After purchasing an optical component, exercising proper care can maintain its quality and extend its usable lifetime. Choosing the proper cleaning supplies and using the proper techniques are as important as cleaning the component itself. Improper cleaning practices can damage polished surfaces or specialized coatings that have been used on a substrate or lens. Always check with the manufacturer of the component to determine proper care and cleaning procedures.

Materials to be used when cleaning optics

Materials used for cleaning most optical components include pressurized gas (filtered dry nitrogen), lint-free lens tissue, mild soap, lint-free cotton swabs, lint or powder-free gloves and an organic solvent, such as reagent-grade isopropyl alcohol, reagent-grade acetone, or lens cleaning solution. The following are general guidelines but, because results differ, there are no guarantees.

Lenses

Dust is the most common contaminant and can usually be removed using pressurized gas. If more cleaning is necessary, hold the lens in lens tissue and apply a few drops of reagent-grade acetone or lens cleaning solution. Slowly turn the lens while applying pressure in the center and working outward, to pull dirt off the lens instead of redistributing it on the surface. Fingerprints on a coated lens should be cleaned as soon as possible to avoid staining or damaging the optic. Larger dirt particles, however, should be removed with a dust-free blower before attempting to clean the optic with lens tissue. Larger particles trapped under the cloth will scratch the surface you are attempting to clean. If the lens is still dirty after using acetone - for instance, if the oil was just redistributed and not cleaned off the optic - then a mild soap solution can be used to gently wash the lens. Repeat the procedure with acetone to eliminate streaks and soap residue.

Mirrors and Larger Optics

After blowing off dirt and dust with pressurized gas, the drag method of cleaning can be used to remove fingerprints or other contaminants. In the drag method, lens tissue saturated with reagent-grade isopropyl alcohol or reagent-grade acetone is slowly dragged across the surface. If done correctly, the solvent will evaporate uniformly without leaving streaks or spots. Bare metallic coatings are delicate and cannot be cleaned in this manner. Dirt and fingerprints will permanently damage a bare metal-coated mirror, so preventive measures should be taken to prolong the lifetime of the coating.

Micro-Lenses

These lenses may also be cleaned using acetone but, due to their extremely small size, they require special handling and care. Delicate tweezers may be used to securely hold a micro-lens by its edge, or a vacuum pick-up tool may be used.