Figure 1
Circular averaged correction factor for shading and deviation functions from CCDslow. The grid-patterned mask (10 mm × 10 mm) has 173 holes of diameter 2 mm. Water scattering was used. The sample-to-camera distance was 2.2 m. The correction factor, Y, is defined so that I(X)corrected = Y × I(X)apparent, where I(X)apparent and I(X)corrected are apparent and corrected circular averaged intensities at the radial pixel X. Y for each grid points were plotted as circles and squares for distortion and shading, respectively. The correction factors of distortion and shading were approximated by quadratic and bimodal equations, respectively (solid lines): Y = 1 + 8.82 × 10−6X − 1.71 × 10−7X2 and Y = 1 + 4.87 × 10−4X − 2.50 × 10−6X2 + 6.13 × 10−9X3 + 5.08 × 10−13X4 for deviation and shading, respectively. |