SBIR-STTR Award

A need exists for spaceborne optical telescopes having the resolution of large aperture telescopes and diffraction limited performance over a wide field of view. Since existing launch systems prohibit the orbiting of such large telescopes, optically phased arrays of smaller telescopes (subtelescopes) must be used. Proper positioning of the subtelescopes, and optical phasing of the combined images, result in optical resolution equivalent to that of a much larger single telescope. Such arrays require diffraction limited subtelescopes which are well-corrected for field curvature and distortion, and which have closely matched focal lengths. Active control systems are required to adjust optical path lengths, tilts, etc., in order to maintain optical phasing. The goal of this work is the development of a conceptual design for a phased array telescope which will remain optically phased over a 30 arcminute field of view from visible through mid-infrared wavelengths. This effort will include the design of suitable subtelescopes, the conceptual design of an active control system, and the specification of an array configuration. The results of the proposed program will show whether phased array telescopes are feasible, and will lead to the detailed design of a laboratory demonstration model in subsequent phases of work.

Keywords:
TELESCOPES PHASED ARRAY SYNTHETIC APERT IMAGING SURVEILLANCE RESOLUTION FIELD OF VIEW

Under Phase I, several phased array imaging telescope designs were developed. These designs meet the image quality specifications stated for Phase I and demonstrated a thorough understanding of the conditions to be satisfied for optical phasing to occur. In particular, it was shown that the subtelescopes should introduce a small amount of distortion in order for optical phasing to occur. Detailed analysis of these designs will be performed under Phase II. This will include 1. error budget analysis, 2. tolerance analysis, 3. alignment plan development, 4. optical component testing and manufacturing procedures, 5. polarization analysis, 6. stray light analysis, 7. active control system conceptual design and 8. structural design. An additional phased array telescope containing fewer mirrors than the designs of Phase I will be designed to demonstrate the achievable performance of such a minimal system. Phase II will allow a detailed comparison of the several designs to be performed, thus showing the advantages/disadvantages of, for example, reducing the number of optical components. The results of Phase II will lead to the production of design drawings for and subsequent construction of a phased array telescope under Phase III of the research effort. Successful completion of the proposed work will lead to a) detailed design of phased array imaging telescopes, allowing b) comparison of large aperture telescope design options. Phased array imaging telescopes will permit c) high resolution space-based surveillance; d) space-based astronomy with unprecedentedresolution.