LEDs as Precision Irradiance Sources for Calibration of the SNAP Focal Plane
Abstract
The SNAP mission objectives require a large focal plane array of detectors capable of high precision photometric measurements. Typically astronomical missions calibrate their optical train with stars. But for large focal planes, the mission overhead necessary to calibrate gigapixel arrays with repetitive spectrophotometric observations of stars alone is likely to be prohibitive. One approach is to use stars for the calibration of a subset of the pixels and an LED-projector system to tie the relative response of the calibrated pixels to the rest of the focal plane detectors. Here we describe our work to characterize a variety of pulsed, commercially-available LEDs as precision irradiance sources from the optical to the near infrared; to study how these characterizations are affected by aging, low temperature environments, and radiation; and to investigate simple LED-based projector systems that can deliver light from these LED irradiance sources to the focal plane detectors for detector calibration. These precision on-board LED projector systems are being designed both to deliver an accurately calibrated number of photons as a function of wavelength to the focal plane detectors for standard tests of detector performance and to monitor in-flight filter/detector and/or spectrophotometer response.
We thank the Office of Science at the Department of Energy for funding of this research.- Publication:
-
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 2004
- Bibcode:
- 2004AAS...205.6706M