Design and Manufacturing of a Fourier Transform Microspectrometer

Spectrometry has long been used for measuring chemical compositions and purity of materials in industrial, medical and environmental applications by detecting material dependent absorption of wavelength. Traditional spectrometers, however, are table-top instruments, and they are generally too large, and too costly to be ported outside of lab environments. Micro-electro-mechanical-systems (MEMS) technology offers promising possibilities to build compact and cost-effective miniature instruments, including spectrometers. In this paper, we present a fiber-coupled Fourier-transform microspectrometer of a nominal size of 3 cm times 3 cm times 3 cm, constructed using 3D hybrid microassembly. The microspectrometer targets wavelengths in the Visible and NIR spectra. We use modular microscale parts, including minimum energy compliant MEMS fasteners, in order to configure a die-sized microoptical bench. A scanning micromirror is snapped into a MEMS thermal actuator, and we measure interference fringes from a Michelson interferometer. Light coupling, miniature electronics and power are included in the spectrometer package. We discuss the design, robotic assembly, packaging and experimental characterization of this MEMS-based instrument.