Real Time NOx Measurement Using Spectroscopic Holography for Advanced Combusion Applications

This proposal details the necessary steps to adapt the newly developed technique of Resonant -- Holographic Interferometric Spectroscopy (RHIS), a powerful spectroscopic technique, to measure NOx in real time at facilities such as the combustion test rigs at NASA Lewis. RHIS combines the three-dimensional capabilities of holography, the phase sensitivity of interferometry, and the species selectivity of spectroscopy. State-of-the-art RHIS instrumentation under development at MetroLaser is based on probing with UV and visible lasers. The innovations in this proposal are to extend the wavelength range of RHIS into the near IR, to provide real-time data and to adapt the technique to measure NOx; an important by-product of combustion linked to ozone depletion. Extension of RHIS into the IR greatly increases its versatility because the use of laser diodes dramatically reduces its complexity, size, and expense. The main challenge for RHIS in the IR is the lack of suitable holographic material. To meet this challenge, significant effort will be devoted during Phase I to examine nascent photorefractive materials for IR sensitive RHIS. In addition to IR sensitivity, photorefractives require no development processing, can be read in real-time, and are reusable.