基于光声光谱技术的密封舱内多组分痕量气体浓度检测系统研究

This project explores an on-line detection system based on self-calibrated Photoacoustic Spectroscopy technique used to measure the multi-component trace gas concnetration. Mircomachined photoacoustic cell and cantilever microphone are fabricated and designed. When a narrowband light beam is introduced into the photoacoustic cell ,if gas molecules is excited by the light, The non-radiative decay of excited molecules generates heat variations, which leads to pressure variations. Researches should be done on the fabrication of miromachined resonant photoacoustic cell to make sure the resonant frequency is the same with modulation frequency. The self-calibration gas cencentration technique based on differential optical absorption also should be studied to avoid the surrounding disturbance on the . Researches is focused on supercontinumm light source,photonics crystal fiber and F-P filter is utilized to achieve th high power, wavelength tunable and flattening fiber laser. Based on harmonic detection technology phaselocked detection circuit is utilized to realize the carbon monoxide CO and ammonia NH3 trace gas measurement system in manned spacecarft carbin with small size and low power consumption. The lowest detetion limit is 100 ppb(part per billion by volume).

：本项目探索一种基于自校准光声光谱技术的痕量多组分气体浓度在线检测系统。当窄带光入射进光声池式，如果光波长与气体分子特征波长一致，麦克风探测到受激的气体分子引起的声压信号涨落，实现对气体浓度的测量。本项目通过研究微型光声池设计与加工技术，使光声池的谐振频率与激光调制频率一致。并且采用差分光路避免外界环境对测量的干扰，实现对气体浓度的自校准与标定。本项目重点研究宽带可调谐激光光源技术，探索使用基于F-P滤波器的超连续光子晶体光纤激光器作为光源，实现高功率、宽带可调谐范围的激光波长输出。采用谐波检测技术设计锁相检测电路，实现小型化、高可靠的载人航天舱内一氧化碳CO和氨气NH3浓度的同时在线测量，系统最低测量极限为100ppb。

本项目的预期目标是要研制满足空间站环境气体检测需求（高灵敏度、小型化、快速响应、长期免标定）的样机，实现对氨气和二氧化碳气体的高灵敏检测，通过参考气室实现波长锁定，提高系统长期稳定性。氨气和二氧化碳是空间舱室内的有害气体组分，也是呼出气体的主要组分，微量气体组分检测技术对于空间站火灾预警以及航天员健康诊断具有重要意义。光声光谱技术是一种最有潜力解决该问题的检测技术。根据研究目标和计划，本项目重点研究光声光谱检测技术的内容如下：.㈠创新性地采用头部拉锥的金属化光纤作为光声共振耦合器件，基于倏逝波原理实现光声信号共振增强，解决吸收探测单元的小型化问题；.㈡研制基于光子晶体光纤轻小型参考气室用于在线自标定，探索光子晶体光纤中填充气体的工艺，控制气体填充压强、分析光子晶体光纤干涉模式问题，获得精确的气体填充光谱；.㈢采用掺铥光纤放大器增强光声信号，用于提高检测灵敏度；.㈣采用单个DFB激光器实现对氨气和二氧化碳2种气体的同时检测，研制小型化光声光谱气体传感器样机。.三年来，我们不仅按照设想完成了项目任务，还将产生的理论和实验成果扩展和深化，在气体传感领域做出了丰富成果，共发表文章9篇，其中SCI4篇，EI2篇，中文核心2篇，国际会议文章1篇，申请国家发明专利3项。