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Study on Broad-band Heterodyne Absorption Spectroscopy Using an Infrared Optical Parametric Oscillator as a Light Source

以红外光参量振荡器为光源的宽带外差吸收光谱研究

基本信息

批准号：
06650065
负责人：
SUGIMOTO Nobuo
金额：
$ 1.47万
依托单位：
National Institute for Environmental Studies
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

Heterodyne absorption method using spectral spread of short-pulse laser was studied for applications of infrared parametric oscillator to long-path absorption measurement of atmospheric trace species. In this method, heterodyne beat signals of laser pulse transmitted through a sample are recorded with a high-speed transient digitizer. The spectra of the sample within the spectral width of the laser are analyzed by Fourier transformation. In FY1994, experiments using the pulses generated from a single-mode He-Ne laser by an electro-optic modulator were conducted, and the principle of the measurement method was demonstrated. In FY1995, a single-mode optical parametric oscillator punped by a injection-seeded second harmonic Nd : YAG laser was used as a pulsed light source. Though the experiment was originally planned in the 3-micron region, it was carried out at 850 nm because of difficulties in the local oscillator and high-speed detector at 3 mocrons. A external-cavity semiconductor laser was used as a local oscillator at 850 nm. The spectra of the output of the optical parametric oscillator were measured with the method, and errors in the measurement were studied. A theoretical study was also conducted on applications of the method to atmospheric long-path absorption measurements. It was shown that the method is useful, for example, for airborne long-path absorption lidar for measuring trace species such as methane and carbon monoxide.

研究了利用短脉冲激光谱展度的外差吸收法，将红外参量振荡器应用于大气痕量物质的长光程吸收测量。在该方法中，通过样品传输的激光脉冲的外差差拍信号被高速瞬态数字化仪记录。通过傅里叶变换分析激光光谱宽度内样品的光谱。 1994年度，利用电光调制器从单模He-Ne激光器产生的脉冲进行了实验，并论证了测量方法的原理。 1995财年，采用注入种子二次谐波Nd:YAG激光器的单模光参量振荡器作为脉冲光源。尽管该实验最初计划在3微米区域进行，但由于3微米区域的本地振荡器和高速探测器存在困难，最终在850纳米处进行。使用外腔半导体激光器作为 850 nm 的本地振荡器。利用该方法测量了光参量振荡器的输出光谱，并研究了测量误差。还对该方法在大气长程吸收测量中的应用进行了理论研究。事实证明，该方法对于用于测量甲烷和一氧化碳等痕量物质的机载长路径吸收激光雷达等很有用。