Design, implementation, and on-sky performance of an advanced apochromatic triplet atmospheric dispersion corrector for the Magellan adaptive optics system and VisAO camera

摘要

We present the novel design, laboratory verification, and on-sky performanceof our advanced triplet atmospheric dispersion corrector (ADC), an importantcomponent of the Magellan Adaptive Optics system (MagAO), which recentlyachieved first light in December 2012. High-precision broadband (0.5-1.0microns) atmospheric dispersion correction at visible wavelengths is essentialboth for wavefront sensing (WFS) on fainter guide stars, and for performingvisible AO science using our VisAO science camera. At 2 airmasses (60 degreesfrom zenith) and over the waveband 500-1000 nm, our triplet design produces a57% improvement in geometric rms spot size, a 33% improvement in encircledenergy at 20 arcsec radius, and a 62% improvement in Strehl ratio when comparedto a conventional doublet design. This triplet design has been fabricated,tested in the lab, and integrated into the MagAO WFS and the VisAO sciencecamera. We present on-sky results of the ADC in operation with the MagAOsystem. We also present a zero-beam-deviation triplet ADC design, which will beimportant to future AO systems that require precise alignment of the opticalaxis over a large range of airmasses in addition to diffraction-limitedbroadband dispersion correction.