Design and Development of a Snapshot Imaging Spectropolarimeter
Abstract
A snapshot imaging spectropolarimeter is under development. The instrument operates through the synthesis of the techniques of computed tomography imaging spectrometry (CTIS) and channeled spectropolarimetry. CTIS is a technique of imaging spectrometry in which an image of a scene is captured through a computer-generated holographic disperser. Spatially resolved spectra are reconstructed from the diffracted orders in post-processing. Channeled spectropolarimetry is a method of encoding the four components of a spectrally varying Stokes vector into a single Irradiance spectrum. The combination of the two techniques provides the basis of an imaging spectropolarimeter capable of acquiring a complete data set in a single focal plane array integration time with no moving parts. Our description of the instrument includes a review of the basic principles of both techniques. The diffraction orders generated by the CTIS disperser amount to projections through the scene's object cube, which provide an analogy to the medical imaging technique of computed tomography. Channeled spectropolarimetry is analogous to sideband modulation (as may be used in radio communication). Thick (high order) retarders and a polarizer are employed to introduce modulation. This viewpoint provides a starting point for the formulation of system requirements and reconstruction techniques. The requisite spectral resolution of the embedded spectrometer and selection of carrier frequencies by design of the retarders are addressed. We also discuss the design of a prototype snapshot imager for the visible spectrum and describe a non-imaging spectropolarimeter for the development of calibration and data reduction techniques.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 2002
- Accession Number
- ADP023075
Entities
People
- Ann M. Locke
- Christopher P. Tebow
- David Sass
- Derek S. Sabatke
- Eustace L. Dereniak
- John P. Garcia
Organizations
- University of Arizona