Process for measuring forward and rearward three-dimensional curves and

Abstract

A process for measuring forward and rearward three-dimensional curves and the thickness at the circumference of a contour-ground eyeglass lens by means of a computer-controlled eyeglass lens edge grinding machine. As the corrective lens is being ground, the rotation of the corrective lens is interrupted when a measurement point is reached, and the corrective lens is shifted axially relative to the grinding disk away from the center section and toward the edges of the grinding disk until the forward and rearward edges at the circumference of the corrective lens touch the tracing device. The path or the time consumed in moving from the center section to the point of contact with the tracing device is recorded, and the measured values are stored in the computer, the shaft halves holding the corrective lens rotate further, until the next measurement point is reached, when a measurement is again taken. The process is continued until the shaft halves holding the corrective lens have completed at least one full revolution. This type of measurement value acquisition avoids errors due to very severe concavity in very thick lenses.