Abstract: Methods for eliminating artifacts in two-dimensional optical metrology utilizing the interline CCD detectors are based on a dark-subtraction principle. The self-dark subtraction method takes advantage of strong correlation between the noise patterns in illuminated and dark regions within the same image. Image artifacts are removed and the S/N ratio is improved significantly by subtraction of selected dark region of the image from the illuminated one within the same frame. The dark-frame subtraction technique reduces a “smear” effect by applying a digital processing based on subtraction of the dark frame images from the normal light frame images. A combination of these methods significantly improves performance of two-dimensional optical metrology systems such as spectrometers, ellipsometers, beam profile reflectometers/ellipsometers, scatterometers and spectroscopic scatterometers.