Ronchi-calibrated bidirectional fast volume-repeat OCT for high-speed 4D imaging

We present a bidirectional scanning and distortion correction framework for high-speed, wide-field 4D SS-OCT imaging. Forward and backward scans are combined to improve acquisition efficiency, while a Ronchi-based calibration is introduced to correct direction-dependent geometric distortion at high frame rates. Stripe boundary features are extracted to establish calibration markers, and a polynomial model is employed to map nonlinear sampling coordinates to true spatial positions. The resulting distortion maps enable remapping to a common linear grid with consistent spatial sampling. This approach increases the acquisition duty cycle by 50%, achieving volumetric imaging rates of 15 Hz over an expanded lateral field of view of 4 × 4 mm². We demonstrate the capability of the proposed method in trabecular meshwork dynamics imaging with reduced phase-wrapping artifacts resulting from inter-volume motion. This method enables practical high-speed, wide-field 4D functional OCT imaging.