JPH07120218A - Method for measuring eccentricity of lens, reflection mirror, etc., and machine utilizing the method - Google Patents

Abstract

PURPOSE:To measure the eccentricity and inclination of a non-spherical surface lens in a diversified form by allowing flux of light to enter a part outside an optical axis and then evaluating the amount of eccentricity of the nonspherical surface from the position of the flux of reflection light. CONSTITUTION:A measuring instrument body 121 is laid out to a non-spherical surface lens 11 of a lens to be inspected and a slide mirror 110 is removed from a light path. Further, an image-forming lens 4 and a focus lens 2 are laid out so that a CCD camera 10 can observe a reflection bright point image for the radius of curvature of the lens 11 and the lens holder 2 is rotated to measure eccentricity by the vertical incidence method. Then, the mirror 110 is inserted into the light path to allow the light of a light source to enter nearly vertically the lens surface at the peripheral part of the lens 11. Also, the lenses 4 and 102 are laid out so that the camera 107 can observe a reflection bright point image for the radius of curvature of the peripheral part of the lens 11, the holder 2 is rotated, and measurement is made by the oblique incidence method. The reflection bright point image captured by the camera 107 using the both incidence methods is subjected to image processing by an A/D image board 112 and a personal computer 113 and further the personal computer 113 calculates the eccentricity and inclination of the lens 11 and displays them 114.

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 the eccentricity and inclination of an aspherical lens, an inhomogeneous medium lens, or the like, or a measuring method capable of evaluating the good or bad of those lenses, and the measuring methods thereof. Related to the machine using.

[0002]

2. Description of the Related Art In conventional optical devices such as cameras, microscopes and endoscopes, if the lens used in the device is decentered with respect to the optical axis, the image forming performance deteriorates. Therefore, in order to prevent such an obstacle, the eccentricity measurement of the lens is performed in the assembly process of the device and the lens processing process.

FIG. 20 shows a conventional device (Japanese Patent Laid-Open No. 56-16).
2031).
In the figure, 1 is a pinhole, 2 is a rotatable lens holder, 3 is a projection lens, 4 is an imaging lens, 5 is a half prism that divides the amount of light into two, 6 is an eyepiece lens, 7 is a prism,
Reference numeral 8 is a spherical lens which is a lens to be inspected, and 9 is a reflection image of the pinhole 1 by the spherical lens 8. Therefore, when the lens eccentricity of the spherical lens is measured by the conventional device, the real image of the pinhole 1 is made incident on the spherical lens 8 and the reflected image 9 thereof is enlarged and observed. Then, when the spherical lens 8 is placed on the lens holder 2 and rotated, if the spherical center 10 of the upper surface of the spherical lens 8 exists on the rotation axis of the lens holder 2, the reflected image 9 will not shake. When the spherical lens 8 is decentered, the reflected image 9 shakes with the rotation of the lens holder 2, so that the decentering of the spherical lens 8 can be measured by measuring the amount of shake.

[0004]

However, in the above method, the aspherical lens 1 as shown in FIG. 18 (a) is used.
Aspherical like 1 For a lens with two decentering degrees of freedom, Was impossible to measure. However, in the figure, V is the apex of the aspherical surface when there is no eccentricity, l is the rotation axis, and m is the normal vector at the point V. As a method of measuring the eccentricity of the aspherical lens, a distance sensor 12 as shown in FIG. 18B is used, and a change in the distance d between the sensor and the lens light surface when the aspherical lens 11 is rotated. Is known and is converted into an eccentricity and an inclination. However, a device using this method is expensive, and the working distance (the maximum value of the distance d between the sensor and the lens light surface) of the device is as small as about 5 mm to 15 mm, which makes it difficult to work. there were.

The present invention has been made in view of the above problems of the prior art, and an object thereof is to measure the eccentricity and inclination of aspherical lenses having various shapes. , Long working distance, excellent operability, low manufacturing cost of the device, and more convenient measurement of eccentricity of the spherical lens compared to the conventional device, production site, etc. Therefore, it is an object of the present invention to provide a measuring method that is also useful when determining the quality of the eccentricity, and a machine that uses the measuring method.

[0006]

In order to achieve the above object, the present invention measures the eccentricity and inclination of an aspherical lens or the like from at least the eccentricity of the local curvature center measured by the oblique incidence method. Further, the invention is characterized in that the light flux is made incident on one or more portions outside the optical axis on the aspherical surface or the like, and the eccentricity can be obtained from the reflected light flux of the light flux.

Hereinafter, based on FIG. 17, the same members as those of the conventional apparatus are designated by the same reference numerals, and the principle configuration of the lens eccentricity measuring machine according to the present invention will be described. In the figure, 101 is a light source (visible semiconductor laser or the like), 2 is a rotatable lens holder, 3 is a projection lens, 4 is an imaging lens, 5 is a half prism, 11 is an aspherical lens which is a lens to be inspected, 12 Is a distance sensor, 102 is a focus lens, 103 is a mirror, 104 is a real image formed by the focus lens 102, 105 is a microscope objective lens that magnifies the real image 104, 106 is a 10 × zoom lens, 107 is a CCD camera, and 108 is Super pause board, 109 is a display, 110 is a slide mirror that can be inserted in the optical path,
Reference numeral 111 is a manual or electric rotating mirror, 112 is an AD conversion image board (or an image processing board), 113 is a personal computer that performs image processing calculations described later, 114 is a color display that displays measurement results, and 115 is a printer. A half mirror that divides the amount of light into two may be used instead of the half prism 5, or a polarization beam splitter may be used for the purpose of avoiding the influence of the return light of the light source 101. However, when the polarization beam splitter is used, it is necessary to add a quarter wavelength plate between it and the imaging lens 4.

First, the operation of the measuring instrument when the lens to be inspected is a spherical lens will be described. Light emitted from the light source 101 sequentially passes through the light projecting lens 3, the half prism 5 and the image forming lens 4, and enters the spherical lens 8 as a real image. The reflected image of the real image on the surface of the spherical lens 8 is sequentially passed through the imaging lens 4, the half prism 5, and the focus lens 102 to form a real image 104, and further, the real image 1
Reference numeral 04 is enlarged by the microscope objective lens 105, and an image is formed on the CCD camera 107 by the 10 × zoom lens 106. The electronic image signal sent from the CCD camera 107 is displayed on the display 109 via the super pause board 108.
Sent to and a real-time image is displayed on it. Here, if the spherical lens 8 is decentered, the light source image displayed on the display 109 also moves when the spherical lens 8 is rotated, so that decentering of the lens can be found. The above measuring means will be referred to as a normal incidence method.

Next, when the lens to be inspected is the aspherical lens 11, the eccentricity measurement according to the vertical incidence method is performed, and then the slide mirror 110 is placed between the aspherical lens 11 and the imaging lens 4. In the optical path, and the optical path is further bent by the rotating mirror 111 so that the light source light enters the peripheral portion of the aspherical lens 11 substantially perpendicularly to the lens surface (hereinafter, this state is referred to as an oblique incidence state). ). Further, in order to measure how much the reflection image of the aspherical lens 11 moves when the lens holder 2 is rotated and the aspherical lens 11 is rotated, the reflection image of the aspherical lens 11 is sequentially rotated. The CCD camera 107 captures an image formed through an optical path that passes through the mirror 111, the slide mirror 110, the imaging lens 4, the half prism 5, the focus lens 102, the microscope objective lens 105, and the 10 × zoom lens 106. The above is called the oblique incidence method. In both the vertical incidence method and the oblique incidence method, it is easier for the optical system of the measuring instrument to receive the reflected light flux when the light flux is made to enter the lens surface substantially vertically, but it is not necessarily vertical if the reflected light flux can be received. There is no. See FIG.

The reflected image of the light source light imaged by the normal incidence method and the oblique incidence method is subjected to image processing by the AD image board 112 and the personal computer 113, and further, the personal computer 113 calculates the decentering and inclination of the aspherical lens. The result can be displayed on the color display 114. Further, since the focus lens 102 and the microscope objective lens 105 are configured so as to be movable in the optical axis direction by driving a pulse motor or the like, the position of the light source bright spot image is changed with respect to the lens and the optimum position is obtained. It is possible to form an image on the image plane and to adjust the focus of the CCD camera 107 on the reflection image of the light source bright spot by the lens surface.

Further, the imaging lens 4 and the focus lens 1
02, the position and angle of each of the rotating mirror 111 are controlled by the personal computer 113. Further, the distance between the imaging lens 4 and the aspherical lens 11 may be adjusted by moving the position of the lens holder 2 in the vertical direction with respect to the optical axis, or the imaging lens 4 or the slide mirror 110. It is also possible by vertically moving a member disposed above the position. The rotating mirror 111 is configured to be rotatable in order to allow a light beam to enter (or exit) in the peripheral portion of the aspherical lens 11 substantially perpendicularly to the lens surface.
Further, for the same purpose, the lens holder 2 and the aspherical lens 1
The positional relationship of each constituent member of the present measuring machine except 1 may be changed in a symmetrical direction in the drawing, or only the rotating mirror 111 may be arranged at a symmetrical position. Further, although the distance sensor 12 has been conventionally used, the distance between the peripheral portion of the aspherical lens 11 and the distance sensor 12 is measured by the distance sensor 12, and the distance generated when the aspherical lens 11 is rotated. It is also possible to obtain the eccentricity of the aspherical surface from the change of, and it is also possible to use the normal incidence method and the oblique incidence method together.

Next, based on FIG. 18 (a) and FIG.
A method for obtaining the eccentricity amount, that is, the eccentricity and inclination of the lens from the movement of the light source image when the aspherical lens is rotated, which is measured by the normal incidence method and the oblique incidence method, will be described. In the figure, V: surface apex of an aspherical surface without eccentricity 1: rotational axis m: normal vector at point V (-m in FIG. 18A)
R: Paraxial radius of curvature when the aspherical surface is eccentric (Fig. 19).
In (a), R> 0) L _T : Center of contact circle in meridian plane (center of local curvature) at one point Q in the peripheral portion of the aspheric surface φ: ∠CVL _T size (φ in FIG. 19A) > 0) θ: ∠L _T PV size (θ <0 in FIG. 19A) P: intersection of straight line QL _T and VC And However, when the lens holder 2 is rotated, the eccentricity of the spherical center C measured by the vertical incidence method The eccentricity of the center L _T of the local curvature measured by the oblique incidence method And Further, the subscripts x and y represent Cartesian coordinates in the tangent plane at the point V or the point Q, and With point V as the origin, Represents a vector having x and y components of Cartesian coordinates with the point Q as the origin. or, Is a vector representing the X and Y components of the Cartesian coordinates when the rotation axis of the lens holder 2 is in the Z axis direction, as shown in FIG.

[0013] Is the gradient of the aspherical surface expressed in radians, and its components ε _X and ε _Y are the azimuths of the normal vector m at the point V in FIG. 18A in the X and Y planes. When the corner is A , And at this time, the following expression holds (the sign of R is determined so that R> 0 in FIG. 19 (a)). Therefore, by solving the simultaneous equations of equation (3),
The values of δ _X , δ _Y , ε _X , and ε _Y are obtained respectively. That is, Can be asked. The line segment QL _T in FIG. 19A, that is, the local radius of curvature is calculated by the equation of the aspherical surface. When expressed by Given in.

In the method described above, the rotation axis l of the lens holder is rotated. However, if the position of the bright spot image without eccentricity is known in advance, it is possible to rotate the lens holder. Therefore, it is not necessary to rotate the lens holder. Further, as the eccentricity measurement value, the peripheral point L may be measured at several points. That is, two or more L ₁ ,
From the eccentricity measurement values of L ₂ , ... And the ball center C, the least squares method is used. May be obtained, or the measurement of the ball center C may be stopped and the eccentricity of two or more L ₁ , L ₂ , ... It is also possible to ask This state is shown in FIG.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS. 1 to 16 by assigning the same reference numerals to the same members as shown in FIG. FIG. 1 is an external view of a lens eccentricity measuring machine according to a first embodiment of the present invention. In the figure, 121 is a measuring machine main body, 122 is a switching unit having a built-in slide mirror 110 and fixed to the measuring machine main body 121, 123
Is a switching knob, 124a is a slide stage that supports the measuring instrument main body 121 and moves the main body 121 in the optical axis direction of the spherical lens 11 that is the lens to be inspected, 124b is a slide knob, and 2 is the aspherical lens 11 that is mounted and can be rotated. The rotary holder 125 is a control box in which a control board of the measuring instrument, a power source of the light source 101, and the like are built. or,
The display 109, the personal computer 113 and the color display 114 are provided for calculating the above-mentioned eccentricity and the like.

It should be noted that the measuring device main body 121 includes a light source 101, a light projecting lens 3, an imaging lens 4, a half prism 5, a focus lens 102, a microscope objective lens 105, a 10 × zoom lens 106 and a CCD shown in FIG. Camera 1
The lens eccentricity measuring unit including 07 is built in. Further, the imaging lens 4 and the focus lens 102 are
The mechanism is movable in the optical axis direction by a slide stage 124a driven by a stepping motor (not shown) or the like, and is arranged at a desired position according to an instruction from the control box 125. Furthermore,
In the switching unit 122, the switching mirror 123 can switch the slide mirror 110, and the measuring machine body 121 can be moved in the optical axis direction via the slide stage 124a by rotating the slide knob 124b. Has been done. Also, on the personal computer 113,
The above-described super pause board 108, AD conversion board 110, etc. are built in.

The operation will be described below. First, in order to secure an arbitrary work area for the aspherical lens 11 as the lens to be inspected, the measuring instrument main body 121 is arranged by the slide knob 124b, and the slide mirror 110 is changed over so as to enable measurement by the vertical incidence method. To remove from the optical path. Further, the imaging lens 4 and the focus lens 102 are respectively arranged at desired positions according to an instruction from the control box 125 so that the reflected bright spot image can be observed by the CCD camera 107 according to the radius of curvature of the aspherical lens 11. In this state, the lens holder 2 is rotated and the measurement is performed by the vertical incidence method. At this time, CCD
The reflected bright spot image captured by the camera 107 is displayed on the display 109 via the superpose board 108 and can be observed. Also, AD conversion image board 1
The amount of movement of the position of the center of gravity of the reflected bright spot image due to the rotation of the lens holder 2 is obtained by 10, and the amount of eccentricity is calculated by the
13 and the calculation result is displayed on the color display 114.

Next, in order to perform the oblique incidence measurement method, the slide knob 123 is slid to insert the slide mirror 110 into the optical path, and the light is incident on the lens surface in the peripheral portion of the aspherical lens 11 almost perpendicularly to form an aspherical surface. The imaging lens 4 and the focus lens 102 are arranged at desired positions according to an instruction from the control box 125 so that the reflected bright spot image can be observed by the CCD camera 107 in accordance with the radius of curvature of the peripheral portion of the lens 11. In this state, the lens holder 2 is rotated and the measurement is performed by the oblique incidence method. The subsequent observation on the display 109 and the method of calculating the amount of eccentricity of the lens are as described above. As described above, the eccentricity amount of the aspherical lens 11 is calculated from the measurement results of the normal incidence method and the oblique incidence measurement method by the personal computer 119 based on the above equations (1) to (3).

FIG. 2 shows a second embodiment according to the present invention. The basic measuring principle and configuration are the same as those of the apparatus shown in the first embodiment, but in FIG. Since the imaging lens 4 and the half prism 5 are configured by a single lens system 131 including a plurality of lenses, the configuration of the lens eccentricity measuring unit is simplified. Further, 132 and 133 are shutters provided for the reason described later. The two half prisms 5 are always arranged in the optical path.
Further, by moving the light source 101 and the lens system 131 respectively, the position of the bright spot image of the light source 101 with respect to the aspherical lens 11 and the reflected image thereof can be focused on the CCD camera 107. Also, the above object can be achieved by adjusting the distance between the members arranged above the position of the aspherical lens 11 or the shutter 133.

Since the apparatus according to the present embodiment is configured as described above, the shutter 132 blocks the optical path during vertical incidence, and the shutter 133 blocks the optical path during oblique incidence measurement, so that the slide mirror 110 is not required. It is possible to measure the eccentricity of the lens without doing so, and the configuration of the unit can be simplified.

The apparatus shown in FIG. 2 (b) has a mirror 1
By providing 34, the imaging lens 4 is provided as compared with the measuring machine shown in the first embodiment without using the lens system 131.
Since the slide mirror 110 can be omitted, the structure can be further simplified. Also in this apparatus, the half mirror 5 is always arranged in the optical path, and the position of the bright spot image of the light source 101 with respect to the aspherical lens 11 is moved by moving the light projecting lens 3 and the focus lens 102 respectively in the optical axis direction. And the reflected image thereof can be focused on the CCD camera 107. The above object can also be achieved by adjusting the distance between the members arranged above the position of the aspherical lens 11 or the shutter 132. still,
In both of the devices shown in FIGS. 2A and 2B, in the case of the oblique incidence method, the eccentricity can be measured even if one of the positional relationships between the aspherical lens 11 and the eccentricity measuring device is shifted in the left-right direction. is there.

FIG. 3 shows a third embodiment of the present invention (a).
Is a top view of the device, and (b) is a side view of the device seen from the AX axis direction. In the apparatus of this embodiment, as shown in the drawing, a light source 101, a half prism 5, a lens system 131 similar to that shown in the first embodiment, and a rotary mirror 111 are arranged in series on the optical axis on a moving stage 141. In particular, the rotating mirror 111 is constructed so as to be rotatable about the AX axis, and the half mirror 5, the microscope objective lens 105, the 10 × zoom lens 106 and the CCD camera 107 are each a half prism from the optical axis. They are arranged in series on the other optical axis bent by 5.

Therefore, the light emitted from the light source 101 is, in order, the half prism 5, the lens system 131 and the rotating mirror 11.
The light enters the aspherical lens 11 through the optical path 1. The incident light is reflected by the aspherical lens 11, and the rotating mirror 1
The lens 11 passes through the lens system 131, the half mirror 5, the microscope objective lens 105, and the 10 × zoom lens 106 in this order to form an image on the CCD camera 107. In the case of the normal incidence method, the light beam is incident on the lens surface of the aspherical lens 11 in the direction of the arrow V in the figure, while in the case of the oblique incidence method, the rotating mirror 111 rotates and the light beam is an aspherical lens. It is incident on the lens surface of 11 in the direction of arrow G ₁ or G _{2 in} the figure (see FIG. 3B). At this time, the moving stage 141 moves in the horizontal direction so that the light beam can be incident on the lens surface of the aspherical lens 11 at an appropriate angle. Further, in order to optimize the light beam incident position and the image forming position on the optical axis with respect to the lens surface of the aspherical lens 11, the microscope objective lens 105, the 10 × zoom lens 106 and the CCD camera 107 are integrated respectively. Move on the optical axis. Further, instead of the above method, the same effect can be obtained by moving the lens system 131.

As described above, the device according to this embodiment is different from the device according to the second embodiment in that the shutters 132, 1
It has the advantage that it does not require 33 and has a very simple device configuration, thus keeping costs in the manufacturing process low. Here, to give an example of the design value of each optical component, the focal length of the lens system 131 is 9
0mm, F number is 2.0, microscope objective lens 105
Is 10 times, 20 times, 40 times, or 10 times, the focal length of the zoom lens 106 is 11 to 110 mm, or 22 to
220 mm, the wavelength of the light source 101 is 685 to 640 nm,
The CCD size of the CCD camera 107 is 1/2 to 1/4.
Inches.

FIG. 4 shows a fourth embodiment according to the present invention. This embodiment is characterized in that two eccentricity measuring units shown in the second embodiment are provided. That is,
As shown in the figure, fix the unit A in a vertically built state,
Further, since the unit B is fixed in an inclined state and two sets of eccentricity measuring units are arranged, the rotating mirror 11
No. 1 is unnecessary, and the vertical incidence method and the oblique incidence method can be performed simultaneously, so that the time required for measurement can be shortened. The method of processing the measurement data is the same as the method shown in the first embodiment. The present embodiment as described above is applied to a lens centering machine, and it is convenient to center the lens while monitoring the amount of eccentricity. Of course, other embodiments of the present invention can be applied to the lens centering machine, and all the embodiments can be applied to a lens joining machine or the like to perform lens processing. It is possible. The inclination angles of the units A and B can be arbitrarily adjusted. Further, one of the eccentricity measuring units is fixed in a vertically standing state, and the aspherical lens 11 is held horizontally and tilted, respectively. The same effect can be obtained by using only two sets of the above units. Further, when only the measurement by the oblique incidence method is performed as described later, the unit A may be omitted.

As shown in FIG. 5, the optical axis 1 is around the aspherical surface.
When it is almost perpendicular to 51, the incident light flux of the bright spot image becomes parallel to the optical axis as indicated by arrow E in the figure when measuring the eccentricity of the peripheral portion. Therefore, even in the oblique incidence state, the incident light flux becomes parallel to the arrow D as in the case of the vertical incidence method. However, including such a case, in the present invention, the method of measuring the eccentricity around the aspherical surface is oblique incidence. I will call it the law.

FIG. 6 shows a fifth embodiment of the present invention.
In this embodiment, as shown in the figure, the light source 101, the imaging lens 4,
By arranging two sets of each of the focus lens 102 and the CCD camera 107 and injecting a light beam obliquely with respect to the lens surface of the aspherical lens 11, the spherical center C of the central part of the aspherical surface and the local curvature of the peripheral part are changed. This is a method of measuring the center L _T and obtaining the eccentricity of the aspherical surface. As described above, if the incident light flux of the bright spot image is applied to at least two different portions on the aspherical surface, it is possible to obtain the eccentricity and the inclination of the aspherical surface by performing an analysis of them. .

FIG. 7 shows two centers L of local curvature._TOver
And L_SIt is the figure which each showed. So far, the child
Center of curvature L in the meridian plane_TI've been thinking only because it's local
There is only one center of curvature if one point Q on the aspheric surface is determined.
I've been trying. However, sagittal local
Center of curvature L_SIs also considered, the center of curvature at the point Q
There are two. Therefore, the light flux of the point light source is incident
The reflected image by the aspherical surface when_TThen the paper in Figure 7
It becomes an ellipse extending in the direction perpendicular to the plane, and L _SThen before
It becomes an ellipse extending in a direction parallel to the paper surface. That's all
When measuring eccentricity, L_T, L_SOr somewhere in between
Any of the eccentricity of the points may be used,Should be calculated by the aspherical equation. or,
L_SAnd L_TAnd L_SMidpoint LT with_TSFrom the eccentricity ofIn order to obtainIt can be obtained from the formula replaced with. However, at this time, θ,
φ is also L_S, L_TSCorresponding to and replace.

That is, the radius of the local curvature in the sagittal direction is as shown in FIG. Is given by equation (4). Note that θ <0 in FIGS. 8 and 9. In this case, as shown in FIG. 9, the following equation (5a),
Expression (5b) is established in place of Expressions (2d) and (2b). Incidentally, L _S is always φ = 0. or, Is the eccentricity of the sagittal local curvature in the Cartesian coordinate system x, y, z with the point Q as the origin. Therefore, by solving equations (5a) and (5b) simultaneously, Can be asked.

Further, the eccentricity of the intermediate point L _TS between L _T and T _S In order to obtain, the above equation (5a) and the following equations (6a) and (6b) should be solved simultaneously. As described above, in the case of the eccentricity measurement at the midpoint between L _T and L _S , the reflected image of light is substantially circular, so that the focus of the measuring machine is easy to perform and accurate measurement is possible.

In addition to the above, L _T and L
Eccentricity of _S From equation (2b) and equation (5b) May be asked. In short, if there are two independent measurement values of eccentricity, it is possible to obtain from the combination thereof. Therefore, in addition to the above combinations, If you measure two of these, It is possible to obtain There is no problem even if the measurement quantities of are combined. In any case, depending on their combination, equation (2a),
Two of the formula (2b), the formula (5b), and the formula (6a) are simultaneously calculated.

When it is not necessary to measure the eccentricity with high accuracy at the production site of the lens, the pass / fail judgment may be made only by the oblique incidence method. That is, L _T , L _S , L
Measure the eccentricity of at least one of the _TS , If is small, the lens is roughly Because it can be estimated to be small.

However, even when highly accurate eccentricity measurement is required, eccentricity measurement by one oblique incidence method It is possible to ask. An example of that case will be described below. This example is based on the eccentricity measurement of L _{T at} one θ. However, it is also possible to similarly obtain L _S and L _TS .

At the time of measurement, the lens to be inspected 11 is supposed to rotate around the rotation axis l of the measuring machine, and the locus of L _T at that time is observed. When the rotational angular velocity of the lens is ω, the time is t, and the azimuth angles of ε and δ at t = 0 are e and d, respectively, and the third and fourth rows of the equation (3) are expressed by an equation including a time change, Equation (7) is obtained. The locus of points represented by is observed with the eccentricity measuring machine of the present invention. here, When the expression (7) is expanded by substituting with, the result is as follows. However, the coefficient of cos ωt is set as D, and the coefficient of sin ωt is set as E. However, the coefficient of sin ωt is G and the coefficient of cos ωt is F.

Next, t will be deleted from the equations (8) and (9), and the relational expression between x and y will be obtained. This is the trajectory of L _T. Expressions (8) and (9) are given by cosω
Solving for t, sinωt, Since cos ² ωt + sin ² ωt = 1, Δ≡DG
-If you put EF, To get When this equation (11) is expanded, it becomes as follows. However, the coefficients of x ² , xy, and y ² are set as K, 2L, and M, respectively. This equation (12) is a correct elliptic equation.
That is, the locus of L _T becomes an ellipse as shown in FIG.

As shown in FIG. 10, the major axis a of the ellipse, the minor axis b, and the inclination angle γ of the major axis are quantities measurable by the measuring machine of this embodiment. Above K, L,
Let's express it as M. The expression (12) can be expressed by using a matrix as follows. The eigenvalues of the matrix U are α ₁ and α ₂ . α ₁ and α ₂ are two roots of the following equation (14) for α. Since U is a real symmetric matrix, it is possible to use a 2 × 2 orthogonal matrix P so that P ⁻¹ UP is a diagonal matrix. And at this time, the elliptical Given in. If you put Are standardized eigenvectors of eigenvalues α ₁ and α ₂ , respectively. As unnormalized α ₁ and α ₂ eigenvectors, Take Next, by standardizing this, the following equation (1
8) is obtained. To get

In this way, from the trajectory of L _T , a,
b, γ is obtained, and (x, y) at a specific time t ₀
By measuring the value (x ₀ , y ₀ ) of the above, from equations (8) and (9), x ₀ = Dcosωt ₀ + Esinωt ₀ ··· (23) y ₀ = Fcosωt ₀ + Gsinωt ₀ ···. (24) is obtained, and four unknowns ε, δ, d, and e are obtained by solving the equations (19), (20), (21), and (23) or (24) simultaneously. You can That is,
Eccentricity Can be asked. The equations for the four unknowns are (19), (20), (21), (2
Since there are 5 of 3) and (24), 4 of these may be selected and solved. Further, if the least square method is used to obtain ε, δ, d, and e that satisfy the five expressions as much as possible, highly accurate measurement can be performed. In this way, the amount of eccentricity can be obtained from a single oblique incidence measurement.
_It can be obtained not only from the locus of _T , but also from the loci of L _S and L _TS .

From one oblique incidence measurement as described above, the decentering amount of the aspherical lens The number of measurement times is half that of the above-mentioned method of measuring from the two methods of normal incidence method and oblique incidence method, and since it is calculated by analysis from one measurement, the measurement error is Has an advantage that it is easy to correct the error. Further, the above-described method of the present invention can be applied not only to the eccentricity measuring machine but also to the lens processing machine. That is, the eccentricity measuring device capable of oblique incidence measurement as described above is attached to the lens centering device, and the eccentricity of the lens is adjusted so that the locus of the bright spot reflection image falls within the allowable circle, and then the centering is performed. If processing is performed, it is possible to manufacture an aspherical lens having a small decentering. Further, even when two or more lenses are cemented, if an eccentricity measurement of oblique incidence is performed and the lenses are centered and cemented as described above, an aspherical cemented lens with a small eccentricity can be obtained. Further, in the above, the eccentricity of the aspherical surface was obtained, but similarly, it is possible to obtain the eccentricity of the spherical surface only by the oblique incidence measurement,
It is also possible to find the eccentricity of each of the combination lenses that combine aspherical surfaces.

Furthermore, the present invention can be applied to the case where the second surface 162 of the lens is an aspherical surface as shown in FIG. In that case, the eccentricity of the aspherical surface may be obtained after removing the apparent spherical center C and the center L of the local curvature caused by the eccentricity of the first surface 161. Even if both surfaces are aspherical surfaces, the amount of eccentricity of each surface can be obtained by performing the same measurement.

FIG. 12 shows a sixth embodiment according to the present invention, in which the aspherical lens 11 is mounted on the lens holder 171 having a mirror-like bottom surface to measure the eccentricity. The eccentricity measuring unit and the eccentricity measuring method used in this embodiment are the same as those shown in the above embodiments.

The measurement method shown in FIGS. 11 and 12 is used when the lens to be tested is an inhomogeneous medium lens (for example, trade name "SELFOC" manufactured by Nippon Sheet Glass Co., Ltd.) This is effective because the effect of eccentricity can be comprehensively measured. In this case, if the two surfaces are spherical surfaces, the eccentricity of the medium as well as the eccentricity of both surfaces can be obtained by performing three or more measurements by combining normal incidence and one or more oblique incidences. If either one of the surfaces is aspherical, measurement under different conditions may be added. As shown in FIG. 13, the inhomogeneous medium lens 11-2
Is the eccentricity of the two planes ε ₁ and ε ₂ and the eccentricity δ of the medium.
It is determined by the four vector quantities _M and ε _M. However, it is assumed that both surfaces of the lens are spherical. Therefore, since there are four eccentric degrees of freedom in terms of vector quantities, measurement is also performed with two vertical incidences and one oblique incidence, or one vertical incidence and two oblique incidences, or three vertical incidences. There is a need. The eccentric degree of freedom of the axisymmetric inhomogeneous medium is the same as in the case of the aspherical surface in the above embodiments, and two vector quantities δ _M and ε _M
It is necessary to keep in mind that it depends on. Incidentally, FIG. 11 and FIG.
In the case of the example shown in FIG. 2, the calculation formula for obtaining the eccentricity and inclination of the aspherical surface is different from the above expression (3), but from the reflected luminous flux of the luminous flux incident on two or more different parts of the aspherical surface, The eccentricity and inclination can be obtained in the same manner as the method shown in the embodiment.

FIG. 14 is a diagram showing a seventh embodiment of the present invention, showing an example in which the measuring method according to the present invention is applied to an anamorphic lens (a kind of rotationally asymmetric lens having a surface such as a rugby ball) 181. ing. In terms of lens design, it is assumed that the two main curvatures C _X and C _Y at the point V in the figure are on the Z axis of the Cartesian coordinates at the point V, and X−
The Y plane is a tangent plane at the point V, and the directions of the two main curvatures C _X and C _Y are the XY plane. In an actually processed lens, C _X and C _Y are not always on the Z axis. At this time, anamorphic lens 1
When 81 is mounted on the lens holder 2 and rotated, the positions of the reflected images of the vertically incident light beam D and the obliquely incident light beam E on the CCD camera 107 are indicated by the dotted lines in FIGS. 15A and 15B, respectively. It changes like. However, FIG.
2B is a diagram showing a reflection image of the light flux E, and FIG. On the other hand, when C _X and C _Y are present on the Z axis, the loci of the reflected images on the CCD camera 107 are as shown by the solid lines in FIGS. 15 (a) and 15 (b), respectively. By analyzing these two loci, it is possible to obtain the eccentricity (including the azimuth) of the anamorphic lens 181.

FIG. 16 is an explanatory view of an eighth embodiment of the present invention, showing an example of a double-bonded spherical lens 191, (a) is a conventional method, and (b) is a method to which the present invention is applied. It is the figure shown. In the case of measuring the eccentricity of a spherical lens by making a light beam incident vertically, a method of making a light beam incident toward the spherical center of the lens first surface 192 has been conventionally performed. However, as shown in FIG.
In a state where the spherical center C ₁ of 2 and the spherical center C ₂ of the third surface 193 are close, it will be imaged at the same time reflected image on the CCD camera 107 in the two planes, in either lens surface There was a problem that it became unclear whether or not the eccentricity was measured.

However, even in the above case, if the device according to the present invention is used, the light projecting lens 3, the imaging lens 4 and the focus lens 10 in the eccentricity measuring unit of the device are used.
By adjusting the positional relationship between the two, FIG.
As shown in (b), a light flux that forms an image is made incident between the first surface 192 and the third surface 193 of the lens, and the distance difference is formed between the image forming positions I _{1 and} I _{2 of the} reflected image. Can be provided,
Therefore, only one of the two reflected images can be blurred and invisible. As described above, by using the device of the present invention, it is possible to distinguish the reflection image of each lens surface by shifting the magnification of the reflection image on each lens surface from the same size.

In order to measure the eccentricity of the lens outer circumference with respect to the lens optical axis, the image forming lens 4 of the measuring machine is mounted on the outer circumference of the lens.
(Or the lens system 131) may be brought into focus, the outer circumference may be detected by image processing, the center thereof may be obtained, and the deviation from the optical axis may be calculated. These processes are performed by the AD conversion image board 11
0, the personal computer 113 or the like. Of course, instead of the image processing, the outer periphery of the television image may be specified by clicking the mouse or the like, and the eccentricity of the outer periphery may be obtained.

[0046]

As described above, the eccentricity measuring method according to the present invention and the machine using the same are not only used for spherical and aspherical lenses, but also for eccentricity of aspherical reflecting mirrors and molds of lenses made of molds. It has an excellent advantage that it enables measurement, has a long working distance of the device, and keeps the manufacturing cost low.

[Brief description of drawings]

FIG. 1 is an external view of a device of a first embodiment of a lens eccentricity measuring machine according to the present invention.

FIG. 2 is a diagram showing a second embodiment of the lens eccentricity measuring machine of the present invention, FIG. 2 (a) is a diagram showing an example in which an optical system 131 is applied to the configuration of the eccentricity measuring unit, and FIG. 2 (b) is a mirror. It is the figure which showed the example which provided 134 in the eccentricity measurement unit.

FIG. 3 is a diagram showing a third embodiment of the present invention, (a)
Is a top view of the device, and (b) is a side view of the device seen from the AX axis direction.

FIG. 4 is a diagram showing a fourth embodiment of the present invention.

FIG. 5 is an explanatory diagram of a direction of an incident light flux of a bright spot image at the time of measuring eccentricity of a peripheral portion of a lens in which a periphery of an aspheric surface is substantially perpendicular to an optical axis.

FIG. 6 is a diagram showing a fifth embodiment of the present invention.

FIG. 7 is an explanatory diagram of two centers L _T and L _S of local curvature.

FIG. 8 is an explanatory diagram of a sagittal local curvature center L _S.

FIG. 9 is an explanatory diagram of a method of measuring the eccentricity and inclination of an aspherical lens by using the eccentricity of the center L _S of the sagittal local curvature.

FIG. 10 is an explanatory diagram showing a locus of the local curvature center L _T when eccentricity measurement is performed by only one oblique incidence method.

FIG. 11 is a diagram showing a state in which the device according to the present invention is applied to a lens in which the second surface of the lens is aspherical.

FIG. 12 is a diagram showing a sixth embodiment of the present invention.

FIG. 13 is an explanatory diagram of four vectors related to decentering measurement of a non-homogeneous medium lens.

FIG. 14 is a diagram showing a seventh embodiment of the present invention.

15A and 15B are views showing reflected images of a vertically incident light beam D and an obliquely incident light beam E in a seventh embodiment captured on a CCD camera 107. FIG. 15A is a reflected image of the light beam D and FIG. It is the figure which showed the reflection image.

16A and 16B are explanatory diagrams of a method of measuring decentering in a double-bonded spherical lens, FIG. 16A shows a conventional method, and FIG. 16B shows a method to which the present invention is applied.

FIG. 17 is a principle configuration diagram of a lens eccentricity measuring machine according to the present invention.

18A is an explanatory diagram of inclination and decentering of an aspherical surface of an aspherical lens, and FIG. 18B is an explanatory diagram of a conventional decentering measuring method of an aspherical lens using a distance sensor.

FIG. 19 (a) is an explanatory view of a method of measuring decentering and inclination of an aspherical lens by a normal incidence method and an oblique incidence method, and FIG. 19 (b) is a center L ₁ , L ₂ , ... Of two or more local curvatures. FIG. 6 is an explanatory diagram of a method of obtaining the eccentricity and the inclination of the lens from the measured values of the eccentricity of the and the spherical center C.

FIG. 20 is a device configuration diagram of a conventional lens eccentricity measuring machine.

[Explanation of symbols]

1 Pinhole 2 Lens Holder 3 Projection Lens 4 Imaging Lens 5 Half Prism 6 Eyepiece 7 Prism 8 Spherical Lens (Test Lens) 9 Reflected Image 10 Ball Center 11 Aspherical Lens (Test Lens) 12 Distance Sensor 101 Light Source (Visible semiconductor laser etc.) 102 Focus lens 103 Mirror 104 Real image 105 Microscope objective lens 106 10x zoom lens 107 CCD camera 108 Super pause board 109 Display 110 Slide mirror 111 Rotating mirror 112 AD conversion board 113 Personal computer 114 Color display 115 Printer 121 Measurement Machine body 122 Switching unit 123 Switching knob 124a Slide stage 124b Slide knob 125 Control box 131 Lens system 132, 133 system Ter 134 Mirror 141 Moving stage 151 Optical axis 161 First surface of lens 162 Second surface of lens 171 Lens holder with bottom mirror 181 Anamorphic lens 191 Two-sided spherical lens 192 First surface of lens 193 lens second surface V aspheric surface apex C during no eccentricity of the C _1, C ₂ spherical center C _x, C _y principal curvature D, E beam L _T, L _S, the center P linear QL of L _TS local curvature Intersection with VC Q One point around the aspheric surface R Paraxial radius of curvature when the aspheric surface is eccentric d Distance l Center of rotation (rotation axis) m Normal vector φ ∠CVL _T or ∠CVL _S or ∠CVL _TS Size of θ ∠L _T PV or ∠L _S PV or ∠L _TS PV

Claims (7)

[Claims] 1. An optical element or mold comprising an aspherical surface or an inhomogeneous medium, in which a light beam is made incident on at least one portion outside the optical axis, and the eccentricity of the aspherical surface is evaluated from the position of the reflected light beam. Eccentricity measurement method for lenses, reflectors, molds, etc. 2. An eccentricity measuring machine using the eccentricity measuring method according to claim 1, or a lens processing machine such as a lens centering machine or a lens joining machine. 3. An eccentricity measuring method for a lens, a reflecting mirror, a mold, etc., characterized in that a light beam is made incident on at least two parts of an aspherical surface and the amount of eccentricity of the aspherical surface is obtained from the position of the reflected light beam. 4. A lens, characterized in that an eccentricity amount of an aspherical surface is obtained from a locus of a reflected light beam when a light beam is incident on at least one part of the aspherical surface outside the optical axis and the object is rotated. Eccentricity measuring machine for reflectors and molds. 5. A lens processing machine such as a lens eccentricity measuring machine or a lens bonding machine, which obtains an eccentricity amount of a lens surface with respect to the lens outer circumference by photographing and analyzing an image of the lens outer circumference. 6. A lens eccentricity measuring machine characterized by evaluating an eccentricity error of an aspherical lens from eccentricity of a local curvature center measured by an oblique incidence method. 7. A lens eccentricity measuring method characterized in that a light beam is made incident on at least one portion on the aspherical surface outside the optical axis, and an eccentricity error of the aspherical surface is evaluated from the reflected light beam.