![]() Windows Ultimate Boot CD v 3.1.10A | 250MB Premium file Windows Ultimate Boot CD v 3.1.10A UgotFile The Extreme Adaptive Optics Testbed at UC Santa Cruz is being used to investigate and develop technologies for high-contrast imaging, especially wavefront control.> Download Windows Ultimate Boot CD v 3.1.10A crack<< 'Extreme' adaptive optics systems are optimized for ultra-high-contrast applications, such as ground-based extrasolar planet detection. Some errors are introduced by phase and amplitude mixing because the MEMS is not conjugate to the pupil, but independent measurements of MEMS reflectivity suggest that some error is introduced by small non-uniformities in the reflectivity. We find systematic intensity variations of about 2% rms, and intensity variations with the MEMS more » to be 6%. Results from experimental measurements and wave optic simulations of amplitude variations on the ExAO testbed are presented. Corresponding contrast measurements, however, are limited by amplitude variations, including those introduced by the micro-electrical-mechanical-systems (MEMS) deformable mirror. At the Laboratory for Adaptive Optics on the Extreme Adaptive Optics testbed, we have already demonstrated wavefront control of better than 1 nm rms within controllable spatial frequencies. High-contrast adaptive optics systems, such as those needed to image extrasolar planets, are known to require excellent wavefront control and diffraction suppression. We are constructing a high-contrast AO testbed to verify key concepts of our system, and present preliminary results here, showing an RMS wavefront error of <1.3 nm with a flat mirror. = at angular separations of 0.2-0.8 inches around a large sample of stars (R<7-10), sufficient to detect Jupiter-like planets through their near-IR emission over a wide range of ages and masses. Closed-loop performance and simulated far-field measurements using a Kolmogorov phase plate to introduce atmosphere-like optical errors are also presented. I also present contrast measurements of 2 x 10 -7 made with the MEMS device and identify amplitude errors as the limiting error source. Individual contributors to final wavefront quality have been identified and characterized. I demonstrate feasibility of the MEMS deformable mirror for meeting the stringent residual wavefront error requirements of an extrasolar planet imager with closed-loop results of 0.54 nm rms within controllable spatial frequencies. Wavefront measurements and simulations indicate that contrast is limited by wavefront error, not diffraction. I present 6.5 x 10 -8 contrast measurements with a prolate shaped pupil and flat mirror demonstrating that the testbed can operate in the necessary contrast regime. A state-of-the-art, 1024-actuator micro-electrical-mechanical-systems (MEMS) deformable mirror was installed and characterized to provide active wavefront control and test this novel technology. The ExAO testbed at the Laboratory for Adaptive Optics was designed with low wavefront error and precision optical metrology, which is used to explore contrast limits and develop the technology needed for an extrasolar planet imager. Laboratory demonstrations are critical to instrument development. Contrast is ultimately limited by residual static wavefront errors, so an extrasolar planet imager will more » require wavefront control with an accuracy of better than 1 nm rms within the low- to mid-spatial frequency range. Such instruments will be technically challenging, requiring high order adaptive optics with > 2000 actuators and improved diffraction suppression. ![]() Contrast is defined as the intensity ratio of the dark wings of the image, where a planet might be, to the bright core of the star. High contrast adaptive optics systems, also known as Extreme Adaptive Optics (ExAO), will require contrasts of between 10 -6 and 10 -7 at angles of 4-24 λ/D on an 8-m class telescope to image young Jupiter-like planets still warm with the heat of formation. Direct methods would probe new parameter space, and the detected light can be analyzed spectroscopically, providing new information about detected planets. Indirect techniques only probe about 15% of the orbital parameter space of our solar system. For example, radial velocity techniques measure the doppler shift in the spectrum of the star produced by the presence of a planet. Most planets identified to date have been detected indirectly-not by emitted or reflected light but through the effect of the planet on the parent star. Direct imaging of extrasolar planets is an important, but challenging, next step in planetary science.
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