针对传统气体传感器普遍存在的价格昂贵、精度低、放置不方便等缺点，构建了一套对射式激光湿度分析系统。该系统采用半导体激光器作为光源，在测量机柜两边分别架设光发送单元和光接收单元，通过将激光穿过中间的测量部分即可测得该部分的湿度数值。实验结果表明，这种对射式传感系统标定的决定系数R2为0.9976; 3 m光程下的湿度含量与理论值的复测误差分别为0.82%、0.46%、0.44%、0.42%; 待仪器稳定后的40 min测试中，实测放置柜内湿度含量的范围波动最大为30，样本总体标准差值为7.88，平均相对误差为0.4%。

To overcome the shortcomings of high cost, low precision and inconvenient placement of traditional gas sensors, a set of opposite laser humidity sensing system is constructed. The system uses a semiconductor laser as a light source. A light transmitting unit and a light receiving unit are respectively arranged on both sides of a measuring cabinet. When a laser beam passes through the measuring portion in the middle of the measuring cabinet, the humidity value of the portion can be measured. The experimental results show that the calibration coefficient R2 of the opposite sensing system is 0.9976. The retesting errors of the humidity content and the theoretical calculation value in the three-meter optical path are 0.82%, 0.46%, 0.44%, and 0.42% respectively. Within the 40-minute test after the instrument stabilizes, the humidity content range in the actual test cabinet is fluctuated to a maximum of 30. The standard deviation is 7.88 and the relative error is 0.4%.