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Optical Mirror Cleaning Procedures

General Cleaning Procedures for Optical Reflectors

Electroformed reflectors are optical elements used in various systems and environments.

Applications range from motion picture projectors, stage lights, and searchlights, to microlithography illumination systems and medical or scientific instruments.

Contamination of the reflective surface occurs in a multitude of ways. The contaminant may be as simple as dust from a laboratory atmosphere or as severe as stains and water spots from outdoor use. It can also result from photopolymerization of vapors by the ultraviolet irradiance from the lamps.

Cleaning must begin with an assessment of the nature of contamination, mitigated by the type of surface to be cleaned. Cleaning involves a sequence of operations which may include all of the following, or optionally; steps may be omitted if considered superfluous based upon the initial assessment.

Methods for Cleaning

  • Dusting to remove particulate accumulation using compressed gas, or wiping with a soft cloth or a soft bristle brush.
  • Flushing with aromatic, aliphatic, or aqueous solvents to remove soluble adherents.
  • Scouring with an aqueous slurry of precipitated chalk or other mild abrasive.
  • Washing with a soft cloth and a solution consisting of 600 ml of deionized water, 400 ml isopropanol and 5 ml of a non-ionic detergent solution such as Joy.
  • Rinsing with a primary alcohol or acetone.
  • Drying with a compressed gas stream or soft cloth.

Precautions

  • Whenever possible, avoid contact with metal surfaces which do not have protective overcoats with anything except liquids or gasses.
  • Allow reflectors to cool before cleaning.
  • Wear protective eyewear and if solvents are used in a closed environment, suitable respirators are recommended.

Approved Cleaning Materials

    • Solvents
      • Aliphatic: methanol, isopropanol, ethanol, acetone.
      • Aqueous: distilled water, deionized water.
    • Gasses
      • Clean, dry, filtered air.
      • Compressed nitrogen.
      • Laboratory air from a bulb syringe.
    • Cloths.
      • Webril Wipes.
      • Laundered birdseye weave diapers.
      • Surgical cotton.
    • Scouring compounds.
      • Precipitated chalk.
      • Precipitated barium sulfate.
      • 0.1 micron aluminum oxide polishing compound.

 

The chart below shows the recommended cleaning procedures for reflectors with a specific coating. It is extremely important that you know which coating your reflector has prior to cleaning.

Cleaning Procedures for Optical Mirrors

  RhAlAuAgAQAFEFERDCC
Dusting
Comp. GasXXXXXXXXX
Soft ClothXXXXXX
BrushXXX
Flushing
AliphaticXXXXXXXXX
AqueousXXXXXXXX
ScouringXX
WashingXXXXXXX
Rinsing
AlcoholXXXXXXXXX
Drying
Comp. GasXXXXXXXXX
ClothXXXXXX
** This Chart Displays Cleaning Procedures for Optical Mirrors with a Specific Coating

These recommendations are only general guidelines and Optiforms is not liable for any damage caused during a cleaning operation. Please use caution when cleaning your reflectors.