AAS 198th Meeting, June 2001
Session 77. The Promise and Pitfalls of High Contrast Imaging
Display, Thursday, June 7, 2001, 9:20am-4:00pm, Exhibit Hall

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[77.06] High Contract Imaging with High Order Curvature Adaptive Optics Systems: Application to Star Formation Studies

O. Lai, F. Menard, C. Dougados (CFHT)

It is remarkably difficult to detect faint sources in the vicinity of bright ones, especially if extended. This is a long standing problem in astronomy and numerous techniques have been implemented to improve the contrast of imagers (e.g., coronography, speckle interferometry, adaptive optics). As part of a study to upgrade the current adaptive optics facility at the Canada-France-Hawaii Telescope to provide a higher order adaptive optics imaging system, we present numerical simulations to show that a relatively modest set-up of 85 or 104 subapertures/electrodes can provide extremely high order corrections on the 3.6m telescope and allow very high contrast imaging. Results show that Strehl ratios of up to 92 and images will be diffraction-limited in the optical, down to 550nm, on relatively faint stars with respect to other existing high order AO systems. For comparison, 900 actuators are needed on Shack-Hartmann based AO systems to reach the same level of performance on a similar-sized telescope, with the obvious drawbacks of increased cost, reliability and limited sky coverage. This new scheme could be used as a testbench for future high-order AO systems to be implemented on extremely large telescopes.

In this contribution, the case of star formation will be considered as a science driver. The numerical simulations will be used to quantify the expected gain in resolution and contrast when imaging faint nearby companions, extended circumstellar disks and ionised jets seen in emission lines only.

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