An out-of-plane FR4-MEMS Scanning Grating for NIR Spectrometer Applications

In this paper, we present a novel portable IR spectrometer featuring a scanning diffraction grating for simultaneous out-of-plane rotational oscillations and spectral dispersion. The scanning grating design is based on a 12×12 mm resonant scanner fabricated from an FR4 printed circuit board and operated via MEMS electromagnetic actuation. The harmonic response and damping characteristics of the relatively large aperture scanner prototype is investigated through measurements and numerical simulations. Compared to the state-of-the-art, the FR4-MEMS scanning grating achieves exceptional scanning efficiency (0.13 °/mA) and a low operating frequency (190 Hz). A compact volume spectrometer design (99×84×59 mm
³
) is made possible by the integration of the scanning grating, photodetector and drive and readout electronics on a single PCB. Measurements demonstrate that a spectral range of 1230-2190 nm and a spectral resolution of around 10 nm is achieved with the NIR spectrometer prototype.