Keysight Laser Source Modules User’s Guide 77Cleaning Instructions 5How to clean optical devices which are sensitive to mechanical stress and pressureSome optical devices, such as the Keysight 81000BR Reference Reflector,which has a gold plated surface, are very sensitive to mechanical stress orpressure. Do not use cotton- swabs, soft- tissues or other mechanicalcleaning tools, as these can scratch or destroy the surface.Preferred ProcedureUse the following procedure on most occasions:1 Blow away any dust or dirt with compressed air.Procedure for Stubborn DirtTo clean devices that are extremely sensitive to mechanical stress orpressure you can also use an optical clean polymer film. This procedure istime- consuming, but you avoid scratching or destroying the surface.1 Put the film on the surface and wait at least 30 minutes to make surethat the film has had enough time to dry.2 Remove the film and any dirt with special adhesive tapes.Alternative ProcedureFor these types of optical devices you can often use an ultrasonic bathwith isopropyl alcohol. Only use the ultrasonic bath if you are sure that itwon't cause any damage anything to the device.1 Put the device into the bath for at least three minutes.2 Blow away any remaining liquid with compressed air.If there are any streaks or drying stains on the surface, repeat the cleaningprocedure.