Abstract: The embodiments herein relate to a method for deriving topography of an object surface. A linearly polarized light wave is directed towards the object surface and a reference surface. Images of reflected linearly polarized light wave for a plurality of wavelengths are obtained. The images are obtained for at least four polarizations for each of the plurality of wavelengths. The reflected linearly polarized light wave is a reflection of the linearly polarized light wave directed towards the object surface and the reference surface. The topography of the object surface based on the obtained images is obtained.

Abstract: A method for quantitative measurement of surface accuracy of an area is provided. This comprises directing a monochromatic flat light wave towards a predefined surface area, recording an image of the reflected light with a camera and lens system focused on said surface area, and deducing surface accuracy parameters from the recorded image. The method is characterized in that said surface accuracy parameters are determined by obtaining a Fourier transform of the recorded image. Then, fitting predetermined Fourier components to a Fourier spectrum of said Fourier transform, wherein said Fourier components are determined along the major and across the minor elongation axes of the Fourier transform as at least a large Gaussian component, and a peak of the spectrum. Followed by, determining surface accuracy parameters of said surface area from said Fourier components.