Imaging spectrometer for high resolution measurements of stratospheric trace constituents in the ultraviolet

A high resolution spectrometer has been developed for studies of minor constituents in the middle atmosphere at ultraviolet wavelengths. In particular, the instrument is intended for observations of upper stratospheric U V bands. The spectrometer has a slit width of 0.08 A obtained by means of an echelle grating and a cross-disperser grating. The image plane detector is an intensified charge coupled device consisting of a high gain proximity focused image intensifier that is fiber optically coupled to a 2-D CCD array. An instantaneous bandwidth of 9.2 A is resolved across 488 pixels at 0.018 A/pixel, permitting simultaneous acquisition of multiple lines of selected OH bands and the neighboring background. The spectrometer and the approach have been successfully demonstrated as a technique for measuring the concentration of OH on two high altitude balloon flights. We report the instrument design and its achieved performance.