Solar imaging with a segmented adaptive mirror.

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.

A programmable analog neural network processor.

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.

Quantitative simulation of image correction for astronomy with a segmented active mirror.

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.

Single photon x-ray detection with a CCD image sensor.

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.