JP2010032549A - Lens holding device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely hold a lens without using a driving mechanism of large scale such as a motor, an air cylinder and the like, in the case of adjusting eccentricity of a lens. <P>SOLUTION: The amount of the eccentricity of the lens can be obtained as follows: a Hartmann plate is arranged between a lens system and a light source; light from the light source is made incident on the lens system through a plurality of small holes arranged on the Hartmann plate in a point symmetry; the Hartmann image is utilized obtained by the light passed through the lens system; and regarding to the plurality of spot positions of the Hartmann image, the eccentricity of a lens can be obtained by calculating the components equivalent to coma aberration from a distribution of spot positions. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an eccentricity measuring method and an eccentricity adjusting device, and more particularly to measuring the eccentricity of a lens in an assembly process of an assembled lens and adjusting the eccentricity of a lens based on the measured eccentricity. The present invention relates to a lens gripping device that grips the lens so that its eccentricity can be adjusted.

  In a combined lens composed of a plurality of lenses, the lens may be decentered such as shifting or tilting in the direction perpendicular to the optical axis. Removal of this decentering is necessary to maintain the performance of the lens optical system. It is an important element.

  As represented by high-definition cameras and compact cameras, severe eccentricity tolerances are demanded as lens systems have been improved in performance and image quality in recent years. Also, the general use of aspherical lenses is a factor that requires strict eccentricity tolerance.

  Compensate for the aberrations of other lenses by adjusting the decentration in the lens assembly process or actively adding minute decentration to a specific lens in situations where strict decentering tolerances are required for the lens system described above. There is an increasing demand for eccentricity adjustment such as compensation.

  In the measurement of the eccentricity of the lens system used during lens assembly, geometrical eccentricity measurement that measures the center of curvature of the lens surface to be measured by reflection eccentricity measurement and non-uniform refractive index of the lens surface itself by transmission eccentricity measurement. It has been proposed to simultaneously measure optical decentration measurement for measuring a focal point including the property (see Patent Document 1). In this Patent Document 1, a test optical element is installed on a base that can rotate an axis, a test surface of the test optical element is irradiated with light, and the test optical element is rotated by reflected light or transmitted light. An eccentricity measuring method for measuring the eccentricity of the surface to be measured by observing the movement locus of the light spot is shown.

  As a measure corresponding to the geometric eccentricity measurement, there has been proposed an eccentricity measurement method for measuring an eccentricity amount of a test surface of an optical element such as a lens (for example, see Patent Document 2). Patent Document 2 shows that eccentricity is measured by irradiating a test lens with light transmitted through two diffraction gratings that are orthogonal to each other, rotating the test lens, and imaging the focused spot of the test lens. Has been.

  Further, as a measure corresponding to the optical eccentricity measurement, there has also been proposed an eccentricity measurement method for measuring an eccentricity amount of a test surface in an optical element using transmitted light (see, for example, Patent Document 3).

JP 2007-017431 A Japanese Patent Laid-Open No. 2006-3489 Japanese Patent Laid-Open No. 11-287615

Lens design method (first edition, 6th edition, 1987) Matsuya Yoshiya Kyoritsu Publishing Co., Ltd., page 81

  In an optical system, actual image formation through the optical system due to various causes causes a shift called aberration from an ideal image formation. Aberrations that disturb the imaging performance of the optical system are classified into chromatic aberrations that occur due to differences in color wavelengths and monochromatic aberrations that occur in monochromatic light. Furthermore, monochromatic aberrations are classified into spherical aberration, coma aberration, astigmatism, field curvature, and distortion aberration, if limited to the third-order aberration (Seidel aberration) having the lowest order.

  Among these, coma aberration is a combination of light passing through the center and light passing through the peripheral part of a group of light rays obliquely incident on the entrance pupil, with the light rays coming from off-axis object points not gathering at one point on the image plane. It is a phenomenon that does not converge on a single point on the image plane.

  The inventor of the present application can handle this eccentricity as coma aberration when the lens is decentered by shifting with respect to a direction perpendicular to the optical axis in a lens system including a combined lens composed of a plurality of lenses. I paid attention to.

  Measuring the coma aberration caused by the decentering of the lens from the optical axis in a short time with high accuracy is an important factor for improving the accuracy and efficiency of adjusting the axis of the assembled lens.

  The conventional decentration measurement shown in Patent Documents 2 and 3 has the following problems. Therefore, when measuring coma aberration that occurs when the lens is decentered from the optical axis. However, it cannot be said to be preferable in terms of accuracy, measurement time, and efficiency of adjusting the eccentricity.

  For example, the eccentricity measuring method for measuring geometric eccentricity disclosed in Patent Document 2 described above includes the following problems.

(A) Since the eccentricity measurement is a method of measuring the eccentricity from the shape of the surface to be measured, the optical characteristics are not directly measured.
(B) Since the eccentricity measurement measures the lens eccentricity one by one, there is a problem that the efficiency of measurement and adjustment is low.
(C) Since it is necessary to take into account the influence of the lens on the assumption of the optical model, the decentration amount measurement of the lens incorporated in the assembled lens composed of a plurality of lenses must be taken into consideration. There is a problem that the deviation from the aspect affects the measurement accuracy.
(D) When transmitted light is used in the decentration measurement, there is a problem that high measurement accuracy cannot be expected due to spherical aberration generated from a single lens.

  According to the eccentric amount measurement for measuring the optical eccentricity shown in Patent Document 3 described above, although some of the problems caused by using the reflected light are eliminated, this eccentric amount measurement is performed on the lens surface. Measures the geometric shape of the lens, which is the amount of deviation between the center of curvature of the lens and the center axis of the lens, and measures the coma aberration that occurs when the lens of the assembled lens is decentered from the optical axis It also includes the following problems.

(E) Since it is necessary to rotate the lens, it is required to rotate the rotating shaft with high accuracy.
(F) Since the total amount of eccentricity is measured, a specific adjustment amount for adjusting the lens cannot be obtained, and adjustment takes time.

  Therefore, in the conventionally proposed eccentricity measurement, it is preferable to measure coma aberration caused by the eccentricity of the lens from the optical axis with high accuracy and to adjust the eccentricity with high efficiency. Needless to say, the eccentricity measurement has a problem in terms of measurement accuracy. Further, the eccentricity adjustment using the measured eccentricity has a problem in terms of adjustment efficiency.

  An object of the present invention is to provide a lens gripping device capable of holding a lens without using a complicated and large driving mechanism such as a motor or an air cylinder when adjusting the eccentricity of the lens.

  The present invention relates to an eccentricity measuring method for measuring the eccentricity of at least one lens of a combined lens and an eccentricity adjusting device for adjusting the eccentricity of the lens, and the lens is eccentric from the optical axis. The eccentricity from the optical axis of at least one lens of the assembled lens is adjusted on the basis of the amount of eccentricity measured from the coma aberration that occurs.

  The present invention uses an image (hereinafter referred to as a Hartmann image) obtained by a light beam that has passed through a Hartmann plate incident on a combined lens and emitted from the combined lens, and a plurality of spot positions of the Hartmann image. , The amount of decentration of the lens is obtained by calculating a component corresponding to coma from the distribution of spot positions.

  By using a Hartmann image, the amount of decentering of coma aberration that occurs when the lens is decentered from the optical axis without requiring many steps such as measuring the decentering of the lens one surface at a time. Can be obtained with a small number of measurements. Furthermore, the eccentric amount can be adjusted with high efficiency by moving the lens using the eccentric amount.

  In the eccentricity measuring method of the present invention, a Hartmann plate is disposed between the lens system and the light source, and light from the light source enters the lens system through a plurality of small holes arranged symmetrically with the Hartman plate. . The light incident on the Hartmann plate is shielded except for the small holes, and only the light that has passed through the small holes in the Hartmann plate is incident on the assembled lens, and the light emitted from the assembled lens is decentered in the lens of the assembled lens. Follow the corresponding trajectory.

  The spot position on the acquired Hartmann image corresponds to the position where a plurality of light beams that have passed through the plurality of small holes in the Hartmann plate are incident on the imaging surface, and is formed by a point-symmetric small hole made up of each of the plurality of spot positions. The amount of deviation of the center of gravity between the plurality of spot groups thus formed depends on the amount of eccentricity of the lens.

  In the eccentricity measuring method of the present invention, a plurality of spot groups composed of a plurality of spots are set, and the deviation of the center of gravity between these spot groups is obtained.

  The plurality of point-symmetrical small holes of the Hartmann plate are arranged so that the center of gravity of the plurality of small holes coincides with the center of the Hartmann plate, and are arranged inside and outside the center to be point-symmetric. An inner small hole group and an outer small hole group made of a plurality of small holes are formed.

  In the eccentricity measurement according to the present invention, the position of the spot corresponding to each small hole is calculated from the signal intensity of the acquired Hartmann image, and the centroid position of the inner spot group corresponding to the inner small hole group (hereinafter referred to as the inner centroid position). And the centroid position of the outer spot group corresponding to the outer small hole group (hereinafter referred to as the outer centroid position). The amount of lens eccentricity is obtained from the amount of deviation between the calculated inner centroid position and outer centroid position.

  Deviations can be obtained from a minimum of three spots as a plurality of spots. The plurality of point-symmetrical small holes of the Hartmann plate are arranged at three points: a central point of the Hartmann plate and two points having the center point as a point-symmetrical center.

  In the eccentricity measurement of the present invention, the lens is determined based on the amount of deviation between the midpoint of the image position corresponding to two points on both ends of the spot corresponding to the small hole of the point-symmetrical Hartmann plate and the spot position corresponding to the central small hole of the Hartmann plate. The amount of eccentricity can be determined.

  In an aspect in which the position deviation is obtained using the center of gravity of the spot position, a predetermined proportionality coefficient depending on the lens system is used between the calculated position deviation amount of the center of gravity and the lens eccentricity when the eccentricity is small. Since there is a fixed proportional relationship, the lens eccentricity can be obtained by multiplying the calculated displacement amount of the center of gravity by a predetermined proportional coefficient.

  The first embodiment of the eccentricity measuring apparatus of the present invention has passed through a Hartmann plate having a plurality of small holes arranged symmetrically with point, light source means for irradiating light to the Hartmann plate, and a small hole in the Hartmann plate. An image processing unit that captures light that has passed through the lens system; and an image processing unit that determines the positions of spots formed by the plurality of light beams that have passed through the plurality of small holes in the Hartmann plate based on the Hartmann image captured by the image capturing unit. And a calculating means for extracting a component corresponding to the coma aberration from the calculated distribution of the plurality of spot positions and converting the extracted component into a lens decentering amount.

  Further, the second form of the eccentricity measuring device of the present invention has a light source means, an image pickup means, and an image processing means, as well as the first form. An inner small hole group and an outer small hole group each having a plurality of point-symmetrical small holes are formed so as to be point-symmetric with respect to the center of the plate and doubled inside and outside the center. The computing means of the second form includes an inner center-of-gravity position of a plurality of spot positions forming an inner spot group corresponding to the inner small hole group and an outer side of the plurality of spot positions forming an outer spot group corresponding to the outer small hole group. The center of gravity position is calculated, the coma due to the decentering of at least one lens in the lens system from the optical axis is determined from the amount of deviation between the inner center of gravity and the outer center of gravity, and the amount of eccentricity is calculated from the calculated coma. To do.

  Further, the third form of the eccentricity measuring device of the present invention has a light source means, an image pickup means, and an image processing means, as well as the first form, and the Hartmann plate has a plurality of small holes, They are arranged at three points: the center point of the plate and two points with the center point as the center of point symmetry. The computing means of the third form calculates the lens eccentricity from the amount of deviation between the midpoint of the line segment between the two spot spots formed by the small holes at both ends of point symmetry and the spot obtained by the small hole at the center point. .

  In this configuration, the image pickup means is assembled by the driving means and moved in the optical axis direction of the lens, thereby adjusting the position of the image pickup surface to acquire a Hartmann image on a different image pickup surface, and using a Hartmann image on a different image pickup surface. The data used for the eccentricity calculation can be acquired.

  The eccentricity adjusting device of the present invention includes a Hartmann plate having a plurality of small holes arranged symmetrically with point, light source means for irradiating light to the Hartmann plate, and passing through a small hole in the Hartmann plate and then passing through the lens system. Based on the Hartmann image captured by the imaging means for capturing the image of the light, the eccentricity adjustment driving means for moving at least one lens in the lens system in the direction orthogonal to the optical axis direction, and the Hartmann image captured by the imaging means Image processing means for determining a spot position formed by a plurality of light beams that have passed through a plurality of small holes in the plate, and coma aberration caused by decentering of at least one lens provided in the lens system from the optical axis from the amount of deviation of the spot position Calculating means for calculating the lens eccentricity corresponding to.

  In this configuration, the eccentricity adjusting driving means adjusts the eccentricity of the lens included in the lens system by moving the lens by the lens eccentricity obtained by the computing means.

  Since the decentration adjustment device of the present invention can accurately calculate the coma aberration, the decentration adjustment is performed with a small number of decentering adjustments or compensation is performed so that the coma aberration of the entire system is minimized. Can do.

  Furthermore, the eccentricity measuring device and the eccentricity adjusting device of the present invention have a configuration for gripping a target lens in order to measure or adjust the eccentricity of the lens. The lens gripping device includes a frame portion that surrounds the periphery of the opening that houses the lens system, and a lens pressing portion that touches the outer periphery of the lens included in the lens system and grips the lens.

  The lens pressing portion includes a plurality of pressing pins that come into contact with the lens, a support portion that supports at least one pressing pin of the plurality of pressing pins so as to be slidable with respect to the frame portion, and the support portion is elastic with respect to the frame portion. And a holding portion for holding the holding end of the spring portion on the frame. In a state where no external force is applied to the spring portion, the spring portion holds the support portion and the pressing pin in place by the elasticity of the spring portion. On the other hand, in the state where the external force is applied to the spring portion, the spring portion The support part and the pressing pin are moved in the direction of the opening by elastic deformation of the part. The lens can be gripped by bringing a plurality of pressing pins into contact with the outer periphery of the lens.

  According to said each aspect, the following effects are acquired.

  The amount of eccentricity is calculated based on the spot position obtained by imaging the light that has passed through the Hartmann plate on the imaging surface. The amount of computation required to calculate the amount of eccentricity depends on the number of spots obtained from the Hartmann image, so reducing the number of small holes in the Hartmann plate reduces the amount of computation required to calculate the amount of eccentricity. Time can be shortened.

  In the present invention, the amount of eccentricity can be calculated as long as there are at least three spot positions. Since the number of spot positions is small, the spot positions can be easily separated and the measurement accuracy can be improved.

  According to the lens gripping device of the present invention, by using the elastic force of the spring member as the driving force of the holding pin that grips and holds the lens, a complicated and large driving mechanism such as a motor or an air cylinder is not used. Can be configured.

  In the eccentricity adjusting device, it is necessary to provide a mechanism for supplying an adhesive to a gap between the lens and the lens frame and a mechanism for solidifying the adhesive close to the lens, and a space for providing a mechanism for gripping the lens is limited. Yes. Therefore, the lens can be gripped even in a limited space by using the lens gripping device having the configuration of the present invention.

  According to the lens gripping device of the present invention, when adjusting the eccentricity of the lens, the lens can be securely gripped without using a complicated and large drive mechanism such as a motor or an air cylinder.

  In addition, according to the decentering adjustment device of the present invention, in the decentering adjustment, the coma aberration generated when the lens is decentered from the optical axis and the lens decentering amount that causes the lens are measured with high accuracy. High adjustment efficiency can be obtained.

It is a figure which shows the parameter of a 3rd aberration expansion type | formula. It is a figure for demonstrating the shift | offset | difference of ay direction. It is a figure for demonstrating the optical system comprised from two thin lenses. It is a figure which shows the eccentric state of the optical system comprised by two thin film lenses. It is a figure for demonstrating a lateral aberration curve. It is a figure for demonstrating a lateral aberration curve. It is a figure for demonstrating the aberration which a light ray generate | occur | produces with lens eccentricity. It is a figure for demonstrating the path | route of the light ray of the Hartmann test | inspection of this invention. It is a figure for demonstrating an aberration. It is a figure for demonstrating the example of arrangement | positioning of the small hole of a Hartmann board. It is a figure for demonstrating the example which has arrange | positioned the Hartmann board in the position of the entrance pupil plane of a lens system. It is a figure for demonstrating the outline | summary of the optical image system in the eccentric amount measurement of this invention. It is a flowchart for demonstrating the outline algorithm which calculates | requires the eccentric amount of a lens from the Hartmann image which imaged the Hartmann pattern of this invention. It is a flowchart for demonstrating derivation | leading-out of the lens eccentric amount of this invention. It is a figure for demonstrating calculation of the best image surface. It is a figure which shows the relationship between lens eccentricity and the position shift of a spot position. It is a figure which shows the spot image of a Hartmann image. It is a schematic block diagram of the eccentricity measuring apparatus and eccentricity adjustment apparatus of this invention. It is a figure for demonstrating the installation state of the correction lens which attached the workpiece | work of this invention. It is a figure for demonstrating the installation state of the correction lens which attached the workpiece | work of this invention. It is a figure for demonstrating the attachment or detachment state with respect to the correction | amendment lens of the workpiece | work of this invention. It is a figure for demonstrating one structural example of the correction lens of this invention. It is a figure for demonstrating the operation example of the correction lens of this invention. It is a perspective view of the lens holding | suppressing part of this invention. It is sectional drawing of the lens holding | suppressing part of this invention. It is a figure which shows the structural example of the assembled lens used for the Example of eccentricity adjustment of this invention. It is a figure which shows the example of the lateral aberration in the structural example of this invention. It is a figure which shows the example of the displacement of the gravity center position by eccentricity of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, an outline of measuring coma aberration generated when the lens is decentered from the optical axis using the Hartmann image of the present invention will be described with reference to FIGS. 1 to 11, and from the Hartmann image obtained by imaging the Hartmann pattern. An algorithm for obtaining the amount of eccentricity of the lens will be described with reference to FIGS. 12 to 17, and examples of the configuration of the eccentricity measuring device and the eccentricity adjusting device of the present invention will be described with reference to FIGS. This embodiment will be described with reference to FIGS.

  An outline of measurement of the amount of eccentricity of coma aberration will be described with reference to FIGS. When the lens included in the lens system 20 including the combined lens is decentered, aberration occurs in the light beam passing through the lens system. The present invention pays particular attention to coma that is sensitive to decentration, and this coma is simplified by using a Hartmann plate with a small number of small holes as much as possible, improving measurement accuracy, measuring efficiency of decentering, and Improve adjustment efficiency.

[Eccentricity and coma]
The relationship between decentration and coma will be described. A combined lens composed of a plurality of lenses is designed so that the aberration is sufficiently small so that the image is not blurred as much as possible in an imaging or projection application such as a camera or a projector.

In a region where the aberration is small, the magnitude is generally expressed by the following expression as a development expression of the third-order aberration.

  The details of the above formulas (1) and (2) are described in Non-Patent Document 1. Here, the direction of the optical axis is represented by z, and the direction orthogonal to the optical axis direction z is represented by x and y.

FIG. 1 is a diagram showing parameters of a third-order aberration expansion equation. The entrance-side surface of the lens system 20 is an entrance pupil plane 31 and the exit-side surface is an exit pupil plane 32. In the above formulas (1) and (2), I _{j to} V _j in the formula (1) represent Seidel aberration coefficients by the j-th lens among the lenses constituting the lens system 20 of the combined lens, and Σ Indicates that the aberrations produced by each lens are summed for all lenses.

Here, when parallel rays parallel to the optical axis are incident on the lens system 20 including the combined lens, (N ₁ tan ω) = 0 because ω = 0. Therefore, Δx and Δy in equations (1) and (2) are “0” except for the first item.

  Hereinafter, the aberration in the y direction will be described. FIG. 2 is a diagram for explaining y-direction aberration. As shown in FIG. 2, focusing only on the aberration Δy in the y direction, assuming that the incident ray is only in the yz plane, and introducing an optical axis height H satisfying −R ≦ H ≦ R, the aberration is expressed by the formula ( It is expressed by setting Φ = 0 in the first item of 1).

  Here, for simplification, j = 1, 2 will be described based on an optical system composed of two thin lenses 21, 22 as shown in FIG.

The distance from the optical axis of the light beam of the first lens 21 and the second lens 22 is the optical axis height H ₁ and the optical axis height H ₂ , the distance between the two lenses is d, and the focal length of the first lens 21 is Assuming f ₁ , the aberration Δy is expressed by the following equation (3).

In FIG. 3, H, H ₁ , and H ₂ are positive values when they are above the optical axis and negative values when they are below the optical axis. The aberration Δy shown in Expression (3) is shown for an optical system without decentering.

  Next, a case where eccentricity occurs will be described. FIG. 4 is a diagram showing an eccentric state of an optical system composed of two thin film lenses (lenses 21 and 22).

Aberration Δy when eccentricity of ΔH along the y-direction is generated 'in the second lens 22 of the optical system described above, the constant by replacing with H ₂ of formula (3) (H ₂ - [Delta] H) kappa Is expressed by the following equation (4).

The aberration Δy ′ expressed by the above equation (4) indicates that the aberration of the second item proportional to H ² is added to the aberration Δy of the first item by causing the lens 22 to be decentered by ΔH. .

  Equation (4) indicates that when a light ray is incident in the y plane, the same aberration as coma aberration occurs due to the eccentricity of the lens in the y direction.

Using this equation (4), for example, in an optical system with an aberration Δy (H ³ ) = 0 in the y direction, the aberration Δy ′ of ^three rays whose optical axis heights of incident light are −H, 0, and + H, respectively. When calculating
It becomes.

  Among the above three aberrations Δy ′, the incident light aberration Δy ′ when the incident light optical axis height is −H and the incident light aberration Δy ′ when the incident light optical axis height is + H both have the same value. The image is formed at the position.

  This means that the amount of eccentricity ΔH can be obtained by conversion by tracing light rays passing through both ends and the center of the lens aperture and evaluating the amount of deviation at the imaging position.

FIG. 4 schematically shows this situation, and FIG. 5 shows a lateral aberration curve. In the lateral aberration curve of FIG. 5, the horizontal axis indicates the distance H from the optical axis, and the vertical axis indicates the aberration Δy ′. Since the aberration Δy ′ at both ends is proportional to H ² , the amount of the same sign is obtained depending on whether the distance H is positive or negative.

Further, in the equation (4), considering the case where the aberration Δy (H ³ ) ≠ 0, the first item of aberration Δy (H ³ ) is proportional to H ^3, and therefore, ^three of −H, 0, + H The aberration Δy ′ of the light beam is as follows, and the lateral aberration curve is as shown in FIG.

At this time, the average aberration at both ends is
It becomes.

This average aberration is the same amount as the aberration when the aberration Δy (H ³ ) = 0. That is, even if the aberration Δy (H ³ ) remains in the state where the optical system is not decentered, the influence of the aberration Δy (H ³ ) can be eliminated by averaging the aberrations of the light rays at both ends. The amount of eccentricity can be derived from the average value.

  In FIG. 6, this decentering amount corresponds to the difference in aberration between the straight line connecting both ends of the lateral aberration curve and the center, and at least three rays that are point-symmetric about the optical axis such as the center and both ends. Indicates that the amount of eccentricity can be estimated.

  Next, in the general case where the light beam is not in the y plane, the aberration that occurs due to lens decentering will be described.

  FIG. 7 is a diagram for explaining the aberration that the light beam is caused by the lens eccentricity. FIG. 7 shows a two-element lens.

  Expressions (1) and (2) represent general expressions including a case where the incident light beam is not parallel to the optical axis (ω ≠ 0).

When the incident light beam is parallel to the optical axis (ω = 0), when the light beam is incident at an angle of φ with respect to the y direction, the aberrations Δy and Δx when there is no decentering are the following (5), It is represented by (6).

  When an eccentricity ΔH in the y direction occurs in the second lens 22, the position where the light ray hits the lens 22 is shifted by −ΔH with reference to the center of the second lens. Here, ΔH is limited to the y direction. However, as long as the axially symmetric lens configuration considered here is used, it has generality and can be applied not only to the y direction.

The aberrations Δy ′ and Δx ′ when there is eccentricity are expressed by the following equations (7) and (8) when the eccentricity ΔH is small as in the case of the equation (3). And the coma term depending on the angle φ from the incident zy plane.

The second term of each of the aberrations Δy ′ and Δx ′ represented by the equations (7) and (8) is proportional to the eccentricity ΔH,
It is shown that the same aberration as the coma aberration having a coefficient of is generated, which is the same as the aberration Δy ′ in the case where the light beam represented by the equation (4) is incident in the y plane.

  As described above, coma aberration occurs not only in the case of φ = 0 but also in φ ≠ 0. Therefore, it is not limited to the case of entering the y plane by the light beam of φ = 0, and arbitrary (R, φ) light rays are emitted. By using it, the state of eccentricity can be investigated.

  For example, when using light beams at symmetrical positions such as φ = ± 90 °, as described above, using the three light beams at both ends and the center, only the decentration is not affected by the original spherical aberration Δy. Can be calculated.

In addition, for the sake of simplicity, the two-lens configuration lens is shown in the expression (3) and after, but the aberration Δy is expressed by the following expression (9), and can be applied to an optical system having an arbitrary number of lenses of three or more. is there.

In this case, the aberration Δy ′ shown in the equation (7) can be expressed by the following equation (10), and the aberration Δy ′ accompanying the lens decentering is also proportional to H ² .

Here, ζ _j is the ratio (H / H _j ) between the incident optical axis height H and the optical axis height H _j of the light beam at the j-th lens. In addition, although said Formula (9), (10) has shown about the y direction, it is the same also about an x direction.

In the aberration [Delta] y 'of the above formula (10), the aberration amount caused by lens decentering of the second item is proportional to H ^2. This aberration component shows the same tendency as coma aberration. Hereinafter, this aberration will be referred to as coma (or simply coma) accompanying lens decentering.

  In the above description, when an eccentricity occurs in one place of the assembled lens, the purpose is to adjust the eccentricity. However, when there are two or more occurrences of coma aberration, it is possible to adjust so that the coma aberration as a whole is minimized by positively giving eccentricity to one of them. In other words, the method of the present invention can be applied as it is for the purpose of adjusting one portion of the assembled lens as a compensator so as to improve the image.

[Detection of coma aberration by Hartmann inspection]
Next, detection of coma using the Hartmann test will be described based on the relationship between the decentration and coma. In Hartmann inspection, a mask called a Hartmann plate with a small hole is placed in the middle of the lens opening or the lens on the optical axis to block the light, and the light passing through the small hole is regarded as a “light beam”. This is an inspection method for evaluating the performance of an optical system by determining the path of light rays in the optical system.

  According to the Hartmann test, by obtaining the path of the “ray”, information that is an index of the performance of the optical system, such as a spot diagram on the image plane and the minimum circle of confusion diameter, is extracted based on the aberration. be able to.

  Since this Hartmann test can determine the path of the “ray”, the situation of Seidel aberration can be examined by appropriately setting the position of the small hole. For example, as shown in FIG. 8, a shielding plate 31A in which small holes 31a are arranged in the y direction is arranged at the position of the entrance pupil plane 31 of the lens system 20, and after passing through the small holes 31a, the exit pupil plane of the lens system 20 When emitted from 32, each light beam 40 has an aberration Δy on the imaging surface 33. An aberration curve can be drawn by connecting the aberrations Δy of the respective rays 40.

FIG. 9 is a diagram showing an aberration curve obtained by connecting the aberration Δy. Since the coma is proportional to H ² as described above, as shown in FIG. 9B, when the optical axis height H of the incident light is taken on the horizontal axis and the aberration Δy is taken on the vertical axis, the aberration curve ( 9 (b) shows a convex parabola up or down.

  Therefore, the coma component can be evaluated by extracting the three points at both ends and the center of the aberration curve obtained by connecting the aberration Δy and obtaining the deviation from the straight line of these three points.

  Accordingly, the present invention provides a Hartmann plate with a total of three small holes, two points symmetrical with respect to the center point, and obtains three spot positions on the imaging surface obtained by the light passing through the small holes. The coma aberration is obtained by making the spot positions of the three points correspond to the three points at both ends and the center defining the aberration curve.

  FIG. 9A shows an example of a Hartmann plate. This Hartmann plate is provided with a total of three small holes, two points arranged symmetrically with respect to the center point in the y direction.

  FIG. 9B is a plot of spot positions obtained with the Hartmann plate having the three small holes against the optical axis height H. FIG.

  Since the three spot positions in FIG. 9B are points on the aberration curve shown in FIG. 5, the coma aberration can be obtained from the three spot positions.

  In a general Hartmann inspection, a shielding plate in which a large number of holes are formed is used in order to examine the aberration state in detail. In contrast, coma aberration measurement using the Hartmann plate of the present invention can be performed by extracting aberrations at a minimum of three points at both ends and the center of the aberration curve.

  As described above, in the detection of coma using the Hartmann inspection of the present invention, the number of small holes in the Hartmann plate can be reduced to a minimum of three points. The extracted image analysis and the derivation of the amount of aberration based on it can be performed quickly. In addition, since the Hartmann spot in the image can be easily separated, instability factors such as misidentification of the spot are reduced, so that detection with high reliability is possible.

  In the measurement according to the embodiment of the present invention, it is preferable to use three or more small holes in order to avoid statistical errors due to the small number of small holes in the Hartmann plate and improve the measurement accuracy.

  In order to satisfy this condition, for example, as shown in the arrangement example of the small holes in the Hartmann plate in FIG. 10, nine small holes are arranged in the vertical and horizontal directions, or four small holes are further arranged in an oblique direction, for a total of 13 small holes. A configuration in which is provided is preferable.

  In the arrangement example shown in FIG. 10, out of a total of 13 small holes provided in the Hartmann plate, one small hole is disposed at the center, and four small holes are disposed on the inside in a point symmetry in the x and y directions. Eight small holes are arranged point-symmetrically in the x, y direction and 45 ° direction. The four small holes arranged on the inner side and the eight small holes arranged on the outer side are arranged at equal angles on concentric circles.

  FIG. 11 shows an example in which a Hartmann plate is arranged as the shielding plate 31A arranged at the position of the entrance pupil plane 31 of the lens system 20. The light that has passed through the small hole 31 a of the Hartmann plate is emitted from the exit pupil plane 32 after passing through the lens system 20. On the imaging surface 33, 13 light ray trajectory points corresponding to 13 small holes are formed in a spot shape. The 13 spots 33a formed on the imaging surface 33 are two-dimensionally distributed on the imaging surface 33 with aberrations corresponding to the decentering of the lens system.

  Note that the Hartmann plate does not necessarily have to be installed in alignment with the entrance pupil, and the lens decentering amount can be calculated using a coma aberration amount and a lens decentering amount conversion coefficient corresponding to the installation position.

  Next, an algorithm for obtaining the lens eccentricity from the Hartmann image obtained by imaging the Hartmann pattern will be described with reference to FIGS.

  First, in the measurement of the amount of eccentricity according to the present invention, each image in the optical system when the amount of eccentricity of the lens is obtained from an image obtained by photographing a Hartmann pattern will be described with reference to FIG.

  In the eccentricity measurement of the present invention, two types of images, a front Hartmann image and a rear Hartmann image, are used.

  FIG. 12 is a view for explaining the outline of the optical image system in the eccentricity measurement of the present invention. In the optical system shown in FIG. 12, a Hartmann plate 6 having a Hartmann pattern mask is disposed on the light source (not shown) side with respect to the lens system 20 having a combined lens including a lens to be measured. The Hartmann plate 6 is provided with a plurality of small holes 6a for forming a Hartmann pattern. The light that has passed through the small hole 6 a of the Hartmann plate 6 forms a spot image at the rear position after passing through the lens system 20. The light emitted from the lens system 20 forms a minimum circle of confusion at the position of the best image plane 35.

  On the optical path, the image formed in front of the best image plane 35 is a defocused image that is wider than the diameter of the circle of confusion formed on the best image plane 35. Here, the Hartmann pattern image captured at this position is referred to as a front Hartmann image 34. On the other hand, an image formed behind the best image plane 35 on the optical path is a blurred image that is wider than the diameter of the circle of confusion formed by the best image plane 35. Here, the image of the Hartmann pattern imaged at this position is referred to as a rear Hartmann image 36.

  The flowchart of FIG. 13 shows a schematic algorithm for determining the amount of eccentricity of the lens from the Hartmann image obtained by imaging the Hartmann pattern of the present invention and performing the eccentricity adjustment.

  First, for the Hartmann image obtained by imaging the Hartmann pattern, after confirming by the previous image processing whether the amount of light of the reflected pattern is in a state suitable for subsequent image processing (S1), Each spot position corresponding to the Hartmann pattern is obtained from the Hartmann image (S2), and the amount of eccentricity of the lens is derived based on the obtained spot position (S3).

  If the derived lens eccentricity is larger than a predetermined target value (S4), the lens eccentricity adjustment is performed using the obtained lens eccentricity (S5). The steps S3 to S5 are repeated until the derived lens eccentricity is smaller than the target value.

  In the pre-image processing step of S1, for example, bias calibration and sensitivity unevenness calibration are performed on the detector of the imaging apparatus.

  Next, derivation of the lens eccentricity will be described with reference to FIGS. In the following, description will be given according to the flowchart for explaining the derivation of the lens eccentricity in FIG.

  FIG. 15 is a diagram for explaining the calculation of the best image plane. In FIG. 15, at the spot position of the front Hartmann image 34 and the spot position of the rear Hartmann image 36, the spot positions corresponding to the small holes of the same Hartmann plate are connected by line segments. Here, an example in which 13 line segments are formed by 13 spot positions is shown. However, in FIG. 15, only five of the thirteen rays are shown.

  When spots corresponding to each other in the front Hartmann image 34 and the rear Hartmann image 36 are connected, a plane including the smallest circle of confusion with a small diameter can be calculated in the vicinity of the imaging plane, and this plane becomes the best image plane 35 (S31).

  FIG. 16 shows the relationship between lens decentering and spot position displacement. FIG. 16A shows the spot position when there is no lens eccentricity, and FIG. 16B shows the spot position when there is lens eccentricity.

  As shown in FIG. 16B, the position of the spot on the best image plane is displaced due to lens decentering. Relative position of the lens is measured on the best image plane by calculating from the amount of deviation between the center of gravity of the inner spot group and the center of gravity of the outer spot group rather than simply calculating from the amount of deviation of the spot position. It is easy to improve accuracy because it only needs to be done.

  The spot image of the Hartmann image in FIG. 17 is an example of an acquired image by the Hartmann plate shown in FIG. 11, and a total of 13 spots are distributed on the Hartmann image 37. Among the 13 spots, the remaining 12 spots excluding the center spot are distributed almost symmetrically with respect to the center, and the inner spot group 38 is composed of a total of 5 points including the inner four points and the center. And an outer spot group 39 consisting of eight outer points.

  The inner spot group 38 and the outer spot group 39 respectively correspond to small holes in the Hartmann plate arranged symmetrically with respect to the point. When the optical system has eccentricity, a shift occurs in the position of the center of gravity between each spot group.

  The present invention obtains the center of gravity obtained from the inner spot group and the center of gravity obtained from the outer spot group (S32).

  The positional deviation between the centroid position of the inner spot group calculated in S32 and the centroid position of the outer spot group is calculated (S33).

  The center-of-gravity shift amount between the center of gravity of the inner spot group and the center of gravity of the outer spot group represents the amount of coma aberration, that is, the amount of residual eccentricity of the lens to be adjusted. The amount of lens eccentricity is calculated from the positional deviation between the centroid position of the inner spot position and the centroid position of the outer spot position calculated in S33.

  When the amount of deviation is small, a proportional relationship is established between the amount of deviation and the amount of eccentricity based on the equations (7) and (8). Therefore, the amount of deviation is obtained from the center of gravity by multiplying the amount of deviation by a predetermined proportional coefficient. The amount of deviation can be converted into the amount of lens eccentricity (S34).

  Next, configuration examples of the eccentricity measuring device and the eccentricity adjusting device of the present invention will be described with reference to FIGS.

  FIG. 18 is a schematic configuration diagram of the eccentricity measuring device and the eccentricity adjusting device of the present invention. The eccentricity measuring apparatus 1 includes a workpiece holder 5 that holds the assembled lens of the workpiece 2, a Hartmann plate 6, an adjustment unit 7 that adjusts the amount of eccentricity of the lens, and a lens gripping unit 8 that grips the lens incorporated in the workpiece 2. A light source means 9 for irradiating the work 2 with light, an image pickup means 3 for picking up a light beam that has passed through the work 2, a control means, an image processing means, and a PC 11 including a calculation means. The eccentric amount of the lens is measured based on the captured image.

  The workpiece 2 is a combined lens formed by combining a plurality of lenses, and is incorporated in the lens frame 2c. Here, a configuration including a lens 2a fixed in the lens frame 2c and a lens 2b for performing eccentricity adjustment is shown.

  The light source means 9 is means for irradiating light to the lens of the work 2. In the case of irradiating parallel light, the light source means 9 can be constituted by a point light source 9a and a collimator 9b, for example.

  The light source means 9 is not limited to a light source that irradiates parallel light, and a light source that irradiates divergent light or a light source that irradiates light may be used depending on a target lens system.

  The light source means 9 can be constituted by a combination of a light source and a correction lens. By combining the correction lens, the focal position can be adjusted and aberration can be corrected to be an aplanato.

  In the above description, it has been assumed that coma aberration occurs due to decentering of a part of the combined lens. On the other hand, when decentering occurs in a part of the combined lens, other aberrations such as astigmatism and a change in field curvature may be caused significantly instead of coma. Even in these cases, coma aberration is significant in the entire optical system including the correction lens by combining an appropriate correction lens like “pupil aberration” described in Non-Patent Document 1. It is possible to make an optical system. By using such a correction lens, it can be applied to an optical system in which astigmatism and curvature of field are desired to be adjusted.

  The workpiece holder 5 is a member that holds the workpiece 2, and includes a workpiece holder 5a that holds a lens frame 2c incorporating the assembled lenses 2a and 2b, and a base portion 5b that supports the workpiece holder 5a. A Hartmann plate 6 is provided in the holding portion 5a.

  In addition, the lens gripping means 8 includes a frame portion 8a that surrounds the central opening portion around the periphery and places the workpiece 2 held by the workpiece holder 5 in the opening portion, and the workpiece 2 arranged in the frame portion 8a. And a plurality of lens pressing portions 8b that hold and hold the outer peripheral side portion of the lens 2b to be adjusted by pressing at a plurality of positions.

  At least one of the plurality of lens pressing portions 8b is movable by a driving means 8c described later. The plurality of lens pressing portions 8b may be configured such that a part of the pressing portion is movable by the driving means 8c and the other pressing portions are held, and all the pressing portions are movable.

  The driving means 8c pushes the lens pressing portion 8b in the direction of the work 2, and brings the tip portion of the lens pressing portion 8b into contact with the outer peripheral side portion of the lens 2b. Accordingly, the plurality of lens pressing portions 8b grip the outer periphery of the lens 2b within the lens frame 2c. The drive means 8c is driven and controlled by the grip driver 17b.

  On the base portion 5b, an adjusting means 7 for adjusting the eccentric amount of the lens is provided. The adjusting means 7 includes an X-axis driving means 7a and a Y-axis driving means 7b, and the position of the frame portion 8a in the XY direction can be adjusted with respect to the base portion 5b. Since the frame portion 8a holds and holds the lens 2b subject to eccentricity adjustment by the plurality of lens pressing portions 8b, adjusting the position of the frame portion 8a in the XY direction by the adjusting means 7 causes the lens 2b to move in the XY direction. The position is adjusted. On the other hand, since the lens frame 2c of the work 2 is fixed to the base portion 5b via the work holding portion 5a, the position adjustment of the lens 2b to be adjusted with respect to the lens frame 2c is adjusted by adjusting the position of the lens 2b in the XY direction. Will be done.

  The X-axis drive means 7a and Y-axis drive means 7b provided in the adjusting means 7 are driven and controlled by an XY-axis drive driver 17c.

  The imaging means 3 captures an image formed by the light beam emitted from the lens of the work 2 and the captured image is sent to the PC 11 and used for eccentricity measurement and eccentricity adjustment. For example, a CCD camera or the like can be used as the imaging unit 3 and a Z-axis driving unit 4 is attached. The Z-axis drive unit 4 is driven and controlled by a Z-axis drive driver 17a. The image picked up by the image pickup means 3 is subjected to image processing by the image processing means 13.

  The light source means 9, the work holder 5, the adjusting means 7, and the imaging means 3 are arranged in accordance with one optical axis. The light emitted from the light source means 9 passes through the Hartmann plate 6 held by the workpiece holder 5 and then enters the lens of the workpiece 2. The imaging means 3 images the Hartmann pattern of the passing light that has passed through the lens and outputs an image signal of the captured image. The imaging unit 3 is movable in the optical axis direction by the Z-axis driving unit 4, and a position where the imaging unit 3 captures an image is movable in the optical axis direction.

  The Z-axis drive driver 17a, the lens gripping driver 17b, and the XY-axis drive driver 17c are controlled by the control unit 12 provided in the PC 11. Further, the PC 11 includes a calculation unit 14 that performs signal processing on the image signal of the captured image captured by the imaging unit 3 by the image processing unit 13 and calculates an eccentricity amount.

  The eccentricity adjusting device 10 includes a mechanism for adjusting the eccentricity by moving the lens position of the work 2 based on the calculated eccentricity amount, and a lens having the eccentricity adjusted, together with the configuration of the eccentricity measuring device 1 described above. A mechanism for fixing to the lens frame is provided.

  The mechanism for adjusting the lens position includes an adjusting means 7 including an X-axis driving means 7a and a Y-axis driving means 7b, and an XY-axis driving driver 17c for driving and controlling the adjusting means 7. As described above, the lens gripping means 8 is a lens holding member that presses the lens 2b in contact with the outer peripheral side of the lens 2b as a mechanism for holding the lens 2b in the lens frame 2c so as to be movable in the xy direction with respect to the lens frame 2c. A driving unit 8c that holds the tip of the lens holding unit 8b in contact with the outer peripheral side of the lens 2b, and a lens holding driver 17b that controls the driving of the driving unit 8c. Further, the adjusting means 7 moves the frame portion 8a in the XY direction to finely move the lens 2b held by the lens pressing portion 8b in the XY direction with respect to the lens frame 2c, thereby performing eccentricity adjustment. .

  The control means 12 of the PC 11 instructs the adjustment amount to the XY axis drive means 7a, 7b of the adjustment means 7 via the XY axis drive driver 17c based on the eccentricity calculated by the calculation means 14, and the frame 8a is set to XY. Move in the direction to adjust the position. The eccentricity is adjusted by this position adjustment.

  Prior to this position adjustment, the driving means 8c is instructed to drive via the lens gripping driver 17b, the lens pressing portion 8b is pushed in the direction of the lens 2b, and the tip is brought into contact with the outer peripheral side portion of the lens 2b. And hold it. Thereby, the lens 2b is held in a free state with respect to the lens frame 2c, and the position of the lens 2b with respect to the lens frame 2c is adjusted by adjusting the position of the lens 2b held in the frame 8a with respect to the lens frame 2c. can do.

  The mechanism for fixing the lens 2b whose position is adjusted and eccentrically adjusted to the lens frame 2c includes an adhesive dispenser syringe 15 for supplying an adhesive to a contact portion between the lens 2b and the inner edge of the lens frame 2c, an adhesive A dispenser syringe moving means 19 for moving the dispenser syringe 15 and an adhesive solidifying means 16 for solidifying the adhesive adhered by the adhesive dispenser syringe 15 are provided. When an adhesive that is cured by ultraviolet rays is supplied from the adhesive dispenser syringe 15, an ultraviolet irradiation device can be used as the adhesive solidifying means 16.

  The adhesive dispenser syringe 15 injects the adhesive by the syringe drive unit 17e. The syringe drive unit 17e is mainly composed of an electromagnetic valve or the like, and controls the pressure supplied by opening / closing control of the electromagnetic valve, and controls the injection of the adhesive from the adhesive dispenser syringe 15.

  The dispenser syringe moving means 19 is composed of an air cylinder or the like, and moves the adhesive dispenser syringe 15 between the injection position and the standby position.

  The control means 12 of the PC 11 controls the dispenser syringe moving means 19 via the dispenser syringe movement driver 17d to move the adhesive dispenser syringe 15 between the injection position and the standby position. Further, the control means 12 of the PC 11 controls the syringe drive unit 17 e to control the injection of the adhesive from the adhesive dispenser syringe 15.

  While the optical axis of the lens is being adjusted, the dispenser syringe moving means 19 moves the adhesive dispenser syringe 15 to a standby position at an obliquely upper position and keeps it waiting. After the optical axis adjustment is completed, the dispenser syringe moving means 19 moves the adhesive dispenser syringe 15 diagonally downward to move the needle of the adhesive dispenser syringe 15 to the bonding portion. Thereafter, the adhesive dispenser syringe 15 injects the adhesive by driving from the syringe drive unit 17d.

  The adhesive solidifying means 16 is driven by a solidification driver 17f that receives a control signal from the control means 12 of the PC 11.

  The mechanism for fixing the lens 2b to the lens frame 2c is not limited to the above-described configuration using ultraviolet rays, and other configurations may be applied. Further, in FIG. 18, the light source means 9 is shown as being arranged at a lower position with respect to the eccentricity measuring apparatus 1, but the light source means 9 may be arranged at an upper position with respect to the eccentricity measuring apparatus 1. Good.

  19 and 20 are diagrams for explaining the installation state of the workpiece holding portion 5a of the workpiece holder 5 to which the workpiece 2 is attached. The eccentricity measurement of the assembled lens and the eccentricity adjustment of the lens based on the measured eccentricity amount are performed by attaching the workpiece 2 of the assembled lens to the workpiece holding portion 5 a of the workpiece holder 5.

  Depending on the optical characteristics such as the focal length of the assembled lens that performs eccentricity measurement and eccentricity adjustment, it is difficult to form an image on the imaging surface of the imaging means 3, and therefore a correction lens 5c that adjusts the focal length is incorporated inside. A work holder 5 is used. FIG. 20 shows an example using the workpiece holder 5 incorporating the correction lens 5c.

  Further, the light source means 9 may be provided with a measurement wavelength variable section 18 that can select a measurement wavelength such as a filter, thereby measuring, for example, the coma aberration in a single color by removing the influence of chromatic aberration, and based on this Eccentricity adjustment can be performed.

  Further, by making the workpiece 2 detachable with respect to the workpiece holding portion 5a of the workpiece holder 5, the eccentricity measurement and eccentricity adjustment of the plurality of workpieces 2 can be performed continuously. FIG. 21 is a diagram for explaining a state in which the workpiece 2 is attached to and detached from the workpiece holding portion 5a.

  In FIG. 21, the workpiece is exchanged by replacing the lens frame 2c of the workpiece 2 with respect to the workpiece holding portion 5a by a workpiece exchange mechanism (not shown). The workpiece 2 whose eccentricity adjustment has been completed is taken out from the workpiece holding portion 5a, and then the workpiece 2 whose eccentricity has not been adjusted is attached to the workpiece holding portion 5a.

  By adding this work exchange mechanism to the eccentricity adjusting device, it becomes easy to incorporate lens adjustment into the line process.

  Next, a configuration example and an operation example of the lens holding means 8 will be described with reference to FIGS.

  In FIG. 22A, the lens gripping means 8 includes a frame portion 8a surrounding the central opening, and a plurality of lens pressing portions 8b provided on the frame portion 8a. 22 and 23 show a configuration example in which lens pressing portions 8bA to 8bD are provided on each of the four sides of the frame portion 8a.

  The lens frame 2c is disposed in the central opening of the frame portion 8a, and the outer peripheral side portion of the lens 2b to be adjusted is disposed at the same height level as the lens pressing portions 8bA to 8bD.

  The lens pressing portions 8bA to 8bD can be configured to be movable in the direction of the central opening with respect to the frame portion 8a. 22 and 23, among the lens pressing portions 8bA to 8bD, the lens pressing portions 8bA and 8bB are movable with respect to the frame portion 8a, and the lens pressing portions 8bC and 8bD are fixed to the frame portion 8a. Is shown.

  The lens pressing portions 8bA to 8bD hold the lens 2b by gripping the outer peripheral side portion of the lens 2b in the lens frame 2c disposed at the opening of the frame portion 8a.

  22 and 23, the movable lens pressing portion 8bA and the fixed lens pressing portion 8bC are arranged to face each other on the same straight line, and the movable lens pressing portion 8bB and the fixed lens pressing portion 8bD are arranged. 1 shows a configuration in which they are arranged to face each other on a straight line orthogonal to the straight line.

  By making the lens pressing portion 8bA and the lens pressing portion 8bB movable, a gap is provided between the tip of the pressing pin 8b1 of the lens pressing portion 8 and the lens 2b when the lens frame 2c is disposed in the frame portion 8a. The arrangement operation can be facilitated.

  When the upper end of the lens 2b is arranged below the end of the lens frame 2c, as shown in FIG. 22B, a groove 2d is formed in a part of the lens frame 2c, and the groove 2d. The tip of the pressing pin 8b1 is brought into contact with the outer peripheral side portion of the lens 2b through the gap.

  Further, when the upper end of the lens 2b is disposed above the end of the lens frame 2c and a part of the lens 2b is exposed from the lens frame 2c, as shown in FIG. It is not necessary to form the groove 2d in 2c, and the tip of the lens pressing portion 8b is brought into contact with the outer peripheral side portion of the lens 2b exposed at the upper end of the lens frame 2c.

  Further, the Hartmann plate 6 is attached in the cylinder of the workpiece holding portion 5a of the workpiece holder 5, and a correction lens 5c is provided as necessary.

  Next, a configuration example of the lens pressing portion 8b will be described with reference to FIGS. 24 and 25 show a configuration example of the lens pressing portion 8 having a mechanism that is movable with respect to the frame portion 8a.

  In this configuration example, the elastic force of the spring material is used.By applying an external force to the spring material and deforming, the tip of the holding pin 8b1 is brought into contact with the outer peripheral side of the lens, and the external force applied to the spring material is This is a mechanism that separates the tip of the lens pressing portion 8 from the outer peripheral side of the lens by restoring the spring material by releasing the application, and an element for returning such as an actuator mechanism such as a motor or an air cylinder or a coil spring is unnecessary. can do.

  The perspective view of FIG. 24 shows a part of the lens pressing portion 8. FIG. 24A shows a state in which each part is attached, and FIG. 24B shows a state in which each part is separated.

  The lens pressing portion 8 includes a pressing pin 8b1 that comes into contact with the outer peripheral side portion of the lens, a supporting portion 8b2 that supports the pressing pin 8b1, a spring portion 8b3 that elastically supports the supporting portion 8b2, and a holding end of the spring portion 8b3. And a holding portion 8b4 for holding the frame portion 8a while preventing movement due to elastic deformation of the frame.

  The spring portion 8b3 can be formed of a single member made of an elastic material, and the single member is elastically deformed. By attaching one end of the pressing pin 8b1 to the support portion 8b2, the pressing pin 8b1 is movable. The support portion 8b2 and the spring portion 8b3 can be integrally formed. 24 and 25 show an example in which the support portion 8b2 and the spring portion 8b3 are integrally formed.

  The frame portion 8a includes a groove 8a2 into which the support portion 8b2 is inserted. By inserting the support portion 8b2 into the groove 8a2, the support portion 8b2 can be slid without being laterally displaced.

  Since the spring portion 8b3 is only held between the holding portion 8b4 and the frame portion 8a with a gap, the spring portion 8b3 does not have a function of suppressing the movement of the support portion 8b2 in the lateral direction with respect to the frame portion 8a. By inserting the support portion 8b2 into the groove 8a2 formed in the frame portion 8a, the support portion 8b2 is allowed to slide back and forth with respect to the lens direction, and the support portion 8b2 moves laterally and is displaced. Can be suppressed.

  Further, the support portion 8b2 is held in the vertical direction while allowing the slide in the front-rear direction by two right and left washers and screws attached to the frame portion 8a so that the support portion 8b2 is not detached from the groove 8a2.

  In the example shown in FIG. 24, the support portion 8b2 and the spring portion 8b3 are integrally formed of an elastic material such as a metal material, and the spring portion 8b3 is bent 90 degrees with respect to the support portion 8b2. Further, both ends of the piece constituting the spring portion 8b3 are holding ends for holding the frame portion 8a, and an intermediate portion sandwiched between the holding ends is displaced by deflection. By applying an external force to the spring portion 8b3 to bend the spring portion, the support portion 8b2 is moved, and the pressing pin 8b1 attached to the support portion 8b2 is moved.

  When the external force applied to the spring portion 8b3 is released, the spring portion 8b3 is returned to its original position by the restoring force due to the elasticity of the spring member, and the tip of the lens pressing portion 8 is separated from the outer peripheral side portion of the lens.

  In the frame portion 8a, a concave portion 8a1 is formed in a portion where the spring portion 8b3 is deformed so as not to hinder the displacement of the spring portion 8b3 when an external force is applied to the spring portion 8b3.

  In order to facilitate the bending of the spring portion 8b3, the thickness of the portion excluding the connecting portion with the support portion 8b2 is reduced in the intermediate portion sandwiched between the holding ends. As a result, the spring portion 8b3 can be deformed with a smaller force.

  A part of the holding part 8b4 is fixed to the frame part 8a with a screw or the like, and by this fixing, the holding end of the spring part 8b3 is sandwiched between the frame part 8a with a gap and held by elastic deformation of the spring part 8b3. It is held while not disturbing the movement of the edge.

  FIG. 25 shows a cross section of the lens pressing portion, FIG. 25 (a) shows a state where no external force is applied, and FIG. 25 (b) shows a state where an external force is applied.

  In FIG. 25 (a), the spring portion 8b3 is held at a position away from the lens (not shown) by the elastic force of the spring member, and the support portion 8b2 and the pressing pin 8b1. In FIG. 25B, when an external force is applied to the spring portion 8b3, the spring portion 8b3 is deformed, and the support portion 8b2 and the pressing pin 8b1 are moved in the lens (not shown) direction.

  When the application of external force is canceled from the state shown in FIG. 25B, the spring portion 8b3 is restored by the spring member, so that the support portion 8b2 and the pressing pin 8b1 move away from the lens (not shown). Returning to the state of FIG.

Next, an embodiment of the present invention will be described with reference to FIGS.
FIG. 26 shows a configuration example of a combined lens used in the decentering adjustment example of the present invention, and FIG. 27 shows an example of lateral aberration in this configuration example. The basic optical data of the assembled lens is shown in Table 1 below.

  In this configuration, with respect to the center of the visual field of the optical system, FIG. 27A shows a lateral aberration curve when there is no eccentricity, and FIG. 27B shows a lateral aberration curve when there is an eccentricity of 10 μm. 27 (c) shows a difference curve of lateral aberration with and without decentration.

In the state where there is no eccentricity shown in FIG. 27A, high-order spherical aberration remains, but no component proportional to H ² is observed. However, when an eccentricity of 10 μm is given to the rear group, an aberration proportional to H ² is added as shown in FIG. Difference in FIG. 27 (c) represents the aberration is proportional to ^{H 2.}

  A Hartmann mask of the Hartmann plate shown in FIG. 11 is placed on this lens at the position of the entrance pupil of the lens system, and a Hartmann image is captured. Out of the light rays that pass through the Hartmann mask, the center of gravity of the position on which the best image plane is irradiated is obtained by the light rays that have passed through the small holes at the five inner points and the small holes at the eight outer points.

  FIG. 28 shows an example of displacement of the center of gravity position due to eccentricity. In FIG. 28 (a), when the lens is not decentered, the center of gravity by the inner five points and the center of gravity by the outer eight points are zero and become the center. On the other hand, when an eccentricity of 10 μm is added to the rear group, the position of the center of gravity is displaced under the influence of coma aberration as shown in FIG. The center of gravity by the inner five points is irradiated to the position of −12.4 μm, and the center of gravity by the outer eight points is irradiated to the position of −14.3 μm. The difference is 1.8 μm.

  Here, the ratio of the amount of eccentricity and the difference between the inner centroid position and the outer centroid position is 10 μm / 1.8 μm = 5.6, and the ratio is multiplied by the difference between the inner centroid position and the outer centroid position. Thus, the amount of eccentricity can be calculated.

  In more detail, when the outer small hole is provided at the end of the entrance pupil, the outer small hole causes light rays to be generated at the end of the entrance pupil. As a configuration for avoiding the influence of this beam reflection, the center of gravity position of the outer small hole is obtained as slightly inside the position obtained by the calculation, and the outer small hole is not the end of the entrance pupil, for example, about 80 to 90%. It can be set as the inside position.

  The eccentricity measuring method and the eccentricity adjusting device of the present invention are not limited to the above-described embodiments, and various changes can be made without departing from the scope of the present invention. is there.

  The decentering amount measurement and decentering adjustment of the present invention can be applied to the decentering amount measurement and decentering adjustment of a lens included in the assembled lens in the production line in the manufacture of an optical device using the assembled lens.

DESCRIPTION OF SYMBOLS 1 Eccentricity measuring apparatus 2 Workpiece 2a Lens 2b Lens 2c Lens frame 2d Groove 3 Imaging means 4 Axis drive means 5 Work holder 5a Work holding part 5b Base part 5c Correction lens 5d Cylindrical body 6 Hartmann plate 6a Small hole 7 Adjustment means 7a X Axis driving means 7b Y axis driving means 8 Lens gripping means 8a Frame portion 8a1 Recessed portion 8a2 Groove 8b, 8bA to 8bD Lens pressing portion 8b1 Holding pin 8b2 Support portion 8b3 Spring portion 8b4 Holding portion 8c Driving means 9 Light source means 9a Point light source 9a Point light source 9a 10 Eccentricity adjustment device 11 PC
DESCRIPTION OF SYMBOLS 12 Control means 13 Image processing means 14 Calculation means 15 Adhesive dispenser syringe 16 Adhesive solidification means 17a Drive driver 17b Lens holding driver 17c Axis drive driver 17d Dispenser movement driver 17e Syringe drive part 17f Solidification driver 18 Measurement wavelength variable part 19 Dispenser movement Means 20 Lens system 21, 22 Lens 31 Entrance pupil plane 31A Shield plate 31a Eyelet 32 Exit pupil plane 33 Image plane 33a Spot position 34 Front Hartmann image 35 Best image plane 36 Rear Hartmann image 37 Hartmann image 38 Inner spot group 39 Outer spot Group 40 rays ΔH eccentricity Δy aberration κ constant σ dispersion

Claims (1)

A frame that surrounds the periphery of the opening that houses the lens system;
A lens pressing portion that holds the lens in contact with the outer periphery of the lens provided in the lens system;
The lens holding part is
A plurality of pressing pins that contact the lens;
A support portion that supports at least one pressing pin of the plurality of pressing pins in a slidable manner with respect to the frame portion;
A spring portion that elastically supports the support portion with respect to the frame portion;
A holding part for holding the holding end of the spring part on the frame;
The spring portion is
In a state where no external force is applied to the spring part, the support part and the pressing pin are held in place by the elasticity of the spring part,
In a state where a force is applied to the spring part from the outside, the support part and the pressing pin are moved in the direction of the opening by elastic deformation of the spring part,
A lens gripping device characterized by gripping a lens by bringing a plurality of pressing pins into contact with the outer periphery of the lens.