Four-telescope phased array optical simulation

A new geometric and physical optics simulation code for predicting the performance of phased array telescopes is described. A skew aspheric ray trace routine computes a composite spot diagram and an array of optical path differences for the entire telescope system. This includes the four nearly identical afocal telescopes and the single combiner telescope. A second routine then computes subaperture Zernike aberration coefficients. A wave optics code computes point spread functions, and a final code computes optical transfer functions. The simulated performance of Air Force's Multipurpose Multiple Telescope Testbed (MMTT) is then presented and discussed. All optical surfaces of the telescope plus in situ measured aberrations are simulated. The results show that the telescope is nearly diffraction limited at small field angles, but suffers from phase and tilt differences among the telescopes at field angles above two milliradians.