Fast Fabrication of 1.26-Meter-Long Optic for Elliptic Cylindrical Focusing Bending Mirror

As beamline emittance reaching the diffraction limit, the demand for focusing mirrors over one meter in length is ever increasing. Bending mirrors, are competitive for its adjustable radius and high manufacture precision, whose final surface form is managed by a delicate bending of a high precision plane. A special contour plays an essential role and benefits this final touch, given that the computed torque along the length closely correlates with the corresponding width of the optics. However, it poses main challenges with severe edge effect, deformation and metrology to the fabrication of the precursor plane mirror. This paper reports on a fast processing technology for a 1.26-meter-long plane as a bending mirror with irregular shape. A smooth surface with a slope error of 0.67 urad(RMS) and 0.3nm roughness is achieved through deterministic flexible finishing of robot polishing system and annular polishing, providing a high precision and cost-effective method to meet the growing needs for long X-ray mirrors.