Cleaning procedure for optics

Optics can be contaminated in many ways. Contamination can be kept to a minimum by returning the optics to their case or by covering the optics for protection from the outside environment. However, even with all these precautions, the optic will eventually accumulate dust, stains or some other form of contamination.
Inspection of Optical Surfaces.
During inspection, all optics must be handled in the cleanest area available (preferably a clean room or within a laminar flow bench). Proper equipment, like powder free clean room gloves or finger cots must be worn at all times to avoid grease and oils from being transferred to the optic. Lens tissue paper, dust free blowers, hemostats, cotton swabs, cotton tips, and reagent
grade acetone and methanol, will all be needed for cleaning optics. The acetone and methanol must be fairly fresh to avoid leaving any marks on the optics. Reagent Grade Isopropyl alcohol can also be used instead of acetone.
There are two ways in which an optic can be evaluated:
i.) If the optic is being used in a laser based system, contamination on the optic might cause the optic to scatter the laser light, thus reducing power and making the optic “glow”.
ii.) An optic can also be visually inspected by holding it below a bright light source and carefully viewing it at different angles. This will cause the light to scatter off the contamination enabling the viewer to see the various stains and dust particles.