Design and demonstration of micro multi-step mirrors and light source in micro FTIR

To obtain high resolution, high signal-to-noise ratio (SNR), high reliability and real time in wide spectral range, we study the space modulation Micro Fourier Transform Spectrometer (μFTS) based on multi-step mirrors covering the spectral range of 3-5μm and 8-12 μm in theory and experiment. The influences of spectrum reconstruction caused by the diffraction and extended light source in Fourier Transform Infrared Spectrometer (FTIR) are analyzed. A method to reduce the noises in spectrum reconstruction and the relationship between coherent intensity and solid angle of light source are discussed. An extended light source with suitable size is chosen, considering the requirement of SNR and spectrum resolving power in the optical design. Furthermore, the fabrication of micro multi-step mirrors, which is the core part of μFTS, is investigated. Three methods for fabricating multi-step micro mirrors are demonstrated.