A Fourier Transform Spectrometer Based on an Electrothermal MEMS Mirror with Improved Linear Scan Range

Area of Science:

• Optical Engineering
• Microelectromechanical Systems (MEMS)

Background:

• Fourier transform spectrometers (FTS) require precise mirror control for high spectral resolution.
• Microelectromechanical systems (MEMS) offer miniaturization potential for FTS but face challenges in scan range and tilt stability.

Purpose of the Study:

• To develop and experimentally verify a MEMS micromirror for FTS with enhanced scan range and tilt stability.
• To improve the performance of MEMS-based FTS through closed-loop control and advanced actuator design.

Main Methods:

• Utilized a modified lateral-shift-free (LSF) bimorph actuator for MEMS mirror design.
• Implemented a closed-loop control system with a position-sensitive device (PSD) for precise tilt angle sensing and feedback.
• Integrated the MEMS mirror into a Fourier transform spectrometer setup.

Main Results:

• Achieved a stable linear piston scan of 430 µm with minimal mirror plate tilting (< ±0.002°).
• Increased the usable piston scan range to 78% of the MEMS mirror's full capability.
• Attained a spectral resolution of 0.55 nm at 531.9 nm wavelength.

Conclusions:

• The proposed closed-loop controlled MEMS micromirror significantly enhances FTS performance.
• This MEMS-based FTS design represents a substantial improvement over previous technologies.
• The technology holds promise for compact and high-resolution spectroscopic applications.