A Mid-Infrared Quantum Cascade Laser Ultra-Sensitive Trace Formaldehyde Detection System Based on Improved Dual-Incidence Multipass Gas Cell. - Tao Wu; Renzhi Hu; Pinhua Xie; Lijie Zhang; Changjin Hu; Xiaoyan Liu; Jiawei Wang; Liujun Zhong; Jinzhao Tong; Wenqing Liu (Sensors, 2023)