Geometric models of the ultra-precision grinding for large non-axisymmetric optical aspheric surfaces

Traditionally 2-axis Numerical Controlled (NC) machine is used to manufacture axisymmetric aspheric surface. If a coding disc offering accurate readings of the rotation angle is installed on the spindle, large non-axisymmetric aspheric surfaces can be manufactured on an ultra-precision 2-axis NC grinding machine by employing a diamond wheel. Geometric models for machining non-axisymmetric aspheric surfaces are presented based on a curvature analysis to solve the problems of high production cost and low efficiency in machining. The machining approach is verified to be simple and reliable by computer simulation. According to the geometric models, 3-D machining can be achieved by reforming a 2-axis machine. This will allow equipment investment be decreased.