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Atmospheric Phenomenology and Instrument Performance Modeling
Every remote sensing project that is undertaken at Michigan Aerospace Corporation begins with a complete
numerical simulation of the system (using MODTRAN and other modeling software) to predict performance and make informed
design decisions. Simulation capabilities include optical ray tracing, modeling of atmospheric scattering mechanisms,
modeling of radiative transfer processes, and modeling of the chemistry of the atmosphere as applied to passive ground
and space-based remote sensing instruments. Listed below are some of our key capabilities in several areas.
Modeling Capabilities for Lidar Systems
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Realistic LIDAR simulation routines that can be used for ranging or fixed-volume instruments that account for telescope focus, angle of laser propagation with respect to telescope optical axis, telescope-laser axis offsets and near field focus effects for short range instruments as well as LIDAR configurations that can have any elevation angle.
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Backscatter prediction from atmospheric molecules and aerosols. Our simulation models are flexible and incorporate several aerosol models and the ability to use new ones.
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Backscatter prediction in the presence of clouds, rainfall and various other atmospheric constituents such as smoke.
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MAC also has the ability to simulate the effects of Brillioun scattering through the atmosphere, which is especially important for applications that are sensitive to spectral lineshape such as Doppler wind LIDAR.
Modeling Capabilities for Receivers
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MAC’s specialty is end-to-end modeling of Doppler wind LIDAR and passive wind imaging instruments. These instruments typically rely on Fabry-Perot etalons in order to resolve the Doppler shift either from atmospheric backscatter or emission lines in the upper atmosphere. We are able to accurately predict the performance of these instruments for the measurement of winds, temperature and density as well as for aerosol content.
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For every LIDAR instrument, a complete model is developed that accounts for the system efficiency, noise characteristics of the detectors, expected solar background, the characteristics of the Fabry-Perot system, the light field illumination from fiber optics and expected outputs in terms of data products and their associated errors.
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MAC’s simulation modeling capabilities for Fabry-Perot based instruments are extensive and our models account for many of the defects commonly encountered when using these devices. These include defocus, plate bowling defects and aperture broadening. Also, our Fabry-Perot models incorporate broadening effects from the random thermal motions of molecules as well as hydrodynamic effects from acoustic or Brillioun scattering.
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This diagram shows how the various models interact with each other to predict performance for a Doppler wind LIDAR.
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