Magnetically focused electronographic image converters for space astronomy applications

A series of magnetically focused, electronographic image converters has been developed for use in far-uv photography and spectroscopy. The use of internal reflecting optics has enabled full advantage to be taken of the very high quantum yields of front-surface alkali halide photocathodes, resulting in over-all detection efficiencies a factor of 10 to 30 higher than similar systems using SC-5 film. An all-reflecting objective spectrograph using this system with Schwarzchild optics has been constructed for obtaining stellar spectra in the 1000-1400-A wavelength range, as well as a similar system based on Schmidt type optics for stellar spectroscopy in the 1230-2000-A wavelength range. Also, smaller Schmidt type instruments have been developed for direct stellar photography in the far uv.