On-Orbit Performance of the HST Optical Telescope Assembly

In evaluating the performance of the Hubble Space Telescope, much attention has been directed to the source of spherical aberration in the primary mirror and its impact on mission performance. However, other characteristics of both the primary and secondary mirrors, such as other low-order Zemike aberrations, mid-spatial frequency ripple, and micro-roughness merit examination since they too are crucial to image quality and straylight performance. Performance predictions using ground metrology data agree with an assessment of the on-orbit image quality based on phase retrieval results using Wide Field/Planetary Camera (WF/PC) and Faint Object Camera (FOC) images together with Wavefront Sensor (WFS) and Fine Guidance Sensor (FGS) data.