Miniature Fourier transform spectrometer with a dual closed-loop controlled electrothermal micromirror

Area of Science:

• Microelectromechanical Systems (MEMS)
• Spectroscopy
• Optical Engineering

Background:

• Miniature Fourier transform spectrometers require precise mirror control for high spectral resolution.
• Existing micromirror designs face limitations in scan range and stability.
• Electrothermal actuators offer potential for compact and efficient motion control.

Purpose of the Study:

• To demonstrate a piston-displacement electrothermal micromirror with closed-loop control for enhanced spectrometer performance.
• To achieve an ultra-large linear scan range with constant velocity.
• To improve spectral resolution and robustness in compact Fourier transform spectrometers.

Main Methods:

• Development of an electrothermal micromirror with integrated piston and tilt control.
• Implementation of a closed-loop control scheme for precise piston actuation.
• Experimental characterization of the scan range, velocity, and spectral resolution.

Main Results:

• Achieved a usable linear scan range of up to 505 μm.
• Demonstrated constant scan velocity using the closed-loop piston control.
• Measured a spectral resolution of 20 cm⁻¹ (0.57 nm at 532 nm) in a compact spectrometer.

Conclusions:

• The closed-loop electrothermal micromirror significantly enhances performance for miniature Fourier transform spectrometers.
• The system offers improved spectral response, higher resolution, and increased robustness to disturbances.
• This technology paves the way for more advanced and compact spectroscopic instruments.