A system and method for simulating atmospheric turbulence for testing optical components. A time varying phase screen representing atmospheric turbulence is generated using Karhunen-Loeve polynomials and a splining technique for generating temporal functions of the noise factor for each Zernike mode. The phase screen is input to a liquid crystal spatial light modulator. A computer display allows the user to set geometric characteristics, and select between methods for generating atmospheric turbulence including Karhunen-Loeve polynomials, Zernike polynomials, and Frozen Seeing.