Micro-electromechanical technologies for next-generation spectroscopic systems

[Truncated abstract] Next-generation spectroscopic systems combine the spatial imaging capabilities of traditional camera systems with tuneable narrowband optical filtering to capture images that contain both spectral and spatial information; a hyperspectral image. Each pixel encompasses a spectrum of light from a different spatial location within a scene, allowing the application of spectroscopic techniques to identify and classify objects that are indistinguishable using spatial and intensity information alone. While such systems exist today, they are based on bulk optics, and their size and cost precludes their use in many desirable applications. Micro-electromechanical systems (MEMS) technology provides a path to the realisation of compact and potentially low cost instrumentation capable of use in applications beyond the reach of current systems. MEMS technology uses techniques developed for the semiconductor industry to produce and operate devices that incorporate mechanical and electrical aspects for sensing and actuation on a scale of microns to millimetres. Optical MEMS are a class of MEMS that uses these mechanical and electrical aspects in the manipulation of light. A pertinent example is a MEMS-based tuneable Fabry-Perot filter, which employs optical resonance to enable the transmission of a controllable narrow band of wavelengths from a broadband incident spectrum. Micro-electromechanical actuators are employed in this device to alter the length of the optical cavity in the Fabry-Perot filter and hence change the pass wavelength of the narrow wavelength band. Conceptually, an array of these pixel-scale filters placed before an array of infrared detectors would be the key element in a compact next-generation spectroscopic imaging system...