Dip a cotton bud in some Iso Propyl Alcohol, rub it over the lens of the laser, then blow over the lens with compressed air. This evaporates the Alcohol. Don't do it when the laser is on. If you search Ebay for 'compressed air duster spray can' you can buy , you guessed it, compressed air in a can. For Iso Propyl Alcohol Google 'TMB Electronics Iso Propyl Alcohol', As for cotton buds......ask a woman, they got shit loads of the things.