A MEMS Based Fourier Transform Spectrometer and Its Scan Stability Study

Abstract

An Fourier Transform Spectrometer (FTS) based on an H-shaped electrothermally actuated microelectromechanical system (MEMS) scanning mirror has been developed. The MEMS scanning mirror can generate about 200 μm at 5 Hz with only 5 Vpp and maintain a very small tilting of about 0.029 • without using any complex compensation or closed-loop control. This high scanning performance is achieved by using a unique H-shaped frame supported by symmetrically distributed thirty-two pairs of innovative three-level-ladder bimorph actuators. This MEMS FTS can cover a wide spectral range of 1000-2500 nm. A spectral resolution of 64.1 cm −1 , or 11 nm at 1310 nm, is achieved.

A Customized Two Photon Fluorescence Imaging Probe Based on 2D scanning MEMS Mirror Including Electrothermal Two-Level-Ladder Dual S-Shaped Actuators

“…Stacking more levels in the actuators architecture has been explored to achieve large piston displacements and to increase the frequency stability and its flat range before resonance [ 26 , 27 ].…”

“…J. Chai et al [ 27 ] reported a MEMS mirror with three levels of dual S-shaped bimorph actuators dedicated to develop a Fourier transform spectrometer and obtained a more stable scanning with large displacement, but the response time of this shape of actuators was significantly high (28 ms) and needed a high driving voltage (up to 10 V) to achieve a large scanning range [ 27 ].…”

Review of MEMS Based Fourier Transform Spectrometers

“…When the temperature changes, thermal stress is generated, due to the difference of the CTEs of the two bimorph layers. The beam curls toward the layer with a lower CTE value when the temperature rises; then, a transverse beam bending is generated [9]. The electrothermal MEMS micromirrors designed for FTS can also produce in-plane and out-of-plane motions, which are described below.…”

“…A spectral resolution of 64.1 cm −1 was achieved for this MEMS FTS (see Figure 33b). Chai et al presented a portable FTS using an H-shaped electrothermal MEMS mirror [9]. The mirror plate was connected to a unique H-shaped frame supported by symmetrically distributed thirty-two pairs of innovative three-level-ladder FDSB actuators (see Figure 33a).…”

Wafer-Level Vacuum-Packaged Translatory MEMS Actuator with Large Stroke for NIR-FT Spectrometers

“…Various MEMS concepts for optical path-length scanning have been reported, typically targeting an out-of-plane translation with large stroke required for the classical dual-beam Michelson interferometer FTS set-up, consisting of fixed and moving mirrors (here realized by an MOEMS) and an optical beam splitter. For large-stroke out-of-plane translation of the MEMS mirror, different actuation principles have been investigated so far: electrostatic [ 5 , 6 , 7 , 8 ], piezoelectric [ 9 , 10 , 11 ], magnetic [ 12 , 13 , 14 , 15 ], and electrothermal [ 16 , 17 , 18 , 19 , 20 , 21 , 22 ], typically using resonant operation for larger strokes, e.g., [ 7 , 8 , 11 ], but also using quasi-static actuation, e.g., [ 10 , 17 ]. Most of these different MOEMS actuation mechanisms suffer from limitations in spectral resolution due to parasitic effects of MEMS-based path-length modulation: first of all, mirror tilt [ 11 , 17 , 19 ], deformation of the mirror due to dynamically (owing to inertia) or statically (due to mirror suspension or optical coating) induced mechanical stress.…”