Imaging Hard X-ray Telescope Developments in United States and Europe

The hard X-ray (20 keV up to 1 MeV) energy band is a good window for us to learn the high energy radiation processes in astrophysics. The imaging hard X-ray telescopes provide better resolution and sensitivity for studying hard X-ray astrophysics. In this paper, the recent years developments of imaging hard X-ray telescopes in United States and Europe are introduced, including1) EXITE2-a phoswich imaging hard X-ray telescope designed and operated by Harvard-Smithsonian Center for Astrophysics (CFA);2) EXIST-an imaging hard X-ray all-sky survey, which will be carried by ULDB (EXIST-LITE) or mounted on international space station (EXIST-ISS) in the year of 2010 and 3) HERO-a newly developed hard X-ray optics instrument, built by NASA/MSFC.