NASA Logo, National Aeronautics and Space Administration
Intelligent Systems Division Banner
IOTA Interferometer Facility

IOTA Interferometer Facility at Kitt Peak, Arizona 

Real-time Detection of Fringe Signal

Real-time Detection of Fringe Signal

OBJECTIVES:
In general, to improve the performance characteristics of earth-based and space-based telescopes:

Light waves from astronomical objects are distorted as it travels through the earth's atmosphere. The simplest case of this is the twinkling of stars. For earth-based telescopes, these distortions place a limit on the resolution of seeing. Space-based telescopes such as the Hubble Space Telescope are high above the atmosphere and do not have this problem. Until recently, the detection and correction of atmospheric distortions were difficult to achieve. Adaptive optics approaches have been used to compensate for atmospheric distortions.

Most adaptive optics systems use custom-built, very expensive optical and computer systems to detect and compensate for wavefront distortions. Recent studies have shown that neural network technologies can be used to detect and provide corrections to an adaptive optics system using a relatively simple optics setup. This approach would reduce the cost of adaptive optics systems and offer improved performance.

Space-based telescopes have other sources of disturbances that affect seeing. The telescope’s structural vibrations can be a significant problem. It is anticipated that signal detection techniques being developed for earth-based telescopes can also be applied to detect low level signals from the background of noise due to structural vibrations.

BACKGROUND

Code IC’s Smart Systems Research Lab and Code SSA’s Infrared Astronomy Team at NASA Ames are working together to improve the performance capabilities of the IOTA Interferometer Facility at Kitt Peak, Arizona. The planned improvements are phased over a period of three years. In the first phase, work is focused on improving the fringe signal detection and measurement system, also called the fringe tracker project. In the second phase, work will focus on developing algorithms to improve the performance of the adaptive optics in the existing infrared interferometer. The third phase will focus on implementation and testing of the adaptive optics control algorithms at the IOTA facility.

* For more information on the IOTA: Infrared Optical Telescope Array, see
http://tdc-www.harvard.edu/mthopkins/iota.html

First Gov logo
NASA Logo - nasa.gov