If you suspect a contamination of your optics and want to clean them from dust: Do not use duster spray to clean any optics otherwise condensed gas will contaminate the optics. Externally attached optics should be cleaned as instructed by the respective manufacturer. Generally, the best way is to use optical paper and isopropyl alcohol.
The re-certification procedure of the BeamSquared device includes the cleaning of all optics and mirrors inside the product. Based on a regular use of the BeamSquared, Ophir suggests a re-certification once a year. A re-certification of the BeamSquared system not only reassures you on the performance of your camera, it prevents any issues such as outlined above. The re-certification process will correct bad pixels when possible, clean the imager, and certify that the device is still performing to factory specifications. Any necessary changes, repairs or replacements will be detected upfront and action will be taken after coordination with the customer.