Complementary differential detection for fast focusing using dual single-pixel detectors

This paper introduces a complementary differential detection technique based on dual single-pixel detectors, aimed at achieving rapid focusing. By utilizing dual single-pixel detectors for complementary modulation differential detection, focusing is achieved by identifying the maximum differential in modulation intensity. Existing single-pixel focusing methods require multiple modulation patterns, and their focusing speed is limited by the DMD frame rate. In contrast, the proposed method employs a single fixed optical modulation pattern, eliminating the need for full-frame image acquisition and complex algorithm computations. It also does not require additional auxiliary hardware, reducing the time needed for data collection and processing, simplifying system complexity, and significantly enhancing the focusing speed and usability of imaging systems. In experiments, the focusing frame rate reached up to 100 kHz, surpassing the limitations of DMD frame rates and synchronizing with the sampling rate, thereby effectively improving system efficiency.