LENS HOLDING TOOL AND LENS HOLDING METHOD

Abstract

A lens holding tool for holding a plurality of lenses as a workpiece in a grinding or polishing process includes: a base portion; and a plurality of lens receiving portions respectively provided at a plurality of positions on a surface of the base portion so as to protrude from the surface. Each of the plurality of lens receiving port has a lens receiving face configured to be in contact with at least a part of a support surface which is an end face of each of the plurality of lenses, and an outer circumference of the lens receiving face is positioned higher than the surface of the base portion.

Description

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a continuation of PCT international application Ser. No. PCT/JP2014/062347 filed on May 8, 2014 which designates the United States, incorporated herein by reference, and which claims the benefit of priority from Japanese Patent Application No. 2013-227598, filed on Oct. 31, 2013, incorporated herein by reference.

BACKGROUND

1. Technical Field

The disclosure relates to a lens holding tool and method for holding lenses in a grinding or polishing process of the lenses.

2. Related Art

As a method for performing a grinding or polishing process on an end face of a plurality of lenses at the same time, a method using a recessed plate is known (for example, see Japanese Laid-open Patent Publication No. 2-152760, Japanese Laid-open Patent Publication No 7-136915, Japanese Laid-open Patent Publication No. 2001-9692, and Japanese Laid-open Patent Publication No. 2003-103444). The recessed plate is a lens holding tool where a plurality of counterbore holes (hereinafter referred to as countersinks) for holding lenses is formed on a surface of a spherically-shaped base material. In a lens processing method using the recessed plate, each countersink is caused to hold a lens as a workpiece and a processing tool, such as a grindstone, on which a spherical processing surface having a desired curvature is formed, is caused to come into contact with these lenses and is rotated. Thereby, it is possible to collectively grind or polish end faces of a plurality of lenses into spherical surfaces having the same curvature. Further, when the recessed plate is used, it is possible to perform processing in a more stable manner than a case in which lenses are processed one by one, so that there is an advantage that the processing accuracy is improved.

SUMMARY

In some embodiments, a lens holding tool for holding a plurality of lenses as a workpiece in a grinding or polishing process includes: a base portion; and a plurality of lens receiving portions respectively provided at a plurality of positions on a surface of the base portion so as to protrude from the surface. Each of the plurality of lens receiving portions has a lens receiving face configured to be in contact with at least a part of a support surface which is an end face of each of the plurality of lenses, and an outer circumference of the lens receiving face is positioned higher than the surface of the base portion.

In some embodiments, a method for causing a lens holding tool to hold a plurality of lenses as a workpiece in a grinding or polishing process is provided. The lens holding tool has a base portion and a plurality of lens receiving portions on the base portion. Each of the plurality of lens receiving portions has a lens receiving face. The method includes: applying an adhesive to at least one of the lens receiving face and a support surface which is an end face of each of the plurality of lenses; placing each of the plurality of lenses on the lens receiving face to cause the support surface and the lens receiving face to be in contact with each other through the adhesive; positioning each of the plurality of lenses with respect to each of the lens receiving portions; and curing the adhesive. Each of the lens receiving portions protrudes from a surface of the base portion, and an outer circumference of the lens receiving face is positioned higher than the surface of the base portion.

The above and other features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are schematic diagrams illustrating a structure of a lens holding tool according to a first embodiment of the present invention;

FIG. 2 is an enlarged cross-sectional view illustrating a lens receiving portion illustrated in FIGS. 1A and 1B;

FIG. 3 is a perspective view illustrating a ring that is supplementarily used when causing the lens receiving portion illustrated in FIGS. 1A and 1B to hold a lens;

FIG. 4 is a cross-sectional view for explaining an adhesive application step, a lens placement step, and a positioning step of a lens holding method according to the first embodiment of the present invention;

FIG. 5 is a cross-sectional view for explaining the positioning step of the lens holding method according to the first embodiment of the present invention;

FIG. 6 is a cross-sectional view illustrating a structure of a lens holding tool according to a modified example 1-1 of the first embodiment of the present invention;

FIG. 7 is a cross-sectional view illustrating a structure of a lens holding tool according to a modified example 1-2 of the first embodiment of the present invention;

FIG. 8 is a cross-sectional view illustrating a structure of a lens holding tool according to a second embodiment of the present invention;

FIG. 9 is a cross-sectional view for explaining a positioning step of a lens holding method according to the second embodiment of the present invention;

FIG. 10 is a diagram illustrating a structure of a lens holding tool according to a third embodiment of the present invention;

FIG. 11 is a diagram for explaining a positioning step of a lens holding method according to the third embodiment of the present invention;

FIG. 12 is a diagram illustrating a structure of a lens holding tool according to a fourth embodiment of the present invention;

FIG. 13 is a diagram for explaining a positioning step of a lens holding method according to the fourth embodiment of the present invention;

FIG. 14 is a cross-sectional view illustrating a structure of a lens holding tool according to a fifth embodiment of the present invention;

FIG. 15 is a partial cross-sectional view illustrating a lens receiving portion illustrated in FIG. 14;

FIG. 16 is a partial cross-sectional view for explaining an adhesive application step, a lens placement step, and a positioning step of a lens holding method according to the fifth embodiment of the present invention;

FIG. 17 is a partial cross-sectional view for explaining a lens receiving portion attaching step of the lens holding method according to the fifth embodiment of the present invention; and

FIG. 18 is a cross-sectional view illustrating a structure of a lens receiving portion according to a modified example 5-1 of the fifth embodiment of the present invention.

DETAILED DESCRIPTION

Hereinafter, embodiments of a lens holding tool and a lens holding method according to the present invention will be described with reference to the drawings. The present invention is not limited by the embodiments. The same reference signs are used to designate the same elements throughout the drawings. The drawings are schematic and size relationships and ratios of portions are different from actual ones. Also, size relationships and ratios of portions between the drawings may be different from each other.

First Embodiment

FIGS. 1A and 1B are schematic diagrams illustrating a structure of a lens holding tool according to a first embodiment of the present invention. FIG. 1A is a top view illustrating a state in which a plurality of lenses as a workpiece is held by the lens holding tool. FIG. 1B is an A-A cross-sectional view of FIG. 1A. As illustrated in FIGS. 1A and 1B, the lens holding tool 100 according to the first embodiment of the present invention includes a base portion 101 having a shaft portion 102 and a plurality of lens receiving portions 104 which is provided so as to protrude from a surface 103 of the base portion 101. A plurality of lenses 10 as a workpiece is held by the lens receiving portions 104, respectively, through adhesives 112. Although FIG. 1A illustrates an example in which seven lens receiving portions 104 are provided, the number of the lens receiving portions 104 only has to be three or more. These lens receiving portions 104 are arranged so as to be rotationally symmetrical on the surface of the base portion 101.

The base portion 101 is a member made of metal or alloy, and forms a part of a spherical body. The surface 103 of the base portion 101 has a convex spherical shape. The shaft portion 102 is provided on a surface opposite to the surface 103 on the same axis as that of the rotation center of the base portion 101.

FIG. 2 is an enlarged cross-sectional view illustrating the lens receiving portion 104. The lens receiving portion 104 has a cylindrical shape whose outer diameter is substantially the same as an outer diameter D1 of the lens 10. The lens receiving portion 104 is provided so that a rotation symmetry axis R1 of the cylinder is perpendicular to a surface in contact with the same spherical surface 103′ as the surface 103 at a position of the rotation symmetry axis R1.

A lens receiving face 105, which is an upper end face of the lens receiving portion 104, is in contact with a support surface 12, which is an end face opposite to a process surface 11 of the lens 10, and supports the lens 10. In the first embodiment, corresponding to the support surface 12 of the convex spherical shape, the lens receiving face 105 has a concave spherical shape which has a spherical center on the rotation symmetry axis R1 and whose curvature radius is substantially the same as that of the support surface 12.

The shape of the lens receiving face 105 is not limited to the concave spherical shape. For example, when the support surface 12 has a concave spherical shape, the lens receiving face 105 may have a convex spherical shape corresponding to the shape of the support surface 12. Alternatively, when the support surface 12 has a planar shape, the lens receiving face 105 may have a planar shape.

The height of an outer circumference 106 of the lens receiving face 105 is higher than that of the surface 103 of the base portion 101. Thereby, it is possible to prevent a processing tool such as a grindstone from being in contact with the surface 103 of the base portion 101 during processing of the lens 10, regardless of the thickness of an edge portion (a flange portion) of the lens 10. The height of an inner circumference 107 of the lens receiving face 105 as seen from the surface 103 of the base portion 101 is determined by the height of the outer circumference 106, the curvature radius of the lens receiving face 105, and the width of the lens receiving portion 104 in the radial direction. Therefore, the inner circumference 107 may be lower than the surface 103 of the base portion 101.

An opening 108 inside the lens receiving portion 104 is dug such that the lens 10 does not contact with the base portion 101 according to the curvature radius of the support surface 12 of the lens 10. The position of a bottom surface of the opening 108 may be lower than the surface 103 of the base portion 101.

Next, a lens holding method and a lens processing method according to the first embodiment of the present invention will be described with reference to FIGS. 3 to 5.

FIG. 3 is a perspective view illustrating a ring 110 that is supplementarily used when causing the lens receiving portion 104 to hold the lens 10. As illustrated in FIG. 3, the ring 110 is a cylindrical member whose inner diameter D2 is substantially the same as the outer diameter of the lens receiving portion 104 (that is, the outer diameter D1 of the lens 10). The ring 110 can be attached to and detached from (fitted into) the lens receiving portion 104. The ring 110 is fitted into the lens receiving portion 104 so that a positioning surface of the lens 10, which is in parallel with the rotation symmetry axis R1 (see FIG. 2) of the lens receiving portion 104 and whose distances from the rotation symmetry axis R1 are the same, is formed around the lens receiving portion 104 by an inner circumferential surface 111 of the ring 110.

FIG. 4 is a cross-sectional view for explaining an adhesive application step, a lens placement step, and a positioning step of the lens holding method according to the first embodiment. FIG. 5 is a cross-sectional view for explaining the positioning step.

When causing each of the lens receiving portions 104 to hold the lens 10, first, as illustrated in FIG. 4, the adhesive 112, such as wax or ultraviolet curing resin, is applied to the lens receiving face 105. The adhesive 112 may be applied to the support surface 12 of the lens 10 or may be applied to both the support surface 12 and the lens receiving face 105.

Subsequently, the lens 10 is placed on the lens receiving face 105 with the support surface 12 of the lens 10 facing the lens receiving face 105, and the support surface 12 of the lens 10 and the lens receiving face 105 are caused to be in contact with each other through the adhesive 112. In this case, it is preferable to adjust the position of the lens 10 such that the outer circumference of the lens 10 and the outer circumference of the lens receiving portion 104 are substantially coincident with each other.

Subsequently, the ring 110 is fitted into the lens receiving portion 104 by putting the ring 110 from above the lens 10, and the outer circumferential surface of the lens 10 and the outer circumferential surface of the lens receiving portion 104 are caused to be in contact with the inner circumferential surface 111 of the ring 110. Thereby, as illustrated in FIG. 5, a state in which the lens 10 is positioned with respect to the lens receiving portion 104 is maintained.

Next, the adhesive 112 is cured. For example, when the wax is used as the adhesive 112, the adhesive 112 is cured by cooling. When the ultraviolet curing resin is used as the adhesive 112, the adhesive 112 is cured by irradiating the adhesive 112 with ultraviolet rays through the lens 10. Thereby, the lens 10 is held in a state in which the lens 10 is positioned with respect to the lens receiving portion 104. After the adhesive 112 is cured, the ring 110 is removed.

The operations as described above are performed on each of the lens receiving portions 104 provided in the lens holding tool 100, so that the lens 10 is held by all the lens receiving portions 104 (see FIGS. 1A and 1B).

Subsequently, the lens holding tool 100 is attached to a lens processing device (not illustrated in the drawings) so that the shaft portion 102 is rotatable. Then, a processing tool, where a processing surface having a spherical shape (for example, a concave spherical shape) with a desired curvature is formed, is caused to be in contact with the process surface 11 of the lens 10, and the processing tool is rotated. Thereby, the process surface 11 of each lens 10 is polished or ground into a spherical shape (for example, a convex spherical shape) corresponding to the shape of the processing surface.

After the processing of the lens 10 is completed, the lens 10 is detached from the lens receiving portion 104 by dissolving the adhesive 112 by using organic solvent or the like. Thereby, it is possible to obtain simultaneously a plurality of lenses 10 where the process surface 11 is polished into a spherical shape having the same curvature.

As described above, according to the first embodiment, the lens receiving portion 104 is provided so that the lens receiving portion 104 protrudes from the surface 103 of the base portion 101, and the lens 10 is held by the lens receiving face 105 of the lens receiving portion 104. Consequently, it is possible to process the lens 10 by holding the lens 10 in the lens holding tool 100, regardless of the thickness of the edge portion of the lens 10.

Further, according to the first embodiment, the positioning of the lens 10 is performed by fitting the ring 110 to the lens receiving portion 104, and the adhesive 112 is cured in this state. Consequently, it is possible to fix the lens 10 at an appropriate position in the lens receiving portion 104. Therefore, even when the edge portion of the lens 10 is thin, it is possible to cause the lens receiving portion 104 to hold the lens 10 without generating positional shift.

Further, according to the first embodiment, the lens receiving portion 104 is formed into a cylindrical shape, and the lens receiving face 105 is caused to be in contact with a part of the support surface 12 of the lens 10. Consequently, it is possible to reduce distortion generated when the lens 10 adheres to the lens receiving face 105.

In the first embodiment, the surface 103 of the base portion 101 is formed into a convex spherical shape so that a plurality of lens receiving faces 105 is arranged in a convex shape in order to grind or polish the process surface 11 of the lens 10 into a convex spherical shape. However, when grinding or polishing the process surface 11 of the lens 10 into a concave spherical shape, it is preferable to form the surface 103 of the base portion 101 into a concave spherical shape so that a plurality of the lens receiving faces 105 is arranged in a concave shape. Further, when a plurality of the lens receiving faces 105 is arranged corresponding to a processed shape (the curvature) of the process surface 11, the shape of the surface 103 of the base portion 101 is not particularly limited and need not necessarily be a spherical shape. For example, the surface 103 of the base portion 101 may be formed into a polyhedron, and one lens receiving portion 104 may be provided to each surface of the polyhedron.

Modified Example 1-1

Next, a modified example 1-1 of the first embodiment of the present invention will be described.

FIG. 6 is a cross-sectional view illustrating a structure of a lens holding tool according to the modified example 1-1. As illustrated in FIG. 6, the lens holding tool 120 according to the modified example 1-1 includes a plurality of lens receiving portions 121 provided on the surface 103 of the base portion 101. In FIG. 6, only one lens receiving portion 121 is illustrated in an enlarged scale. The structure of the base portion 101 is the same as that of the first embodiment.

The lens receiving portion 121 includes cylindrical protrusion portions 122 and 123 provided coaxially in a double ring shape. The outer diameter of the protrusion portion 122 of the outermost periphery is substantially the same as the outer diameter of the held lens 10. Lens receiving faces 124 and 125, which are upper end faces of the protrusion portions 122 and 123, are in contact with the support surface 12 of the lens 10 and support the lens 10. In the modified example 1-1, the lens receiving faces 124 and 125 have a concave spherical shape which has a common spherical center on a rotation symmetry axis R2 of the outer protrusion portion 122 and whose curvature radius is substantially the same as that of the support surface 12.

The positions of the lens receiving faces 124 and 125 are not limited in particular as long as an outer circumference 126 of the outer lens receiving face 124 is located higher than the surface 103 of the base portion 101. For example, the inner lens receiving face 125 may be located lower than the surface 103 depending on the curvature radius of the support surface 12.

In this way, the cylindrical protrusion portion 123 is further provided inside the cylindrical protrusion portion 122 that supports the peripheral edge of the lens 10. Consequently, it is possible to stably support the lens 10 without causing deflection and the like in the lens 10 even when the diameter of the lens 10 is large.

In the modified example 1-1, the lens receiving portion 121 is formed to include the double cylindrical protrusion portions 122 and 123. However, three or more cylindrical protrusion portions may be included. Further, a column-shaped protrusion portion may be provided instead of the inner protrusion portion 123. In this case, the upper end face of the protrusion portion having the column shape is formed into a concave spherical shape which has a spherical center shared with the lens receiving face 124 of the outer protrusion portion 122 and whose curvature radius is substantially the same as that of the support surface 12.

Modified Example 1-2

Next, a modified example 1-2 of the first embodiment of the present invention will be described.

FIG. 7 is a cross-sectional view illustrating a structure of a lens holding tool according to the modified Example 1-2. As illustrated in FIG. 7, the lens holding tool 130 according to the modified example 1-2 includes a plurality of lens receiving portions 131 provided on the surface of the base portion 101. In FIG. 7, only one lens receiving portion 131 is illustrated in an enlarged scale. The structure of the base portion 101 is the same as that of the first embodiment.

The lens receiving portion 131 has a column shape whose outer diameter is substantially the same as that of the lens 10. A lens receiving face 132, which is the upper end face of the lens receiving portion 131, is in contact with the support surface 12 of the lens 10 and supports the lens 10. In the modified example 1-2, the lens receiving face 132 has a concave spherical shape which has a spherical center on a rotation symmetry axis R3 of the outer circumferential surface of the lens receiving portion 131 and whose curvature radius is substantially the same as that of the support surface 12.

The position of the lens receiving face 132 is not limited in particular as long as an outer circumference 133 of the lens receiving face 132 is located higher than the surface 103 of the base portion 101. For example, a central portion 134 of the lens receiving face 132 may be located lower than the surface 103 depending on the diameter and the curvature radius of the lens receiving face 132.

As described above, the lens receiving portion 131 is formed into a column shape. Consequently, it is possible to cause the lens receiving face 132 to be in contact with the entire support surface 12 as well as to stably hold the lens 10. Further, as the structure of the lens receiving portion 131 is simple, it is possible to manufacture the lens holding tool 130 in a simple process.

Modified Example 1-3

Next, a modified example 1-3 of the first embodiment of the present invention will be described.

In the first embodiment described above, when attaching the lens 10 to the lens holding tool 100, the adhesive 112 is cured in a state in which the ring 110 is fitted into the lens receiving portion 104. However, if it is possible to prevent positional shift of the lens 10 with respect to the lens receiving portion 104, the ring 110 need not necessarily be used. For example, after the outer circumferences of the lens 10 and the lens receiving face 105 are positioned to be aligned to each other, the adhesive 112 may be cured in a state in which the lens 10 and the lens receiving face 105 are held by hands so that they are not shifted from each other. Alternatively, a vacuum hole that opens in the lens receiving face 105 is provided in the lens receiving portion 104 and the base portion 101, and the vacuum hole is used for depressurization after the outer circumferences of the lens 10 and the lens receiving face 105 are positioned to be aligned to each other, and thereby the lens 10 is vacuum-sucked to the lens receiving face 105. In this state, the adhesive 112 may be cured.

Second Embodiment

Next, a second embodiment of the present invention will be described.

FIG. 8 is a cross-sectional view illustrating structure of a lens holding tool according to the second embodiment of the present invention. As illustrated in FIG. 8, a lens holding tool 200 according to the second embodiment includes a base portion 201 and a plurality lens receiving portions 104 which is provided so as to protrude from a surface 202 of the base portion 201. In FIG. 8, only one lens receiving portion 104 is illustrated in an enlarged scale.

The base portion 201 is a member made of metal or alloy, which forms a partial shape of a spherical body, in the same manner as the base portion 101 illustrated in FIG. 1B. The surface 202 of the base portion 201 forms a spherical shape, and a shaft portion (not illustrated in the drawings) coaxial with the rotation center of the base portion 201 is provided on a surface opposite to the surface 202.

The structure of the lens receiving portion 104 is basically the same as that in the first embodiment. However, in the second embodiment, the lens receiving portion 104 causes the lens receiving face 105 to be in contact with a region inside the outer circumference of a support surface 22 of a lens 20, and holds the lens 20 whose diameter is greater than the outer diameter of the lens receiving portion 104.

An annular groove portion 203, which is coaxial with the lens receiving portion 104 and whose inner diameter is greater than the outer diameter of the lens receiving portion 104, is formed around each of the lens receiving portions 104. As described later, the groove portion 203 is used to cause the lens receiving portion 104 to hold the lens 20.

FIG. 9 is a cross-sectional view for explaining a positioning step of a lens holding method according to the second embodiment. In the second embodiment, a ring 210 is used as an auxiliary support means to cause the lens receiving portion 104 to hold the lens 20. The ring 210 is a cylindrical member whose inner diameter is substantially the same as an outer diameter D3 of the lens 20 and which can fit into the groove portion 203. The ring 210 is fitted into the groove portion 203 so that a positioning surface of the lens 20, which is in parallel with a rotation symmetry axis R1 of the lens receiving portion 104 and whose distances from the rotation symmetry axis R1 are the same, is formed around the lens receiving portion 104 by an inner circumferential surface 211 of the ring 210.

When causing the lens receiving portion 104 to hold the lens 20, an adhesive 212 such as wax or ultraviolet curing resin is applied to the lens receiving face 105 (or the support surface 22 of the lens 20). Then, the lens 20 is placed on the lens receiving face 105 with the support surface 22 of the lens 20 facing the lens receiving face 105, and the support surface 22 of the lens 20 and the lens receiving face 105 are caused to be in contact with each other through the adhesive 212.

Further, the ring 210 is fitted into the groove portion 203 by putting the ring 210 from above the lens 20, and the outer circumferential surface of the lens 20 is caused to be in contact with the inner circumferential surface 211 of the ring 210. Thereby, the positioning of the lens 20 is performed with respect to the lens receiving portion 104. After the adhesive 212 is cured in this state, the ring 210 is removed. Thereby, it is possible to obtain the lens holding tool 200 in which the lens 20 is held in an appropriate position.

As described above, according to the second embodiment, it is possible to process the lens 20 by causing the lens receiving portion 104 to hold the lens 20 whose diameter is greater than the outer diameter of the lens receiving portion 104.

Instead of the lens receiving portion 104, the lens receiving portion 121 in the modified example 1-1 or the lens receiving portion 131 in the modified example 1-2 may be employed in the second embodiment.

Third Embodiment

Next, a third embodiment of the present invention will be described.

In FIG. 10, (a) is a top view illustrating a structure of a lens holding tool according to a third embodiment of the present invention, and (b) is a B-B cross-sectional view of (a). As illustrated in FIG. 10, a lens holding tool 300 according to the third embodiment includes a base portion 301 and a plurality of lens receiving portions 104 which is provided so as to protrude from a surface 302 of the base portion 301. In FIG. 10, only one lens receiving portion 104 is illustrated in an enlarged scale.

The base portion 301 is a member made of metal or alloy, which forms a partial shape of a spherical body, in the same manner as the base portion 101 illustrated in FIG. 1B. The surface 302 of the base portion 301 forms a spherical shape, and a shaft portion (not illustrated in the drawings) coaxial with the rotation center of the base portion 301 is provided on a surface opposite to the surface 302.

The structure of the lens receiving portion 104 is the same as that of the first embodiment. On the surface 302 around each of the lens receiving portions 104, a pin hole 303 is formed in at least three positions along the outer circumference of the lens receiving portion 104. As described later, the pin hole 303 is used to cause the lens receiving portion 104 to hold the lens 10. It is preferable to arrange the pin holes 303 as uniformly as possible. In FIG. 10, three pin holes 303 are arranged to be threefold rotation symmetrical with respect to the rotation symmetry axis R1.

In FIG. 11, (a) is a top view for explaining a positioning step of a lens holding method according to the third embodiment, and (b) is a B-B cross-sectional view of (a). In the third embodiment, at least three pins 304 are used as an auxiliary support means to cause the lens receiving portion 104 to hold the lens 10. Each pin 304 is a member having a pillar shape (for example, column shape). Each pin 304 can be fitted into the pin hole 303. By fitting these pins 304 into the pin holes 303, positioning markers 305 of the lens 10, which are in parallel with the rotation symmetry axis R1 of the lens receiving portion 104 and whose distances from the rotation symmetry axis R1 are the same, are formed in at least three positions around the lens receiving portion 104.

When causing the lens receiving portion 104 to hold the lens 10, an adhesive 306 is applied to a lens receiving face 105 (or a support surface 12 of the lens 10). Then, the lens 10 is placed on the lens receiving face 105 with the support surface 12 of the lens 10 facing the lens receiving face 105, and the support surface 12 of the lens 10 and the lens receiving face 105 are caused to be in contact with each other through the adhesive 306. Further, the pins 304 are inserted into the pin holes 303 and the outer circumferential surface of the lens 10 is caused be in contact with the side surface of each pin 304, and thereby the positioning of the lens 10 is performed with respect to the lens receiving portion 104. After the adhesive 306 is cured in this state, the pins 304 are removed. Thereby, it is possible to obtain the lens holding tool 300 in which the lens 10 is held in an appropriate position.

As described above, according to the third embodiment, it is possible to perform the positioning of the lens 10 with a simple configuration.

Further, it is possible to cause the lens receiving portion 104 to hold a lens whose diameter is greater than the outer diameter of the lens receiving portion 104 by arranging three or more pin holes 303 along a circle which is coaxial with the outer circumference 106 of the lens receiving portion 104 and whose diameter is greater than the diameter of the outer circumference 106. Instead of the lens receiving portion 104, the lens receiving portion 121 in the modified example 1-1 or the lens receiving portion 131 in the modified example 1-2 may be employed in the third embodiment.

Fourth Embodiment

Next, a fourth embodiment of the present invention will be described.

In FIG. 12, (a) is a top view illustrating a structure of a lens holding tool according to a fourth embodiment of the present invention, and (b) is a C-C cross-sectional view of (a). As illustrated in FIG. 12, a lens holding tool 400 according to the fourth embodiment includes a base portion 401 and a plurality of lens receiving portions 104 which is provided so as to protrude from a surface 402 of the base portion 401. In FIG. 12, only one lens receiving portion 104 is illustrated in an enlarged scale.

The base portion 401 is a member made of metal or alloy, which forms a partial shape of a spherical body, in the same manner as the base portion 101 illustrated in FIG. 1B. The surface 402 of the base portion 401 forms a spherical shape, and a shaft portion (not illustrated in the drawings) coaxial with the rotation center of the base portion 401 is provided on a surface opposite to the surface 402.

The structure of the lens receiving portion 104 is the same as that of the first embodiment. A groove portion 403 is formed at a predetermined position near each of the lens receiving portions 104. As described later, the groove portion 403 is used to cause the lens receiving portion 104 to hold a lens 10.

In FIG. 13, (a) is a top view for explaining a positioning step of a lens holding method according to the fourth embodiment, and (b) is a C-C cross-sectional view of (a). In the fourth embodiment, a V-shaped jig 404 is used as an auxiliary support means to cause the lens receiving portion 104 to hold the lens 10, The V-shaped jig 404 includes a main body portion 406 provided with two flat surfaces 405 crossing in a V shape, and a leg portion 407 which supports the main body portion 406 and which can be fitted into the groove portion 403. The leg portion 407 is fitted into the groove portion 403, and thereby a positioning surface where the outer circumferential surface of the lens 10 can be in contact with at two positions which are in parallel with a rotation symmetry axis R1 of the lens receiving portion 104 and whose distances from the rotation symmetry axis R1 are the same, is formed by the two flat surfaces 405 in the vicinity of the lens receiving portion 104.

When causing the lens receiving portion 104 to hold the lens 10, an adhesive 408 is applied to a lens receiving face 105 (or a support surface 12 of the lens 10). Then, the lens 10 is placed on the lens receiving face 105 with the support surface 12 of the lens 10 facing the lens receiving face 105. The support surface 12 of the lens 10 and the lens receiving face 105 are, then, caused to be in contact with each other through the adhesive 408. Further, the leg portion 407 of the V-shaped jig 404 is inserted into the groove portion 403, and an outer circumference 13 of the lens 10 is caused to be in contact with the two flat surfaces 405. Thereby, the positioning of the lens 10 is performed with respect to the lens receiving portion 104. After the adhesive 408 is cured in this state, the V-shaped jig 404 is removed. Thereby, it is possible to obtain the lens holding tool 400 in which the lens 10 is held in an appropriate position.

As described above, according to the fourth embodiment, it is possible to easily perform the positioning of the lens 10.

It is also possible to cause the lens receiving portion 104 to hold a lens whose diameter is greater than the outer diameter of the lens receiving portion 104 by changing the position of the two flat surfaces 405 which form the V-shaped jig 404, and/or the angle at which the flat surfaces 405 cross each other. In this case, it is possible to cope with positioning of various lenses whose diameters are different from each other by only changing the V-shaped jig 404 inserted into the groove portion 403. Further, instead of the lens receiving portion 104, the lens receiving portion 121 in the modified example 1-1 the lens receiving portion 131 in the modified example 1-2 may be employed in the fourth embodiment.

Fifth Embodiment

Next, a fifth embodiment of the present invention will be described.

FIG. 14 is a cross-sectional view illustrating a structure of a lens holding tool according to the fifth embodiment of the present invention. As illustrated in FIG. 14, s lens holding tool 500 according to the fifth embodiment includes a base portion 501 and a plurality of lens receiving portions 510 which is provided so as to protrude from a surface 503 of the base portion 501. FIG. 14 illustrates a state in which a lens 50 as a workpiece is held by each of the lens receiving portions 510 through an adhesive 520. FIG. 14 illustrates, as an example, a cross-section (a cross-section corresponding to the line A-A in FIG. 1A) in a case in which seven lens receiving portions 510 are provided in the same arrangement as that in FIG. 1A. However, the number of the lens receiving portions 510 only has to be three or more.

The base portion 501 is a member made of metal or alloy, which forms a partial shape of a spherical body. A shaft portion 502 coaxial with the rotation center of the base portion 501 is provided on a surface opposite to the surface 503 which forms a concave spherical shape. A column-shaped counterbore hole 504 is formed at a plurality of positions in the surface 503 and a female screw hole 505 is formed in the bottom surface of each counterbore hole 504.

FIG. 15 is a partial cross-sectional view illustrating the lens receiving portion 510 in an enlarged scale. The lens receiving portion 510 is configured to be attached to and detached from the base portion 501. The lens receiving portion 510 includes a column portion 511 whose outer diameter is substantially the same as an outer diameter D4 of the lens 50 and a male screw portion 512 which is provided on the bottom portion of the column portion 511 and can be screwed with the female screw hole 505.

A lens receiving face 513 is an upper end face of the column portion 511. The lens receiving face 513 is in contact with a support surface 52, which is an end face opposite to a process surface 51 of the lens 50, and supports the lens 50. In the fifth embodiment, corresponding to the support surface 52 of the convex spherical shape, the lens receiving face 513 has a concave spherical shape which has a spherical center on a rotation symmetry axis R4 of the outer circumferential surface of the column portion 511 and whose curvature radius is substantially the same as that of the support surface 52.

The height of the column portion 511 is set so that an outer circumference 514 of the lens receiving face 513 is higher than the surface 503 of the base portion 501 when the lens receiving portion 510 is attached to the base portion 501, based on a relationship with the depth of the counterbore hole 504 formed in the base portion 501. Thereby, it is possible to prevent a processing tool such as a grindstone from being in contact with the base portion 501 during processing of the lens 50, regardless of the thickness of an edge portion of the lens 50. The height of a central portion 515 of the lens receiving face 513 is determined by the diameter and the height of the outer circumference 514 and the curvature radius of the lens receiving face 513. Therefore, when the lens receiving portion 510 is attached to the base portion 501, the height of the central portion 515 may be lower than the surface 503.

FIG. 16 is a partial cross-sectional view for explaining an adhesive application step, a lens placement step, and a positioning step of a lens holding method according to the fifth embodiment. FIG. 17 is a partial cross-sectional view for explaining a lens receiving portion attaching step of the lens holding method.

First, as illustrated in FIG. 16, when the lens receiving portion 510 is detached from the base portion 501, the adhesive 520 is applied to the lens receiving face 513 (or the support surface 52 of the lens 50). Subsequently, the lens 50 is placed on the lens receiving face 513 with the support surface 52 of the lens 50 facing the lens receiving face 513, the support surface 52 of the lens 50 and the lens receiving face 513 are caused to be in contact with each other through the adhesive 520, and positioning of the outer circumferences of the lens 50 and the lens receiving face 513 is performed. In this step, the positioning may be performed by fitting a ring whose inner diameter is substantially the same as the outer diameter of the lens receiving face 513 (that is, the outer diameter D4 of the lens 50) to the column portion 511 and the lens 50, in the same manner as in the first embodiment. Then, the adhesive 520 is cured in this state.

Subsequently, as illustrated in FIG. 17, the lens receiving portion 510 to which the lens 50 is attached is inserted into each counterbore hole 504 of the base portion 501, and the male screw portion 512 is screwed into the female screw hole 505. Thereby, it is possible to obtain the lens holding tool 500 in which the lenses 50 are held in appropriate positions (see FIG. 14).

As described above, according to the fifth embodiment, the lens receiving portion 510 can be attached to and detached from the base portion 501. Consequently, it is possible to easily perform an operation to attach the lens 50 to the lens receiving portion 510. In particular, the lens 50 is attached in a state in which the axis of the lens receiving portion 510 is oriented in the vertical direction. Thereby, it is possible to suppress positional shift of the lens 50 during a period until the adhesive 520 is cured.

Further, in the fifth embodiment, the surface 503 of the base portion 501 is formed into a concave spherical shape so that a plurality of lens receiving faces 513 is arranged in a concave shape in order to grind or polish the process surface 51 of the lens 50 into a concave spherical shape. However, when grinding or polishing the process surface 51 of the lens 50 into a convex spherical shape, it is preferable to form the surface 503 of the base portion 501 into a convex spherical shape so that a plurality of the lens receiving faces 513 is arranged in a convex shape. Further, when a plurality of the lens receiving faces 513 is arranged corresponding to a processed shape (the curvature) of the process surface 51, the shape of the surface 503 of the base portion 501 is not particularly limited and need not necessarily be a spherical shape.

Also in the fifth embodiment, in the same manner as in the first embodiment and the modified example 1-1, the lens 50 may be supported by an end face including one or more ring-shaped surfaces.

Modified Example 5-1

Next, a modified example 5-1 of the fifth embodiment of the present invention will be described.

In the fifth embodiment described above, the lens receiving portion 510 is fixed to the base portion 501 by screwing the male screw portion 512 into the female screw hole 505. However, the fixing means is not limited to this.

For example, as illustrated in FIG. 18, a lens receiving portion 530 may be formed of a column-shaped member where a lens receiving face 531, which is an upper end face that can be in contact with the support surface 52 of the lens 50, is provided. FIG. 18 illustrates a state in which the lens 50 is attached to the lens receiving face 531 by the adhesive 520. In this way, when no screw portion is provided to the lens receiving portion 530, the lens receiving portion 530 may be fixed to the counterbore hole 504 (see FIG. 17) by using an adhesive. Accordingly, it is also possible to attach the lens receiving portion 530 to a conventional recessed plate where only a counterbore hole is provided in the surface of the base portion. Alternatively, an engaging means is provided to the lens receiving portion 530 and the counterbore hole 504, and the lens receiving portion 530 and the counterbore hole 504 may be mechanically fixed.

According to some embodiments, the lens receiving portion is provided so as to protrude from the surface of the base portion. Because a lens as a workpiece is held such that one end face of the lens is in contact with the lens receiving face, it is possible to secure a sufficient clearance between the surface of the base portion and the processing tool. With this structure, it is possible to cause the lens holding tool to hold a plurality of lenses as a workpiece and perform a grinding or polishing process at the same time regardless of the shape of the lenses.

Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

Claims

1. A lens holding tool for holding a plurality of lenses as a workpiece in a grinding or polishing process, the lens holding tool comprising:

a base portion; and

a plurality of lens receiving portions respectively provided at a plurality of positions on a surface of the base portion so as to protrude from the surface, wherein

each of the plurality of lens receiving portions has a lens receiving face configured to be in contact with at least a part of a support surface which is an end face of each of the plurality of lenses, and an outer circumference of the lens receiving face is positioned higher than the surface of the base portion.

2. The lens holding tool according to claim 1, wherein each of the plurality of lens receiving portions has at least a single cylindrical shape whose upper end face is the lens receiving face.

3. The lens holding tool according to claim 1, wherein each of the plurality of lens receiving portions has a column shape whose upper end face is the lens receiving face.

4. The lens holding tool according to claim 1, wherein each of the plurality of lens receiving portions has: a first protrusion portion having a column shape whose upper end face is the lens receiving face; and a second protrusion portion having at least a single cylindrical shape whose upper end face is the lens receiving face and which is provided outside of an outer circumference of the first protrusion portion.

5. The lens holding tool according to claim 1, wherein at least three lens receiving portions are provided as the plurality of lens receiving portions.

6. The lens holding tool according to claim 1, wherein each of the plurality of lens receiving portions is integrated with the base portion.

7. The lens holding tool according to claim 1, wherein each of the plurality of lens receiving portions is configured to be attached to and detached from the base portion.

8. The lens holding tool according to claim 1, wherein an outer diameter of each of the plurality of lens receiving portions is equal to an outer diameter of the lens receiving face.

9. A method for causing a lens holding tool to hold a plurality of lenses as a workpiece in a grinding or polishing process, the lens holding tool having a base portion and a plurality of lens receiving portions on the base portion, each of the plurality of lens receiving portions having a lens receiving face, the method comprising:

applying an adhesive to at least one of the lens receiving face and a support surface which is an end face of each of the plurality of lenses;

placing each of the plurality of lenses on the lens receiving face to cause the support surface and the lens receiving face to be in contact with each other through the adhesive;

positioning each of the plurality of lenses with respect to each of the lens receiving portions; and

curing the adhesive, wherein

each of the lens receiving portions protrudes from a surface of the base portion, and an outer circumference of the lens receiving face is positioned higher than the surface of the base portion.

10. The method according to claim 9, wherein

the positioning of each of the plurality of lenses comprises attaching a support unit to the lens holding tool, wherein the support unit is configured to be attached to and detached from the lens holding tool, and when the support unit is attached to the lens holding tool, a positioning marker or a positioning surface with which an outer circumferential surface of each of the plurality of lenses is configured to be in contact is formed in at least two positions which are in parallel with a rotation symmetry axis of each of the plurality of lens receiving portions and whose distances from the rotation symmetry axis are the same, and

the support unit is removed after curing the adhesive.

11. The method according to claim 10, wherein the support unit is a cylindrical member having an inner circumferential surface configured to be in contact with the outer circumferential surface of each of the plurality of lenses.

12. The method according to claim 9, wherein

each of the plurality of lens receiving portions is configured to be attached to and detached from the base portion, and

the method further comprises attaching each of the plurality of lens receiving portions which adheres to each of the plurality of lenses, to the base portion after curing the adhesive.

13. The method according to claim 9, wherein

each of the plurality of lenses has a process surface configured to be processed, and

the process surface is positioned higher than the outer circumference of the lens receiving face.

14. The method according to claim 9, wherein an outer diameter of each of the plurality of lenses is equal to or greater than an outer diameter of each of the plurality of lens receiving portions.