Spectral Calibration of the SLSTR Focal Plane Assemblies

We describe a novel technique - Fourier transform spectroscopy - that we have developed to characterise the spectral and polarisation responses of the Sentinel-3 SLSTR optical channels. Our method has a number of advantages over conventional approaches employing a grating monochromator, including excellent spectral registration and resolution, intrinsic rejection of self-emission from the test setup and fast measurement times. Our measurements are traceable, through the spectral responsivity of a reference detector and the wavelength of a HeNe laser, to national standards.We illustrate our method with sample results from the spectral calibrations of the four SLSTR focal plane assemblies tested to date.