Method of blocking plastic lenses for surfacing

摘要

An improved method and apparatus for blocking plastic lenses wherein an intermediate member in the form of a stiff, lightweight disc is interposed between the lens blank and a low melting point blocking material such that heat from the blocking material is absorbed by the member so as to prevent distortion of the lens blank. The face of the member is shaped so as to intimately conform to the standard convex side of the lens blank and is of a peripheral extent so as to provide stiffening support essentially over the entire surface thereof. The avoidance of lens distortion also enables lenses blocked in this manner to be re-blocked, if necessary, for corrective grinding.