1. Reflective Systems Naomi Pequette
OSLO
Reflective Systems
Naomi Pequette

2. 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)

3. 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)

4. Hubble Ray Trace

5. 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

6. 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

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

8. Ruining the Hubble 2
Ideal Hubble Design
Actual Hubble Design

9. Image from apod.nasa.gov