Portable snapshot infrared imaging spectrometer

摘要

A practical, field-capable, 3.0 to 5.0 μm mid-wave infrared Computed-Tomography Imaging Spectrometer (CTIS) has been demonstrated. The CTIS employs a simple optical system in order to measure the object cube without any scanning . The data is not measured directly, but in a manner which requires complicated post-processing to extract an estimate of the object's spectral radiance. The advantage of a snapshot imaging spectrometer is that it can collect information about a dynamic event which a standard scanning spectrometer could either miss or corrupt with temporal artifacts. Results were presented for reconstructions of laboratory targets with sampling up to 46 x 46 x 21 voxels over a variable field-of-view, or 0.1 μm spectral sampling. Demonstration of the snapshot capability has been performed on both static targets and targets with rapidly varying content. The contents of this dissertation are directed towards two ends. The primary undertaking is a realization of the theoretical model of the CTIS is a practical, field-capable MWIR instrument. The design, calibration, and operation of the MWIR CTIS are explained in detail in the text and appendices. Of additional interest is the advancement of the theory to improve the design and functionality of the spectrometer. A new algorithm for design of the holographic disperser component of the CTIS is introduced. The design process dramatically extends the set of possibilities for the disperser. In order to improve the reconstruction potential of the spectrometer, the analytic expressions which describe the CTIS have been expanded into a principal component basis set. The result is a technique for creating an initial estimate of the object and a technique for improving the reconstruction algorithm.