JPS6351824B2 - - Google Patents

Description

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

[Conventional technology]

Conventionally, in order to finish the surface of an optical element such as a lens, prism, or reflecting mirror 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 pad.

FIG. 3 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 a material to be polished, and the material to be polished 12 is circular. The material to be polished 12 is fixedly supported with its lower surface adhered to a support 14 . The support body 14 is rotatable around an axis X, and the material to be polished 12 is fixed to the support body 14 so as to be rotationally symmetrical about the axis X. Polished material 12
The upper surface of the is mirror-polished in advance.
However, it is assumed that the illustrated ring zone Y has become convex due to this pre-processing.

In corrective polishing, a polishing pad 16 that is smaller than the size of the material 12 to be polished is used. The polishing pad 16 is fixedly supported by adhesion to a support 18, and one end of a rod 20 is abutted against a recess formed in the center of the upper surface of the support 18.
The rod 20 is swingable in the radial direction of the material to be polished 12 by an appropriate width. 22 is a polishing liquid supply means.

Corrective polishing is performed by rotating the support body 14 in the direction of arrow A while supplying polishing liquid from the polishing liquid supply means 22 onto the upper surface of the material to be polished 12, and simultaneously swinging the support body 18 in the direction of arrow B. will be carried out.

[Problem that the invention seeks to solve]

However, in conventional corrective polishing, the polishing process is performed while the polishing pad 16 is in contact with the material to be polished 12 with uniform pressure over the entire surface.
There has been a problem in that a level difference is likely to occur between a portion of the upper surface of the material to be polished 12 that has undergone correction polishing and a portion that has not undergone correction polishing.

FIGS. 4a and 4b are cross-sectional views of the material to be polished 12 corresponding to the negative cross-section in FIG. Figure 4a
shows the state before corrective polishing, and Fig. 4b shows the state after corrective polishing, and as can be seen from this,
Optically, a considerably large step 24 is formed at a position corresponding to the swing width of the polishing pad 16 during corrective polishing.

For this reason, it has been proposed that the swing width of the polishing pad 16 is not fixed, but is gradually changed to prevent the occurrence of the step. 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 problems]

According to the present invention, in order to solve the above-mentioned problems of the prior art, there is provided a polishing pad that is brought into pressure contact with a material to be polished for polishing, the polishing pad itself being made of an elastic body,
The elastic force distribution of the polishing pad is said to gradually decrease from the center to the periphery, and is characterized in that the elastic force distribution is formed based on the distribution of a large number of pores contained in the elastic body. In the polishing pad, and the polishing pad that polishes by pressing against the material to be polished, the polishing pad itself is made of an elastic body,
The elastic force distribution of the polishing pad is said to gradually decrease from the center to the periphery, and the elastic force distribution is formed based on the distribution of the mixing rate of a material that contributes to the elasticity of the elastic body. and
Abrasive pads are provided.

〔Example〕

Hereinafter, specific embodiments of the polishing pad of the present invention will be described with reference to the drawings.

FIG. 1a is a schematic cross-sectional view showing a first embodiment of the polishing pad and its support according to the present invention.

The polishing pad 16 of this embodiment has a disk-like shape with a uniform thickness. Z is its axis of symmetry.
A support 18 having a flat bottom surface is bonded to the upper surface of the polishing pad 16. When the polishing pad of this embodiment is pressed against a rigid plane while being fixed to the support 18, it is compressed as shown in FIG. receive repulsive force. That is, the polishing pad of this embodiment exhibits an elastic force distribution as shown in FIG. 1c when pressed.

The polishing pad of this example is made by mixing materials that contribute to elasticity in an appropriate distribution when manufacturing polyurethane pads, which are currently widely used for polishing optical elements, or materials that contribute to porosity. It can be obtained by mixing in an appropriate distribution.

FIGS. 2a and 2b are cross-sectional views showing changes in the material to be polished 12 when corrective polishing is performed using the polishing pad of this embodiment. FIG. 2a shows the state before the corrective polishing, and FIG. 2b shows the state after the corrective polishing. According to the polishing pad of this embodiment, since the pad exhibits an elastic force distribution as shown in FIG. be able to.

Although the polishing pads in the above embodiments are shown as being for polishing flat surfaces, the polishing pads of the present invention also include pads for polishing convex or concave surfaces. It will be obvious that a polishing pad for polishing a concave or convex surface can be similarly constructed by appropriately setting the elastic force distribution when pressed against the convex or concave surface.

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

The polishing pad of the present invention can also be used to create and polish an axially symmetric aspherical surface with a small amount of aspherical surface by appropriately setting the polishing time in the method described in the above embodiment.

〔Effect of the invention〕

According to the polishing pad of the present invention as described above, highly accurate polishing can be performed without creating a step on the material to be polished, without using a polishing device having a complicated mechanism.

[Brief explanation of drawings]

1a and 1b are cross-sectional views of the polishing pad of the present invention, and FIG. 1c is a graph of elastic force. Figures 2a and b and Figures 4a and b are cross-sectional views of the material to be polished. FIG. 3 is a perspective view showing the polishing method. 12: Polished material, 14: Support, 16: Polishing pad, 18: Support.

Claims (1)

[Scope of Claims] 1. A polishing pad that polishes by pressing against the material to be polished, the polishing pad itself being made of an elastic body, and the elastic force distribution of the polishing pad gradually decreasing from the center to the periphery. A polishing pad characterized in that the elastic force distribution is formed based on the distribution of a large number of pores contained in the elastic body. 2. In a polishing pad that polishes by pressing against the material to be polished, the polishing pad itself is made of an elastic body, and the elastic force distribution of the polishing pad is said to gradually decrease from the center to the periphery. An abrasive pad characterized in that the elastic force distribution is formed based on the distribution of the mixing ratio of materials that contribute to the elasticity of the elastic body.