Be sure to perform the following actions when possible:

• If you do not know how to clean a surface, ask before touching it.
• Be aware of the health and safety aspects of optical materials and cleaning solvents when handling them.
• Always hold optics on their edges or non-optical surfaces.
• Always use an air duster as a first step when cleaning optics.
• When removing particles with the canned dry air duster, assure that a gas coming out of the canister and not liquid drops.
• After each cleaning process, always make a visual inspection (use a magnifying glass or loupe if necessary) to see if the surface is clean.
• Keep the optical elements in a restricted-access area to prevent handling by untrained and unauthorized personnel.
• If the cleaning process must be repeated, use a new lens paper or tissue (always immersed with cleaning solvent).
• All personnel responsible for cleaning optical elements should read the relevant material safety data sheets (MSDS); the MSDS should be made available by a supervisor or website—they are free to distribute.

Heed the following warnings:

• Never clean optical glass without gently blowing or brushing away smalldust particles first.
• Do not clean a surface with any sort of dry tissue, which can scratch even hard coatings.
• Do not rub optical surfaces (coated or uncoated).
• Never put optics on hard and rough surfaces.
• Do not touch optical surfaces with bare hands.
• Do not re-use used cleaning paper or tissue.
• Do not use any sort of tissue on bare, metallic coated (aluminum, gold) or uncoated (aluminum when used as a mirror after a diamond-turning process) because it will create scratches. Use a cotton swab and solvent suitable for cleaning bare materials to remove localized specks.
• Do not clean plastic elements with cleaning solution that might damage the surfaces. Check out what cleaning solution fits cleaning the plastic element.
• Do not use a canned dry air duster on elements that are sensitive to thermal shock (e.g., CaF2). Be aware of the limitation of using canned dry with some materials.

*LENS TISSUES AND OTHER ACCESSORIES AND CLEANING MATERIALS ARE INEXPENSIVE COMPARED TO THE PRICE OF AN OPTICAL ELEMENT. INSPECT OPTICS FOR DUST AND STAINS BY HOLDING THEM NEAR A BRIGHT, VISIBLE-LIGHT SOURCE. DIFFERENT VIEWING ANGLES CAN DISTINGUISH SCATTERING FROM DUST AND STAINS.