OTHER OPTICS IN-SITU WASHING
- Secondary mirrors: telescope looking at horizon, mirror vertical, sealing skirt easy to put around mirror, contact wash. Monthly loss rate is typically R-0.15% and SC+0.10%
- Upward looking field corrector: our Ø0.5m CFADC cell is sealed. Telescope looking at horizon, liquid collection bag attached below cell. Rinse (no contact because sol-gel AR coated) with 100ml bi-distilled water and 50ml isopropyl alcohol in squeeze bottle.
=> do not disregard them. Semi-annual monitoring and annual washing?
=> it is usually not much extra work, in the design phase of ANY large optical component exposed to ambient air, to think about seals to allow easy and safe in-situ washing. Seal retrofit usually possible.