High-resolution miniature Fourier transform spectrometer based on dual scanning electrothermal MEMS mirrors.

MEMS mirror-based Fourier transform spectrometers (FTS) are powerful in various portable or embedded applications. However, the small scanning range of MEMS mirrors seriously limits MEMS-FTS' spectral resolution. In this work, a dual-MEMS-mirror FTS (DMM-FTS) is proposed that immediately doubles the scanning range and thus improves the spectral resolution by a factor of two. The employed MEMS mirrors are uniquely designed electrothermal MEMS mirrors that can generate a maximum vertical displacement as large as 260 µm. Experimental results demonstrate that this DMM-FTS achieves a stable optical path difference up to 783 µm at a record level. Meanwhile, the maximum dynamic tilt of both MEMS micromirrors is controlled within ±0.004°. Consequently, the developed DMM-FTS achieves a remarkable spectral resolution of 0.5 nm at a wavelength of 532 nm, or 18 cm-1. The mechanical architecture and control strategy of this DMM-FTS are compatible with both near-infrared and mid-infrared systems. This design delivers prominent improvements in spectral analysis performance and holds great potential for various on-site or in-line real-time monitoring applications.