A New Method for Synthesis of Beam-Shaping Mirrors for Off-Axis Incident Gaussian Beams

In quasi-optical transmission systems, it is usually required to transform a certain Gaussian beam into another one characterized by a different set of parameters. Mirrors with quadratic surface contour functions, such as paraboloidal, ellipsoidal, and toroidal mirrors, are widely used for such a transformation. However, quadratic surface contours do not provide sufficient conversion efficiencies needed for the transformation of off-axis Gaussian beams into desired Gaussian millimeter-wave field distributions. Therefore, it is necessary to develop a new method for the transformation of off-axis Gaussian beams. This paper presents such a method for the synthesis of beam-shaping mirrors for off-axis Gaussian beam transformation. Based on this new method, a matching optics unit consisting of two mirrors has been designed to transform a Gaussian-mode-like field distribution into a Gaussian beam with desired parameters.