JPH03208552A - Polishing method - Google Patents

Abstract

PURPOSE:To form the poloshing area surface shape corresponding to the desired time with the lenient and continuous change of a polishing removal quantity over the whole polishing area, by bringing a polishing tray into contact with the polishing area of the surface of the body to be polished with its sliding for the desired time while pressing it with the pressure distribution form becoming smaller gradually from its center part over to the outer peripheral part. CONSTITUTION:The contact 3 of a polishing tray 1 is brought into contact with the polishing area of the surface of the body to be polished with its sliding for the desired time while pressing it in the pressure distribution form becoming smaller gradually from its center part over to the outer peripheral part. Consequently, the polishing area surface shape corresponding to the desired time is formed by changing leniently and continuously the polishing removal quantity over the while polishing area.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a polishing method, and particularly to a polishing method suitable for polishing optical elements with high precision.

[Prior Art] Conventionally, in order to finish the surface of optical elements such as lenses, prisms, or reflectors to extremely high precision, the surface, which has been polished to a certain degree of precision, is partially corrected and polished using a small-diameter polishing plate. things are done.

FIG. 5 is a schematic perspective view for explaining a specific example of such corrective polishing. In the figure, reference numeral 12 denotes an optical glass parallel plane plate which is an object to be polished, and the object to be polished 12 is circular. The object to be polished 12 is fixedly supported by bonding its lower surface to a support 14 . The support 14 is rotatable around the axis X, and the object to be polished 12 is fixed to the support 14 so as to be rotationally symmetrical about the axis X. The upper surface of the object to be polished 12 has been mirror-polished in advance by pre-processing.

However, it is assumed that the portion of the belt Y shown in the figure has become convex due to this pre-processing.

In the correction polishing, a polishing plate 15 smaller than the size of the object 12 to be polished is used. The polishing plate 15 is the polishing pad 1
6 fixedly supported by adhering it to a support 18,
A rod 2 is placed in the recess formed in the center of the upper surface of the support 18.
One end of 0 is abutted. The rod body 20 is an object to be polished l.
It is possible to swing in the radial direction of 2 with an appropriate width. 22 is a polishing liquid supply means.

The support body 14 is rotated in the eight directions of the arrows while supplying the polishing liquid onto the upper surface of the object to be polished 12 from the polishing liquid supply means 22,
At the same time, corrective polishing is performed by swinging the support 18 in the direction of arrow B.

[Problems to be Solved by the Invention] However, in conventional corrective polishing, the polishing plate 15
Because the polishing process is performed while the polishing pad 16 is in contact with the object 12 with uniform pressure over the entire surface, a difference in level is likely to occur between the part of the upper surface of the object 12 that has undergone correction polishing and the part that has not. There was a problem.

FIGS. 6(a) and 6(b) are cross-sectional views of the object to be polished 12 corresponding to the section 1-1 in FIG.

FIG. 6(a) shows the state before the corrective polishing, and FIG. 6(b) shows the state after the corrective polishing. As can be seen from these figures, the polishing plate 15 during corrective polishing
Optically, a fairly large step 24 is formed at a position corresponding to the swing width.

For this reason, the swing width of the polishing plate l5 is not fixed;
It has been proposed to prevent the occurrence of steps by gradually changing the swing width. However, such a mechanism for continuously changing the oscillation width is quite complicated and has the disadvantage that the polishing device becomes expensive.

[Means for Solving the Problems] According to the present invention, in order to solve the problems of the prior art as described above, the contact surface of the polishing dish is changed from the center to the outer periphery of the polishing area of the surface of the object to be polished. sliding contact for a desired time while pressing with a pressure distribution pattern that gradually decreases over the entire polishing area, and forming a polishing area surface shape corresponding to the desired time by gently and continuously changing the amount of polishing removed over the entire polishing area. A polishing method is provided, characterized in that:

In the present invention, when the center of the contact surface with the object to be polished is a convex or flat surface, the polishing plate used is one in which the radius of curvature of the contact surface gradually decreases from the center to the outer periphery. When the center of the contact surface with the object to be polished is a concave surface, there is an embodiment in which the contact surface has a radius of curvature that gradually increases from the center to the outer periphery.

Furthermore, in the present invention, there is an embodiment in which a polishing plate having a smaller diameter than the object to be polished is used to correctively polish a part of the polishing area on the surface of the object to be polished. [Example] Hereinafter, with reference to the drawings, , a specific example of the polishing method of the present invention will be described.

FIG. 1 is a schematic sectional view showing a first embodiment of a polishing plate used in the polishing method of the present invention.

The polishing plate of this embodiment consists of a polishing pad 1 having a uniform thickness and a support body 2 thereof. They have a disk-like shape, and Z is their axis of symmetry. The contact surface 3 of the polishing plate of this embodiment with the object to be polished (ie, the lower surface of the polishing pad 1 in the figure) is a convex surface as a whole, and the curvature of the contact surface 3 gradually changes in the radial direction. That is, at the center of the contact surface 3 (i.e., a point on the axis of symmetry Z), the radius of curvature is R1,
The center of curvature is 01, and on the other hand, the radius of curvature at the outer periphery of the contact surface 3 is R, and the center of curvature is 02 (where R+ > R*). From the center to the outer periphery of 3, the radius of curvature is R
It gradually changes from 1 to R, and along with this, the center of curvature also gradually moves from 01 to O.

FIG. 2 shows the distribution of pressure applied to the polishing pad 1 when polishing a concave surface with a radius of curvature R1 using the polishing plate of this embodiment. As shown in the figure, the pressure is high at the center of the polishing dish, and the pressure is low at the outer periphery.

In the above embodiments, the contact surface with the object to be polished is a convex surface and concave surface polishing is performed, but if R1 is set to infinity, the same applies to surface polishing. Figure 3 (
a). (b) is a sectional view showing changes in the object to be polished 12 when corrective polishing of the plane is performed using the polishing plate in such a case. FIG. 3(a) shows the state before the corrective polishing, and FIG. 3(b) shows the state after the corrective polishing. According to the polishing plate of this embodiment, since the pressure distribution as shown in FIG. 2 is exhibited, corrective polishing for flattening the band-like convex portion can be performed satisfactorily without creating a step.

FIG. 4 is a schematic sectional view showing a second embodiment of a polishing plate used in the polishing method of the present invention.

The contact surface 3 of the polishing plate of this embodiment with the object to be polished is a concave surface as a whole. Furthermore, the radius of curvature at the center of the contact surface 3 is R3
The center of curvature is o3, and the radius of curvature of the outer circumference of the contact surface 3 is R4. Its center of curvature is 04 (however, Rs<R.). Furthermore, although not shown, the radius of curvature from the center to the outer periphery of the contact surface 3 is R. to R4, and along with this, the center of curvature also gradually moves from 03 to 04.

This second embodiment also shows a pressure distribution state similar to that shown in FIG.

Although the above embodiments have been explained by taking corrective polishing as an example, it goes without saying that the polishing plate of the present invention can also be used for other ordinary polishing.

Furthermore, in the above explanation, the curvature of the desired final shape of the polishing area of the object to be polished is the same as the curvature of the center of the polishing plate, but this can be achieved by setting the polishing time appropriately. The present invention can also be used to leave an aspherical surface as it is by changing and setting the polishing time as appropriate, or to create and polish an axisymmetric aspherical surface with a small amount of aspherical surface from a spherical or flat surface. You can also do it.

[Effects of the Invention] As explained above, according to the polishing method of the present invention, the polishing plate is pressed against the polishing area of the surface of the object to be polished in a manner in which the pressure distribution gradually decreases from the center to the outer periphery. By making sliding contact for a time, it is possible to smoothly and continuously change the amount of polishing removed over the entire polishing area, and form the surface shape of the polishing area according to the desired time, thus creating a step on the object to be polished. High-precision polishing can be performed without causing any damage.

[Brief explanation of drawings]

1 and 4 are both sectional views of a polishing plate used in the polishing method of the present invention. FIG. 2 is a graph showing the pressure distribution of the polishing pad. Figure 3(a). 6(b) and FIGS. 6(a) and 6(b) are both cross-sectional views of the object to be polished. FIG. 5 is a perspective view showing the polishing method. 1: Polishing pad, 2: Support, 3: Contact surface, 12: Object to be polished, 14.18: Support, 15: Polishing plate, 16: Polishing pad, 20: Rod,
22: Polishing liquid supply means.

Claims (3)

[Claims] (1) In a method of polishing an object to be polished using a polishing plate, the contact surface of the polishing plate is pressed against the polishing area of the surface of the object to be polished in a manner in which the pressure distribution gradually decreases from the center to the outer periphery. A polishing method characterized by forming a surface shape of the polishing area according to the desired time by making sliding contact for a time and gradually and continuously changing the amount of polishing removed over the entire polishing area. (2) As the polishing plate, if the center of the contact surface with the object to be polished is a convex or flat surface, use one in which the contact surface has a radius of curvature that gradually decreases from the center to the outer periphery;
Polishing according to claim 1, wherein when the center of the contact surface with the object to be polished is a concave surface, the contact surface has a radius of curvature that gradually increases from the center to the outer periphery. Method. (3) The polishing method according to claim 1, wherein a part of the polishing area on the surface of the object to be polished is corrected and polished using a polishing plate having a smaller diameter than the object to be polished.