JPH09184787A - Analysis/evaluation device for optical lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure, analyze, and evaluate an optical lens such as an object lens for microscope and a stepper lens with improved performance. SOLUTION: A flux of light (a) emitted from an interferometer 1 passes through lenses 2 and 3 to be detected being arranged oppositely, is reflected by a reference means 4, and returns to an interference fringe generation means 1 again via the lenses 2 and 3 to be detected, thus generating interference fringes. Data are measured by a light reception means 5 for receiving generated interference fringes and a measuring means 6. An analyzing means 7 analytically converts measured interference fringes to transmission wave front. The obtained interference fringes or transmission wave fronts are stored by a storage means 8 and are subjected to specific operation processing by a processing means 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring and evaluating the performance of an optical lens by using an interferometer, and more particularly to a method such as a microscope objective lens or a reduction exposure projection lens (so-called stepper lens). The present invention relates to a high-performance and highly accurate analysis / evaluation apparatus for optical lenses.

[0002]

2. Description of the Related Art Conventionally, as a typical interferometer, a Fizeau type and a Twyman-Green (Twym) type are used.
(an-Green) type has been known for a long time, and regarding these interferometers and interferometers, Daniel Mala
cara's "Optical Shop Testin"
g ”(John Wiley & Sons, Inc.
1978).

As an example, the Twyman-Green type interferometer introduced in this book is shown in FIG. This is a device that measures the transmitted wavefront of the lens under test using a reference mirror. FIG. 15 shows a measurement example of the microscope objective lens introduced in the same book. Although these methods use the above-described method, FIG. 15 (d) shows a method in which two objective lenses are opposed to each other and two transmitted wave fronts are measured (hereinafter, this method is referred to as "opposed method"). That).

Further, Japanese Unexamined Patent Publication No. 62-127601 discloses an apparatus for measuring a spherical mirror having a deep spherical portion with high accuracy. As a method for measuring the transmittance of the objective lens, there is a method described in JP-A-7-92084 or JP-A-7-92085. Although there is a difference between these methods as a finite system or an infinite system, FIG.
Since the method shown in (d) is used, the transmittance can be measured with high accuracy.

[0005]

Objective lenses for microscopes are generally designed and manufactured with high performance and high precision. Here, “high performance” means that the NA is increased and various aberrations are satisfactorily corrected and designed over a wide range to realize a high-resolution microscope image. Further, in order to maintain such "high performance", a manufacturing technique for manufacturing and assembling each designed optical component with high accuracy is required.

However, the performance evaluation of such an objective lens for a microscope is mainly conducted by visual observation (so-called sensory evaluation) using a reference sample or the like, and in practice, very subtle differences and defects can be found. It can be difficult.

Conventionally, a method for evaluating an objective lens by utilizing the above-mentioned interferometric measurement has been tried, but it is difficult to measure with this method only, especially when the NA is not higher than an intermediate level and the system is not dry. To measure the objective lens, see FIG.
It is suitable to use the spherical concave mirror shown in (a) or FIG. 15 (a). In other cases, the convex mirror shown in FIG. 14B is not suitable for an objective lens having no working distance,
The plane mirror shown in FIG. 14 (c) or FIG. 15 (b) cannot obtain the interference fringes of the asymmetrical component, and FIG.
When the hemispherical prism shown in (1) is used, mechanical problems such as aberrations in the prism occur.

Although it has been introduced in the above-mentioned book that the wavefront that is the sum of two can be obtained in the objective lens facing method shown in FIG. 15D, in reality, only this measurement results in an asymmetrical aberration component (coma). , Ass) are canceled out, and the obtained wavefront may not lead to accurate evaluation.

On the other hand, even in the case of using the spherical concave mirror shown in FIG. 15 (a), a hemispherical concave concave mirror with a very high accuracy is required to measure an objective lens having a high NA. Is difficult to produce. Further, in an immersion objective lens used for living organisms, the concave mirror must be immersed in the immersion medium, and the fluidity of the medium also affects the interference fringes.

Japanese Unexamined Patent Publication No. 62-127601 discloses a means of correcting the wavefront aberration by inputting NA by an external input in order to solve the problem of ball loss, but in the end, a spherical concave mirror or the like is used. Since it will be used, the above-mentioned problems are unavoidable. Also, to measure the assembled optical system,
A step for measuring the NA in advance is also required, and when the NA is high, the actual wavefront and the wavefront obtained from the interference fringes are significantly different from each other.

As described above, the conventional methods are
An interferometer cannot be constructed sufficiently for a high NA optical lens such as a microscope objective lens. In addition, the problem that the error factor is large in the measurement result is likely to occur, and it is difficult to apply it as a practical analysis and evaluation device even if the measurement method is examined.

The present invention has been made in view of the above problems, and measures high-performance and high-precision optical lenses such as objective lenses for microscopes and stepper lenses, which have been difficult in the past, and It is an object of the present invention to provide an apparatus capable of performing analysis / evaluation.

[0013]

In order to achieve this object, an optical lens analyzing and evaluating apparatus according to the present invention comprises an interference fringe generating means and a lens to be inspected when the interference fringe generating means generates the interference fringes. At least two optical lenses, interference fringe light receiving means, measuring means for measuring the interference fringes received by the interference fringe light receiving means, analysis means for analyzing the interference fringes measured by the measuring means, and The optical lens to be measured has relatively unique coordinates. The optical lens is provided with a storage unit for storing the interference fringes analyzed by the analyzing unit and a processing unit for performing a predetermined calculation on the interference fringes stored by the storage unit. It is characterized by having a system and being held so as to have a fixed positional relationship.

In a preferred embodiment of the present invention, the optical lenses have the coordinate system in a plane perpendicular to the optical axis, and each of the optical lenses is rotatable relative to the optical axis. Composed. In a preferred embodiment of the invention, if there are two optical lenses to be measured, these two optical lenses are arranged facing each other and further, at least one of said optical lenses has a pupil plane or an aperture plane. Reference means arranged to reflect the transmitted light or the transmitted wavefront may be provided in the vicinity of the. In a preferred embodiment of the present invention, when at least three optical lenses are measured, two optical lenses to be measured can be selected from the three optical lenses.

FIG. 1 shows a conceptual diagram of the present invention. A general interferometer can be used as the interference fringe generating means 1, and any type can be used as long as it can generate an interference fringe. At least two lenses 2 and 3 to be inspected are necessary.
If the opposing method is used as shown in FIG. 5 (d), the light beam a emitted from the interferometer can be passed through the high-NA light beam b converted through the lenses 2 and 3 to be inspected. The light beam c is reflected by the reference means 4, returns to the interference fringe generation means 1 again via the lenses 2 and 3 to be inspected, and the interference fringes are generated. The light receiving means 5 and the measuring means 6 for receiving the generated interference fringes are used to measure the data defined as described above. The analysis means 7 analytically converts the measured interference fringes into a transmitted wavefront. The obtained interference fringes or transmitted wavefronts are once held or stored in the storage means 8, and the processing means 9 performs a predetermined arithmetic processing described later.

A light beam c emitted from the lens 3 to be inspected
It often has a slight spread, and it becomes difficult to focus around the generated interference fringes, making it difficult to obtain a correct interference image. Therefore, it is desirable that the reference unit 4 be configured as a plane mirror so as to reflect the transmitted light or the transmitted wave front in the vicinity of one of the pupil surface and the diaphragm surface of the lens to be inspected, and be close to the lens to be inspected 3. Alternatively, as shown in FIG. 2, a relatively gentle concave surface may be used, or an afocal system having a small NA as shown in FIG. Get the same effect as.

Here, each of the two lenses 2 and 3 to be inspected is provided with a unique coordinate system for holding a relative positional relationship in a reference plane perpendicular to the optical axis. The “reference plane” may be a pupil plane, an aperture plane, a contact surface, or the like as long as it is perpendicular to the optical axis, and a reference serving as a guide for the in-plane coordinate system may be provided on the outer circumference of the frame or the like. Specifically, it suffices to always check where the reference marking of the lens to be inspected is located. Further, when the reference surface is rotated about the optical axis, the marking can be easily positioned, and the optical lens can be always held in a fixed positional relationship even during a plurality of measurements.

Even when two or more optical lenses are recombined to selectively measure two lenses at a time, the same effect can be obtained with respect to the target optical lens by performing the same process. Further, in the present invention, in the interference fringes or transmitted wavefront of the high-performance and high-precision optical lens described above, it is possible to effectively measure the symmetrical or asymmetrical aberration to be measured or analyzed, and during the measurement, It is also possible to give asymmetrical aberration components a certain direction at all times.

In a preferred embodiment of the present invention, it has transmitted light or transmitted wave fronts W1, W2, W3 measured by recombining the optical lenses and one transmitted wave front W of the optical lens, and The calculation is characterized by being expressed by the equation (1). W = (W1 + W2-W3) / 2 (1)

In a preferred embodiment of the present invention, the transmitted wavefronts Wa, Wb, Wc of the optical lenses measured as a set of at least three optical lenses and the measured transmitted light and transmitted wavefronts W1, W2, W3 are as follows. (2), and W1 = Wa + Wb W2 = Wb + Wc W3 = Wa + Wc (2) The calculation in the processing means is represented by the following formula (3). Wa = (W1 + W3-W2) / 2 Wb = (W1 + W2-W3) / 2 Wc = (W2 + W3-W1) / 2 (3)

In a preferred embodiment of the present invention, transmitted wavefronts Wa, Wb of at least two optical lenses,
--- has Wb which is the formula (1), the measured transmitted light and the transmitted wavefront W, and the calculation in the processing means is represented by the formula (4). Wa = W-Wb (4)

When there is at least three pieces of transmitted wavefront (interference fringe) information stored in the storage means 8 and the transmitted wavefront W of the lens under test is contained therein, the arithmetic processing of the equation (1) is performed. Only W can be calculated by In order to perform this calculation effectively, it is necessary to position the lens under test (2, 3 in FIG. 1) during measurement, and the plurality of transmitted wavefronts to be calculated must match the positional relationship during measurement. I have to. That is, when the above-described reference surface is rotated to perform marking positioning, the positional relationship of the transmitted wavefront to be calculated becomes a fixed positional relationship equivalent to that during measurement, and direct calculation can be performed. Even if it is not positioned, if the marking position is known, only the azimuth of the reference plane will differ, so if the transmitted wavefront to be calculated is rotated as much as necessary on the data to match it, the same as above. It can be processed. Therefore, even considering from the calculation,
It is obvious that not only the symmetric aberration component but also the symmetric asymmetric aberration component is preserved in the calculated transmitted wavefront, which is suitable for evaluation of the optical lens.

If there are at least three sets of transmitted wavefronts Wa, Wb, and Wc of the lens to be inspected, if measurement is performed by combining them so as to obtain equation (2), then W using equation (3) is used.
It is possible to efficiently calculate a, Wb, and Wc. Furthermore, the transmitted wavefront Wa of at least two or more test lenses,
When Wb is clear in the formula (1) in Wb, ...
If W (= Wa + Wb) is measured, it can be easily calculated by the formula (4).
It is also possible to calculate a.

Several methods can be considered for the data expression of the wavefront distribution analyzed from the interference fringes. Generally, image data or matrix data is used, but in this case, since data is stored for each pixel, it is sufficient to perform calculation for each corresponding pixel among a plurality of measurement data. This method does not necessarily have to be the same type of optical lens, because only the measurement area required by the measurement means or the analysis means needs to be defined.

In interferometry, it is common to approximate the analyzed wavefront distribution to an aberration function. The Zernike polynomial is particularly often used and is described in detail in "Principles of Optics II" (pages 691-713). Zernike polynomials are Standard Zer
Although it is divided into a Nike and a Fringe Zernike, the Fringe Zer is easy to use in interferometry because of its simplicity.
Nike is often used. The Zernike polynomial normalizes the pupil plane of the optical system within the unit circle, expresses each aberration component by a series expansion with the radius ρ and the angle θ by peaking at the origin, and therefore can be evaluated analytically. Further, the above-mentioned image data or matrix data has a large amount of data, and an error is likely to occur in the measurement area, which causes a problem in matching when performing calculation. The Zernike polynomial has coordinate axes with the origin as a reference, and can improve the correspondence with marking and the reliability of calculation. Furthermore, the necessary data is only the coefficient of each term of the polynomial, which is preferable because the amount of data and the calculation time can be reduced. However, since the aberration component is expanded into a polynomial, high frequency components (mostly noise) that appear during actual measurement are likely to be cut.

In a preferred aspect of the present invention, the optical lens is a microscope objective lens. In a preferred aspect of the present invention, a parallel plate is arranged between the optical lenses so as to be detachable and positionally adjustable. In a preferred embodiment of the present invention, a member for holding an immersion medium inserted between the optical lenses is provided.

In particular, the optical lens analysis and evaluation apparatus according to the present invention is suitable for a microscope objective lens. In addition, although some objective lenses used in the biological field require a cover glass, the present invention deals with this by inserting a plane-parallel plate having a thickness of two pieces of gabber glass between opposed objective lenses. be able to. In this case, it is preferable that the tilt and position of the cover glass can be adjusted. Further, for the objective lens of the immersion system, which has a higher NA, the surface tension of the immersion medium is used to
It can be applied by inserting and holding between opposing objective lenses. The most commonly used immersion medium is water, oil, etc., but when the working distance of the objective lens is long, a medium with low viscosity such as water cannot be held by surface tension, so a hollow tubular structure as shown in FIG. It is preferable to provide the holding member.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 5 shows a first embodiment of the present invention.
The interferometer 1 is a Fizeau type, and includes a laser light source 10 such as a He—Ne laser, a mirror 11 having a reference surface, and a mirror 1.
It has a piezo element 12 for moving 1 and an image sensor 5 for detecting interference fringes. The measurement calculation processing unit 13 sends a signal to the piezo element 12, slightly moves the mirror 11, and performs measurement by a phase shift method (also referred to as a phase modulation method) for reading an interference intensity signal from the image pickup element 5. 6, an analysis processing unit 7 for converting the measured interference image into a wavefront map, a storage processing unit 8 for holding or storing the measured liquid level maps, an arithmetic process for performing a predetermined calculation on a plurality of measured liquid level maps It has a part 9. These may be integrally formed, or may be separately formed.

The light emitted from the laser light source 10 is split at the reference surface of the mirror 11 into two optical paths, a reference optical path and a test optical path a. The test optical path a is emitted from the interferometer 1 to the outside and enters the test lens 2. The lenses 2 and 3 to be inspected, which are arranged in a facing manner, are configured to be rotatable about the optical axis. The parallel luminous flux a is converted into a luminous flux b having a high NA through the lens 2 to be inspected by the facing method, and is converted into a luminous flux c via the lens 3 to be inspected. The light beam c is reflected by the plane mirror 4, passes through the lenses 2 and 3 to be inspected, and becomes the light beam a again and enters the interferometer 1. In the interferometer 1, it is possible to observe the interference image of the reference optical path and the test optical path divided by the mirror 11 by using the image sensor 5.

Here, the light beam c is a parallel light beam similar to the light beam a, but since the laser beam actually has a spread,
It is not always a parallel light flux. Therefore, the lens 3 under test
When the plane mirror 4 is too far away from the lens 3 to be inspected and the light reflected by the plane mirror 4 is not the same as the light emitted from, the phenomenon that the peripheral image is out of focus in the interference image observed by the image sensor 5 may occur. To be observed. Therefore, in order to reflect the emitted light to the test lens 3 as necessary and sufficient, it is desirable that the plane mirror 4 be as close to the test lens 3 as possible.

The phase shift method is described in detail in "Introduction to Applied Optical Optical Measurement" by Toyohiko Yatagai (pp. 131-135, Maruzen Co., Ltd.). In this method, for example, FIG.
In the interferometer 1, the interference intensity can be changed by minutely moving the reference surface of the mirror 11 by using a piezo element or the like, and a plurality of interference images are captured to obtain the wavefront distribution (or phase distribution) of the object to be inspected. Is to measure
It enables highly accurate interference measurement.

The inspected lenses to be measured are three objective lenses for infinity correction of the same kind for microscopes, and their transmitted wavefronts are Wa, Wb, and Wc, respectively. Alignment marks are attached to the outer circumferences of the respective objective lenses, and when the objective lenses 2 and 3 are attached like the alignment marks, they are rotated so that the alignment marks match. The measurement is performed three times using the interferometer 1 and the measurement processing unit 6 of the measurement calculation processing unit 13 by combining the objective lenses so that W1 = Wa + Wb W2 = Wb + Wc W3 = Wa + Wc (2). Each of these interference fringe data is analyzed using the analysis processing unit 7 for each measurement and converted into the transmitted wavefront maps W1 to W3,
It is stored in the storage processing unit 8. The measurement transmitted wavefronts W1 to W3 are processed by the arithmetic processing unit 9 as follows: Wa = (W1 + W3-W2) / 2 Wb = (W1 + W2-W3) / 2 Wc = (W2 + W3-W1) / 2 (3) It is separated into the transmitted wavefront of the objective lens. The held measurement wavefronts W1 to W3 may be matrix data by the image sensor 5 or Zernike coefficients.

In the matrix data, the pixel data corresponding to W1 to W3 may be calculated, and on the other hand, Ze
With the rnike coefficient, only the calculation of each term coefficient is performed, so the amount of data is small and it is simple. The evaluated aberration components are mainly spherical aberration, coma and astigmatism, but symmetrical aberration components are spherical aberrations, asymmetrical aberration components are coma aberrations,
It is astigmatism. If the alignment mark is set at a common position during the measurement of W1 to W3, the asymmetrical aberration component is not canceled and the formula (3) can be directly calculated, which is simple.

By converting the data of these objective lenses into a liquid level map again, it becomes possible to measure with high accuracy and evaluate and analyze even a high-performance optical lens. Further, the expressions (2) and (3) are included in the measurement of the permeation liquid surface Wa of one objective lens during a plurality of measurements, and if the measurements are W1 to W3, Wa can be calculated. Further, even a finite objective lens can be applied by inserting a lens that converts convergent light into parallel light.

(Second Embodiment) FIG. 6 shows a second embodiment of the present invention. The interferometer 1 is a Twyman-Green type, and has a laser light source 10 such as a He-Ne laser, a mirror 11 having a reference surface, a piezo element 12 for moving the mirror 11, and an image sensor 5 for detecting interference fringes. . The measurement calculation processing unit 13 has a function similar to that of the unit used in the first embodiment.

The light emitted from the laser light source 10 is split by the beam splitter incorporated in the interferometer 1,
There are two optical paths, the reference optical path and the test optical path a. The test optical path a is emitted from the interferometer 1 to the outside and enters the test lens 2.
Similar to the first embodiment, the opposed type test lenses 2 and 3 are configured to be rotatable about the optical axis, and the parallel light flux a is a high NA light flux b through the test lens 2. Is converted into a light beam c through the lens 3 to be inspected. The light beam c is reflected by the plane mirror 4. Also in this embodiment, the plane mirror 4 is placed close to the lens 3 to be inspected in order to observe the interference image well. The light beam c becomes the light beam a again through the lenses 2 and 3 to be inspected and enters the interference 1.
In the interferometer 1, it is possible to observe the interference image of the reference optical path and the test optical path divided by the mirror 11 by using the image sensor 5.

The lenses to be measured are two types of objective lenses for microscopes of infinity correction of the same kind, and their transmitted wavefronts are Wa and Wb, respectively. At this time, Wb is assumed to be known using the method of the first embodiment or this configuration. Alignment marks are provided on the outer circumferences of the respective objective lenses, and when the objective lenses 2 and 3 are opposed to each other, they are rotated so that the alignment marks are aligned. The measurement is performed only once by using the interferometer 1 and the measurement processing unit 6 of the measurement calculation processing unit 13 so that W = Wa + Wb (5). Each of these data is analyzed by the analysis processing unit 7 for each measurement, converted into a wavefront map, and stored in the storage processing unit 8. The measured transmitted wavefront W is subjected to the processing of Wa = W−Wb (4) in the calculation processing portion 9, and the transmitted wavefront Wa of the objective lens is separated. Similar to the first embodiment, the stored measurement wavefront W is the same as the Zernike matrix data obtained by the image sensor 5.
Although it may be a coefficient, it is necessary to match the data holding method of Wb because there is a calculation of W and Wb. Further, if the aberration component to be evaluated is also set to have the Wb alignment mark at a common position with known data, the same effect as that of the first embodiment can be obtained, and the calculation can be easily performed by the equation (4). be able to.

Thus, for example, when measuring four or more objective lenses, one set of three lenses is measured by the method as in the first embodiment, and the remaining one is more simply and highly accurately in this embodiment. It can be measured and can be evaluated and analyzed. The first and second
The embodiment is not limited to the above-described embodiment, and the interferometer 1 is only required to generate and detect interference fringes, and the same effect can be obtained by using any type. For example, if a Mach-Zehnder interferometer is used, interference fringes can be generated without using the plane mirror 4 because the lens under test has an afocal configuration.

Similarly, the measurement is not limited to the phase shift method, and the interference fringes may be measured, that is, the wavefront map can be calculated analytically. For example, a conventional method is a fringe analysis method. In the above embodiments, an example of a microscope objective lens is shown, but the analysis and evaluation apparatus according to the present invention can be easily applied to any optical system having the same specifications as the objective lens. For example, it can be applied to a stepper lens or a camera lens with a small F number.

(Third Embodiment) FIG. 7 shows an analysis / evaluation apparatus according to the third embodiment. The interferometer 1 and the measurement arithmetic processing unit 13 connected to the interferometer 1 have the same configuration as that shown in the first or second embodiment. The optical path a to be inspected emitted from the interferometer 1 enters the inspected lenses 2 and 3 of the opposed type. As described above, the light beam c emitted from the lens 3 to be inspected has a spread as shown in FIG. For this reason,
The concave mirror 4 having a very gentle radius R causes the light beam c
When arranged inside, the light flux reflected by the concave mirror 4 is effectively incident on the lens 3 under test again. Radius R is concave mirror 4
Is set so that the light beam c is reflected in the vicinity of the pupil surface or the diaphragm surface of the lens under test. As a result, as in the first and second embodiments, it is possible to observe accurate interference fringes in the image sensor 5 inside the interferometer 1 without causing focus deviation to the periphery.

(Fourth Embodiment) FIG. 8 shows an analysis and evaluation apparatus according to the fourth embodiment. The interferometer 1 and the measurement calculation processing device 13 connected to the interferometer 1 are the same as those in the third embodiment. In the first to third embodiments, the reason why the interference image is not properly focused is that the light flux c is not parallel light and that the image forming relationship up to the image pickup element 5 is broken. That is, the plane mirror 4 of FIG. 1 and the pupil planes of the lenses 2 and 3 to be inspected do not have a conjugate positional relationship.
Therefore, also in this embodiment, as shown in FIG.
By inserting the afocal system in the light beam c, the plane mirror in the reference means 4 and the pupil planes of the lenses 2 and 3 to be inspected have an optically conjugate positional relationship. Here, if the afocal system is configured to have an NA smaller than the NA of the lens to be inspected, the light beam c reflected by the reference means 4 enters near the pupil plane or diaphragm surface of the lens to be inspected, which is more effective. In addition, accurate interference fringes can be observed.

(Fifth Embodiment) FIG. 9 shows an analysis / evaluation apparatus according to the fifth embodiment. The test lenses 2 and 3 measured by the facing method are objective lenses for a biological microscope. Interferometer 1
And the measurement processing unit 13 connected to the interferometer 1 is the third
And the same as the fourth embodiment. In this embodiment, a plane-parallel plate 14 and a mounting jig 15 that supports the plane-parallel plate 14 are provided.

Most of the objective lenses for living organisms use a cover glass. When such an objective lens is used in a facing manner, as shown in FIG. 9, a parallel flat plate having a thickness of two cover glasses is used. The face plate 14 may be inserted using the attachment jig 15. In particular, since the plane-parallel plate 14 is inserted into a high NA light flux, a mounting jig 15 that can adjust the inclination and position is preferable.

Many biological objective lenses are of the immersion type. When measuring such objective lenses, an immersion medium 16 (water, special oil, etc.) is used as shown in FIG. It may be inserted between the plane-parallel plate 14 and each of the lenses 2 and 3 to be inspected. In this case, since the objective lens generally has a short working distance, the objective lenses are held so as to face each other by the surface tension of the medium 16.

When the working distance is long, a holding member 17 for holding the immersion medium 16 may be provided as shown in FIG. As the holding member 17, as shown in FIG. 12A, a tubular member having a hole for inserting the medium 16 and made of rubber or another elastic material is used. If the holding member 17 is made slightly longer than the working distance of the objective lens, it can be fixed by pressing between the objective lenses. In addition, as shown in FIG.
Only the portion 17a contacting the objective lens may be made of an elastic material. The portion 17b sandwiched between the portions 17a of the holding member 17 can be made of a rigid material such as metal or plastic. The plane-parallel plate 14 is shown in FIG.
Not only can it be attached as described above, but the holding member 17 can be configured to be supported if necessary. In that case, the positioning may be performed with reference to the contact surface or the like.

Furthermore, in the case of an objective lens having a long working distance and no cover glass, an integral holding member 17 as shown in FIG. 13 can be used. In this case, since the volume of the holding member 17 is larger than that in the case of FIG. 11, the handling becomes easier. Further, as shown in FIGS. 12 (c) and 12 (d), a holding member 18 of a type fitted to the outer periphery of the objective lens can be used.

As described above, according to this embodiment, various microscope objective lenses can be measured. Further, in order to facilitate the insertion of the immersion substance, the holding member 17,
It is preferable to provide a hole on the outer circumference of 18.

As is apparent from the above description, the optical lens analysis / evaluation apparatus according to the present invention can be configured as follows in addition to those described in the claims. (1) The optical lens has the coordinate system in a plane perpendicular to the optical axis, and each of the optical lenses is relatively rotatable about the optical axis. Analytical evaluation device for optical lenses.

(2) When the number of optical lenses to be measured is two, these two optical lenses are arranged so as to face each other, and are located near the pupil plane or diaphragm surface of at least one of the optical lenses. The optical lens analysis and evaluation apparatus according to claim 1, further comprising a reference unit arranged to reflect the transmitted light or the transmitted wavefront. (3) There are at least three or more optical lenses to be measured, and two optical lenses to be measured are selected from each of these three optical lenses. Analysis and evaluation device for lenses.

(4) Transmitted light or transmitted wavefronts W1, W2, W3 measured by recombining the optical lenses, and one transmitted wavefront W of the optical lens, and the calculation in the processing means is expressed by the equation (1). The optical lens analysis / evaluation apparatus according to claim 1, wherein W = (W1 + W2-W3) / 2 (1)

(5) Transmitted wavefronts Wa, Wb, Wc of the optical lenses measured with at least three optical lenses as a set
And the measured transmitted light and the transmitted wavefronts W1, W2 and W3 have the relationship of the following equation (2), W1 = Wa + Wb W2 = Wb + Wc W3 = Wa + Wc (2) The calculation in the processing means is the following (3). The optical lens analysis / evaluation device according to (4), wherein Wa = (W1 + W3-W2) / 2 Wb = (W1 + W2-W3) / 2 Wc = (W2 + W3-W1) / 2 (3)

(6) In the transmitted wavefronts Wa, Wb, --- of at least two or more optical lenses, the following formula (1) is satisfied.
b, and the transmitted light and the transmitted wavefront W that have been measured, and the calculation in the processing means is expressed by equation (4). Wa = W-Wb (4) (7) The optical lens analysis and evaluation apparatus according to claim 1 or 4, wherein the optical lens is a microscope objective lens.

(8) The optical lens analysis and evaluation apparatus according to claim 1, wherein a parallel plate is arranged between the optical lenses so as to be detachable and positionally adjustable. (9) The optical lens analysis and evaluation apparatus according to claim 1, further comprising a member for holding an immersion medium inserted between the optical lenses. (10) The optical lens analysis / evaluation apparatus according to any one of (4) to (6), wherein the transmitted wavefront to be measured and the transmitted wavefront of the subject lens to be calculated are approximated to a Zernike polynomial. .

[0054]

As described above, according to the optical lens analysis / evaluation apparatus of the present invention, the transmitted wavefront of a high-performance and high-precision optical lens can be measured and evaluated with high accuracy even if an interferometer is used. You can Further, the optical lens analysis and evaluation apparatus according to the present invention can be applied to so-called general interference, and can be applied to various optical lenses (in particular, microscope objective lenses).

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the outline of an optical lens analysis and evaluation apparatus according to the present invention.

FIG. 2 is a schematic diagram showing an example of a reference unit.

FIG. 3 is a schematic view showing another example of the reference means.

FIG. 4 is a schematic view showing an example of a holding member.

FIG. 5 is a configuration diagram of a first embodiment of an optical lens analysis and evaluation apparatus according to the present invention.

FIG. 6 is a configuration diagram of a second embodiment of an optical lens analysis and evaluation apparatus according to the present invention.

FIG. 7 is a configuration diagram of a third embodiment of an optical lens analysis and evaluation apparatus according to the present invention.

FIG. 8 is a configuration diagram of a fourth embodiment of an optical lens analysis and evaluation apparatus according to the present invention.

FIG. 9 is a configuration diagram of a fifth embodiment of the analysis / evaluation apparatus for an optical lens according to the present invention.

FIG. 10 is a schematic diagram of an embodiment using an immersion medium.

FIG. 11 is a schematic view of an embodiment in which an immersion medium is held in a holding member.

FIG. 12 is a schematic view showing a modified example of a holding member.

FIG. 13 is a schematic view showing another modified example of the holding member.

FIG. 14 is a schematic diagram of a conventional method for measuring an objective lens.

FIG. 15 is a conceptual diagram of a conventional method for measuring an objective lens.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Interference fringe generating means 2 Test lens 3 Test lens 4 Reference means 5 Light receiving means 6 Measuring means 7 Analyzing means 8 Storage means 9 Processing means 10 Laser light source 11 Mirror 12 Piezo element 13 Measurement arithmetic processing unit 14 Parallel plane plate 15 Mounting Jig 16 Immersion substance 17 Holding member

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] February 26, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0025

[Correction method] Change

[Correction contents]

In interferometry, it is common to approximate the analyzed wavefront distribution to an aberration function. A particularly popular one is the Zernike polynomial, which is Max Born and Emil Wolf:
"Principles of Optics II" ( (Tokai University Press, 1991,)
Pp. 691-713). Zernike polynomials are Standard Zernike and Fringe Z
The Fringe Zernike is often used in interference measurement because of its simplicity. Zernike polynomials are normalized pupil plane of the optical system within the unit circle, a radius ρ and the angle θ with the origin as a peak, each aberration component to represent in series expansion, can be evaluated analytically. Further, the above-mentioned image data or matrix data has a large amount of data, and an error is likely to occur in the measurement area, which causes a problem in matching when performing calculation. The Zernike polynomial has coordinate axes with the origin as a reference, and can improve the correspondence with marking and the reliability of calculation. Furthermore, the necessary data is only the coefficient of each term of the polynomial, which is preferable because the amount of data and the calculation time can be reduced. However, since the aberration component is expanded into a polynomial, high frequency components (mostly noise) that appear during actual measurement are likely to be cut.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0040

[Correction method] Change

[Correction contents]

(Third Embodiment) FIG. 7 shows an analysis / evaluation apparatus according to the third embodiment. The interferometer 1 and the measurement arithmetic processing unit 13 connected to the interferometer 1 have the same configuration as that shown in the first or second embodiment. The optical path a to be inspected emitted from the interferometer 1 enters the inspected lenses 2 and 3 of the opposed type. As described above, the light beam c emitted from the sample lens 3 has a spread such as shown in FIG. For this reason,
The concave mirror 4 having a very gentle radius R causes the light beam c
When arranged inside, the light flux reflected by the concave mirror 4 is effectively incident on the lens 3 under test again. Radius R is concave mirror 4
Is set so that the light beam c is reflected in the vicinity of the pupil surface or the diaphragm surface of the lens under test. As a result, as in the first and second embodiments, it is possible to observe accurate interference fringes in the image sensor 5 inside the interferometer 1 without causing focus deviation to the periphery. ─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] February 26, 1996

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Figure 9

[Correction method] Change

[Correction contents]

[Figure 9]

Claims (1)

[Claims] 1. An interference fringe generating unit, at least two optical lenses which are lenses to be inspected when the interference fringe generating unit generates an interference fringe, an interference fringe light receiving unit, and an interference fringe light receiving unit. Measuring means for measuring interference fringes, analyzing means for analyzing the interference fringes measured by the measuring means, storage means for storing the interference fringes analyzed by the analyzing means, and interference stored by the storing means. An optical lens analysis, which is provided with processing means for performing a predetermined calculation on the stripes, and the optical lenses to be measured each have a relatively unique coordinate system and are held in a fixed positional relationship. Evaluation device.