Algorithm for the Measurement of the Parameters of Off-axis Conic Surface

To ensure the accuracy of conic surface in the fabrication of off-axis aspheric section, it is important to control the current surface parameters, such as the lateral displacement, tilt angle, the paraxial radius and the conic constant. From the normal equation for conic aspheric, new equation of conic aspheric was derived in new correlation system. Base on the new equation, the lateral displacement, tilt angle and the paraxial radius can be calculated with Conjugate Direction Method to minimize the RMS of deviation. The experimental result of the paraboloid and hyperboloid with different shapes are presented, the fitting accuracy arrived to 10nm rms. Thus the deviation of the off-axis aspheric section can be controlled effectively.