Development of Radiometric System Models for Performance Comparison of Proposed Instruments zyxw Betina Pavri* , Greg Beannan, Jack Margolis, Philip Moynihan, and Karen Liu Jet Propulsion Laboratory, 4800 zyxwvu Oak Grove Drive, Pasadena, CA 90041 ABSTRACT Radiometric models have been used to optimize instrument design or evaluate impacts of changes to the design during integration and test. Tradeoffs such as spectral and spatial resolution, telescope and spectrometer temperature, aperture, f/No., integration time, optics and filter transmissions, and so forth can be quickly changed to evaluate changes to the signahoise ratio or other performance metria. An alternative use of such models is to identi@ promising instrument proposals for further study. A series of models were constructed to evaluate general instrument designs as an illustration of this process.Thesemodelsincluded two grating spectrometers (whiskbroom and pushbroom) and a spatially modulated interferometer. All were given a common set of radiometric inputs and telescope optical prescription. Results of the modeling illustrate the performance differences between instrument types, although signalhoise predictions should be evaluated along with other parameters such as manufacturability, precision of calibration, and so forth. Such modelingallowsinstrument developers to demonstrate to potential customers improvements in their instruments, andthe advantages of their product over other instruments for a specific application. If a common set of inputs is used for the different instrument models, this technique gives customers one metric with which to evaluate the disparate proposals. Keywords: radiometricmodeling, performance modeling, systems engineering 1. BACKGROUND Two classes of passive, spectrographic instruments may be applied to the stand-off detection of chemical agents: hyperspectral and multispectral. Hyperspectral instruments include grating spectrometers and Fourier Transform Spectrometers (FTSs). Multispectral options include Acoustical Optical Tunable Filter(AOTF)instrumentsandFabry-Perot (etalon) instruments, including Liquid Crystal Tunable Filter (LCTF) instruments. However, many recent AOTF and LCTF designs are now approaching hyperspectral resolution, so they may be technologies to watch. Fixed-filter systems would also fall in the multispectral category, but are not considered here as they are not easily modified (reprogrammed) during operation if this becomes necessary. Further author information - B.P. (correspondence): betina.e.pavri@jpl.nasa.gov (818)354-6379 P.M. philip.i.moynihan@jpI.nasa.gov (818)354-4130