Lens-Free, Wide-FOV Structured Light Sensing Enabled by Slanted Grating Optical Switch Arrays

Abstract

High-precision three-dimensional (3D) sensing is essential for robotics and automation. However, conventional structured light (SL) systems often lack spatial reconfigurability for high-dynamic-range (HDR) scenarios, while reconfigurable SL pattern generators such as optical phased arrays (OPAs) and lens-assisted focal plane switch arrays (FPSAs) are limited by element-factor-induced efficiency roll-off and off-axis aberrations at wide angles. This paper proposes an adaptive, lens-free SL patterning engine based on a 1 × 64 optical-switch-addressed slanted grating antenna array on a Si3N4–SOI hybrid platform. The element factor is tuned by adapting the Bragg condition for 3D diffraction manipulation, achieving a wide field of view (FOV) of 100° × 29.6°. A weakly perturbed waveguide grating improves the longitudinal divergence to 0.054°. System-level validation demonstrates that the engine effectively compensates for reflectivity contrasts up to 16 dB, utilizing adaptive power adjustment to resolve targets in HDR scenes. We achieve a sub-millimeter 3D reconstruction root-mean-square error (RMSE) of 501.3 μm at a distance of 247 mm in the central region and maintain robust sub-millimeter fidelity across a large FOV. This architecture provides a robust approach for next-generation solid-state, intelligent 3D sensing.