Simultaneous short exposure measurements of anisoplanatism using compensated images at optical and near infrared wavelengths

Abstract

Work is in progress towards a series of observations to characterize the short- and long-exposure performance of an adaptive optics system as a function of wavelength and field-of-view. A principal goal of this effort will be to characterize the anisoplanatism observed in the infrared while using an off-axis visual guide star for tracking. More generally, we will investigate the effects of various methods for real-time and post-facto image tracking upon image quality in the presence of anisoplanatism. The instrumentation for the experiment is similar to that reported in [1], with the addition of an infrared sensor. Images are formed using the 1.5-meter telescope at the U. S. Air Fore Phillips Laboratory Starfire Optical Range and its adaptive optics system [2]. A beamsplitter sends the visible portion of the spectrum to a high speed, 64 by 64 pixel MIT/Lincoln Laboratory CCD array with high quantum efficiency and low readout noise. Re-imaging optics enable both components of wide binaries to be formed on the same array with a plate scale of 289 nrad/pixel. The infrared portion of the spectrum is imaged onto a 256 by 256 pixel NICMOS III detector with Infrared Labs electronics yielding approximately 100e- read noise. We are able to obtain simultaneous wave front sensor, optical, and infrared data with integration times of from 1 to 50 milliseconds.