Anamorphic condensing optics for a slitless spectrograph

The use of a slitless spectrograph to obtain the spectra of wakes of hypervelocity projectiles launched in a free flight ballistic range has several advantages. The use of this instrument as a general spectroscopic tool is, however, especially limited for large objects. This is because resolution is determined by final trajectory image size as well as dispersion. The spectral resolution can be improved without altering the desirable properties of the instrument by using an anamorphic system to demagnify the wake image width only. Requirements are given for anamorphic optics used to focus the luminous wakes of hypervelocity projectiles onto the entrance focal plane of a slitless spectrograph. A system currently in use that meets these requirements is described. A comparison of spectra taken with anamorphic and spherical condensing systems is made.