基于MEMS微镜的长波近红外光谱仪的设计与实现

为适应光谱仪微型化、集成化的发展趋势，详细分析了MEMS微镜应用于微型长波近红外光谱仪的方法和涉及的主要问题，例如分光系统的设计、MEMS微镜的选择、探测器与前置放大电路的设计等。并将50 Hz谐振频率、峰峰驱动电压为10V的MEMS微镜、高灵敏度的InGaAs单元探测器，结合立特罗式分光光路，设计和实现了900～2 055 nm波段的微型长波近红外光谱仪样机，其中1 000～1 965 nm谱段的光谱分辨率介于9.4～16 nm之间。采用MEMS扫描微镜技术后，一方面简化了光谱仪中的复杂机械结构，使尺寸可以更小;另一方面实现了单探测器的长波近红外光谱仪，与阵列长波近红外探测器光谱仪相比，成本有所降低。作为应用实例，此样机成功对纯水以及乙醇-水溶液的长波近红外光谱进行了测量，实现了乙醇-水溶液的浓度预测分析，其中本样机测量的纯水长波近红外光谱与文献相符。

Design and Implementation of a Long Wavelength Near InfraRed Spectrometer Based on MEMS Scanning Mirror

Long Wavelength Near InfraRed(LW-NIR) spectrometer has wide applications. Miniaturization and low-cost are two major goals of the development of LW-NIR spectrometer in the industrial or research community. Under the background that having a trend of spectrometer miniaturization and integration, method and main problems involved in miniaturization of LW-NIR spectrometer through MEMS scanning mirror, such as the design strategy of the light-splitting optical system, selection considerations of the MEMS scanning mirror, design method of the preamplifier circuit, etc, have been presented in detail. A prototype of miniaturized LW-NIR spectrometer, with the spectrum range of detection of 900～2 055 nm, is designed and implemented using MEMS scanning mirror, InGaAs single detector unit with high sensitivity. Littrow optical layout is used for its light-splitting optical system, and the spectral resolution is between 9.4～16 nm at 1 000～1 965 nm detection wavelength range. The prototype is successfully applied in LW-NIR spectrum measurement on pure water and ethanol aqueous solution, and a forecast analysis on ethanol aqueous solution concentration is also demonstrated. Through adopting MEMS scanning mirror into the spectrometer system, the complexity of the mechanical scanning fixtures and its controlling mechanism is greatly reduced therefore the size of the spectrometer is reduced. Furthermore, due to MEMS scanning mirror technology, LW-NIR spectrometer with single InGaAs detector is achieved, thus the cost reduction of the NIR spectrometer system is also realized because the expensive InGaAs arrays are avoided.