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This Spotlight focuses on the use of MEMS Fourier-transform infrared spectrometers as a core building block in optical gas sensing. Micro-optical bench technology is discussed, followed by the basics of the sensing technique. An overview of the system components and their state of the art is given, including the light source, the miniaturized interferometer and gas cell, the optical connectivity, and detection for both the near-infrared and the mid-infrared spectral ranges. A comparison shows the pros and cons of each regime, accounting for the absorption cross-sections of the gases and the signal-to-noise performance of the system components. The impact of the limitation on the signal-to-noise ratio and spectral resolution due to miniaturization on the gas sensor performance is also discussed. An experimental setup to evaluate the sensor performance and extract its sensitivity is explained, and experimental results of detecting acetylene and carbon dioxide gases are presented. The book concludes with a discussion of the foreseen challenges and potential. |
