Data reduction and calibration procedures are introduced for a,novel rotating-analyser-type spectral imaging ellipsometer. Using a monaxial power spectrograph, we developed a unique spectral imaging ellipsometer. It combines one-dimensional imaging ellipsometry with spectroscopic ellipsometry, and enables real-time measurement of the optical parameters and dimensional structures of patterned or multilayered thin film. It also has more calibration factors than conventional ellipsometers. We therefore present a method using Jones matrices for describing the polarization sensitivity of the spectrograph and random noise of the CCD array. For a patterned SiO2 layer on a silicon wafer, we used the spectral imaging ellipsometer to obtain a one-dimensional thickness profile.