Holographic A-band Multi-Channel Substrate Guided Wave-Based System

The Department of Energy is seeking the development of a cost-effective and improved environmentally stable fieldable oxygen A-band spectrum atmospheric measurement technology that can be more widely deployed. This technology will collect the data necessary to develop an accurate radiation transfer model for the Earth atmosphere, one of the most important issues in the analysis and prediction of terrestrial climate. Current technology cannot meet the parameters for the required spectral resolution combined with a high out-of-band rejection ratio in a simple, robust, and cost-effective oxygen A-band spectrometer. Instrument stability is also of concern because this technology must operate reliably and autonomously under all weather conditions. In response, we propose to develop a new imaging holographic A-band multi-channel substrate-guided spectrometer with the required spectral resolution and a high out-of-band rejection ratio. The proposed approach applies two reflection substrate-guided wave-based holograms as dispersing elements laminated to a substrate. The solid integration of two high-resolution gratings enables high stability and image quality of the output spectrometer slit for entire resolved A-band spectrum. And, it will be faster and cost efficient. A proof-of-concept benchtop prototype will be developed and built in Phase I. It will be calibrated and tested in a laboratory environment with standard light sources, and outside the lab for cloudy sky A-band spectrum measurement. Commercial Applications and Other Benefit: The proposed technology will enable a low-cost, compact, stable, and mass-producible spectral measurement device. The proposed spectrometer will reduce the overall cost of spectrometers compared to current spectrometers that use diamond ruled or common surface relief holographic gratings. This development will not only meet the DOE need an for A-band measurement instrument, but will enhance atmospheric measurement for analyzing absorption and scattering spectra from the ultraviolet to the infrared, enabling investigators to analyze not only path-length distribution of solar photons in clouds, but also gas concentration in the atmosphere. This technology also has significant commercial application in the optical industry, optical tomography, robot vision and material science, remote sensing of the atmosphere and near-Earth space