介绍了一种基于施密特-卡塞格林望远镜的光纤收发一体长光程差分光学吸收光谱(LP-DOAS)系统, 并应用于实际大气HONO和NO2的测量。 该测量系统采用光纤收发一体设计, 相比于目前广泛使用的卡塞格林式差分光学吸收光谱系统更能充分利用望远镜主镜有效面积, 具有较高的光学效率。 分析了暗电流, 偏置以及望远镜内部反射光对系统的影响, 在晴好天气下, 望远镜内部反散光所占大气谱光强比例小于1%。 且通过与传统卡塞格林式差分光学吸收光谱系统进行了实际大气NO2的测量对比, 相关系数r达到0.968, 验证了新系统测量的准确性。 利用该测量系统在河北固城开展了对大气HONO和NO2高灵敏度、 高时间分辨率的外场观测, 在光程为2 490 m下系统对HONO和NO2探测限(2σ)分别为84.2和144.6 ppt。 测量期间的平均时间分辨率约为30 s, HONO和NO2浓度最大值分别为3.2和37.8 ppb, 最小值均低于探测限, 并根据观测期间的数据结果计算夜间HONO/NO2平均值为0.12。

A new type of fiber coupling Long-Path Differential Optical Absorption Spectroscopy System(LP-DOAS) based on schmidt - cassegrain telescope was introduced in detail in this paper and it was applied to the accurate measurement of the actual atmospheric HONO and NO2. This measuring system simplified the structure of traditional LP-DOAS system, combining with the design of optical fiber coupling.It made full use of the telescope primary mirror’s effective area. The effects of the offset, dark current and telescope stray light to the new LP-DOAS system were discussed in this paper; On a clear day, the ratio between telescope stray light and the optical intensities was less than 1%. To verify the accurate of the new LP-DOAS system, the atmospheric NO2 were simultaneously measured with the new LP-DOAS system and traditional LP-DOAS system. The correlation coefficient R2 was up to 0.968. The observation of atmospheric HONO was carried out by using the fiber coupling LP-DOAS in Gucheng, Hebei Province, China, and the detection limit (2σ) of HONO and NO2 was 84.2 and 144.6 ppt , respectively, with 2 490 m path length and the average time resolution of about 30 s. In the whole measurement in Gucheng, the maximum of HONO and NO2 were 3.2 and 37.8 ppb, respectively, and the minimum were both under the detection limits; the ratio of HONO/NO2 at night was calculated.