Fourier transform infrared spectrometer based on an electrothermal MEMS mirror

This paper presents a micro Fourier transform infrared spectrometer (mu FTIR), enabled by an H-shaped electrothermal microelectromechanical systems (MEMS) mirror. A special driving method was developed for obtaining a linear, uniform-speed motion of 186 mu m, and the tilting angle of the MEMS mirror was as small as 0.06 degrees, so there was no need of complex closed-loop control. A telecentric lens was employed in the interferometer of the mu FTIR to reduce the influence of the MEMS mirror tilting effect. Also, a new phase interpolation algorithm, instead of the traditional fringe interval method, was applied in the process of the spectral reconstruction to improve the spectral stability. Finally, the new pFTIR was applied in the composition prediction of soybeans, and the experimental results show that it can accurately measure grain moisture, protein, and fat contents. (C) 2018 Optical Society of America