108 Keysight 81618A/9A and Keysight 81620B/3B/4B/6B/8B Optical Heads User’s Guide5 Cleaning InformationAdditional Cleaning InformationThe following cleaning procedures may be used with other opticalequipment:• How to clean bare fiber ends on page 108• How to clean large area lenses and mirrors on page 108How to clean bare fiber endsBare fiber ends are often used for splices or, together with other opticalcomponents, to create a parallel beam. The end of a fiber can often bescratched. You make a new cleave. To do this:1 Strip off the cladding.2 Take a new soft tissue and moisten it with isopropyl alcohol.3 Carefully clean the bare fiber with this tissue.4 Make your cleave and immediately insert the fiber into your bare fiberadapter in order to protect the surface from dirt.How to clean large area lenses and mirrorsSome mirrors, as those from a monochro mator, are very soft and sensitive.Therefore, never touch them and do not use cleaning tools such ascompressed air or polymer film.Some lenses have special coatings that are sensitive to solvents, grease,liquid and mechanical abrasion. Take extra care when cleaning lenses withthese coatings.Lens assemblies consisting of several lenses are not normally sealed.Therefore, use as little liquid as possible, as it can get between the lensesand in doing so can change the properties of projection.Preferred ProcedureUse the following procedure on most occasions.1 Blow away any dust or dirt with compressed air.Procedure for Stubborn DirtUse this procedure when there is greasy dirt on the lens: