Large space optics technologies are developed for government support civilian and defense applications. Within a funding constrained environment, partnerships among members of the large space optics community serve to accelerate the pace of technology development and insertion of technology products into space operations. Although missions and operating requirements are quite different for the partners, NASA and DOD have teamed to address areas of common concern. One particularly successful partnership activity is aimed at significantly reducing areal density, cost and fabrication time for large optics. Other opportunities are being explored among the government partners.
Within the last decade, the declassification of adaptive optics techniques and systems developed for defense purposes opened new opportunities to the astronomical community. Since the military resolution requirements are not qualitatively different from the astronomical ones, astronomers may profit from the quite sizable investments already made. On the other hand, the astronomical observations are much more demanding than the military ones with respect to the required accuracy, stability and sensitivity. In 1994, after contacts made during an adaptive optics meeting in Munich, we started a joint project to observe the ejected matter from the luminous blue variable (LBV) P-Cygni with the AMOS compensated imaging system (CIS). In this paper we describe the problems encountered and the experience gained in more than two years of operations with CIS. The satisfactory results obtained so far prompted us to plan a more ambitious program. We aim to profit from the acquired know-how for preparing a proposal of astronomical observations designed in such a way of taking the utmost advantage of the capabilities of the new USAF AEOS adaptive optics system.
We report on the results of an experiment to analyze and characterize the optical index of refraction structure of an air jet flow using chaotic measures. A laboratory jet flow was interrogated at several downstream positions using a thin laser beam jitter technique and the resulting time series jitter data were analyzed to determine phase space portraits, correlation dimensions, and Lyapunov exponents. These measures help describe the complexity and dynamics of the flow features. As expected, the results indicate an increase in complexity of the flow structure with downstream position. One interesting feature of the results is a sudden increase in the correlation dimension at a position of 5.5 nozzle diameters downstream of the opening, indicating a dramatic increase in complexity. These measurements and chaotic analyses of the jet-flow transition region have interesting implications for the understanding and modeling of the optics of aircraft boundary layers and wakes, stratified atmospheric layers, and atmospheric turbulence.
Unlike biological vision, most techniques for computer image processing are not robust over large samples of imagery. Natural systems seem unaffected by variation in local illumination and textures which interfere with conventional analysis. While change detection algorithms have been partially successful, many important tasks like extraction of roads and communication lines remain unsolved. The solution to these problems may lie in examining architectures and algorithms used by biological imaging systems. Pulsed oscillatory neural network design, based on biomemetics, seem to solve some of these problems. Pulsed oscillatory neural networks are examined for application to image analysis and segmentation of multispectral imagery from the Satellite Pour l'Observation de la Terre. Using biological systems as a model for image analysis of complex data, a pulsed coupled networks using an integrate and fire mechanism is developed. This architecture, based on layers of pulsed coupled neurons is tested against common image segmentation problems. Using a reset activation pulse similar to that generated by sacatic motor commands, an algorithm is developed which demonstrates the biological vision could be based on adaptive histogram techniques. This architecture is demonstrated to be both biologically plausible and more effective than conventional techniques. Using the pulse time-of-arrival as the information carrier, the image is reduced to a time signal, temporal encoding of imagery, which allows an intelligent filtering based on expectation. This technique is uniquely suited to multispectral/multisensor imagery and other sensor fusion problems.
We derive an expression for the wavelength (lambda) o giving maximum resolution for an adaptive-optics compensated telescope. An approximate expression for average on-axis intensity is written to account for the competing effects of diffraction and residual (post-compression) phase error; this expression is then differentiated with respect to the imaging wavelength (lambda) to yield (lambda) o. The analytically predicted (lambda) o is compared to simulation results and correspondence is shown to be good at widely separated seeing conditions and adaptive optics geometries.
We analyze the use of a single laser or natural guidestar to correct atmospheric distortion for a wide field of view (WFOV) imaging system. We concentrate on the absolute system limits without regard to radiometrics or compensation method by evaluating the best system OTF possible at field points in and beyond the isoplanatic patch. The improvement of OTF at mid- spatial frequencies is several decades over the non-corrected OTF even at field angles of one arc minute, and we conclude that post processing should be able to recover much more information in adaptive optics systems even at wide FOVs than uncompensated systems.