Taken from August 2012 Laser safety newsletter
Through everyday use, optics can come in contact with contaminants such as dust, water, and skin oils. These contaminants increase scatter off the optical surface and absorb incident radiation, which can create hot spots on the optical surface, resulting in permanent damage. Optical components with coatings are particularly susceptible to this sort of damage. There are a select number of proven techniques for cleaning optics. We all know not all optics can be cleaned in the same way or material. Today there are a number of excellent resources on how to clean optics. Below are some of those web site addresses:
http://www.newport.com/Technical-Note-Care-and-Cleaning-of-Optics/141176/1033/content.aspx
www.edmundoptics.com/learning-and-support/…/marketing-literature/?…
http://www.astro-tom.com/tips_and_advice/cleaning_optics.htm
http://www.coherent.com/Service/index.cfm?fuseaction=forms.page&pageID=39
http://www.janostech.com/support/cleaning.html