Development and test work in the laboratory frequently requires variation of the size and radiative characteristics of a source which is used to provide the radiant power for effects or detection studies. To provide this capability, a system of multiple moving mirrors has been designed for use in optical beam shaping and image manipulation arrangements applied in optical diagnostic procedures and testing of optical sensor systems. Its particular features are a zoom capability of 30:1 and a total scaling range of 800:1, so that approaching or receding sources can be simulated in the laboratory. In addition, the effective source area and with it the accepted radiative flux can be varied over a range of five magnitudes. A detailed analysis of the system and its in-herent wavefront aberrations is given; the dynamic requirements, and methods to improve the optical performance of the mirror system are discussed.