A MEMS-based resonant-scanning lamellar grating Fourier transform micro-spectrometer with laser reference system

A lamellar grating Fourier transform infra-red (FTIR) micro-spectrometer is presented in which the device is electromagnetically actuated in resonant mode so as to achieve larger displacements with a lower driving voltage. By actuating at resonance, we can also have a design with a higher spring stiffness design such that the micro-spectrometer will have little influence from external perturbation. A data acquisition electronic system is designed such that the interferogram of the IR source can still be acquired at a fixed optical path distance (OPD) intervals. This is achieved by using a reference laser source. Working at a resonant frequency of 330 Hz, a 100 μm (bi-directional) displacement is achieved by the device with an input voltage of 2.2 V. A tunable laser source is used to demonstrate the system performance. The peak of the recorded spectra is very close to the actual wavelength of the IR, with a maximum difference of less than 5 nm.