Advanced Miniature IR Spectral Processor for the Infrared Spectral Monitoring of Spacecraft Vital Life-Support Systems and Remote Astronaut Health Diagnostics 2006-01-2178

Infrared (IR) spectroscopy probes the characteristic vibrational and rotational modes of chemical bonds in molecules to provide direct information about both the chemical composition and the bonding configuration of a sample. The significant advantage of the IR spectral technique is that it can be used with minimal consumables to simultaneously detect a large variety of different chemical and biochemical species with high chemical specificity. Currently, various VIS/NIR grating spectrometers are employed to cover the spectral range between 0.3 and about 2.2 (μm. Bulk-optic Fourier Transform (FT)-IR spectrometers employing variations of the Michelson interferometer are generally used to provide spectral measurements above 2.5 (μm. The FT-IR systems tend to be mechanically complex, bulky (>15 kg), and require considerable processing, maintenance and recalibration.

For space-based systems, the important drivers are reliability, power consumption, mass and simplicity of operation. MPBT has advanced its patent-pending IOSPEC^™ technology for miniature integrated IR spectrometers to provide high performance comparable to large laboratory spectrometers but in a very compact and ruggedized footprint weighing under 2.0 kg. It also bridges the gap between current VIS/NIR and FT-IR spectrometers by providing continuous coverage in the important 1 to 5 (μm spectral range at a relatively high nominal resolution of about 4 to 8 nm. The throughput limitation of single-slit diffractive spectrometers are overcome by replacing the traditional input slit with a programmable array of 16 slits to multiplex the input optical signal.

This paper discusses recent advances in the binary-coded IOSPEC technology towards providing an integrated chemical analysis system for manned space systems and planetary rovers. An active shutter array is being developed based on a thin-film structure that enables broad-band optical switching and multiplexing at ms speeds with no moving parts for reliable long-term operation. Voltage-controlled optical switching has been obtained at 30 to 40 V. The efficiency of optical coupling to linear detector arrays is also being substantially improved using an integrated-optic condenser at the output of the guided-wave spectrometer to minimize the required height of the detector pixels relative to the height of the system input aperture. A novel, low-power MIR light source is also being developed to facilitate the spectral analysis of solid and liquid samples.

A monolithically-integrated suite of miniature instruments is currently being developed for the Canadian Space Agency based on the IOSPEC^™ technologies to enable laboratory-quality remote chemical and biochemical analysis for future planetary explorers, as well as the analysis of liquids and solids for potential biohazards.