Transmittance measurement of a heliostat facility used in the preflight radiometric calibration of Earth-observing sensors

J. Czapla-Myers; K. Thome; N. Anderson; J. McCorkel; N. Leisso; W. Good; S. Collins

doi:10.1117/12.828873

21 August 2009 Transmittance measurement of a heliostat facility used in the preflight radiometric calibration of Earth-observing sensors

J. Czapla-Myers, K. Thome, N. Anderson, J. McCorkel, N. Leisso, W. Good, S. Collins

Author Affiliations +

Proceedings Volume 7452, Earth Observing Systems XIV; 74520P (2009) https://doi.org/10.1117/12.828873
Event: SPIE Optical Engineering + Applications, 2009, San Diego, California, United States

Abstract

Ball Aerospace and Technologies Corporation in Boulder, Colorado, has developed a heliostat facility that will be used to determine the preflight radiometric calibration of Earth-observing sensors that operate in the solar-reflective regime. While automatically tracking the Sun, the heliostat directs the solar beam inside a thermal vacuum chamber, where the sensor under test resides. The main advantage to using the Sun as the illumination source for preflight radiometric calibration is because it will also be the source of illumination when the sensor is in flight. This minimizes errors in the pre- and post-launch calibration due to spectral mismatches. It also allows the instrument under test to operate at irradiance values similar to those on orbit. The Remote Sensing Group at the University of Arizona measured the transmittance of the heliostat facility using three methods, the first of which is a relative measurement made using a hyperspectral portable spectroradiometer and well-calibrated reference panel. The second method is also a relative measurement, and uses a 12-channel automated solar radiometer. The final method is an absolute measurement using a hyperspectral spectroradiometer and reference panel combination, where the spectroradiometer is calibrated on site using a solar-radiation-based calibration.

Citation Download Citation

J. Czapla-Myers, K. Thome, N. Anderson, J. McCorkel, N. Leisso, W. Good, and S. Collins "Transmittance measurement of a heliostat facility used in the preflight radiometric calibration of Earth-observing sensors", Proc. SPIE 7452, Earth Observing Systems XIV, 74520P (21 August 2009); https://doi.org/10.1117/12.828873

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