High-resolution Laser Scanner for Distributed Fiber Bragg Grating

Abstract

In this paper, we present a high-resolution laser scanning system integrating fine machining of objective-only method with high-speed beam steering of a galvanometric scanner. A relay lens configuration transfers scanner angular deflection to the pupil plane of a high-magnification objective without angular loss, maintaining diffraction-limited focusing during rapid scanning. Unlike objective-only approaches limited by throughput and scanner-based systems sacrificing resolution, the proposed system preserves diffraction-limited performance with direct pupil-plane deflection transfer. Using this system, periodic micro-gratings were inscribed inside transparent materials with substantially improved processing speed. Grating periods remained uniform, and fabrication time for identical length structures decreased from minutes to tens of seconds. The system was further applied to Distributed Fiber Bragg Grating fabrication, enabling stable inscription of low-reflection FBG arrays with identical and random Bragg wavelengths. Spatial reflection responses were clearly resolved using radio-frequency modulation interferometry, confirming suitability for distributed sensing. The system enables high-speed, high-precision laser patterning without mechanical rotation assemblies or trepanning mechanisms. As a non-contact approach, it eliminates tool wear, reduces environmental impact from consumables and chemical etchants, and demonstrates strong potential for optical sensor fabrication and next-generation micro-manufacturing.