Pitch polishing and pad polishing
Mr. Honda holds a polishing plate for pad polishing.
The term "lens-polishing" refers to the work performed on a lens using a polishing plate, after the lens is grounded into an approximate shape in the course of the grinding process. The polishing process involves finely shaping the lens to give it the curvature and shape required by the design specifications, and making the surface of the lens smooth.
The polishing surface of the polishing plate may be covered with pitch*1 or with a pad. Polishing with pitch is the traditional method and requires a high degree of technical skill. Since this method allows the production of extremely high-precision lenses, it is used in the manufacture of diversified small-quantity production lenses for steppers, scanners and microscopes. Formerly, Mr. Honda also employed this method of polishing.
Technical innovations over the past 20 years have made pad polishing the predominant polishing method. Polishing plates can be manufactured relatively quickly. Tochigi Nikon now uses pad polishing for all its polishing work, as this method is superior for mass production.
- *1Pitch: a distilled petroleum product known as bitumen