MONOCHROMATIC ALL-SKY SCANNER - A QUANTITATIVE IMAGER OF FAINT ATMOSPHERIC EMISSIONS

Many ground-based studies of the dynamics of the lower thermosphere an d ionosphere have been performed using meridian scanning photometers a nd all-sky cameras. The two instruments strike different balances betw een quality and quantity or sensitivity versus large field of view. A large divergence angle in a wide-angle system requires large bandwidth filters that limit detectability of faint atmospheric emissions that are due to low signal-to-background ratio. All-sky imaging to as low a s 80-deg zenith angle is important in addressing issues such as horizo ntal wavelength of individual waves and size of wave packets in the ne utral atmosphere, and size and dynamics of red arcs and F-layer patche s. A new instrument for remote sensing of the Earth's upper atmosphere and its near-space environment from the ground is described. It affor ds true all-sky imaging at near-monochromatic wavelengths for faint ai rglow and auroral emissions by combining a two-mirror scanner with a z enith-looking photometer. (C) 1997 Optical Society of America.