JP2006119121A - Shape measurement method and device for optical member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure the magnitude of an eccentricity of a double-sided aspheric lens with high accuracy but without taking any trouble. <P>SOLUTION: An eccentricity measurement device 10 has a probe 11 and a sensing pin 13, and scans the surface of the lens 31 installed to a jig 12 to measure its shape. The jig 12 has a rotary stage 17 journalled to a support 16 by a rotary shaft 18, and can measure the shape of both the front and rear faces of the lens 31 by turning over the lens 31 by 180°. After measuring the shape of both the faces of the lens 31, intersection point coordinates of each the face to an optical axis are found by an arithmetic part 26. In the arithmetic part 26, processing for correcting the intersection point coordinates to the optical axis is performed on the basis of the eccentricity or the like of the rotary shaft 18 to measure eccentric amounts of two aspheric faces are measured with high accuracy. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a shape measuring method and a shape measuring apparatus for an optical member for measuring a relative positional difference between curved surfaces using an optical member such as a lens having a plurality of curved surfaces as a measurement object.

  Double-sided aspherical lenses are widely used for optical disk objective lenses, camera objective lenses incorporated in mobile phones, and the like. A double-sided aspherical lens requires that the optical axes of the two aspherical surfaces be aligned with extremely high accuracy. When manufacturing an aspherical lens, the eccentricity between the aspherical surfaces is measured from the actually fabricated lens. Ingenuity has been made, for example, to increase the molding accuracy of the lens by feeding back the measurement result to the manufacturing process.

  Patent Document 1 describes an eccentricity measuring device having a jig in which two positioning pins pressed against the surface of a lens are formed. In this eccentricity measuring apparatus, when measuring the front surface of the lens, the front surface of the lens is pressed against the two positioning pins from below, and the shape of the surface is measured after fixing the position of the lens. When measuring the rear surface of the lens, the lens is once separated from the positioning pin and rotated 180 degrees, the rear surface of the lens is pressed against the two positioning pins from above, the position of the lens is fixed, and then the surface shape is measured. . When the surface shapes of the front and rear surfaces of the lens are measured, the position of the optical axis of each aspheric surface is obtained, and the amount of eccentricity between the aspheric surfaces is calculated.

The eccentricity measuring device described in Patent Document 2 includes a lens holding plate provided with three true spheres for positioning. Part of the three true spheres is exposed from the front and rear surfaces of the lens holding plate. When measuring the front surface of the lens, the vertex positions of the three true spheres are measured, the reference coordinates are determined, and the amount of inclination of the lens holding plate with respect to the scanning plane is calculated. When measuring the rear surface of the lens, remove the lens holding plate from the device and turn it over, then measure the vertex coordinates of the three true spheres in the same way, determine the reference coordinates, and calculate the tilt amount of the lens holding plate Is done. After the surface shapes of the front and rear surfaces of the lens are measured, the position of the optical axis of each aspheric surface and the amount of eccentricity thereof are calculated from the reference coordinates determined by the true sphere and the tilt amount of the lens holding plate.
JP 2002-214071 A JP 2002-71344 A

  However, since the eccentricity measuring apparatus of Patent Document 1 needs to separate the lens from the positioning pin when turning the lens over in order to measure the shape of both surfaces, the reference position of the lens can be kept constant only by striking the positioning pin. There was a problem that it was not possible to maintain and high-precision eccentricity measurement could not be performed. In addition, the eccentricity measuring device described in Patent Document 2 requires time and effort to obtain the vertex coordinates of three true spheres each time each surface of the lens is measured once in order to flip the lens holding plate. There was a problem.

  The present invention has been made in consideration of the above-mentioned problems, and provides a shape measuring method and a shape measuring apparatus for an optical member that can reduce the labor and time required for measurement and enable highly accurate eccentricity measurement. Objective.

  In order to achieve the above object, the present invention measures the shape of each curved surface of an optical member having a plurality of curved surfaces by means of surface shape measuring means for measuring the surface shape of an object, and determines the position of a feature point that each curved surface has. In a method for measuring the shape of an optical member for measuring the size of positional deviation between curved surfaces by comparing the positions of the characteristic points, and supporting a holding body for holding the optical member via a rotating shaft. Each curved surface is displaced to a measurement position where shape measurement by the shape measuring means can be performed by pivoting on the body and rotating the holding body, and the surface shape of the curved surface is measured at each measurement position. The size of the positional deviation between the curved surfaces is measured from the position of the feature point.

  The shape of the true sphere held by the holding body is measured at each measurement position by the surface shape measuring means, and the amount of eccentricity of the rotating shaft is calculated from the obtained position of the vertex of the true sphere, and the amount of eccentricity of the rotating shaft Based on the above, the position of the feature point of each curved surface is corrected.

  Comparing the shape measurement value with the design value to calculate the amount of inclination of each curved surface with respect to the measurement reference surface, and correcting the position of the feature point based on the difference between the two obtained inclination amounts It is characterized by.

  The amount of inclination is calculated from a difference between an inclination of a flat surface portion formed on the holding body and an inclination of a flat seat surface portion that makes a part of the optical member contact.

  The optical member is a double-sided aspherical lens having two aspherical surfaces that are rotationally symmetric with respect to the optical axis. The holding member is rotated 180 degrees to obtain the intersection point with each aspherical optical axis as the feature point. In addition, the position of the intersection is calculated by comparing a shape measurement value of a part of the aspheric surface measured by the surface shape measurement means with a design value of each curved surface.

  The surface shape measuring means includes a probe for measuring the surface shape by scanning the object surface while displacing the stylus so that the distance from the object surface is kept constant.

  The shape measuring apparatus of the present invention is an apparatus that uses the above-described shape measuring method, and includes a shape measuring means that scans the surface of an object and measures its shape, and an optical member on which a plurality of curved surfaces are formed. It is characterized by comprising a holding body to be held and a supporting means for rotatably supporting the holding body via a rotating shaft and displacing the optical member to a position where each curved surface shape can be measured.

  According to the present invention, the holding body that holds the optical member can be arbitrarily rotated by the rotation shaft, and the positional deviation caused by reversing the optical member does not occur. Can be measured, and the time and labor required for measurement can be reduced. Moreover, since the relative inclination amount between the curved surfaces can be measured with high accuracy and in a short time, the shape of the optical member can be accurately measured. Due to such effects, in optical members processed using mold molding, it is possible to finely adjust the alignment position of the mold to increase molding accuracy, to reflect the positional deviation between the curved surfaces and the amount of eccentricity. High-precision simulations close to physical properties can be realized.

  In FIG. 1, an eccentricity measuring apparatus 10 to which the present invention is applied includes a probe 11 that performs three-dimensional shape measurement, and a jig 12 that holds a lens that performs eccentricity measurement. A probe 11 is provided with a stylus 13. The probe 11 moves the stylus 13 in the three directions of the X axis, the Y axis, and the Z axis, which are reference coordinate axes, along the surface of the object to be measured. The eccentricity measuring apparatus 10 uses a horizontal reference plane including the X axis and the Y axis as a scanning reference plane of the stylus 13. The stylus 13 approaches the distance where the interatomic force acts between the tip and the measurement object, and moves forward and backward in the Z-axis direction so that the interatomic force is maintained at a constant magnitude. The stylus 13 is displaced in the Z-axis direction within a range of several micrometers, for example, while the probe 11 moves in three directions within a range of several tens of millimeters, for example. The stylus 13 is provided with a tip portion made of diamond polished to a radius of curvature of, for example, about 5 micrometers. In addition to diamond, ruby, steel ball, etc. may be used.

  The jig 12 includes a support base 16 and a rotary stage 17. The rotary stage 17 is provided with a rotary shaft 18 and a lens holder 19. The rotary stage 17 is pivotally supported on the support base 16. A handle 20 that is rotated is provided at one end of the rotary shaft 18. When the handle 20 is operated, the rotary stage 17 rotates about the rotary shaft 18. The lens holder 19 is provided with a lens pressing plate 21 which is a plate spring for pressing the attached lens. A pin insertion hole 22 is provided on the side surface of the support base 16. A positioning pin 23 for fixing the rotary stage 17 is inserted into the pin insertion hole 22.

  The eccentricity measuring apparatus 10 is provided with a measurement value output unit 25 and a calculation unit 26. The measured value output unit 25 receives displacement information of each coordinate axis direction component obtained by scanning the object surface with the probe 11 and the stylus 13 as an electric signal, converts this into digital data, and outputs it. The calculation unit 26 is preliminarily input with the design formula of the curved surface of the measurement object, compares the measurement value output from the measurement value output unit 25 with the design value input in advance, and matches the measurement value with the design value. An arithmetic process for fitting is performed. In this calculation process, from the difference between the measured value and the design value, the amount of inclination of the measured curved surface with respect to the scanning reference surface and the characteristic points of the curved surface, for example, the vertex coordinates and the optical axis, which are the highest point and the lowest point of the curved surface, are calculated. Can be calculated.

  In FIG. 2, the rotary stage 17 is provided with a stage front surface 17f and a stage rear surface 17b formed flat. The rotary stage 17 is provided with an opening 30 penetrating from the stage front surface 17f to the stage rear surface 17b. The lens holder 19 is attached to the opening 30 from the stage front surface 17 f side of the rotary stage 17. The lens holder 19 is screwed to the rotary stage 17 and can be exchanged when changing the type of lens to be measured. In the lens holder 19, a lens 31 is set on the seating surface 19a. The lens 31 is a double-sided aspheric lens.

  The lens 31 is pressed from above by the lens pressing plate 21 and is held inside the lens holder 19. The lens holder 19 has a hole formed in the center thereof, and the front and back surfaces of the lens 31 face the probe 11 and the stylus 13 by rotating the rotary stage 17 by 180 degrees. A fixing hole 32 is provided on the side surface of the rotary stage 17. The fixing hole 32 penetrates from one side surface of the rotary stage 17 to the other side surface, and the tip portion of the positioning pin 23 inserted from the pin insertion hole 22 of the support base 16 is inserted. By using the positioning pin 23, the rotary stage 17 can be fixed every time the lens 31 is rotated 180 degrees.

In FIG. 3, the principle for obtaining the amount of eccentricity of the double-sided aspheric lens by the eccentricity measuring device 10 will be described. In order to accurately obtain the position of the intersection of each surface of the lens 31 with the optical axis, it is necessary to obtain calibration data resulting from the accuracy of the jig 12 and the like. The calibration data includes inclination amounts θ _r (f), θ _r (b) (addition of an error related to the level of the surface on which the jig 12 is installed and an error of the rotation angle when the rotary stage 17 is inverted. 3 (a)), an inclination amount θ _s (FIG. 3 (b)) which is an error related to the level of the seating surface 19a of the lens holder 19, and parallelism between the stage front surface 17f and the stage rear surface 17b of the rotary stage 17. There are inclination amounts θ _p (f) and θ _p (b) (FIG. 3C) which are errors. Further, as an error of the rotating shaft 18, an inclination amount θ _z that is an error in parallelism with respect to the X axis of the axis 18 a of the rotating shaft 18 and a distance from the axis 18 a on the XY plane to the center of the lens holder 19 ( There is an offset amount) Y _o (see FIG. 8). Note that θ _z represents the amount of inclination with the Z axis as the center of rotation necessary for correcting the axis 18a in the X axis direction.

The magnitude of each tilt error including θ _r , θ _s , and θ _p can be separated into a component centered on the X axis and a rotational component centered on the Y axis. In the following description, it is assumed that the components of the tilt amount with each coordinate axis as the center of rotation are represented by attaching X and Y indices, respectively.

When the inclination amount of the lens front surface 31f obtained by measuring the front surface shape of the lens 31 is θ _m (f), its components θ _mx (f) and θ _my (f) are
θ _mx (f) = θ _lx (f) + θ _sx + θ _rx (f)
θ _my (f) = θ _ly (f) + θ _sy + θ _ry (f) + θ _ky (f)
It is expressed. Θ _l (f) is the true tilt amount of the lens front surface 31 f, and θ _k (f) is the tilt amount of the axis 18 a of the rotating shaft 18 in a state where the stage front surface 17 f faces the probe 11. is there.

Further, when the inclination amount obtained by measuring the shape of the stage front surface 17f of the rotary stage 17 is θ _h (f), the component is
θ _hx (f) = θ _rx (f) + θ _px (f)
θ _hy (f) = θ _ry (f) + θ _py (f) + θ _ky (f)
It is expressed. From these values and the position coordinates X _m (f), Y _m (f) of the optical axis A1 on the XY plane obtained by measuring the shape of the lens front surface 31f, the true position coordinates X _l ( f), Y _l (f) and true inclination amounts θ _lx (f), θ _ly (f) of the lens front surface 31f can be calculated.
X _l (f) = X _m (f) + H _z (f) · sin (θ _hy (f) −θ _py (f)) + L _z (f) · sin (θ _sy )
Y _l (f) = Y _m (f) + H _z (f) · sin (θ _hx (f) −θ _px (f)) + L _z (f) · sin (θ _sx )
θ _lx (f) = θ _mx (f) −θ _sx −θ _hx (f) + θ _px (f)
θ _ly (f) = θ _my (f) −θ _sy −θ _hy (f) + θ _py (f)
However, as shown in FIG. 4, H _z (f) is the distance from the vertex (intersection with the optical axis) of the lens front surface 31f to the axis 18a, and H _z (b) is the axis 18a from the vertex of the lens rear surface 31b. , L _z (f) and L _z (b) are the heights of the surfaces of the lens alone. For H _z (f), H _z (b), L _z (f), and L _z (b), values obtained from design values of the jig 12 and the lens 31 are sufficient due to the nature of measurement. In order to further increase the measurement accuracy, an actual measurement value may be used. Further, as shown in the above equation, θ _r (f) is canceled out in the equation, and the error of the rotation angle of the rotary stage 17 does not affect the measurement result.

The inclination amount θ _m (b) of the lens rear surface 31b obtained by measuring the shape of the lens rear surface 31b is expressed as follows:
θ _mx (b) = θ _lx (b) + θ _sx + θ _rx (b)
θ _my (b) = − θ _ly (b) + (− θ _sy ) + θ _ry (b) + θ _ky (b)
The inclination amount θ _h (b) obtained by measuring the shape of the stage rear surface 17b is expressed as follows:
θ _hx (b) = θ _rx (b) + θ _px (b)
θ _hy (b) = θ _ry (b) + (− θ _py (b)) + θ _ky (b)
It is expressed.

From the above values and the position coordinates X _m (b), Y _m (b) of the optical axis A2 obtained by measuring the shape of the lens rear surface 31b, the true position coordinates X _l (b), Y _l (b) and tilt amounts θ _lx (b) and θ _ly (b) of the lens front surface 31f can be calculated. For Y _l (b), an offset amount Y _o due to the eccentricity of the axis 18a is taken into account.
X _l (b) = X _m (b) −H _z (b) · sin (θ _hy (b) − (− θ _py (b))) − L _z (b) · sin (−θ _sy )
Y _l (b) = − (Y _m (b) −H _z (b) · sin (θ _hx (b) −θ _px (b)) − L _z (b) · sin (θ _sx ) −2 · Y _o )
θ _lx (b) = θ _mx (b) −θ _sx −θ _hx (b) + θ _px (b)
θ _ly (b) = − θ _my (b) −θ _sy + θ _hy (b) + θ _py (b)
However, H _z (b) is the distance from the axis 18a to the apex of the lens rear surface 31b, and L _z (b) is the height of the lens.

In general, it is known that sin θ≈θ and cos θ≈1 when θ is sufficiently small. Therefore,
sin (θ _a + θ _b ) = θ _a + θ _b
In order to obtain the eccentricity S, X _l (f), X _l (b), Y _l (f), and Y _l (b) may be approximated to the following forms, respectively.
X _l (f) = X _m (f) + H _z (f) · (θ _hy (f) + (θ _sy −θ _py (f)) 1)
X _l (b) = X _m (b) −H _z (b) · (θ _hy (b) − (θ _sy −θ _py (b)) 2)
Y _l (f) = Y _m (f) + H _z (f) · (θ _hx (f) + (θ _sx −θ _px (f)) 3)
Y _l (b) = − [Y _m (b) −H _z (b) · (θ _hx (b) + (θ _sx −θ _px (b)) − 2 · Y _o ] 4)

In FIG. 5, the amount of eccentricity S between the optical axis A1 of the lens front surface 31f and the optical axis A2 of the lens rear surface 31b can be obtained by the following equation.
S = ((X _l (f) −X _l (b)) ² + (Y _l (f) −Y _l (b)) ² ) ^1/2 5)
In addition, the lens surface tilts T _x and T _y , which are the relative tilt amounts of the lens front surface 31 f and the lens rear surface 31 b,
T _x = θ _lx (f) −θ _lx (b) 6)
T _x = θ _ly (f) −θ _ly (b) 7)
Can be obtained as

Next, a procedure for measuring the amount of eccentricity of the lens 31 will be described with reference to FIG. Before measuring the shape of the lens 31, a preliminary measurement for obtaining calibration data of the jig 12 is performed. In this preliminary measurement, (θ _sx −θ _px (f)), (θ _sx −θ _px ) is obtained by _obtaining a difference between the inclination of the seating surface 19 a and the inclination of the stage front surface 17 f and the stage rear surface 17 b of the rotary stage 17. (B)), (θ _sy −θ _py (f)), (θ _sy −θ _py (b)) are calculated. Moreover, obtaining the inclination amount theta _z and the offset amount Y _o with respect to the X-axis of the axis 18a using a true sphere 35.

A jig 12 having a lens holder 19 attached to the rotary stage 17 is prepared, and the shape of the seating surface 19a is measured. Tilt amount obtained from the shape measurement of the seating surface 19a by the operation unit 26 is a value including the inclination theta _s of inclination of the jig 12 theta _r and the lens seat surface 19a. Next, a true sphere 35 having the same diameter as the lens 31 is attached to the lens holder 19 attached to the rotary stage 17, and the surface shape of the true sphere 35 is measured. The true sphere 35 is a true sphere having a grade of G10 or higher. In the eccentricity measuring apparatus 10, the probe 11 scans the object surface by moving the stylus 13 in a cross shape along the X axis and the Y axis. Note that the stylus 13 is not limited to the cross-shaped scanning, and may be scanned in a zigzag shape, a radial shape, or a concentric shape. When measuring the decentering of the aspherical lens, a part of the aspherical surface is shaped like a cross. It is sufficient to scan once.

As shown in FIG. 7A, in the state where the probe 11 and the stage front surface 17f of the rotary stage 17 face each other, the probe 11 and the stylus 13 are brought close to the true sphere 35, and the shape of the surface of the true sphere 35 is reached. Measure. In the calculation unit 26, the coordinates X _B (f) and Y _B (f) of the vertex of the true sphere 35 are calculated from the measured value of the true sphere 35. The positioning pin 23 is removed and the handle 20 is operated to invert the rotary stage 17 by 180 degrees. As shown in FIG. 7B, the probe 11 and the stylus 13 are made to face the stage rear surface 17b of the rotary stage 17, the shape of the surface of the true sphere 35 is measured in the same manner, and the true sphere 35 on the stage rear surface 17b is measured. Vertex coordinates X _B (b) and Y _B (b) are calculated.

In FIG. 8, the vertex coordinates X _B (f) of the true sphere 35 calculated at the first measurement position where the probe 11 and the stage front surface 17f of the rotary stage 17 face each other and at the second measurement position where the probe rear surface 17b faces each other. ), Y _B (f), X _B (b), and Y _B (b), an inclination amount θ _z and an offset amount Y _o with respect to the X axis of the axis 18a are calculated. θ _z is
θ _z = 90−tan ⁻¹ ((Y _B (f) −Y _B (b)) / (X _B (f) −X _B (b)))
Is calculated as, Y _o is used Y _B by _{θ z (f), Y B} (b) Y B corrected for '(f) and Y _B' (b),
Y _o = [(Y _B ′ (f) −Y _B ′ (b)] / 2
Is calculated as

In FIG. 9, the positioning pin 23 is removed, the rotary stage 17 is inverted 180 degrees and returned to its original position, and the true sphere 35 set on the lens holder 19 is removed. The lens 31 for measuring the eccentricity S is set in the lens holder 19, and the shape of the stage front surface 17f of the rotary stage 17 is measured (FIG. 9A). By this measurement, each component θ _hx (f), θ _hy (f) of the tilt amount θ _h (f) indicating the level of the stage front surface 17f is obtained. (Θ _sx −θ _px (f)) and (θ _sy −θ _py (f)) can be calculated by subtracting the previously measured inclination amount of the seating surface 19a from θ _h (f). In the description below,
θ _sx −θ _px (f) = θ _spx (f)
θ _sy −θ _py (f) = θ _spy (f)
And

Next, the shape of the lens front surface 31f is measured (FIG. 9B). When the shape of the lens front surface 31f is measured, the measured value and the design value are compared by the calculation unit 26, and the coordinates X _m (f), Y _m (f), Z _m (of the optical axis A1 of the lens front surface 31f are compared. f) and the inclination amounts θ _mx (f), θ _my (f) are calculated.

The positioning pin 23 is removed, and the rotary stage 17 is inverted 180 degrees and set at the second measurement position. The probe 11 and the stylus 13 are brought close to the lens rear surface 31b, and the shape of the lens rear surface 31b is measured (FIG. 9C). The calculation unit 26 calculates coordinates X _m (b), Y _m (b), Z _m (b) of the optical axis A2 of the lens rear surface 31b, and inclination amounts θ _mx (b), θ _my (b). . Next, the shape of the stage rear surface 17b is measured (FIG. 9D), and the tilt amounts θ _hx (b) and θ _hy (b) of the stage rear surface 17b are calculated. (Θ _sx −θ _px (b)) and (θ _sy −θ _py (b)) can be calculated from the inclination amount of the seating surface 19a measured earlier and θ _h (b). In the description below,
θ _sx −θ _px (b) = θ _spx (b)
θ _sy −θ _py (b) = θ _spy (b)
And

After obtaining each value in this way, the position coordinates (X _m (f), Y _m (f), Z _m (f)), (X _m (b), Y _m (b ), a correction operation is performed by theta _z in Z _m (b)). If it is not necessary to consider θ _z , the value obtained from the measurement result may be substituted into the formulas 1) to 4). θ in accordance with correction _z, since Z-axis component of the optical axis A1, A2 is unchanged, the position coordinates of the optical axis A1 of the corrected _{(X m '(f),} Y m' (f), Z m (f )), the position coordinates of the optical axis _{A2 ((X m '(b} ), Y m' (b), when the Z _m (b)), X-axis component and Y axis component of the coordinates of each optical axis, Each is required as a general rotation map,
X _m ′ (f) = cos (θ _z ) · X _m (f) + sin (θ _z ) · Y _m (f)
Y _m ′ (f) = − sin (θ _z ) · X _m (f) + cos (θ _z ) · Y _m (f)
X _m ′ (b) = cos (θ _z ) · X _m (b) + sin (θ _z ) · Y _m (b)
Y _m ′ (b) = − sin (θ _z ) · X _m (b) + cos (θ _z ) · Y _m (b)
It becomes.

Further, each component of θ _m (f) and θ _m (f) corrected by θ _z is expressed as (θ _mx '(f), θ _my ' (f)), (θ _mx '(b), θ _my '(B))
θ _mx '(f) = tan ⁻¹ (−tan (θ _my (f)) · sin (θ _z )) + tan (θ _mx (f)) · cos (θ _z ))
θ _my '(f) = tan ⁻¹ (tan (θ _my (f)) · cos (θ _z )) + tan (θ _mx (f)) · sin (θ _z ))
θ _mx '(b) = tan ⁻¹ (−tan (θ _my (b)) · sin (θ _z )) + tan (θ _mx (b)) · cos (θ _z ))
θ _my '(b) = tan ⁻¹ (tan (θ _my (b)) · cos (θ _z )) + tan (θ _mx (b)) · sin (θ _z ))
It becomes.

Similarly, θ _h (f) and θ _h (b) are also corrected. The components of θ _h ′ (f) and θ _h ′ (b) corrected by θ _z are expressed as (θ _hx ′ (f), θ _hy ′ (f)), (θ _hx ′ (b), θ _hy '(B))
θ _hx '(f) = tan ⁻¹ (−tan (θ _hy (f)) · sin (θz)) + tan (θ _hx (f)) · cos (θ _z ))
θ _hy '(f) = tan ^-1 (tan (θ _hy (f)) · cos (θz)) + tan (θ _hx (f)) · sin (θ _z ))
θ _hx ′ (b) = tan ⁻¹ (−tan (θ _hy (b)) · sin (θz)) + tan (θ _hx (b)) · cos (θ _z ))
θ _hy ′ (b) = tan ⁻¹ (tan (θ _hy (b)) · cos (θz)) + tan (θ _hx (b)) · sin (θ _z ))
It becomes. Note that θ _spx (f), θ _spy (f), θ _spx (b), θ _spy (b) are obtained from θ _h ′ (f) and θ _h ′ (b) by θ _spx ′ (f), θ It is calculated as _spy '(f), θ _spx ' (b), θ _spy '(b).

After performing the above correction processing, the true position coordinates are calculated with respect to the optical axis A1 of the lens front surface 31f and the optical axis A2 of the lens rear surface 31b by substituting each value into the above formulas 1) to 4).
X _l (f) = X _m ′ (f) + H _z (f) · (θ _hy ′ (f) + θ _spy ′ (f))
Y _l (f) = Y _m ′ (f) + H _z (f) · (θ _hx ′ (f) + θ _spx ′ (f))
X _l (b) = X _m ′ (b) −H _z (b) · (θ _hy ′ (b) − (θ _spy ′ (b))
Y _l (b) = − [Y _m ′ (b) −H _z (b) · (θ _hx ′ (b) + (θ _spx ′ (b)) − 2 · Y _o ]
θ _lx (f) = θ _mx '(f) −θ _hx ' (f) + θ _spx '(f)
θ _ly (f) = θ _my '(f) −θ _hy ' (f) −θ _spy '(f)
θ _lx (b) = θ _mx '(b) −θ _hx ′ (b) −θ _spx ′ (b)
θ _ly (b) = − θ _my ′ (b) + θ _hy ′ (b) −θ _spy ′ (b)
From the equations 5) to 7), the decentering amount S and the relative tilt amounts (lens surface tilt) T _x and T _{y of the} lens surface are obtained. A measurement example is shown below.

Note that the same value can be used for θ _z unless the jig 12 is moved or replaced, and θ _sp (f), θ _sp (b), and Y _o are the same unless the lens holder 19 is replaced. Since values can be used, a part of the measurement procedure shown in FIG. 6 can be omitted in the second and subsequent measurements. That is, when measuring different lenses having the same shape, steps 1 to 7 may be omitted, and only steps 8 and after may be performed, and the time required for measurement can be shortened.

Further, in order to obtain the values of θ _sp (f) and θ _sp (b), there are two methods other than measuring the shapes of the seating surface 19a, the stage front surface 17f of the rotary stage 17, and the stage rear surface 17b. . In the first method, a disk having the same shape as the lens and with a guaranteed flatness is attached to the lens holder 19, the shape of the disk and the shape of both surfaces of the stage are measured, and the difference between them is calculated. _sp (f), θ _sp (b) is obtained.

The second method uses a double-sided aspheric lens with high accuracy that is free from decentration and surface tilt. The double-sided aspheric lens is attached to the lens holder 19 and Steps 9 to 13 are performed. Thereby, the tilts θ _m (f, 0) and θ _m (b, 0) of the lens surface and the tilt amounts θ _h (f, 0) and θ _h (b, 0) of the rotary stage 17 are obtained. Also, the double-sided aspheric lens is removed from the lens holder 19, rotated 180 degrees, and attached to the lens holder 19 again. Similarly, steps 9 to 13 are performed, and θ _m (f, 180), θ _m (b, 180), θ _h (f, 180) and θ _h (b, 180) are obtained. θ _spx (f), θ _spy (f), θ _spx (b) θ _spy (b) can be calculated.
θ _spx (f) = [(θ _mx (f, 0) + θ _mx (f, 180)) − (θ _hx (f, 0) + θ _hx (f, 180))] / 2
θ _spy (f) = [(θ _my (f, 0) + θ _my (f, 180)) − (θ _hy (f, 0) + θ _hy (f, 180))] / 2
θ _spx (b) = [(θ _mx (b, 0) + θ _mx (b, 180)) − (θ _hx (b, 0) + θ _hx (b, 180))] / 2
θ _spy (b) = − [(θ _my (b, 0) + θ _my (b, 180)) − (θ _hy (b, 0) + θ _hy (b, 180))] / 2

Further, in obtaining the offset amount Y _o , as a method not using the true sphere 35, a method using a double-sided aspheric lens having sufficient surface accuracy is conceivable. Attach the aspheric lens in the lens holder 19 performs the step 9 to step 13, as X _m 0 to Y _o of the above 4) _{(f, 0), Y m} (f, 0), X m (b , 0), Y _m (b, 0). Further, the double-sided aspheric lens is removed from the lens holder 19 and rotated 180 degrees, and is attached to the lens holder 19 again, and Steps 9 to 13 are performed, and X _m (f, 180), Y _m (f, 180), X _m (b, 180) and Y _m (b, 180) are obtained. In order to obtain Y _o , four values Y _m (f, 0), Y _m (b, 0), Y _m (f, 180), and Y _m (b, 180) are substituted into the following equation. That's fine.
Y _o = [Y _m (f, 0) −Y _m (b, 0) + Y _m (f, 180) −Y _m (b, 180)]

  In the present invention, in order to eliminate backlash between the rotating shaft 18 and the bearing portion of the support base 16, a spring or the like for biasing the rotating shaft 18 may be provided on the bearing portion of the support base 16. For the purpose of improving, it is preferable to apply various devices to the details of the jig 12. Further, in order to hold the lens to be measured, in addition to holding the lens holder 19 from above with the spring force of the lens pressing plate 21, air is sucked from a hole provided in the lens holder 19 so that the edge of the lens is positioned on the lens. Appropriate means such as fixing to the holder or attaching the lens to the lens holder 19 and fixing can be used. Further, when rotating the rotary stage 17, it is not limited to manual operation but may be performed automatically. Furthermore, an optical measuring means such as a laser interferometer may be used for planar measurement of the rotary stage 17.

  The present invention may be used not only for measuring the eccentricity of a double-sided aspheric lens but also for measuring the eccentricity of a single-sided aspherical lens or a spherical lens on the premise that the outer diameter of the spherical surface is accurately measured. It may be used for measurement. Alternatively, as shown in FIG. 10, it may be used to measure the shape of a lens in a broad sense in which a strict optical axis is not defined, such as an eccentric optical member 50 having a curved surface formed of a free curved surface or the like. The vertex coordinates of the highest point P1 or the lowest point P2 are obtained as the feature points of the optical member 50 curved surface S1, the vertex coordinates of the highest point P3 or the lowest point P4 are obtained as feature points of the curved surface S2, and the positional deviation of these feature points is obtained. The relative positional deviation amount between the curved surface S1 and the curved surface S2 may be measured depending on how much discrepancy is generated with respect to the design value. In addition, an optical surface consisting of a plurality of discontinuous planes or curved surfaces, such as an optical member in which a plurality of cones are provided on one optical surface, is a curved surface in a broad sense and an optical surface on which unique feature points are determined. The present invention can be applied as long as it has.

  In addition to the lens, it can be used for measuring the shape of a transparent body or an opaque body made of a material different from glass, such as an optical member having a prism or a mirror surface with a curved surface on the side surface of a pillar, or glass such as gemstone or stone. In addition, the optical member for measuring the surface shape is not limited to one that can be fixed every rotation of 180 degrees, and the measurement position of the optical member can be fixed at various rotation angles such as every 90 degrees or 45 degrees. It is preferable to be able to measure the shape of an optical member having a simple shape. Furthermore, the surface shape measuring apparatus used in the present invention is not limited to the one that measures the surface shape from the scanning displacement based on the interatomic force. If both the stylus 13 and the optical member have conductivity, the surface shape measuring device is a tunnel. Surface shape measurement using electric current may be performed, measurement using various scanning probes may be performed, light such as laser or electromagnetic waves is irradiated to each curved surface portion of the optical member, and reflected light or transmitted light thereof is irradiated. Non-contact / optical measurement for measuring the surface shape may be performed.

It is a perspective view showing an eccentricity measuring device roughly. It is a sectional side view of a jig. It is explanatory drawing which shows the kind of error which a jig | tool has. It is explanatory drawing which shows each coefficient intrinsic | native to a lens and a jig | tool. It is explanatory drawing which shows the principle which calculates the amount of eccentricity. It is a flowchart which shows the procedure which measures the amount of eccentricity. It is sectional drawing of the rotation stage which shows a mode that the surface of a true sphere is measured in order to obtain | require calibration data. It is explanatory drawing which shows the principle which calculates (theta) _z and _Yo . It is sectional drawing of the rotation stage which shows a mode that a lens and the stage surface are measured. It is sectional drawing which shows the optical member different from a general lens.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Eccentricity measuring apparatus 11 Probe 12 Jig 13 Stitch 16 Support stand 17 Rotating stage 17f Stage front surface 17b Stage rear surface 18 Rotating shaft 18a Axis center 19 Lens holder 19a Seat surface 26 Arithmetic unit 31 Lens 31f Lens front surface 31b Lens rear surface 35 True sphere A1 Optical axis A2 Optical axis

Claims (7)

The surface shape measuring means for measuring the surface shape of the object measures the shape of each curved surface of the optical member having a plurality of curved surfaces, obtains the position of each feature point on each curved surface, and compares the position of the feature point In the method of measuring the shape of the optical member for measuring the size of the positional deviation between the curved surfaces,
A holding body for holding the optical member is pivotally supported on a support body via a rotation shaft,
By rotating the holding body, each curved surface is displaced to a measurement position where shape measurement by the surface shape measurement means is possible,
A method for measuring a shape of an optical member, wherein the surface shape of the curved surface is measured at each measurement position, and the size of the positional deviation between the curved surfaces is measured from the position of the obtained feature point.   The shape of the true sphere held by the holding body is measured at each measurement position by the surface shape measuring means, and the amount of eccentricity of the rotating shaft is calculated from the obtained position of the vertex of the true sphere, and the amount of eccentricity of the rotating shaft 2. The method of measuring the shape of an optical member according to claim 1, wherein the position of the feature point of each curved surface is corrected based on the above.   The measured value by the shape measuring means and the design value of the curved surface are compared to calculate the amount of inclination of each curved surface with respect to the measurement reference surface, and the position of the feature point is based on the difference between the two obtained inclination amounts. The shape measuring method of an optical member according to claim 1 or 2, wherein   The inclination amount is calculated from a difference between an inclination of a flat surface portion formed on the holding body and an inclination of a flat seat surface portion that makes a part of the optical member contact. A method for measuring the shape of an optical member. The optical member is a double-sided aspherical lens having two aspherical surfaces that are rotationally symmetric with respect to the optical axis. The holding member is rotated 180 degrees to obtain the intersection point with each aspherical optical axis as the feature point. With
The shape measurement value obtained by measuring the shape of a part of each aspheric surface by the surface shape measuring means is compared with the design value of each curved surface, thereby calculating the position of the intersection and obtaining the amount of eccentricity between the aspheric surfaces. The shape measuring method of an optical member according to any one of claims 1 to 4.   6. The surface shape measuring means includes a probe for measuring a surface shape by displacing a stylus while keeping a distance from an object surface constant. A method for measuring the shape of an optical member. Shape measuring means for scanning the surface of an object and measuring the shape thereof, a holding body for holding an optical member on which a plurality of curved surfaces are formed, and the holding body are rotatably supported via a rotating shaft. An optical member shape measuring apparatus comprising: a supporting means for displacing the optical member at a position where the shape can be measured.

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