CHROMOSPHERIC HELIUM IMAGING PHOTOMETER (AN INSTRUMENT FOR HIGH TIME CADENCE 1083-NM WAVELENGTH SOLAR OBSERVATIONS)

The scientific motivation, design criteria, and specifications for a n ew ground-based instrument to observe the Sun in the He I 1083-nm spec tral line is described. The instrument employs a liquid-crystal tunabl e Lyot-type spectral filter and an array detector that allows the full solar disk to be observed with a time cadence of minutes. We describe the telescope's optical and mechanical features and discuss computer interface and data-reduction procedures employed. Instrument performan ce during the initial year of operation of the telescope at its high-a ltitude site is summarized. (C) 1998 Optical Society of America.