Optics development for the SPEAR mission

We describe the development of optics for the SPEAR space-mission to map the far ultraviolet (900-1750 a) sky. The SPEAR spectrometers contain unusual reflective optics to optimize sensitivity to diffuse emission. We describe the manufacture, test and performance of the collecting mirrors: Pyrex parabolic cylinders with a 90 degree off-axis angle. We also describe the development of the diffraction gratings: ellipses of rotation that are holographically-ruled with constant spacing and blazed with ion-beam ablation.