微型DMD哈达玛变换近红外光谱仪

Miniature Digital Micro-Mirror Device Hadamard Transform Near-Infrared Spectrometer

提出并设计了一个应用数字微镜(DMD)的哈达玛变换近红外光谱仪。以光栅为分光元件,用DMD代替传统的机械式哈达玛编码模板进行光学调制,用In Ga As单点光电二极管探测调制后的光谱信号。综合考虑分辨率、能量利用率、像差和体积等因素,合理选择狭缝长和宽、光栅入射角及透镜焦距,采用光路分段优化法进行光学设计,通过DMD面阵上的狭缝像和探测器上的点斑尺寸等分析设计结果。模拟分辨率优于4 nm,探测器上点斑尺寸小于3 mm,光学系统尺寸为75 mm×25 mm×85 mm。为提高光谱仪对弱光谱信号的探测能力,在系统前加入了一种集光结构,使从光纤出射的光能的利用率理论值提高24.2%。实验结果表明,该光谱仪的光谱分辨率优于6 nm,通过添加集光结构可以大大提高光谱仪的能量利用效率。该光谱仪具有分辨率高、能量利用率高、体积小、成本低等优点,有广阔的应用前景。

A Hadamard transform near-infrared spectrometer used digital micro-mirror device（DMD） is proposed and designed. A grating is used for light diffraction, a DMD is applied instead of the traditional mechanical Hadamard masks for optical modulation, and an In Ga As single point detector is used as the optical sensor. Suitable length and width of the slit, incident angle of the grating and the focal length of lens are selected by analyzing some key influential factors to the spectrometer′s performance, such as resolution, utilization ratio of light energy, volume of the system and costs. Section optimization method is used during the design of the optical system, and then the images of slit on the DMD, the size of the spot on detector are analyzed. The simulation resolution is less than 4 nm,the spot size on In Ga As single point detector is smaller than 3 mm, and the size of the optical system is 75 mm×25 mm × 85 mm. In order to improve the ability in detecting teeny light signal, a light collecting structure is proposed, which can improve the utilization ratio of light energy by 24.2% theoretically. The experiment results show that the spectral resolution of the system is better than 6 nm, and the light collecting structure can significantly improve the utilization ratio of light energy. It′s obvious that the spectrometer is high-resolution, portable and lowcost, which has broad application prospects.