Near-Infrared Bragg-Grating Skylight Analyzer

78364S The Department of Energy is seeking innovative optical detector methods and instruments to lower the cost of moderate-resolution oxygen A-band spectrometry, capable of collecting information about the distribution of scatterers and absorbers in the atmosphere. This project will develop a new low- and high-resolution, near-infrared, Bragg-grating sky light analyzer based on a thick holographic dispersing element with optical properties optimized for oxygen A-band sky light spectroscopy. The proposed analyzer will be an innovative, low-cost, 0.7 m long and 0.1 m diameter spectrometer with a resolution of 0.7 wavenumber, light efficiency of 5%, and high wavelength stability, significantly surpassing the performance of present spectrometers at comparable prices. In Phase I a proof-of-concept laboratory breadboard will be designed and built with the capability to measure photon pathlength in the oxygen A-band (around 764 nm) for two lines, with a resolution of 0.04 nm. The key components will be multiplexed high efficiency reflection holograms recorded in photothermorefractive glass. Commercial Applications and Other Benefits as described by the awardee: The new spectrometer should extend the analysis of absorption and scattering spectra from the ultraviolet to the infrared, enabling investigators to analyze not only particle size and distribution but also gas concentration in the atmosphere. The new technology should also advance optical tomography for remote sensing of the atmosphere and near-Earth space, robot vision, and intrusion alarms.