Abstract

At the time that the spherical aberration in the Hubble Space Telescope (HST) primary mirror was discovered, the optics for the second generation Wide Field and Planetary Cameras (WF/PC II) had been completed. Like the first generation cameras, the second generation camera optics, shown in Fig. 1, which were designed at Jet Propulsion Laboratories (JPL), were each Ritchey-Chretien telescopes (with a MgFl field flattening lens) operating at f/12.9 and f/30 respectively. The planned upgrade in the second generation cameras was the incorporation of higher performance detectors. It was quickly realized at JPL that the primary mirror of the HST is imaged at or near the secondary mirrors in the WF/PC cameras and that by replacing only the secondaries the imagery at the camera focal planes could be restored. The aspheric departure of compensating secondaries is less than 2 fringes P-V. Fig. 2 shows the geometrical ray caustic in the region of the HST Cassegrain focus in the as-designed and on-orbit configurations.

© 1994 Optical Society of America