Study Of Miniature Fourier Spectrometer Signal Demodulation Based On MOEMS

In recent years, frequent food safety crisis desiderates a kind of fast detected andreliable on-line detecting instrument, which is a certain miniature portable, low cost.As a member of spectra detection, Fourier Transform spectroscopy (FTS) has a large ofadvantages such as Fellgett, Jacquinot, Connes, etc, has developed rapidly which isable to obtain the full band spectrum and owns unique dominated advantages in weakspectrum detection in infrared band, and it has a broad application prospect in foodsafety detection. The tendency of the science instrument is miniature portable, fastdetection, also needs cost control. Recent years, the development of MOEMS(Micro-opto-electro-mechanical Systems) technology provides the technical supportfor instrument minination in FTS to be reality, such as Fourier Transform spectroscopybased on MOEMS.In this thesis, a novel Fourier Transform spectroscopy is proposed based onprogrammable MOEMS element replacing the scanning mirror with stepped casemirror or tilting mirror (without complicated scanning mirror control system), withwhich a stable interference pattern with successive optical path differences is formed,and collecting interference intensity by a single-point detector combined with theprogrammable MOEMS element, this spectroeter is neither spatial modulated nor timemodulated spectrometer, just a combination of the both.Firstly, the theoretical principles are investigated with corresponded numericalsimulations carried out, an interference model based on this spectrometer isconstructed, the feasibility and mechanism study on this FTS with stepped case mirroror tilting mirror is theoretically analyzed，and the system employed a manufacturedtilting mirror ultimately instead of a stepped mirror taking manufactured difficulty intoaccount. Theory results show that the limited tilt angle is0.52°and the spectrumresolution is8nm in the near infrared region, while the limited tilt angle is0.183°, thespectrum resolution is3nm in the visible region. Finally, the main elements andperformance of the system are briefly analyzed.System experimental design parts include hardware and software designaccording to the operation principle. In details, it contains the design of photoelectricdetecting and amplified circuit, data acquisition circuit, the digital drive MEMS mirror control circuit based on FPGA, Finally the joint experimental system for debugging isset up. By processing the interference signal, the spectrum of the optical can beextracted.