Science Astronomical instrumentation, interferometry, adaptive optics, interests: site testing, radial velocities, binary and multiple stars. Achievements: 1981: Interferometric binaries ζ Dra and ι Lyr discovered 1992: The absence of sub-stellar companions in spectroscopic binaries (“brown-dwarf desert”) 1995: Spectroscopic binary with the highest eccentricity, 0.9754 1997: Multiple Star Catalog (updated in 2010 and 2017). 1997: First instrument to monitor turbulence outer scale, GSM 2000: Fourier theory of multi-conjugate adaptive optics 2002-08: New turbulence profiler, MASS 2004: Theory of ground-layer adaptive optics 2006: All close spectroscopic binaries are triple 2006-09: Development of lunar scintillometer for site testing 2007-17: Speckle-interferometry at 4m telescopes, new binaries, orbits 2009-13: SAM AO system completion 2010-12: Development of CHIRON spectrograph.