Due to the limitation of development time and budget, in this observation, our Ex-AO as a proto-type system, has provided a 30-order (of Zernike polynomial) wave-front correction and reached a correction frequency of 1 KHz (open loop), which is limited by current 97-actuator DM. In the next step, a faster 277-actuaotr DM will be induced, which can provide a precise wave-front correction over 100 orders with a correction frequency of 2 KHz.
The system will be finally updated to a facility dedicated for a 4-meter class telescope including both NTT and the Astrophysical Research Consortium (ARC) 3.5-m telescope at Apache Point Observatory. A professional WFS will be used, which will allow us to image faint stars with magnitude down to 10. And a broad-band NIR filter will be added to further increase the throughput of the whole system. Finally a step-transmission filter based coronagraph will be integrated in the Ex-AO for high-contrast imaging research.
Because of the limitation of physical space, none AO system has been installed on a 4-meter class telescope, which can deliver a state of the art performance. For these telescope, only Cassegrain or Nasmyth focus are available. Well our Ex-AO system, with a compact physical size, is able to be installed on a Nasmyth platform as a visiting instrument and deliver an excellent imaging quality.
Please notify that most of current Ex-AO coronagraphic projects for high-contrast imaging research of exoplanets are mainly on 8-meter class telescopes, which includes GPI/GEMINI and SPHERE/ VLT. Due to the large aperture of the primary, Kilo actuator deformable mirrors (DM) are required to reach an extreme high strehl ratio. Furthermore, an 8-m class telescope are very busy and may not be allocated too much observational time for the direct imaging research of exoplanets, which is a time-consuming work. For our Ex-AO, it will allow us to reach a compatible performance to GPI or SPHERE, with a moderate actuator number DM (say 277 actuators), on a smaller aperture size (4-meter class) telescope with a more opportunity to get the observational time, comparing with an 8-meter telescope.
With integration of previously developed coronagraph (Ren, Dou & Zhu, PASP 2010), the system should deliver an observational contrast of 10E-6 at angular distance of 0.4″ in NIR wavelengths. It will be used for the direct imaging research of young giant exoplanets and brown dwarfs, which would be a compensation for 8-m class GPI/SPHERE projects.