ... Polarization beam splitter 4 ... 1/4 wavelength plate 5 ... Fizeau member 5a ... Reference surface 6 ... Null element 7 ... Diffractive optical element 7a ... Diffraction surface 8 ... Spherical lens 9, 10 ... First 2 lens 11 ... stop 12 ... test surface 13 ... beam expander 14 ... two-dimensional image detector
Claims (5)
を備え、分割された一方の光を参照光として用い、他方
の光を回折光学素子を含む波面形成手段を介して非球面
形状の被検面に対応した波面に変換した後に該被検面に
入射させ、該被検面で反射した測定光と前記参照光との
干渉によって形成される干渉縞を観察することにより前
記被検面の面形状を測定する非球面形状測定装置におい
て、 前記回折光学素子で形成される測定光、すなわち種々の
次数の回折光のうちで測定に使用する次数の回折光が、
一旦集光してから前記被検面に入射するように、前記波
面形成手段を形成し、 前記測定光の集光位置の近傍に絞りを配置したことを特
徴とする非球面形状測定装置。A light splitting means for splitting light emitted from a light source, using one of the split lights as a reference light, and using the other light as an aspherical shape through a wavefront forming means including a diffractive optical element. After being converted into a wavefront corresponding to the test surface, the wavefront is incident on the test surface, and interference fringes formed by interference between the measurement light reflected by the test surface and the reference light are observed, whereby the test surface is measured. In an aspherical shape measuring apparatus for measuring the surface shape of, the measurement light formed by the diffractive optical element, that is, the diffracted light of the order used for measurement among the diffracted lights of various orders,
An aspherical shape measuring apparatus, wherein the wavefront forming means is formed so as to be focused once and then incident on the surface to be measured, and a stop is arranged near a condensing position of the measuring light.
て、 前記回折光学素子が平面基板に形成され、該回折光学素
子の回折面が前記光分割手段を兼ねていることを特徴と
する非球面形状測定装置。2. A non-spherical shape measuring apparatus according to claim 1, wherein said diffractive optical element is formed on a flat substrate, and a diffractive surface of said diffractive optical element also functions as said light dividing means. Spherical shape measuring device.
て、 前記回折面は、前記平面基板の射出面に形成されてお
り、該平面基板の入射面は前記射出面に対して非平行で
あることを特徴とする非球面形状測定装置。3. The aspherical shape measuring apparatus according to claim 2, wherein the diffraction surface is formed on an emission surface of the flat substrate, and the incidence surface of the flat substrate is non-parallel to the emission surface. An aspherical shape measuring device, characterized in that:
前記絞りとの間に配置された１又は複数枚のレンズを更
に有することを特徴とする請求項１、２又は３記載の非
球面形状測定装置。4. The aspheric surface according to claim 1, wherein said wavefront forming means further comprises one or more lenses disposed between said diffractive optical element and said stop. Shape measuring device.
面との間に配置された１又は複数枚のレンズを更に有す
ることを特徴とする請求項１〜４のいずれか１項記載の
非球面形状測定装置。5. The apparatus according to claim 1, wherein said wavefront forming means further comprises one or more lenses disposed between said stop and said surface to be inspected. Aspherical shape measuring device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10153807A JPH11325848A (en) | 1998-05-19 | 1998-05-19 | Aspherical surface shape measurement device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10153807A JPH11325848A (en) | 1998-05-19 | 1998-05-19 | Aspherical surface shape measurement device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH11325848A true JPH11325848A (en) | 1999-11-26 |
Family
ID=15570553
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10153807A Pending JPH11325848A (en) | 1998-05-19 | 1998-05-19 | Aspherical surface shape measurement device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH11325848A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007046938A (en) * | 2005-08-08 | 2007-02-22 | Mitsutoyo Corp | Interferometer |
| JP2008145419A (en) * | 2006-10-02 | 2008-06-26 | Asml Holding Nv | Diffractive null corrector using spatial light modulator |
| CN107525463A (en) * | 2016-06-17 | 2017-12-29 | 株式会社三丰 | The interference of light determines device and interference of light assay method |
-
1998
- 1998-05-19 JP JP10153807A patent/JPH11325848A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007046938A (en) * | 2005-08-08 | 2007-02-22 | Mitsutoyo Corp | Interferometer |
| JP2008145419A (en) * | 2006-10-02 | 2008-06-26 | Asml Holding Nv | Diffractive null corrector using spatial light modulator |
| CN107525463A (en) * | 2016-06-17 | 2017-12-29 | 株式会社三丰 | The interference of light determines device and interference of light assay method |
| CN107525463B (en) * | 2016-06-17 | 2020-10-16 | 株式会社三丰 | Optical interference measuring device and optical interference measuring method |
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