ABSTRACT
A 19-segment adaptive-mirror system is currently being used on the Sacramento Peak 76-cm Tower Telescope to remove wave-front distortions resulting from atmospheric turbulence. The system has proven to be capable of substantially improving the quality of an image, at times achieving 0.33-arcsec resolution in visible wavelengths under 1-3-arcsec seeing conditions. An improvement in resolution seems to occur across a large field of view that is, at times, 30 arcsec in diameter.
ABSTRACT
An analog neural network breadboard consisting of 256 neurons and 2048 programmable synaptic weights of 5 bits each is constructed and tested. The heart of the processor is an array of custom-programmable synapse (resistor) chips on a reconfigurable neuron board. The analog bandwidth of the system is 90 kHz. The breadboard is used to demonstrate the application of neural network learning to the problem of real-time adaptive mirror control. The processor control is 21 actuators of an adaptive mirror with a step-response setting time of 5 ms. The demonstration verified that it is possible to modify the control law of the high-speed analog loop using neural network training without stopping the control loop.
ABSTRACT
Correction by active mirror systems of image distortion due to atmospheric turbulence promises to improve the quality of ground-based astronomical observations. Although the ideal of fully correcting average-to-poor seeing to the diffraction limit of a large telescope cannot be easily realized with current technology, it has been demonstrated that partial correction of severe seeing disturbances can significantly improve image resolution. This paper describes a computer simulation of partial seeing correction by the Lockheed Active Mirror. Quantitative evaluation of the effects of partial correction on simulated wavefronts indicates that, even with a modest number of mirror actuators, one can achieve a diffraction-limited image superimposed on a background of scattered light.
ABSTRACT
Individual x rays of 5.9 and 22.4 keV have been detected and energy analyzed in single pixels of a CCD image sensor. The results indicate the CCD operates as an array of tiny Si solid state detectors providing both high spatial resolution and x-ray energy discrimination. These devices will prove useful sensors at the focus of future x-ray telescopes.