On April 23, 2013，five experts of project group for Thirty Meter Telescope of (referred to as TMT) of United States including Professor Jim Burge （optical testing expert Of Arizona University of United States、Byron Smith(project manager of 4.2 meters discovery channel telescope (DCT)) as well as Myung Cho (advanced optical and mechanical expert of National Optical Astronomy Observatory (NOAO) of United States) led by Gary Sanders (generanal manager of TMT project) visited NIAOT to conduct communication of progress on pre-stressed ring polishing submirrors for TMT main mirror。

　  At the meeting，Gary Sanders(generanal manager of TMT project) and Eric Dr. Williams (director of optical group of TMT project)

　  Respectively recent progress of TMT project and submirrors of TMT main mirror polishing in the cooperative countries。

　  After Prof.LiXinnang (Research Lab of Large Astronomical Optics of NIAOT) introduce progress on pre-stressed ring polishing submirrors for TMT main mirror by NIAOT，experts from TMT project inspected the development on site。

　  Both sides conducted in-depth discussion on some technical details and subsequent plans。

　  During visiting，Prof. Xue Suijian (China TMT Project Manager and director of Department of international cooperation for National Astronomical Observatory) accompanied。

　  TMT proposed by California University and California Institute of Technology of United States is  a  30-meter-class ground-based optical/infrared telescope  with working wavelength at 0.31～28  Nanometer。Its scientific objective range from unraveling nature of dark matter and dark engery、detecting first object of celestial and understanding formation and revolution of Black Hole as well as searching extro-planets etc。