Date of Award
Master of Science
Department of Engineering Physics
Michael R. Hawks, PhD.
A lab and eld based hyperspectral chromotomographic imager has been developed at the Air Force Institute of Technology. It is a prototype used to study the requirements for a space-based system. The imager uses a high speed visible band camera behind a direct-vision prism to image both spatial dimensions and the spectral dimension at the same time. Capturing all 3 simultaneously allows for the hyperspectral imaging of transient events. The prism multiplexes the spectral and spatial information, so tomographic reconstruction algorithms must be used to separate hyperspectral channels. Experiments were conducted to compare reconstructed image quality as a function of spatial, spectral, and temporal complexity. To test spatial complexity, a simulated point source, a standard bar chart, and an amorphous object were imaged. The more simple objects were reconstructed well. When objects dispersed by the prism overlapped in the raw data, reconstructions diminished. To test spectral complexity, atomic emission lines and white light with different types of optical filters were imaged. Because of the way the prism disperses light, shorter wavelengths were reconstructed better than longer ones. The temporal complexity experiments determined 3/4 of a prism revolution is sufficient (with approximately 60 projections) to reconstruct a scene as long as there were a sufficient number of frames in the recording. As few as 12 frames are sufficient in a complete revolution. Finally, a fireball was imaged in a eld experiment. The chromotomographic imager constructed the spectrum of the fireball with very wide spectral lines. Hindrances to reconstruction, such as a cone of missing hyperspectral information, are discussed. Additionally, a comparison of and improvements to the reconstruction algorithms are suggested.
DTIC Accession Number
Dufaud, Kyle J., "An Experimental Evaluation of Image Quality for Various Scenarios In a Chromotomographic System With a Spinning Prism" (2014). Theses and Dissertations. 645.