Compact resonance absorption spectrometer to monitor the profile of the solar He 58.4 nanometer line

A miniature resonance absorption spectrometer is able to perform a routine monitoring in space of the line profile and intensity of the He i resonance line from the solar disk with a time resolution of about 1 min and a spectral resolution of 10(5). It consists of a predispersive spectrometer incorporating a helium gas absorption cell. The instrument has been designed to meet a small size and weight. It was tested on a rocket flight in June 1976. The construction, principles of operation, and laboratory calibration of the instrument are presented. Its capability to resolve details of the order of 0.3 pm FWHM and its sensitivity to the intensity of line wings three order of magnitudes fainter than the peak of the line have been established by laboratory investigation.