Share Email Print

Proceedings Paper

Spectral Irradiance Monitor (SIM) for the SORCE mission
Author(s): Jerald W. Harder; George M. Lawrence; Gary J. Rottman; Thomas N. Woods
Format Member Price Non-Member Price
PDF $14.40 $18.00
cover GOOD NEWS! Your organization subscribes to the SPIE Digital Library. You may be able to download this paper for free. Check Access

Paper Abstract

The Spectral Irradiance Monitor (SIM) will measure the solar spectral irradiance from 0.2- to 2.0 µm with an accuracy of 300 ppm (1?) and a precision of 100 ppm. The SIM will be launched in 2002 on the EOS SORCE mission (SOlar Radiation and Climate Experiment). This instrument is a Fery prism spectrometer with an Electrical Substitution Radiometer (ESR) as the primary detector, and 4 additional photodiodes detectors. SIM incorporates the following design features. 1) Two independent spectrometer channels coupled with a periscope/calibrator mechanism to monitor changes in prism transmission in-flight. 2) A closed-loop wavelength drive provides precise position knowledge in the spectrometer focal plane. 3) An ESR to maintain the long-term absolute calibration of the instrument. The ESR consists of back-to-back 1x10-mm2 diamond bolometers blackened with nickel phosphorous and mounted at the center of a spherical cavity to increase the effective bolometer blackness. A shutter located in front of the spectrometer entrance slit modulates the solar signal at 0.1 Hz; the ESR synchronously detects light at the shutter fundamental. The bolometer bridge control, electrical power replacement, ESR temperature regulation, prism rotation, and shutter actuation are all under digital signal processor control.

Paper Details

Date Published: 15 November 2000
PDF: 11 pages
Proc. SPIE 4135, Earth Observing Systems V, (15 November 2000); doi: 10.1117/12.494225
Show Author Affiliations
Jerald W. Harder, Univ. of Colorado/Boulder (United States)
George M. Lawrence, Univ. of Colorado/Boulder (United States)
Gary J. Rottman, Univ. of Colorado/Boulder (United States)
Thomas N. Woods, Univ. of Colorado/Boulder (United States)

Published in SPIE Proceedings Vol. 4135:
Earth Observing Systems V
William L. Barnes, Editor(s)

© SPIE. Terms of Use
Back to Top