A Comprehensive Review of Precision Glass Molding for Micro/Nano Optical Components

Precision Glass Molding (PGM) has emerged as a pivotal manufacturing technique for producing high-performance micro/nano optical components. Its ability to directly replicate complex geometries, including freeform surfaces, diffractive microstructures, and aspherical profiles into moldable glass makes it especially suitable for scalable mass production across advanced optical applications. This review provides a comprehensive synthesis of the field, covering mold material selection, mold fabrication methods, moldable glass categories, molding processes, and their functional applications. Particular attention is given to mold materials, where thermal stability, mechanical strength, and dimensional integrity remain critical, yet challenges such as thermal expansion mismatch and rapid tool wear continue to limit process reliability. In the area of mold fabrication, ultra-precision machining and emerging hybrid approaches are highlighted for their role in achieving nanometric surface finishes and submicron form accuracy, especially for freeform or hard-material molds. Regarding moldable glasses, three main categories oxide-based glasses, silica glasses, and chalcogenide glasses are compared, each with distinct thermal and interfacial characteristics that demand tailored molding strategies. Advanced techniques, such as ultrasonic vibration-assisted molding and ultra-high temperature PGM, are discussed as promising solutions to replication fidelity and material degradation issues. Beyond technical processes, this review emphasizes the expanding applications of PGM in imaging, sensing, consumer electronics, automotive optics, medical devices, and defense technologies, where compact, thermally stable, and high-precision components are essential. Finally, future trends are identified, including the development of novel material systems, innovative surface engineering, and real-time monitoring technologies, which together are expected to enhance process reliability, scalability, and the integration of PGM into next-generation photonic systems.