Spectroradiometric sensor suite

Polaris Sensor Technologies proposes to develop an UV to LWIR integrated spectroradiometric system with automated spectral characterization of EO/IR imagers and spectral transmission measurement of filters and optical windows. Spectral resolution and spectral bandpass ranges will be user selectable. The available spectral range will extend from 200 nm to at least 14,500 nm, with spectral resolution better than 1% of wavelength. The innovation developed in Phase I will be the process used to relate the integrated response of the imager focal plane array with the time-varying output of a Fourier transform interferometer (FTIR). The Camera Link or Gig-E imager will sample the output of the interferometer, the sampled output will be assembled into a corresponding interferometric signal and deconvolved into the spectral response followed by comparison to truth for characterization of the unit under test. With faster, higher throughput than monochromators, the FTIR is better for the detection and delivery of low-sensitivity spectral signals. Measurement validation will be maintained through the incorporation of NIST traceable sources for radiometric calibration and standard reference materials for wavelength. FTIRs already support spectrometric ranges from the infrared down to 350 nm, but the base spectroradiometer concept still incorporates a monochromator to get the rest of the way down to 200 nm. In addition to developing the method for imager integration, a trade study will be performed to look for alternatives to the UV monochromator, specifically at scanning Fabry-Perot interferometers that might be incorporated in place of the UV monochromator subsystem. Other Phase I tasks will be conducting trades on all subsystem components to evaluate against the base system, and developing the sources interface, the output interface, the UV engine incorporation, and the COTS imagers integration station so they are ready for detailing at the beginning of Phase II. The prototype spectroradiometer built in Phase II will fit on a standard lab bench and provide stable, repeatable measurement under standard laboratory conditions. The heavy use of COTS for subsystems will keep the system affordable. Python will be used to develop the user interface with C++ modules included as needed to support computational performance. The native data output will be as spectral irradiance and as normalized spectral transmittance, but conversion to spectral radiance values or to normalized values will be supported.