Adaptive illumination pulsed time-of-flight sensor

This study introduces an innovative indirect time-of-flight (ToF) sensor and system that employs multi-intensity nearinfrared (NIR) pulses. Unlike the conventional uniform square-wave pulses typically emitted from vertical-cavity surface-emitting lasers (VCSEL) at NIR wavelengths, we developed and tested a pulsed ToF sensor and system utilizing NIR light pulses at 940 nm, where each pulse exhibited at least two distinct power levels. This non-uniform NIR pulse sequence is initiated with a pulse of higher power, succeeded by one or more parts with progressively reduced power levels. The three-tap indirect ToF pixel (7μm) within the OPNOUS’ commercial VGA (480 × 640) ToF module can measure the non-uniform depth ratio, thereby enabling a more accurate determination of the object depth within a scene. The proposed novel indirect ToF ranging method was validated both theoretically and experimentally over a range of 0.6-3.0 meters, demonstrating significantly enhanced depth precision and an extended operational range for distant objects.