JP2008168402A - Grinding device and grinding method of optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily grind a complicated shaped lens in simple constitution. <P>SOLUTION: This grinding device is furnished with: a rotating base 12 to support an aspheric lens 10 which is a grinding object and to rotate around a first rotation axis C1; and a grinding wheel 14 which has a grinding surface 14a in correspondence with a shape of an optical functional surface of the aspheric lens 10, rotates around a second rotation axis C2 intersecting at a prescribed inclination angle θ with the first rotation axis C1, and grinds the aspheric lens 10 by the grinding surface 14a. An optical element having a complicated surface shape is thereby easily ground by duplicate grinding. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical element grinding apparatus and a grinding method.

  2. Description of the Related Art Conventionally, as described in, for example, JP-A-9-254040, a processing method is known in which an optical lens is ground and polished by co-sliding an optical lens that is an object to be ground and a grindstone.

  FIG. 9 is a cross-sectional view for explaining the grinding method described in the above publication. As shown in FIG. 9, in the method described in the above publication, the lens 100, which is an object to be ground, is rotated about the rotation axis C10, and the grindstone 110 is rotated about the rotation axis C11 parallel to the rotation axis C10. Thus, the surface of the lens 100 is ground with the grindstone 110.

Japanese Patent Laid-Open No. 9-254040

  However, in the method described in the above publication, it is necessary to align the edge 110a of the grindstone 110 with the position of the rotation axis C10. For this reason, there is a problem that an unnecessary protrusion 100a is formed at the position of the rotation axis C10 on the surface of the lens 100. For this reason, the surface accuracy of the lens 110 is lowered, and a process of polishing and removing the protrusion 100a in a subsequent process is necessary.

  Here, when the grindstone 110 is enlarged to the broken-line shape 110b shown in FIG. 9 and the cross-sectional shape of the grinding surface facing the lens 100 is the same as the cross-sectional shape of the lens 100, grinding of the enlarged portion during grinding is performed. There arises a problem that the surface 110c interferes with the surface of the lens 100. This problem is likely to occur particularly when the rotation axis C10 and the rotation axis C11 are close to each other, and the lens 100 cannot be ground.

  Furthermore, recently, with the miniaturization of lenses, lenses having complicated surface shapes such as aspherical shapes are often used. And in the technique described in the said gazette, the problem that these complicated-shaped lenses cannot be ground has arisen.

  FIG. 10 is a schematic diagram showing a problem when the aspherical lens 120 is ground by the method described in the above publication. Here, FIG. 10A describes an aspheric lens 120 having an inflection point 120a on the surface and a grindstone 110 having the same cross-sectional shape as that of the aspheric lens 120. It shows a state in which the rotation axis C11 and the rotation axis C12 are arranged in parallel by the same technique as that described above.

  FIG. 10B is a schematic diagram for explaining the reason why the aspheric lens 120 cannot be ground by the grindstone 110 shown in FIG. In FIG. 10A, it is assumed that the grinding of the point P11 in the vicinity of the inflection point 120a on the surface of the aspheric lens 120 is performed at the point P12 facing the point P11 on the grinding surface of the grindstone 110. The problem shown in FIG. 10B occurs. As shown in FIG. 10B, when the point P12 rotates about the rotation axis C11, the locus of movement of the point P12 becomes the locus R shown in FIG. For this reason, the locus R interferes with the edge of the aspheric lens 120 outside the inflection point 120a in the region closer to the rotation axis C11 than the point P11. For this reason, even if the grindstone 110 has the same cross-sectional shape as the aspherical lens 120, the aspherical lens 120 cannot be ground.

  Furthermore, since the concave lens has a shape in which the peripheral edge rises with respect to the center, it is impossible to grind the concave lens by the method described in the above publication for the same reason as in FIG.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is a new and improved configuration capable of easily grinding an optical element having a complicated shape with a simple configuration. An optical element grinding apparatus and an optical element grinding method are provided.

  In order to solve the above-described problems, according to an aspect of the present invention, a rotating base that supports an optical element that is an object to be ground and rotates about a first rotation axis, and an optical functional surface of the optical element A grinding member that has a grinding surface corresponding to the shape of the first rotating shaft and rotates about a second rotating shaft that intersects the first rotating shaft at a predetermined inclination angle, and grinds the optical element by the grinding surface. And an optical element grinding apparatus comprising:

  According to the above configuration, the optical element that is the object to be ground is supported by the turntable and rotates about the first rotation axis. In addition, the grinding member having a grinding surface corresponding to the shape of the optical functional surface of the optical element rotates around the second rotation axis that intersects the first rotation axis at a predetermined inclination angle. The optical element is ground. Thereby, it becomes possible to easily grind an optical element having a complicated surface shape by co-sliding.

  The ground surface may be a convex surface, and the ground surface of the optical element may be a concave surface. According to this configuration, it is possible to grind an optical element having a concave surface by co-sliding.

  Further, in a cross section along a plane including the first rotation axis and the second rotation axis, at least a part of the grinding surface is symmetrical with respect to the first rotation axis. Also good. According to such a configuration, since the surface near the first rotation axis can be ground with the grinding surface having a cross section symmetric with respect to the first rotation axis, uncut material is generated at the position of the first rotation axis. Can be suppressed.

  The grinding surface may be formed with a plurality of grooves extending radially from the position of the second rotation shaft. According to such a configuration, the polishing liquid supplied to the grindstone can easily flow on the grinding surface through the groove, and the polishing liquid can be efficiently supplied to the entire area of the grinding surface.

  In order to solve the above-described problem, according to another aspect of the present invention, a step of rotating an optical element that is an object to be ground around a first rotation axis, and a grinding surface for grinding the optical element Rotating the grinding member having a second rotation axis around the second rotation axis, and the second rotation axis intersecting the first rotation axis at a predetermined inclination angle. There is provided a method for grinding an optical element, comprising: a step of contacting and pressurizing the optical element and grinding the optical element.

  According to the above configuration, the optical element that is the object to be ground is rotated around the first rotation axis, and the grinding member having a grinding surface for grinding the optical element is rotated around the second rotation axis. . Then, in a state where the second rotation axis intersects the first rotation axis at a predetermined inclination angle, the grinding surface is brought into contact with the optical element and the optical element is ground. Thereby, it becomes possible to easily grind an optical element having a complicated surface shape by co-sliding.

  According to the present invention, it is possible to provide an optical element grinding apparatus and an optical element grinding method capable of easily grinding an optical element having a complicated shape with a simple configuration.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  FIG. 1 is a schematic view showing a grinding apparatus 50 according to the first embodiment of the present invention. The grinding device 50 mainly grinds the optical function surface (light refraction surface) of a lens (optical element). In the present embodiment, the grinding includes polishing. As shown in FIG. 1, a rotating table 12 that rotatably supports the aspherical lens 10 to be ground is provided at the lower part of the grinding apparatus 50. The turntable 12 is rotatable around the rotation axis C1.

  A grinding wheel 14 for grinding is disposed on the upper part of the turntable 12. The grindstone 14 is rotatable about the rotation axis C2. The grindstone 14 is movable in the direction of arrow A (vertical direction) in FIG. 1 in a state where the angle of the rotation axis C2 with respect to the rotation axis C1 is maintained at a predetermined inclination angle.

  The grindstone 14 is provided with a grinding surface 14 a facing the aspherical lens 10. When grinding the aspherical lens 10, the turntable 12 is rotated about the rotation axis C1, and the grindstone 14 is rotated about the rotation axis C2. Then, the upper surface of the aspheric lens 10 is ground by moving the grindstone 14 in the direction of arrow A and bringing the grinding surface 14 a of the grindstone 14 into contact with the upper surface of the aspheric lens 10. At the time of grinding, the polishing liquid is supplied from the polishing liquid supply means (not shown) toward the grinding surface 14a of the grindstone 14.

  Further, during grinding, the rotation direction of the turntable 12 and the grindstone 14 is set so that the surface of the aspheric lens 10 and the grinding surface 14a move in a direction facing each other. Thereby, the surface of the aspherical lens 10 can be ground by co-rubbing.

  FIG. 2 is a cross-sectional view showing the positional relationship between the aspherical lens 10 and the grindstone 14, and shows a cross-sectional view along a plane including both the rotation axis C1 and the rotation axis C2. As shown in FIG. 2, the rotational axis C1 of the aspherical lens 10 and the rotational axis C2 of the grindstone 14 intersect at a predetermined angle θ.

  In the cross-sectional view shown in FIG. 2, the cross-sectional shape of the grinding surface 14a of the grindstone 14 is the same as the cross-sectional shape of the surface of the aspheric lens 10 after grinding. In FIG. 2, an overlap portion D is provided on the grinding surface 14 a of the grindstone 14 below the rotation axis C <b> 1. In FIG. 2, the cross-sectional shape of the grinding surface 14a including the overlap portion is symmetrical with respect to the rotation axis C1.

  FIG. 3 shows a state in which the surface of the aspheric lens 10 is ground in a state where the grindstone is moved in the direction of arrow A in the state of FIG. 2 and the grinding surface 14 a of the grindstone 14 is in close contact with the surface of the aspheric lens 10. FIG. Thus, since the cross-sectional shape of the grinding surface 14a is the same as the cross-sectional shape of the surface of the aspheric lens 10 after grinding, if the grinding surface 14a of the grindstone 14 is brought into close contact with the surface of the aspheric lens 10, The ground surface 14a is in line contact with the surface of the aspheric lens 10, and the surface of the aspheric lens 10 is ground following the cross-sectional shape of the ground surface 14a. Thereby, the surface of the aspherical lens 10 can be ground into a desired shape following the cross-sectional shape of the grinding surface 14a.

  Further, by providing the overlap portion D on the grinding surface 14a, the surface of the aspherical lens 10 can be ground by the grinding surface 14a having a cross-sectional shape that is line-symmetric with respect to the rotation axis C1. Therefore, there is no uncut portion at the position of the rotation axis C1 on the surface of the aspheric lens 10, and it is possible to prevent the projection shape from being formed at this position.

  FIG. 4 is a perspective view showing the grinding surface 14a of the grindstone 14 in detail. The main body of the grindstone 14 is made of a metal such as iron, and the grinding surface 14a is formed by electrodepositing abrasive grains such as diamond on the surface of the metal by electrolytic plating. Further, grooves 14b are formed radially on the ground surface 14a from the center. Therefore, the polishing liquid supplied to the grindstone 14 can easily flow on the grinding surface 14a, so that the polishing liquid can be efficiently supplied to the entire area of the grinding surface 14a, and the grinding efficiency can be increased. Further, since the grinding is performed at the edge of the groove 14b, the grindability can be improved. Further, the grinding powder generated by grinding the aspheric lens 10 can be discharged to the outside through the groove 14b.

  FIG. 5 is a cross-sectional view showing a state where the aspherical lens 16 having an inflection point on the surface is ground. The aspheric lens 16 shown in FIG. 5 has the same shape as the aspheric lens 120 described in FIG. Thus, the aspherical lens 16 having an inflection point can be easily ground by intersecting the rotation axis C1 and the rotation axis C2 at a predetermined angle θ.

  FIG. 6 is a schematic diagram for explaining the principle by which the aspherical lens 16 having an inflection point can be ground by the grinding apparatus 50 of the present embodiment. In FIG. 5, it is assumed that the point P1 on the surface of the aspherical lens 16 and the point P2 on the grinding surface 14a face each other in a direction parallel to the rotation axis C1.

  As shown in FIG. 6, the locus Q obtained by rotating the point P2 with respect to the rotation axis C2 is in contact with the surface of the aspheric lens 16 only at the position of the point P1, and the other is in contact with the aspheric lens 16. There is no contact at the position. In other words, the locus Q of the point P2 is closest to (in contact with) the surface of the aspheric lens 16 at the position of the point P1, and away from the surface of the aspheric lens 16 at other positions. Accordingly, the locus Q of the point P2 does not interfere with other parts of the aspherical lens 16 other than the position of the point P1, and the problem described with reference to FIG. The aspherical lens 16 having a complicated shape can be ground.

  FIG. 7 is a schematic diagram showing a state where the aspherical lens 10 shown in FIG. 2 is being ground, and shows a case where the angle θ formed between the rotation axis C1 and the rotation axis C2 is larger than that in FIG. . In this case, the cross-sectional shape of the grinding surface 14a is the same as that in FIG. 2, and the aspherical lens 10 having the same shape as in FIG. 2 can be formed by appropriately arranging the position of the grinding surface 14a with respect to the rotation axis C1. it can.

  As shown in FIG. 7, when the value of the angle θ is increased, the locus Q of point P2 on the grinding surface 14a becomes steeper with respect to the surface direction of the surface of the aspherical lens 10. Accordingly, by increasing the value of the angle θ, it is more difficult for the locus Q to interfere with other parts of the aspherical lens 16 other than the position of the point P1, and the aspherical lens having a more complicated surface shape. Can be ground. Therefore, the degree of freedom of the shape of the aspherical lens that can be ground can be further increased.

  On the other hand, when the angle θ is increased, the component acting in the direction of the rotational axis C2 decreases and the component in the direction orthogonal to the rotational axis C2 increases as the acting force received by the grindstone 14 when the grindstone 14 is pressed against the aspherical lens 10. To do. For this reason, a force acts in the direction in which the axis of the grindstone 14 bends, and it is likely that unnecessary vibration or the like is likely to occur during grinding, resulting in a decrease in processing accuracy. Therefore, it is preferable to make the angle θ as small as possible within a range where the aspherical lens can be ground.

  In the grinding device 50 according to the present embodiment, the locus Q of the point P2 mentioned above is in contact with the aspheric lens 16 only at the position of the point P1 corresponding to the point P2 at an arbitrary position on the surface of the aspheric lens 16. The value of the angle θ is determined so that does not come into contact with the aspheric lens 16 at other positions. Therefore, by determining the value of the angle θ in accordance with the surface shape of the aspheric lens, it is possible to easily grind the surface even for an aspheric lens composed of complicated curved surfaces.

  FIG. 8 is a cross-sectional view showing a case where the concave surface 18a of the concave lens 18 is ground by the grinding device 50 according to the present embodiment.

  When grinding the concave lens 16, as shown in FIG. 8, it is possible to grind the concave surface 18a by making the cross-sectional shape of the grinding surface 14a of the grindstone 14 a convex shape following the concave surface 18a. As in the case of FIG. 5, the locus Q of point P2 at an arbitrary position on the grinding surface 14a contacts the concave surface 18a only at the position of point P1 facing the point P2 in the direction parallel to the rotation axis C1. Accordingly, the locus Q does not interfere with other parts of the concave lens 18 and the concave surface 18a can be ground.

  Even when the aspherical lens 16 and the concave lens 18 are ground, by providing the overlap portion D, it is possible to suppress the occurrence of uncut portions at the intersection between the surface of the aspherical lens 16 or the concave lens 18 and the rotation axis C1. It is possible to suppress the formation of protrusions on the surface.

  The position of the grindstone 14 with respect to the lens surface during grinding and the angle θ of the rotation axis C2 with respect to the rotation axis C1 are finely adjusted in response to feedback of the shape of the lens after grinding. Therefore, the accuracy of the lens surface can be further improved by performing these adjustments.

  As described above, according to the present embodiment, the surface of the lens is ground in a state where the rotation axis C1 of the lens and the rotation axis C2 of the grindstone 14 intersect at a predetermined inclination angle θ. The lenses 10, 16 or the concave lens 18 can be easily ground. Therefore, the degree of freedom of lens shape that can be polished with a simple configuration can be greatly increased, and it becomes possible to grind a lens having a complicated shape without using special equipment such as an NC machine. Can be dramatically improved.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

It is a mimetic diagram showing grinding device 50 concerning a 1st embodiment of the present invention. It is sectional drawing which shows the positional relationship of an aspherical lens and a grindstone, Comprising: It is a schematic diagram which shows the cross section along the plane containing both the rotating shaft C1 and the rotating shaft C2. FIG. 3 is a cross-sectional view showing a state where the surface of the aspherical lens is ground in a state where the grindstone is moved in the direction of arrow A in the state of FIG. 2 and the grinding surface of the grindstone is in close contact with the surface of the aspherical lens. It is a perspective view which shows the grinding surface of a grindstone in detail. It is sectional drawing which shows a mode that the aspherical lens which has an inflexion point on the surface is ground. It is a schematic diagram for demonstrating the principle with which the aspherical lens which has an inflexion point can be ground with the grinding apparatus of this embodiment. It is a schematic diagram which shows a mode that the aspherical lens 10 shown in FIG. 2 is ground, Comprising: It is a schematic diagram which shows the case where the angle (theta) which the rotating shaft C1 and the rotating shaft C2 make larger than FIG. It is sectional drawing which shows the case where the concave surface of a concave lens is ground with the grinding apparatus which concerns on this embodiment. It is sectional drawing for demonstrating the conventional grinding method. It is a schematic diagram which shows the problem in the case of grinding an aspherical lens by the conventional method.

Explanation of symbols

10, 16 Aspherical lens 12 Turntable 14 Grinding wheel 14a Grinding surface 18 Concave lens

Claims (5)

A turntable that supports an optical element that is an object to be ground and rotates about a first rotation axis;
A grinding surface corresponding to the shape of the optical functional surface of the optical element, and rotating about a second rotation axis that intersects the first rotation axis at a predetermined inclination angle. A grinding member for grinding the optical element;
An optical element grinding apparatus comprising:   The apparatus for grinding an optical element according to claim 1, wherein the grinding surface is a convex surface and the surface to be ground of the optical element is a concave surface.   In a cross section along a plane including the first rotation axis and the second rotation axis, at least a part of the grinding surface is symmetric with respect to the first rotation axis. The optical element grinding apparatus according to claim 1 or 2.   The optical element grinding apparatus according to claim 1, wherein a plurality of grooves extending radially from the position of the second rotation axis are formed on the grinding surface. A step of rotating an optical element as an object to be ground around a first rotation axis;
Rotating a grinding member having a grinding surface for grinding the optical element around a second rotation axis;
A step of contacting and pressurizing the grinding surface against the optical element in a state where the second rotation axis intersects the first rotation axis at a predetermined inclination angle, and grinding the optical element;
A method for grinding an optical element, comprising:

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