Eight-axis-polishing machine for 2 m off-axis aspheric optics

For the purpose of fabricating off-axis aspheric optics, we propose a 8-axis-polishing machine combined with a testing tower whose height is about 9 m. The proposed polishing machine was designed and analysed 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. The maximum capability of the proposed polishing machine is up to 2 m in diameter, and the maximum radius of curvature of the product (optics) is slightly over 7 m. 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.