PUEO NUI: feasible and fast upgrade of the CFHT adaptive optics system for high dynamic range imaging

Rethinking the efficient use of 4m-class telescopes in the dawning era of larger facilities is a timely but challenging debate. The extensive use of PUEO for imaging (and now spectroscopy) has kept CFHT at the forefront of scientific research with adaptive optics since its commissioning in 1996. Even though larger facilities are now starting to think about ways of implementing high order AO systems, we believe the medium size of the CFHT and the excellent quality of our site on Mauna Kea is a perfect combination to reach the highest performances with a high order AO system. The fields of application of high order adaptive optics are exciting: They include extremely high contrast imaging and coronography in the near-infrared and diffraction-limited imaging in the optical, with the corresponding gain in angular resolution. Specific science examples are described in and adjacent paper (Menard et al, these proceedings (4839-133)), and planned instrumentation in the form of four quadrant coronograph or existing dual (or triple) wavelength imagers (such as TRIDENT) would benefit tremendously from >90% Strehl ratios in the K band. Simulations of a high order (104 electrodes) curvature system have been performed and produce the required performance and are presented in an adjacent paper (Lai & Craven-Bartle, (4860-28)). Technologically, the system is quite simple and re-uses most of the opto-mechanics of the existing PUEO. Deformable mirrors and real time computers are well within existing (and commercially available) specifications. An innovative solution of using a dedicated low read noise CCD camera (specifically for curvature systems) overcomes the potential cost drawbacks of using avalanche photo-diodes (APDs). This detector is described in detail in an adjacent paper (Cuillandre et al, these proceedings (4839-31)).

[1]  Lennart Lindegren,et al.  Atmospheric Intensity Scintillation of Stars. III. Effects for Different Telescope Apertures , 1998 .

[2]  Neptune's Cloud Structure and Activity: Ground-Based Monitoring with Adaptive Optics , 1998 .

[3]  V. Béjar,et al.  Brown dwarfs and very low-mass stars in the Pleiades cluster: a deep wide-field imaging survey ? , 1998 .

[4]  J. Beuzit,et al.  Accurate masses of very low mass stars: IV Improved mass-luminosity relations , 2000, astro-ph/0010586.

[5]  D. Mouillet,et al.  HST/NICMOS2 observations of the HD 141569 A circumstellar disk ? , 1999 .

[6]  D. S. Acton,et al.  Cloud Structures on Neptune Observed with Keck Telescope Adaptive Optics , 2003 .

[7]  Francois Rigaut,et al.  Design and performance of an 85-actuator curvature system , 2000, Astronomical Telescopes and Instrumentation.

[8]  Gordon A. H. Walker,et al.  Speckle Noise and the Detection of Faint Companions , 1999 .

[9]  D. Mouillet,et al.  Asymmetries in the HD 141569 circumstellar disk , 2001 .

[10]  Malcolm J. Northcott,et al.  First ground-based adaptive optics observations of Neptune and Proteus , 1997 .

[11]  C. Marois,et al.  TRIDENT: an infrared camera optimized for the detection of methanated substellar companions of nearby stars , 2002, SPIE Astronomical Telescopes + Instrumentation.

[12]  J. Beuzit,et al.  Accurate masses of very low mass stars I . Gl 570 BC ( 0 . 6 M + 0 . 4 M ) ? , ? ? , 1999 .

[13]  Rene Doyon,et al.  Differential imaging coronagraph for the detection of faint companions , 2000, Astronomical Telescopes and Instrumentation.

[14]  Clark R. Chapman,et al.  Search for asteroidal satellites using adaptive optics , 2000, Astronomical Telescopes and Instrumentation.

[15]  G. Duvert,et al.  Discovery of a moon orbiting the asteroid 45 Eugenia , 1999, Nature.

[16]  Lennart Lindegren,et al.  ATMOSPHERIC INTENSITY SCINTILLATION OF STARS. II. DEPENDENCE ON OPTICAL WAVELENGTH , 1997 .

[17]  C. Zheng,et al.  ; 0 ; , 1951 .

[18]  Francois Roddier,et al.  Maximum Gain and Efficiency of Adaptive Optics Systems , 1998 .

[19]  Pierre Riaud,et al.  Estimated performances of a four-quadrant phase mask coronagraph for planet detection , 2003, SPIE Astronomical Telescopes + Instrumentation.

[20]  D. Rouan,et al.  Performance of the Canada‐France‐Hawaii Telescope Adaptive Optics Bonnette , 1998 .

[21]  Clark R. Chapman,et al.  Discovery of companions to Asteroids 762 Pul-cova and 90 Antiope by direct imaging , 1999 .