PHASED ARRAY TELESCOPE IMAGE PROCESSING

AN ANALYTIC MODEL OF A WIDE FIELD, PHASED ARRAY IMAGING SYSTEM WILL BE DEVELOPED. THE MODEL IS BASED ON A MEASUREMENT SYSTEM CAPABLE OF ERROR MEASUREMENT DIRECTLY WITH RESPECT TO THE FINAL IMAGE PLANE. THE BEAMS FROM INDIVIDUAL SUBAPERTURES WILL BE COMPACTED AND CONFORMALLY MAPPED TO A DEMAGNIFIED PUPIL. WE WILL DEVELOP NONREDUNDANT, CODED APERTURE MASKS TO BE INSERTED AT THIS COMPACT PUPIL WHICH WILL SAMPLE SPECIFIC SPATIAL FREQUENCIES WHEN IMAGED. THE RESULTING VISIBILITY FRINGE WOULD BE SAMPLED BY A CHARGE-COUPLED DEVICE (CCD) AREA-ARRAY IN THE FINAL IMAGE PLANE AND FOURIER TRANSFORMED BY A DIGITAL SIGNAL PROCESSOR. THE TRANSORM WILL CONTAIN "SUFFICIENT" INFORMATION FOR THE INDIVIDUAL BEAM PHASE ERROR IN THE SYSTEM IMAGE PLANE. ABSOLUTE GEOMETRY ERRORS CAN BE DETERMINED FROM VISIBILITY FRINGE OBTAINED FROM AN INTERMEDIATE IMAGE-FIELD IMAGED ON THE SAME CCD ARRAY. IF NECESSARY, AN IMAGE SHARPENING ALGORITHM WILL BE DEVELOPED FOR FINAL IMAGE REFINEMENT AND FOR ELIMINATING ANY RESIDUAL ERRORS. EXCEPT ABSOLUTE PISTON, THE NONREDUNDANT VISIBILITY DATA ALLOW IMAGE PLANE MEASURMENT OF ALL THE PHASE ERRORS ABSOLUTELY. THIS HOLDS TRUE FOR BOTH THE EXTERNAL AND INTERNAL REFERENCE SOURCES. A SOFTWARE MODEL OF THE MEASUREMENT SYSTEMS WILL BE DEVELOPED FOR TESTING THE VALIDITY OF THE ALGORITHMS.