Abstract: A real time interferometric comparator apparatus. The apparatus generally includes means for projecting at least a first optical signal onto a complexly shaped surface such as a curved surface of a large reflector antenna of a satellite system, to thereby create an interferogram indicative of irregularities in the curvature of the reflector's surface. A scanning device scans the interferogram and transmits electrical signals in accordance with the scanned interferogram to a processing device which includes a comparator for comparing the scanned interferogram with a model or reference workpiece having a desired, or "perfect", surface. The processing device determines if any errors are present in the scanned interferogram and, if so, transmits error correction signals to an adjusting apparatus associated with the workpiece, to thereby provide a closed loop control system for continuously monitoring and correcting errors in the curvature of the workpiece such as the reflector antenna in real time.

Abstract: The projection of a planar distorted pattern onto a three dimensional surface provides a true or undistorted pattern on that surface. Complex patterns are applied to an irregular or curved surface by a method which includes the formation of a graphics display of the body on a computer graphics display and conversion to a two dimensional CADAM data base containing a planar projection of the pattern intended for application to the curved surface. This pattern information is translated into other forms, such as the form of a numerically controlled milling machine tape or photo mask, which is then used by ancillary method apparatus to form the desired pattern as a part of the method. The process describes the construction of a dichroic parabolic RF reflector.