中文摘要：

搭建了一套基于光腔衰荡光谱技术的光学湿度计．通过测量水分子在1．35和1．56μm波段不同强度的吸收线，可测定水汽的相对含量，测量范围从10—0到低至10—12水平．通过与商用冷镜式露点仪的对比测量，对该装置的定量精度进行了检验．该系统所具备的高灵敏度使得水汽探测极限可达8pptv．

英文摘要：

Moisture measurement is of great needs in semiconductor industry, combustion diagnosis, meteorology, and atmospheric studies. We present an optical hygrometer based on cavity ring-down spectroscopy （CRDS）. By using different absorption lines of H20 in the 1.56 and 1.36 gm regions, we are able to determine the relative concentration （mole fraction） of water vapor from a few percent down to the 10-12 level. The quantitative accuracy is examined by comparing the CRDS hygrometer with a commercial chilled-mirror dew-point meter. The high sensitivity of the CRDS instrument allows a water detection limit of 8 pptv.