Status Update and Closed-Loop Performance of the Magellan Adaptive Optics VisAO Camera

TL;DR

This paper reports laboratory results of the Magellan AO system's closed-loop performance, including the adaptive secondary mirror, pyramid wavefront sensor, and VisAO camera, demonstrating high Strehl ratios and system capabilities.

Contribution

It presents the first laboratory closed-loop performance results of the Magellan AO system with innovative components like the advanced ADC and CRO test system.

Findings

Achieved 37% Strehl in i'-band with 400 modes and simulated turbulence.

Advanced ADC shows 58% improvement over conventional designs.

Successful closed-loop operation of the ASM at 1 kHz.

Abstract

We present laboratory results of the closed-loop performance of the Magellan Adaptive Optics (AO) Adaptive Secondary Mirror (ASM), pyramid wavefront sensor (PWFS), and VisAO visible adaptive optics camera. The Magellan AO system is a 585-actuator low-emissivity high-throughput system scheduled for first light on the 6.5 meter Magellan Clay telescope in November 2012. Using a dichroic beamsplitter near the telescope focal plane, the AO system will be able to simultaneously perform visible (500-1000 nm) AO science with our VisAO camera and either 10 micron or 3-5 micron science using either the BLINC/MIRAC4 or CLIO cameras, respectively. The ASM, PWS, and VisAO camera have undergone final system tests in the solar test tower at the Arcetri Institute in Florence, Italy, reaching Strehls of 37% in i'-band with 400 modes and simulated turbulence of 14 cm ro at v-band. We present images and test results of the assembled VisAO system, which includes our prototype advanced Atmospheric Dispersion Corrector (ADC), prototype calcite Wollaston prisms for SDI imaging, and a suite of beamsplitters, filters, and other optics. Our advanced ADC performs in the lab as designed and is a 58% improvement over conventional ADC designs. We also present images and results of our unique Calibration Return Optic (CRO) test system and the ASM, which has successfully run in closed- loop at 1kHz. The CRO test is a retro reflecting optical test that allows us to test the ASM off-sky in close-loop using an artificial star formed by a fiber source.