METHOD FOR ESTIMATING THE INFLUENCE OF SPECKLES ON A QUALITY OF A RADIOMETRIC CALIBRATION OF AN IMAGING SPECTROMETER

The invention relates to a method for estimating the influence of speckles on a quality of a radiometric calibration of an imaging spectrometer (10), wherein the spectrometer (10) comprises a telescope assembly (13), a detector (14) with multiple detector pixels (16) and a dispersive element (18), which causes a dispersion (k), and wherein light, in particular sunlight, is coupled into the spectrometer via a diffuser (12) for the calibration. The method comprises the step of calculating a numerical contrast value CDetektor as CDetektor = 1/√M, wherein M represents a total degree of freedom for influencing variables, which affect the contrast measurable by the detector (14), wherein M is formed by multiple individual degrees of freedom, including an individual degree of freedom MPolarisation, an individual degree of freedom MSpektral and an individual degree of freedom MPixel, wherein MPolarisation depends on a polarisation of the light that enters the spectrometer (10), wherein MSpektral depends on a spectral resolution λres of the spectrometer (10) and a correlation between spectrally different monochromatic intensity distributions, wherein MPixel depends on an individual pixel area ADetektor and a correlation area ASpeckle of a speckle, and wherein the calculation is carried out for an intensity distribution, which is obtained as the superposition of monochromatic intensities, which can be described by monochromatic fields, which are circular, complex Gaussian variables.