Transcending the Space‐Bandwidth and Lighting Trade‐Offs: A Programmable Self‐Mixing Interferometry Imager for Cross‐Scale Surface Inspection

Abstract

ABSTRACT Industrial optical inspection is fundamentally limited by the trade‐off between spatial bandwidth (field‐of‐view vs. resolution) and vulnerability to ambient lighting. This work addresses these challenges by proposing a programmable imager based on amplitude‐modulated laser self‐mixing interferometry integrated with a spot scanner. It transforms point‐measurement interferometry into a high‐speed areal scanning tool with a 500 kHz pixel sampling rate, achieving a high‐fidelity resolution of 8.77 µm across a 200 × 200 mm 2 field in a single scan, delivering a superior space‐bandwidth product that surpasses existing technologies by an order of magnitude. Concurrently, it exhibits inherent illumination invariance, maintaining high‐fidelity imaging under a 50 Hz extreme transient illumination that toggles between <1 lux and 240 klux. The programmable scanning core enables cross‐scale workflow adaptation, from rapid surveys to micron‐level defect analysis. Successful applications in additive manufacturing metrology and surface texture classification validate its role as a robust, data‐rich tool for intelligent inspection.