A New Method to Estimate the Point Spread Function of Satellite Imagers From Edge Measurements

The 2-D Point Spread Function (PSF) of satellite imaging sensors is usually estimated from two perpendicular edge measurements. It has been shown that this method is only valid for a sensor with a low optical factor 'Q' (defined as the wavelength times the F number divided by the pixel pitch), so a new method is required to estimate the PSF for sensors with moderate and high Q. In this work, a new three-edge method that estimates the PSF by quadratic interpolation in the spatial frequency domain is assessed and shown to complement the current two-edge method. The use of both methods allows the estimation of the PSF down to one order of magnitude below its peak response. The new method is assessed using a generic sensor system methodology that considers the optical design parameters of the sensor as independent variables. Results are graphically represented as constant Mean Absolute Percentage Errors (MAPEs) contours drawn on a plane of optical designs in which each point represents an imaging channel with a specific Q and optical aperture's obstruction ratio.