Eight-axis-polishing Machine for Large Off-axis Aspheric Optics

For the purpose of fabricating off-axis aspheric optics, we propose an 8-axis-polishing machine combined with a testing tower whose height is up to 9 m. The proposed polishing machine was designed and analyzed by using a well-known finite element method. The eight axes of the machine have a synchronized motion generated by a computer, and each axis was calibrated by a heterodyne laser interferometer or an optical encoder. After calibration, the maximum positioning error of the machine was less than 2 μm within a whole 2 m × 2 m area. A typical fabrication result of a φ1.5 m concave mirror was also described in this manuscript