1. A method of dressing a polishing pad, comprising:
performing a first dressing on the polishing pad;
performing a first measurement of a surface roughness of the polishing pad using an optical device after the first dressing;
performing a second dressing on the polishing pad after the first measurement;
performing a second measurement of the surface roughness of the polishing pad using the optical device after the second dressing; and
determining a rate of change in the surface roughness based on the first and second measurements,
wherein a third dressing on the polishing pad is performed if the rate of change is larger than a predetermined rate.
2. The method of claim 1, wherein the first and second measurements are performed as the optical device scans at least a portion of the polishing pad.
3. The method of claim 1, wherein the optical device comprises a laser focus displacement meter.
4. The method of claim 2, wherein the optical device comprises a laser focus displacement meter.
5. The method of claim 1, wherein the first and second measurements comprise detecting a maximum height of projecting portions within an area of measurement of the polishing pad and detecting a minimum height of denting portions within the area of measurement.
6. The method of claim 2, wherein the first and second measurements comprise detecting a maximum height of projecting portions within an area of measurement of the polishing pad and detecting a minimum height of denting portions within the area of measurement.
7. The method of claim 3, wherein the first and second measurements comprise detecting a maximum height of projecting portions within an area of measurement of the polishing pad and detecting a minimum height of denting portions within the area of measurement.
8. The method of claim 4, wherein the first and second measurements comprise detecting a maximum height of projecting portions within an area of measurement of the polishing pad and detecting a minimum height of denting portions within the area of measurement.
9. A method of dressing a polishing pad, comprising:
repeating a dressing of the polishing pad for a predetermined period and an optical measurement of a surface roughness of the polishing pad,
wherein the repeating is stopped when a rate of change in the measured surface roughness is determined to be smaller than or equal to a predetermined rate.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A linear guide apparatus comprising:
a guide rail including an axially elongating rolling element rolling groove in each of sides thereof, and extended in an axial direction;
a slider including rolling element rolling grooves respectively opposed to the rolling element rolling grooves of the guide rail, and straddling the guide rail to be relatively movable in the axial direction via a number of cylindrical rollers, the rollers serving as rolling elements interposed between the opposed rolling element rolling grooves; and
a plurality of separators each being independent of each other and having: a separator body interposed between adjacent the cylindrical rollers; and an arm portion integrally formed on the separator body and contacting at least one of axial end flat faces of the cylindrical rollers,
wherein the slider includes a slider body having a rolling element path passing through the body in the axial direction; and a pair of end caps respectively having curved direction change paths through which a pair of the rolling element rolling grooves communicates with the rolling element path, the end caps being respectively fixed to axial end faces of the slider body; a guide groove guiding the arm portions of the separators in a circulation direction of the cylindrical rollers when the cylindrical rollers circulate through the pair of the rolling element rolling grooves, the direction change paths, and the rolling element path,
wherein a width of the guide groove is larger than a width of each of the arm portions, the width of the guide groove in a region of each of the direction change paths is larger than the width of the guide groove in a region where the cylindrical rollers linearly move, and end portions of each of the arm portions are chamfered, the end portions being directed in the circulation direction of the cylindrical rollers, and
wherein the direction change paths comprise an inner guide groove formed on an inner-diameter side of the direction change paths so that end portions thereof smoothly continue from the rolling element rolling groove.
2. A linear guide apparatus according to claim 1, wherein, at a position where the linear motion region is connected to one of the direction change regions, a shape of an inner wall face of an inner side of the guide groove in the direction change path is changed.
3. A linear guide apparatus according to claim 1, wherein the width of the guide groove is made larger at a position being on a side of the linear motion region with respect to a position where the linear motion region is connected to one of the direction change regions.
4. A linear guide apparatus according to claim 1, wherein the arm portions is formed a band-like shape along the circulation direction of the cylindrical rollers.
5. A linear guide apparatus according to claim 1, wherein the arm portion is couplable to the axial end faces of the cylindrical roller.