Showing papers by "Adrian C. Newton published in 1970"
TL;DR: In this article, a method for eliminating the astigmatism of a Czerny-Turner spectrograph is described in which the grating is used in divergent illumination.
Abstract: A method for eliminating the astigmatism of a Czerny-Turner spectrograph is described in which the grating is used in divergent illumination. Expressions are given for the distances of the tangential and sagittal astigmatic images from the camera mirror in terms of the separation between the entrance slit and the collimating mirror and the condition for the elimination of astigmatism is derived. These results are compared with ray tracing data for a practical instrument. Experimental tests of spatial and spectral resolution for an f/15 spectrograph of 06 m focal length are given at wavelengths 5461 and 2800 A. Over a spectral range of 100 A centred on 2800 A a spatial resolution along the slit in excess of 50 cycles mm−1 has been achieved for a flat inclined image plane. For the same spectrograph with the grating in collimated light the spatial resolution is only 3 cycles mm−1.
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