Robotic pneumatic constant-force polishing system and process validation for X-ray mirrors

Grazing-incidence X-ray mirrors constitute the pivotal optical elements for next-generation space-based astronomical observation and synchrotron radiation facilities; their manufacturing accuracy directly governs the focusing efficiency and imaging resolution of high-energy radiation. Consequently, extremely stringent specifications are imposed on both the surface figure (peak-to-valley, PV < 1 μm) and the surface roughness (Ra < 1 nm). To address the high cost and limited flexibility of conventional large-scale gantry optical machining platforms, as well as the insufficient stiffness and challenging force regulation associated with industrial robots, this work develops a pneumatic constant-force polishing system based on a robotic manipulator that integrates “macroscopic trajectory generation” with “microscopic contact-force sensing and active control.” The proposed system exhibits excellent and stable material removal performance in the polishing of single-crystal silicon. Beyond mitigating the longstanding force–position coupling issue in robotic polishing, this study provides an enabling theoretical foundation and a practical technological paradigm for the deterministic fabrication of large-aperture, freeform optical surfaces.