JP2008030160A - Method for centering circular lens and method for manufacturing circular lens using the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for centering a lens 10 for easily and accurately centering even the lens 10 having a free curved surface 12 constituted of asymmetrical surfaces with respect to an optical axis center without using a complicated device in a short time, and a method for manufacturing the lens 10 using the method. <P>SOLUTION: The free curved surface 12 constituted of the asymmetrical surfaces with respect to the optical axis center forming a light transmission region in at least one of optical surfaces of inserts 31 and 32 is provided to center the circular lens 10 pressurized and formed by the two inserts 31 and 32 having optical surfaces for transferring an optical surface of the lens 10. The circular lens 10 is formed by forming a curved surface 14 for clamp having a center on the optical axis and having a thickness increased or decreased in a radial direction with different curvatures on the light incident side and the light outgoing side of the circular lens 10 formed outside the light transmission region for surrounding the circumference of the free curved surface 12. The centering is performed by performing the bell clamp of the curved surface 14 formed on the formed circular lens 10. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for centering a circular lens and a method for manufacturing a circular lens using the method, and more particularly to a method for centering a circular lens having a free-form surface composed of an asymmetric surface with respect to the center of the optical axis, and the method. The present invention relates to a method of manufacturing a used circular lens.

  Conventionally, there are various methods for manufacturing a lens, and glass molding is one of high-precision and low-cost manufacturing methods. This is because a mold made of cemented carbide or ceramic material is coated with a protective coating to improve its corrosion resistance and oxidation resistance, and the optical surface and flange surface are molded by pressing the glass near its softening point. Made by transcription.

  There are two further methods of pressure molding. One is to reduce the distance between the two nestings by putting heated glass in a molding cavity composed of two nestings and optical parts for transferring both optical surfaces of the molded lens. Filling molding is performed by pressure filling with the other, and the other is in the position where there is no barrel part or in contact with the glass, and the pressure molding is performed by reducing the distance between the two nested parts having the optical surface. In the outer peripheral direction, molding transfer is not performed without restricting the expansion of the glass during pressing, for example, a method called extrusion molding.

  In filling molding, if the eccentricity between the outer periphery and the optical surface is kept small, the molding and transfer to the outer periphery of the molded lens is ensured, so the lens positioning reference for mounting after molding is maintained without post-processing of the outer periphery of the molded lens. It can be used as a contact or fitting part, and no machining is required until the molded lens is assembled. However, this method has a fixed cavity volume in the mold, so the glass volume must be smaller than the cavity volume at the time of molding, and is usually a glass material (preform) supplied in the form of a sphere or disk. However, there is a drawback in that the volume management requires accuracy and the cost is high. In addition, since the molded outer periphery is in close contact with the barrel mold, sticking or the like is likely to occur, and in order to reliably remove the molded lens from the mold, a mechanical take-out mechanism such as protruding the insert against the barrel mold is used in the mold. It is necessary to apply.

  However, the mold is exposed to a high temperature in the vicinity of the softening point of the glass when the preform is pressure-molded. Therefore, the sliding portion of the drive mechanism of the insert is prone to malfunction due to oxidation or mixing of glass powder. The reliability will be low. In addition, since a gap is required for sliding, the eccentric accuracy of both molds is deteriorated due to the fitting tolerance when driving the insert. In order to compensate for this, the machining accuracy of other mold parts that affect eccentricity must be increased, and the cost of the mold also increases.

  On the other hand, in the extrusion molding method in which the outer peripheral portion is not regulated during pressure molding, the volume accuracy of the preform may be loose, and the mold and the mold do not have a complicated drive mechanism, so both the preform and the mold are inexpensive. Therefore, the extrusion molding method is now common. However, it is necessary to perform centering after molding, but this centering process involves optical centering, centering with a dial gauge, and bell clamp method. Among them, the bell clamp method is generalized as a centering method for optical lenses because it can be processed at a low cost in a relatively short time.

  In this bell clamp method, as shown in FIG. 5 (A) as an example, the molded lens 100 is fed between the fixed shaft 101 and the clamp shaft 102, and the clamp shaft 102 as shown in FIG. 5 (B). Is moved toward the lens 100 so that the fixed shaft 101 and the clamp shaft 102 are completely in contact with the surface of the lens 100. When the fixed shaft 101 and the clamp shaft 102 hold the lens 100 and the fixed shaft 101 and the clamp shaft 102 are rotated as shown in FIG. 5C, the lens 100 is fixed as indicated by 103. The shaft 101, the rotating shaft 105 of the clamp shaft 102, and the optical axis 104 of the lens 100 can slide in a direction where they coincide with each other, and can be centered.

  Therefore, in this state, the centering lens 100 is obtained by processing the periphery of the lens 100 rotating together with the fixed shaft 101 and the clamp shaft 102 with the processing tool 106 as shown in FIG. 5D. Can do.

  On the other hand, among lenses used in the image field, there are lenses that are difficult to process by the bell clamp method. For example, in Patent Document 1, an optical phase modulation mask, which is an optical element having a rotationally asymmetric surface shape, is arranged in an optical system used for an endoscope, and the luminous flux is regularly dispersed and restored by digital processing. An imaging apparatus that enables image capturing with a deep depth of field has been proposed.

  The optical phase modulation mask used here has an axially asymmetric surface shape. However, the centering by the above-described bell clamp method is symmetrical with respect to the optical axis on the surface of the lens and has a thickness in the radial direction. If there are no different parts, accurate centering cannot be performed. The optical phase modulation mask shown in Patent Document 1 has a surface shape that is axially asymmetric with respect to the optical axis, and the bell clamp method cannot be used.

For such a problem, for example, in Patent Document 2, when R1 and R2 are the radius of curvature of the lens and r1 and r2 are the radius of the bell holder used for the bell clamp,
Z = | (r1 / R1) ± (r2 / R2) | / 2 (1)
Since the bell clamp is difficult if the Z calculated in (3) is small, a clamp surface is set outside the effective diameter portion used as the lens of the mold lens having a small Z value, and the difference in curvature between the front and back surfaces of this clamp surface is effective. There is shown a molded lens that can be bell clamped by making it larger than the difference in curvature between the front and back surfaces of a virtual curved surface in which the design shape of the diameter portion is extended.

  Similarly, Patent Document 3 discloses that an effective diameter is coaxial with the rotational symmetry axis of the molding surface of the molded lens in order to enable the bell clamp to a lens having a shallow curvature, which is impossible to perform a normal bell clamp type centering. After the first and second bell holders, which are provided with a curvature portion on the outer periphery of the portion and coaxially arranged opposite to each other, are brought into contact with the curvature portion and are centered, they are coaxial with the first and second bell holders, In addition, the lens is fixed by centering with the third and fourth holders arranged so as to be movable in the axial direction on the inner diameter portion, and then the first and second bell holders are retracted from the lens contact state. A lens centering method in which centering is performed is shown.

  Similarly, in Patent Document 4, the thickness of the effective portion changes in the radial direction outside the effective portion having a rotationally symmetric shape with respect to the optical axis in an optical element in which the change in the thickness of the effective portion is small or constant. An optical element and an optical element alignment method and manufacturing method in which an outer edge portion is provided and centering is performed by a bell clamp method using both surfaces of the outer edge portion as reference surfaces are shown. The outer edge portion faces outward. Both the shape that becomes thicker and the shape that becomes thinner are possible, and even if the effective portion has a continuous curvature, the effective portion may have a different curvature.

  Further, in Patent Document 5, in order to automatically center or center the cylindrical lens (cylindrical lens), first, the cylindrical surface lens is vacuum-adsorbed on the fixed lens holder, and the opposing surface is made of an elastic body or the like. It is clamped with a jig, moved onto the measurement surface of the lens via an electric micrometer gauge head on a probe moving table, and the lens shaft is rotated to measure and store the eccentricity of the lens for each angle. At the same time, the two highest values of the stored values are analyzed to derive the ridge line direction, and the numerical values at two points in the direction perpendicular to the ridge line are extracted and the average value is calculated. The lens axis is rotated and stopped so that the direction in which the average value is large is on the rotation center line of the grindstone and the traveling direction, and the grindstone is pushed out here, and the lens is controlled by feedback control until the measured average value is reached. A method and an apparatus for automatically centering a cylindrical surface lens in a lens centering machine are shown in which it is assumed that centering is completed when the measured average value is within the standard value by repeatedly correcting the eccentricity of the lens. Yes.

JP 2003-235794 A Japanese Patent Laid-Open No. 7-117143 JP-A-9-109275 JP-A-10-319212 JP 2000-210854 A

  However, the clamping methods shown in Patent Document 2, Patent Document 3, and Patent Document 4 are for optical elements having a rotationally symmetric surface shape, and for optical elements having a rotationally asymmetric surface shape as described above. There is no mention, and the lens centering method disclosed in Patent Document 3 requires a total of four bell holders, and the centering tool itself is expensive.

  Furthermore, the automatic centering method and apparatus disclosed in Patent Document 5 are expensive because it is necessary to prepare a vacuum suction device, a jig equipped with an elastic body for clamping a cylindrical lens, an electric micrometer gauge, and the like. In addition, the amount of eccentricity of the lens is measured for each angle, and it is necessary to derive the ridge line direction and feedback control, which takes time until centering, and for optical elements with rotationally asymmetric surface shapes, depending on the measurement results There is a problem that it is difficult to determine whether to move the optical element.

  Therefore, in the present invention, a lens centering method that can easily center in a short time and with high accuracy without using a complicated device even with a lens having a free-form surface that is asymmetric with respect to the center of the optical axis. And it is a subject to provide the manufacturing method of the lens using the centering method.

In order to solve the above problems, the centering method of the circular lens in the present invention,
A centering method of a circular lens having a free-form surface composed of an asymmetric surface with respect to the optical axis center forming a light transmission region on at least one of the optical surfaces,
A clamping curved surface is formed outside the light transmission region surrounding the free curved surface, and is symmetric from the center of the optical axis and has a thickness that increases or decreases with different curvatures on the light incident side and the light emitting side. It is characterized by centering by bell-clamping on a curved surface.

In addition, in order to solve the above-mentioned problem, the manufacturing method of the circular lens in the present invention,
A method for producing a circular lens having a free-form surface comprising an asymmetric surface with respect to the optical axis center forming a light transmission region in at least one of the optical surfaces,
For clamping with a thickness that increases or decreases with a different curvature on the light incident side and the light exit side, which is symmetric with respect to the optical axis center of the optical surface, outside the light transmission region surrounding the free curved surface of the circular lens. A curved surface is arranged, the curved surface for clamping is bell-clamped, processed by being centered, and manufactured.

  In this way, a free-form optical surface consisting of an asymmetric surface with respect to the center of the optical axis is formed on the circular lens, like an optical element having a rotationally asymmetric surface shape as shown in Patent Document 1. And by placing a curved surface for clamping around the free curved surface and centering while clamping with the curved surface for clamping, even if the light transmission area is a free curved surface, the center of the lens can be accurately adjusted by the bell clamp method. Therefore, processing around a circular lens can be performed easily and with high accuracy in a short time without using a complicated device, and even with a lens having a complicated shape, the cost can be reduced. Can be manufactured.

  Further, two nestings are prepared for forming the circular lens, and an optical surface corresponding to a free curved surface formed of an asymmetric surface with respect to the optical axis center is formed on at least one nesting, and the periphery of the free curved surface is surrounded. A circular lens having a free curved surface can be easily manufactured by arranging the curved surface for clamping and press-molding with the insert to produce a circular lens.

  When the free curved surface is on the objective side, the curved surface for clamping formed around the free curved surface has a concave shape, so that the peripheral light incident on the lens can be further refracted to the outer periphery of the lens. It is possible to reduce ghost and flare caused by light, and when fixing a circular lens manufactured in this way to a lens barrel, etc., the fixed side (edge part) is widened so that the optical axis can be easily aligned and fixed securely. The lens can be made.

  Furthermore, by using such a circular lens centering method and circular lens manufacturing method for a glass molded lens, a more accurate circular lens centering method and circular lens manufacturing method can be obtained.

  As described above, the centering method of the circular lens according to the present invention and the manufacturing method of the circular lens using the method include a circular lens having a free curved surface having an asymmetric surface with respect to the optical axis center, which has been difficult in the past. The optical phase modulation mask as described above can be supplied with high accuracy.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

  FIG. 1 shows a free-form surface composed of a surface that is asymmetric with respect to the center of the optical axis, which is centered and manufactured using the method for centering a circular lens according to the present invention and the method for manufacturing a circular lens using the method. In the example of the circular lens, the free curved surface shown here is exaggerated for easy understanding, (A) is a view of the circular lens as viewed from the objective side, (B) is a sectional view, and FIG. (A) is a free-form surface comprising an asymmetric surface with respect to the center of the optical axis on the object side, and its surroundings, manufactured using the circular lens centering method according to the present invention and the circular lens manufacturing method using the method FIG. 3 schematically shows a glass molding nesting in the method for manufacturing a circular lens according to the present invention. FIG. 3B shows an example of a lens having a curved surface for clamping that surrounds the lens. 4 and 4 are formed on the objective side of a circular lens. An example in which so as to reduce the harmful light around a curved lamp as concave.

  In FIG. 1, reference numeral 10 denotes a free-form surface comprising an asymmetric surface with respect to the center of the optical axis, which is centered and manufactured using the circular lens centering method according to the present invention and the circular lens manufacturing method using the method. A circular lens 11 has an optical surface formed of a normal spherical surface or an aspherical surface, and 12 represents a free curved surface formed of a surface in which the light transmission region is asymmetric with respect to the center of the optical axis. Like the optical phase modulation mask, the surface has a rotationally asymmetric surface shape and is a surface that is asymmetric (axially asymmetric) with respect to the optical axis 13 of the circular lens 10, and the right and left of a line perpendicular to the optical axis at a certain position. However, it does not include a surface having surface symmetry such as a spherical surface or an aspherical surface and simply decentering the optical axis of the lens, and is an asymmetric surface with respect to the optical axis center. . 14 surrounds the free-form surface 12 which is the light transmission region, has a center on the optical axis 13 and is directed toward the radial direction so as to have different curvatures on the light incident side and the light emitting side of the circular lens 10. The curved surface for bell clamp where the thickness decreases (or may increase), 15 is the outer periphery of the lens after processing, and 16 is the approximate position of the bell holder when the circular lens 10 is clamped by the bell clamp method.

  The circular lens 10 manufactured by the circular lens centering method and the circular lens manufacturing method using the method according to the present invention has a free-form surface composed of an asymmetric surface in the light transmission region with respect to the optical axis center. Therefore, the center of the free curved surface 12 cannot be centered by the bell clamp method described above. Therefore, in the present invention, the optical axis 13 is centered outside the light transmission region surrounding the free-form surface 12, and different curvatures including positive and negative are provided on the light incident side and the light emission side of the circular lens 10. The optical transfer surface of the lens molding insert is formed so as to form the clamping curved surface 14 whose thickness increases or decreases in the radial direction, and for example, 16 of the clamping curved surface 14 of the circular lens 10 formed thereby is formed. The center of the lens is centered by bell clamping at the position shown in FIG.

  FIG. 2A shows a free-form surface that is a light transmission region that is an asymmetric surface with respect to the center of the optical axis on the objective side, which is manufactured using the centering method of the circular lens according to the present invention of FIG. (B) is an example of a lens that does not have a free curved surface. (A) and (b) shown in the upper stage (A), (c) and (d), (e) and (f), (g) and (h), ( k) and (m), and (n) and (p) respectively indicate a lens having a free curved surface and a lens not having the same lens.

  In the drawing, 20a, 20c, 20e, 20g, 20k, and 20n in (A) are free-form surfaces as described above in the respective lenses, and 21a, 21c, 21e, 21g, 21k, and 21n are formed of ordinary spherical surfaces or aspheric surfaces. Lens surfaces 22a, 22c, 22e, 22g, 22k, and 22n are clamping curved surfaces surrounding the free curved surface 20, 23 and 24 are lines indicating the range of the free curved surface, and 25 is an optical axis of each lens. Also, in (B), 26b, 26d, 26f, 26h, 26m, and 26p are light incident side curved surfaces in the respective lenses, 27b, 27d, 27, 27h, 27m, and 27p are light emission side curved surfaces in the respective lenses, and 28 is It is the optical axis of each lens. The numbers with R in (B) indicate the radii of the respective curved surfaces, and the positive / negative signs indicate that the curved surface is convex (positive) or concave (negative) with respect to the light incident side. It shows. The lens curved surface and the free curved surface shown in FIGS. 1 and 2 are examples, respectively, and are naturally not limited to the numerical values and shapes shown here.

  First, the lenses shown in (a) and (b) are convex lenses as a whole with convex (positive) curved surfaces on both the light incident side and the light exit side, and the lenses (c) and (d) are also light incident. Although the curved surfaces on the side and the output side are convex (positive), a concave lens is formed as a whole. The lenses (e) and (f) are concave (negative) on the light incident side and have a curved surface opposite to the convex (positive) on the output side to constitute a concave lens as a whole, and the lenses (g) and (h) are Although the light incident side is convex (positive) and the output side is concave (negative) and has the opposite curved surface as in (e) and (f), it constitutes a convex lens as a whole. The lenses (k) and (m) are convex lenses as a whole with concave (negative) curved surfaces on both the light incident side and the output side, and the lenses (n) and (p) are also formed on the light incident side and the output side. Although this curved surface is concave (negative), it constitutes a concave lens as a whole.

  The free-form surfaces 20a, 20c, 20e, 20g, 20k, and 20n shown in FIG. 2A are rotationally asymmetric surface shapes like the optical phase modulation mask shown in Patent Document 1, but (B As is clear from comparison with the normal spherical or aspherical lens surface shown in FIG. 5), the difference from the normal surface is small. However, since these free-form surfaces are asymmetric with respect to the optical axis and asymmetric with respect to the center of the optical axis as described above, and the radial thickness is different, the centering by the bell clamp cannot be performed.

  Therefore, each lens is provided with a curved surface for clamping indicated by 22a, 22c, 22e, 22g, 22k, and 22n, and the curved surface 21a, 21c, 21e, 21g, 21k, and 21n on the light emission side opposite to the clamp surface. Are provided so as to increase or decrease, but for the bell clamp, each curved surface is negative and positive as shown in (e) and (g) in FIG. Or it is easy if the curvature is in the opposite direction, such as positive and negative. On the other hand, in the case of curvature in the same direction, such as positive and positive, negative and negative, as in (a), (c), (k), and (n), negative and positive, or reverse such as positive and negative Compared with the case of the curvature of the direction, it takes time to center, and when one surface is perpendicular or nearly perpendicular to the optical axis 25 as shown in (c), it is necessary to increase the curvature of the facing surface. It becomes difficult to take.

  2A, when a concave lens is formed by the curved curved surface 22 and the curved surface on the light exit side as shown in FIGS. The lens can be refracted to the outer periphery, reducing ghosts and flares caused by ambient light, and when fixing a circular lens to a lens barrel, the fixed side (edge surface) becomes wider, making it easier to center. The lens can be securely fixed.

  That is, as shown in FIG. 4, the optical surface 11 made of a normal spherical surface or an aspherical surface has the above-described free curved surface 12, and the clamping curved surface 17 surrounding the free curved surface 12 is centered on the optical axis. Since the curved surface for clamping is made larger than the standard R of the free-form surface, the harmful light on the periphery can be reduced, the edge surface can be made thicker, and the accuracy of lens incorporation Can be improved.

  In this way, depending on how the curved surface for clamping is taken, the centering accuracy will be improved if the difference from the curvature of the optical surface is large, and the mounting accuracy will be improved and the wall thickness will be reduced if the edge surface is made thicker. In this case, the volume is reduced and the cost is reduced, and it is more effective to select the shape of the curved surface for clamping according to the purpose. In addition, since a circular lens is shape | molded by pressure molding, it can be set as a reasonable shaping | molding by making the average R (curvature) and positive / negative of a free-form surface correspond.

  The above is the description of the lens that can be manufactured by using the centering method of the circular lens according to the present invention. Next, a method of molding the lens by extrusion molding will be described with reference to FIG. As described above, in the extrusion molding, the barrel part is not used as shown in FIG. 3, or is provided in a position where it does not come into contact with the heated glass material (preform) 30. This glass material is shown in FIG. In order to perform molding while forming a surface corresponding to the free curved surface 12, an optical surface 33 corresponding to the free curved surface 12 and an optical surface 35 corresponding to the bell clamp curved surface 14 are provided on the upper mold 31 which is one nesting. An optical surface 34 corresponding to the normal optical surface 11 is provided on the lower mold 32 which is another nesting.

  Then, the glass material 30 is pressure-molded by the upper mold 31 and the lower mold 32, and is molded to form the free curved surface 12, the bell clamp curved surface 14, and the normal optical surface 11, and the glass material protrudes to the periphery. Is sent between the fixed shaft 101 and the clamp shaft 102 as the molded lens 100 in FIG. Then, as shown in FIG. 5B, the clamp shaft 102 is moved toward the lens 100 (lens 10) so that it is completely in contact with the surface of the lens 100, so that the fixed shaft 101 and the clamp shaft 102 are in contact with the lens 100. 5C, the fixed shaft 101 and the clamp shaft 102 are rotated as shown in FIG. 5C, and the rotation axis 105 of the fixed shaft 101, the clamp shaft 102, and the optical axis 104 of the lens 100 coincide with each other. Glide to center.

  Then, as shown in FIG. 2D, by processing the periphery of the lens 100 (lens 10) rotating together with the fixed shaft 101 and the clamp shaft 102 with the processing tool 106, the heart as shown in FIG. The lens 10 that has been taken out is obtained.

  By forming, centering, and processing the circular lens 10 having the free-form surface 12 in this way, a lens having an extremely small error with respect to the design value is obtained even for a lens having an effective surface that is asymmetric with respect to the optical axis. be able to. Therefore, even a lens having a free-form surface can be assembled with high accuracy without passing through an adjustment process, and as a result, an inexpensive lens unit can be configured.

Further, by making the free-form surface 12 more convex than the surface to be bell-clamped and eliminating the reflection on the rising surface with a mask, sanitization, etc., reflection due to a step can be eliminated.
In the bell clamp method, when the curvatures (R) of both the light incident side and the light emission side are the same or substantially the same, the centering accuracy is deteriorated. Even in such a lens, the clamp of the present invention is provided outside the light transmission region. By forming the curved surface, it is possible to stably perform bell clamping at the peripheral portion.

  According to the present invention, even if the light transmission region is a free-form surface, it is possible to accurately center the lens by the bell clamp method, and processing around the circular lens can be performed in a short time without using a complicated device. A lens having a complicated shape can be easily manufactured with high accuracy and at a low cost.

An example of a circular lens having a free-form surface composed of an asymmetric surface with respect to the center of the optical axis, which is centered using the circular lens centering method according to the present invention and the circular lens manufacturing method using the method. (A) is a view of the circular lens as viewed from the objective side, and (B) is a cross-sectional view. The free-form surface in this figure is exaggerated for the sake of clarity. (A) is a circular lens manufactured by using the circular lens centering method according to the present invention, in which a free curved surface having an asymmetric surface with respect to the optical axis center and a clamping curved surface surrounding the periphery are formed on the objective side. (B) is an example of a lens having no free-form surface. It is the figure which showed roughly the nest to carry out the glass shaping | molding in the manufacturing method of the circular lens which becomes this invention. It is the figure which showed the example at the time of making the curved surface for clamp formed in the objective side in the circular lens which becomes this invention concave, and reducing harmful light around. It is a figure for demonstrating the centering method by a bell clamp.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Circular lens 11 Optical surface 12 which consists of spherical surface or aspherical surface Free curved surface 13 Optical axis 14 Bell clamp curved surface 15 Lens outer periphery 16 Bell holder position 20 Free curved surface 21 Normal spherical surface or aspherical surface 22 Clamping curved surfaces 23, 24 Free curved surface Line indicating range 25 Optical axis 26 Light incident side curved surface 27 Light exit side curved surface 28 Optical axis

Claims (5)

A centering method of a circular lens having a free-form surface composed of an asymmetric surface with respect to the optical axis center forming a light transmission region on at least one of the optical surfaces,
A clamping curved surface is formed outside the light transmission region surrounding the free curved surface, and is symmetric from the center of the optical axis and has a thickness that increases or decreases with different curvatures on the light incident side and the light emitting side. A centering method for a circular lens, wherein the center is centered by bell clamping on a curved surface. A method for producing a circular lens having a free-form surface comprising an asymmetric surface with respect to the optical axis center forming a light transmission region in at least one of the optical surfaces,
For clamping with a thickness that increases or decreases with a different curvature on the light incident side and the light exit side, which is symmetric with respect to the optical axis center of the optical surface, outside the light transmission region surrounding the free curved surface of the circular lens. A method for producing a circular lens, characterized in that a curved surface is arranged, the curved surface for clamping is bell-clamped and processed by centering.   Two nestings are prepared for forming the circular lens, and an optical surface corresponding to a free curved surface composed of an asymmetric surface with respect to the optical axis center is formed in at least one nesting, and the periphery of the free curved surface is surrounded by 3. The circular lens centering method or manufacturing method according to claim 1, wherein a circular lens is manufactured by arranging a curved surface for clamping and press-molding with a nest.   3. The circular lens centering method or manufacturing method according to claim 1 or 2, wherein when the free curved surface is on the objective side, a curved surface for clamping formed around the free curved surface is a concave shape.   A circular lens centering method or a circular lens manufacturing method, wherein the circular lens centering method and the circular lens manufacturing method according to any one of claims 1 to 4 are used for a glass molded lens.

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