Hyperspectral focal plane scanning - an innovative approach to airborne and laboratory pushbroom hyperspectral imaging

摘要

Airborne pushbroom scanning provides an effective method to hyperspectral imaging with a low cost image sensor such as a digital CCD camera. The requirement of a mobile platform, however, has prevented a pushbroom-based hyperspectral imaging system from being used for spectral signature measurement in ground truth or laboratory research. An airborne pushbroom hyperspectral imaging sensor may be genetically different from a laboratory radiometer in terms of central wavelengths, bandpass windows, and signal to noise ratio, etc. These differences have imposed a technology gap between airborne hyperspectral image acquisition and data analysis based on spectral signatures obtained from either ground truth investigation or laboratory research using radiometer. A pushbroom hyperspectral imaging system capable of both airborne and laboratory data acquisition is therefore required to eliminate this gap. This paper presents an innovative approach to pushbroom hyperspectral imaging. The concept will be demonstrated with a prototype system that utilizes a hyperspectral focal plane scanner (HFPS) (patent pending). An HFPS scans an input image within the focal plane of a front lens, disperses an input image line vertically as a function of the spectral wavelengths, and then focuses an output 2D spectral matrix onto the surface of an area sensor. The use of HFPS completely eliminates the requirement of a mobile platform in a pushbroom scanning and therefore allows the system to be used for both airborne and laboratory hyperspectral imaging. In addition, an HFPS can also compensate the forward motion of an airborne platform to increase the effective along-track spatial resolution during pushbroom scanning.