高端光学元件超精密磨削技术研究进展 (封底文章·特邀)

Significance Ultra-precision grinding is a key enabling technology for manufacturing high-end optical components used in extreme ultraviolet lithography, laser fusion, infrared imaging, and space optics. As optical systems evolve toward larger apertures, higher numerical apertures, and wider spectral bands, the performance margins allowed for surface figure error, surface roughness, and subsurface damage become increasingly stringent. In hard and brittle optical materials such as fused silica, sapphire, silicon carbide, and silicon, the machining window for stable ductile-regime removal is narrow, and the coexistence of plastic flow, phase transformation, and brittle fracture makes process optimization nontrivial. Ultra-precision grinding plays a critical bridging role between coarse shaping and ultra-precision polishing: it is expected to provide high material removal rates while delivering a surface and subsurface state that is “polishing-friendly'', thereby shortening the overall manufacturing chain and improving yield. Therefore, systematically summarizing material removal mechanisms, quality prediction and control, key process technologies, and ultra-precision machine tools is essential for guiding both academic research and industrial deployment of high-efficiency, low-damage optical manufacturing. Progress Recent advances can be summarized from four tightly coupled aspects: mechanism, quality modeling, process technology, and machine tool capability. Multi-scale material removal mechanisms. At the atomic scale, molecular dynamics studies reveal that material removal initiates through collective atomic bond breaking accompanied by severe local shear and layered deformation; chip formation is governed by the sequence of atomic accumulation, energy build-up, bond rupture, and material separation (Fig.3). At the micro/nano scale, dislocation slip, twinning, and pressure-induced phase transformation can accommodate plasticity and promote ductile removal, whereas crack initiation and propagation dominate when the local stress intensity exceeds the fracture resistance. The coupling between abrasive geometry, undeformed chip thickness, strain-rate effects, and thermal-mechanical fields determines the ductile-brittle transition and the evolution of subsurface damage. Grinding Quality Prediction and Evaluation Surface roughness and subsurface damage are the two most critical quality indicators in ultra-precision grinding. For roughness, models have evolved from purely geometric formulations toward hybrid frameworks that incorporate probabilistic grain engagement, elastic recovery, and parameter distributions. Representative theoretical and semi-empirical roughness models, together with their applicability and limitations, are compared to support model selection and engineering use (Tab.2). Meanwhile, data-driven approaches are increasingly used to map process parameters and sensing signals to roughness outcomes, enabling rapid prediction and online monitoring; typical convolutional neural network architectures for parameter-topography mapping and vibration-roughness mapping demonstrate how learning-based models can enhance robustness under complex operating conditions (Fig.6). For subsurface damage, prediction frameworks based on indentation fracture mechanics, crack evolution, and combined mechanism descriptions have been established for different materials and loading conditions. These models relate damage depth to crack systems (median/radial and lateral cracks), surface state, and dynamic effects such as spindle vibration, providing multiple pathways for damage estimation and control (Tab.3). Key process technologies for high efficiency and low damage. Progress has been made in grinding wheel design, precision dressing/truing, and the integration of auxiliary energy fields. Structured and engineered wheels can tailor local chip thickness and improve coolant access, while advanced dressing methods (e.g., laser- or electrical-discharge-related approaches) enhance grain protrusion uniformity and shape accuracy, which are crucial for deterministic optical grinding. In addition, ultrasonic vibration-assisted grinding and laser-assisted grinding have become important routes to enlarge the ductile machining window, reduce grinding forces, and suppress crack formation by modifying contact mechanics and near-surface material response. These technologies collectively aim to improve the “damage-to-removal-rate'' tradeoff, especially for high-hardness and high-brittleness substrates. Ultra-precision grinding machines and system-level capability. The achievable surface integrity is ultimately constrained by machine tool motion accuracy, dynamic stiffness, and thermal stability. Recent machines emphasize high-rigidity structural layouts (e.g., T-frame and gantry-type configurations) to enhance dynamic performance and error resistance (Fig.12). Hydrostatic guideways and hydrostatic spindles provide low friction, high damping, and high stiffness, enabling smoother motion and better nano-scale positioning under varying loads. A comparison of key parameters across representative domestic and international ultra-precision grinding machines highlights trends in granite-based beds, multi-axis linear motor drives, and high-end numerical control systems, reflecting the shift toward higher bandwidth and higher stability platforms for optical fabrication (Tab.6). Conclusions and Prospects Substantial progress has been achieved in clarifying the multi-scale removal physics, improving roughness and subsurface damage prediction, developing auxiliary-field-assisted processes, and upgrading machine tool structures and hydrostatic functional units. However, challenges remain in establishing unified predictive models that bridge atomic-to-macro scales, achieving robust controllability across materials and tool states, and compensating thermo-mechanical coupling errors under long-duration, high-stability operation. Future research is expected to focus on mechanism-driven, data-enhanced grinding models; intelligent process regulation through multi-sensor fusion and digital twins; advanced wheel design and high-consistency dressing strategies; and next-generation intelligent ultra-precision grinding machines with stronger thermal management and error compensation. These directions are anticipated to support higher efficiency, lower damage, and higher determinism in the manufacturing of high-end optical components.