Abstract

A method and apparatus for transforming an obscured beam into a uniform intensity pattern at the image plane of the apparatus are described. Apparatus for carrying out the invention comprises two on-axis optical elements which are designed for stigmatic imaging of an incoming obscured parallel laser beam. The first element, a paraboloid mirror, forms an imaginary stigmatic image of the beam at its focal point. The second element, a multi-faceted mirror, comprises identical flat facets disposed on an ellipsoid envelope. The ellipsoid conjugates the focal point of the paraboloid and the image plane. Selection of an image shape and dimension defines the shape and dimension of the facets. Each facet's contribution to the image is a full scale centered spot. The contribution of each facet add up to form a final uniform image. Slight variation of the image dimension, from facet to facet, allows a roll-off of the image and compensates for diffraction ripples by the edges of the facets.