Photoacoustic spectroscopy of CO2 gas

• Main Authors: Hui-Jun Wang, 王惠珺
• Other Authors: Jow-Tsong Shy
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/18754785003762583368

碩士 === 國立清華大學 === 光電工程研究所 === 95 === In this thesis, we study the photoacoustic spectroscopy of CO2 molecule using a 1570 nm DFB diode laser. The output of a 6-mW DFB diode laser is sent into a photoacoustic cell which is filled with carbon dioxide. Because of the photoacoustic effect, the variation of absorption generates an acoustic wave. We use a microphone as a transducer to detect the photoacoustic signal. An additional photoacoustic system was used to remove the background noise. The sensitivity of the system is , which is comparable with other experiments. In order to improve the sensitivity of the photoacoustic system, a Fabry-Perot cavity was placed outside the photoacoustic cell to enhance the light intensity. Until now, we are not able to lock the Fabry-Perot cavity on the laser frequency very well due to some technical problems, e.g., the mechanical instability of the cavity. Further improvements are needed to detect the cavity-enhanced photoacoustic signal in the feature.