Reflective Systems Naomi Pequette OSLO Reflective Systems Naomi Pequette

Hubble Space Telescope OSLO demonstrates the original Ritchey-Chretien design 2 hyperbolic mirrors Design is supposed to eliminate coma, spherical aberration, and provide a larger FOV Produced in such a way that there was 6 waves of spherical aberration (had incorrect conic constant for primary)

The Mirror 2.5m mirror and weighs 748 lbs The reflective coating on the actual mirror was aluminum and over coated with magnesium fluoride (to better reflect UV): the backup mirror (shown) has no coating This mirror was shaped and polished by Eastman Kodak (different from installed mirror)

Hubble Ray Trace

Aberrations in the Ideal Design Shows aberrations as a function of position. RC design suffers from large angle astigmatism: objects far away from the optical axis This design also suffered from positive spherical aberration (paraxial rays bent too much) when the image of off-axis

Aberrations in the Actual Mirror Mirror ground to the wrong shape (2.2 nm too flat on the edges) spherical aberration Main null corrector (measures shape of mirror) was incorrectly assembled and showed had correct shape. 2 other correctors showed spherical aberration…. Correction: relay mirrors in WFPC2 and COSTAR (2 mirrors in light path that were figured to correct for aberration Image from WF/PC showing the light from a star being spread out instead of concentrated in a few pixels

Ruining the Hubble in OLSO Spot diagram with the actual conic constant (-1.01324) Spot diagram with the ideal conic constant (-1.00230) Conic Constants from Allen, The Hubble Space Telescope Optical Systems Failure Report, appendix E

Ruining the Hubble 2 Ideal Hubble Design Actual Hubble Design

Image from apod.nasa.gov