This report describes a characterization of a commercial liquid crystal spatial light modulator (SLM). Several methods for determining optical properties of SLM´s are discussed and evaluated. The methods have been tested both by simulations and by experimental studies. The phase response of an SLM is the relation between the applied voltage and phase modulation. Due to the nature of liquid crystals this relation is non-linear. By using look-up table (LUT) the relation can be adjusted to give a more linear response. Look-up tables, which almost produce a linear phase response, have been constructed by studying the phase response of the SLM. The effects of a non-linear response on laser beam steering and shaping were studied. For beam steering and shaping the optimized LUT improved the performance. The steering efficiency was increased with respect to the intensity in the first order diffraction peak. For beam shaping more of the power in the intended region and less outside was observed.