Hubble Presentations
Spectral Transmission Measurements of Wide Field and Planetary Camera I Optical Components Following HST FSM
Douglas B. Leviton / Code 717.1
Collaborators:
- Ritva Keski-Kuha / Head, Optical Research Section
- Charles Fleetwood / Optical Research Section
- June Tveekrem / Optical Research Section
- Tom French / NSI Optics Function
- Lee Feinberg / HST Project
Overview of Spectral Transmission Measurements: March 28 - June 30, 1994
Rationale
- Opportunity to study effect of exposure of optics to on-orbit environment of HST focal plane.
- Influence handling/processing considerations for next generation HST flight hardware.
Components Measured Over 920-6500 Angstroms Wavelength Range
- Flight and Flight Spare Pickoff Mirrors
- Flight MgF2 Aperture Window
- Flight and Flight Space M1 (detector UV flood) Mirrors
Measurement Approach
- Primary interest below 2000 Angstroms as contamination probe suggest vacuum setup.
- Cleanroom tabletop setup bagged / purged with dry N2 gas to transmit FUV - low cost, fast, clean, keeps suspected contaminants from evaporating.
- Measure HST mirrors relative to reference mirror of known reflectance.
- Technique used to demonstrate COSTAR FUV throughput before FSM.
Conclusions
Substantial Degradations in FUV Transmission for:
- Flight Pickoff Mirror
- Flight MgF2 Aperture Window
Flight M1 Mirror
- Coating peeled at one end on-orbit similar to spare mirror in high temperature thermal vacuum.
- Reflectance changed little in design spectral region.
Flight Spare Optics showed little if any degradation.
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