This paper introduces a lock-in-free mid-infrared photothermal dynamic imaging (PDI) system that achieves nanosecond-resolution imaging by using MHz digitization and match filtering. The system significantly increases imaging speed (two orders of magnitude) and improves signal-to-noise ratio (four-fold) compared to traditional lock-in amplifier methods. This allows for high-throughput metabolic analysis at the single-cell level and effective separation of water background in mid-infrared PDI of living cells. The method provides a valuable tool to characterize biological and material specimens by probing chemically specific photothermal dynamics.

Jiaze Yin, Lu Lan, Yi Zhang, Hongli Ni, Yuying Tan, Meng Zhang, Yeran Bai, Ji-Xin Cheng