Mirror Cleaning

LINKS & FILES (Incomplete, redo links)


Since the beginning of the year 2000, we have implemented a program of regular washing (every 6 months) of the primary mirrors of the 4.0-m, 1.5-m and 0.9-m telescopes. The results are so good that we are now planning to aluminize these mirrors every 4 years only (instead of every 2 years up to now). The 4.0-m M1 is washed in-situ with a system of inflatable seals. We are able to peform the operation in a minimum amount of time (typically 2-3 hours at the 4.0-m) without specific engineering time scheduled. Since August 2000, we are also using an IRIS 908RS device to measure scattered and reflected light from the mirrors (the IRIS replaces the Minolta instrument). In August 2000, we have also installed a grounding cable for the 4m M1 coating in the hope to minimize the accumulation of dust by electrostatic attraction.

Besides, we perform fortnightly C02 snow cleaning of the 4.0-m and 1.5-m primary mirrors. The secondary mirrors keep clean much longer and are typically cleaned with CO2 twice per year.


  • Facts summary slide show presented at the 2001 Mirror cleaning and coating conference (Palomar Observatory)
  • Notes taken during the conference (in Spanish)
  • Mirror cleaning with C02
  • IRIS 908RS reflectometer/scatterometer operation manual.
  • Minolta reflectometer instructions for downloading the data to a PC
  • Calibration difficulties between the old data taken with the Minolta and the new data taken with the Iris. See notes at the end of the IRIS 908RS document.
  • Reflectometry at the 4.0-m Victor Blanco telescope
  • Reflectometry at the 1.5-m telescope
  • Reflectometry at the 0.9-m and Schmidt telescopes
  • Reflectivity of Al, Ag and Au. For bare Al coating: 92.1% (470nm), 91.6% (530nm), 90.5% (650nm) and 88.0% (880nm). Data from Hass G., 1965, Applied optics and optical engineering, ed. Kingslake, Academic Press, New York, vol. III, p309
  • Calendar (1975-2001) of aluminizing and washing
  • Washing procedures at smaller telescopes
  • 0.9m washing 5Feb09
  • 1.0m washing Feb09
  • Blanco R & S follow-up (Excel file)
  • 1.3m follow-up November 2009 (PDF file)
  • 1.5m follow-up November 2009 (PDF file)
  • PROMPT Reflectivity Report November 2009 (PDF file)
  • Blanco 4m Reflectivity follow up January 2010 (PDF file)