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A Hyperspectral Imaging Sensor For The Coastal Environment
Recent advances in large format detector arrays and holographic diffraction gratings have made possible the development of imaging spectrographs with high sensitivity and resolution, ideally suited for space-based remote sensing of earth resources. An optical system composed of dual spectrographs and a common fore-optic has been designed for the visible-near infrared (VNIR) and shortwave bands with 10-nm spectral resolution, providing 30-meter ground resolution from an altitude of 605 km.
Calibration, Characterization and first Results with the Ocean PHILLS Hyperspectral Imager
The Ocean Portable Hyperspectral Imager for Low-Light spectroscopy (Ocean PHILLS), is a new hyperspectral imager specifically designed for imaging the coastal ocean. It uses a thinned, backside illuminated CCD for high sensitivity, and an all-reflective spectrograph with a convex grating in an Offner configuration to produce a distortion free image.
Comparison of Low-Cost Hyperspectral Sensors
Recent advances in large format detector arrays and holographic diffraction gratings have made possible the development of imaging spectrographs with high sensitivity and resolution, at relatively low component cost (<SIOOK.) Several airborne instruments have been built for the visible and near infrared spectral band with 10-nm resolution, and SNR of 200:1.
Ocean Optics
Hyperspectral Imaging airborne sensors have shown their utility in obtaining calibrated data for determining a wide variety of oceanographic products describing the littoral environment, such as water clarity, turbidity, chlorophyll, and benthic classification. However, all sensors have their own set of non-ideal performance characteristics, response functions, stray light artifacts, and noise statistics, which can challenge the validity of the generated data products if not properly handled.
Scene-Based System Modeling Using Optical Design Software
The traditional approach to optical system engineering separates the scene, optics, and detector as static entities, optimizing the design to meet subsystem specifications of aperture, field size, encircled energy, read noise, dynamic range, and other electro-optical properties. The Scene-Based System Model (SBSM) represents a different approach by simulating the scene, optics and detector as a cohesive model using commercially available optical ray-tracing software.
Survey and Analysis of Fore-Optics for Hyperspectral Imaging Systems
Applications for imaging spectrometers are expanding to cover a broader spectral range with higher fidelity, often from the VNIR to the SWIR with one common aperture. These fore-optic systems range from short focal length refractive optics for micro-UAV platforms, to large all-reflective telescopes for surveillance systems. Off-the-shelf lenses and standard prescription telescopes typically do not have the telecentricity and color correction performance to meet foreoptic system requirements for low distortion and broadband operation.
References
- J. Neumann, E. Allman, T. Downes, J. Howard, M. Kruer, J. Lee, D, Linne von Berg, R.Leathers, J.Murray-Krezan, N. Nezis. “Demonstration of the MX-20SW Standoff SWIR Hyperspectral Imaging Ball Gimbal System”. Military Sensing Symposium Passive Sensors, (2008). Note: Spectrometer built by Brandywine Optics.
- “The Schmidt-Dyson: A Fast Space-Borne Wide-Field Hyperspectral Imager.” SPIE Annual Meeting Aug. 2010 R. Lucke, J. Fisher.
- J. Fisher, “Scene-based sensor modeling using optical design software.” SPIE Annual Meeting Vol. 6667. Aug. 2007.
- J. Fisher, W. Welch, “Survey and Analysis of Fore-Optics for Hyperspectral Imaging Systems”, proceedings SPIE Defense and Security Symposium, April 2006.
- J. Fisher, C. Davis, W. Snyder, J. Bowles, R. Leathers, T.V. Downes, D. Korwan, M. Montes, “Simulation of Airborne Imaging Sensors for the Ocean Environment”, Ocean Optics XVI, Tucson, 2002.
- E. Tsiang, J. Cole, M. Deweert, A. Sparks, D. Yoon, J. Fisher, G. Sawai, T. Glover, “Application of a figure of merit for optical remote sensors to an airborne hyperspectral sensor”, SPIE Annual Meeting, Vol. 5546. Aug. 2004.
- C. Davis, J. Bowles, R. Leathers, D. Korwan, T. Downes, W. Synder, W. Rhea, W. Chen, J. Fisher, W.Bisset, R. Reisse, “Ocean PHILLS hyperspectral imager: design, characterization, and calibration”, Optics Express, Feb. 2002.
- J. Fisher, J. Antoniades, L. Xiang, C. Rollins, “A hyperspectral imager for the coastal environment”, International Optical Design Conference, June 1998.
- J. Fisher, M. Baumback, J. Bowles, J. Grossmann, and J. Antoniades “Comparison of Low-Cost Imaging Spectrometers”, SPIE Annual Meeting, July 1998.
- J. Grossmann, J. Bowles, D. Haas, J. Antoniades, M. Grunes, P. Palmadesso, D. Gillis, K Tsang, M Baumback, M. Daniel, J. Fisher, I. Triandaf, “Hyperspectral analysis and target detection system for the Adaptive Spectral Reconnaissance Program”. SPIE AeroSense Conf. April 1998.
- J. Fisher, J. Caulfield, “Digital Characterization of a Neuromorphic IRFPA”, Infrared Information Symposium (IRIS) on Infrared Detectors, Dallas 1995.
- E. H. Takken, M. D. Mermelstein, E. J. Stone, and R. G. Priest, M. Kaelberer, D. Crowder S. Church, D. Brown , J. Fisher . “Observation of IR Source at Ocean Horizon”. Multi-Spectral Symposium, Targets and Backgrounds Meeting, Feb. 1995.