Proceedings Article | 15 May 2012
KEYWORDS: Cameras, Imaging systems, Sensors, Spatial resolution, Spectroscopy, Fiber optics, Hyperspectral imaging, Temporal resolution, Image resolution, Spectral resolution
The development and demonstration of a new snapshot hyperspectral sensor is described. The system is a significant
extension of the four dimensional imaging spectrometer (4DIS) concept, which resolves all four dimensions of
hyperspectral imaging data (2D spatial, spectral, and temporal) in real-time. The new sensor, dubbed "4×4DIS" uses a
single fiber optic reformatter that feeds into four separate, miniature visible to near-infrared (VNIR) imaging
spectrometers, providing significantly better spatial resolution than previous systems. Full data cubes are captured in
each frame period without scanning, i.e., "HyperVideo". The current system operates up to 30 Hz (i.e., 30 cubes/s), has
300 spectral bands from 400 to 1100 nm (~2.4 nm resolution), and a spatial resolution of 44×40 pixels. An additional
1.4 Megapixel video camera provides scene context and effectively sharpens the spatial resolution of the hyperspectral
data. Essentially, the 4×4DIS provides a 2D spatially resolved grid of 44×40 = 1760 separate spectral measurements
every 33 ms, which is overlaid on the detailed spatial information provided by the context camera. The system can use a
wide range of off-the-shelf lenses and can either be operated so that the fields of view match, or in a "spectral fovea"
mode, in which the 4×4DIS system uses narrow field of view optics, and is cued by a wider field of view context
camera. Unlike other hyperspectral snapshot schemes, which require intensive computations to deconvolve the data
(e.g., Computed Tomographic Imaging Spectrometer), the 4×4DIS requires only a linear remapping, enabling real-time
display and analysis. The system concept has a range of applications including biomedical imaging, missile defense,
infrared counter measure (IRCM) threat characterization, and ground based remote sensing.
