Specifies methods of testing of optical instruments and instruments containing optical components, under equivalent conditions, for their ability to resist combined contamination and solar radiation (here, contamination means the contact of optical instruments with corrosive chemical substances). The purpose of testing is to investigate the resistance of an instrument and, in particular, of instrument surfaces, coatings, or synthetic materials, to a short-time exposure to the contamination combined with solar radiation. The tests described are designed for the selection of materials and components for the instruments.