Surface properties of photoablated thermostable polymers are considerably different from those of original, unexposed ones, and of mercury UV lamp exposed surfaces. They also depend on the laser exposure conditions. This paper reports such non-linear phenomena observed on polymer surfaces, caused by excimer laser exposures, like increased hydrophilicity of polymer surfaces, imagewise wetting and metallizations, and new metal compound formations on laser exposed polymer films. Because these features are limited to polymer films with high glass transition temperature, like polyimides and poly(phenylquinoxaline), photo-mechanical effects may be important. In some cases, new interfacial reactions appear between exposed polymer surfaces and deposited metal films. Swelling of polyimide in pre-photoablation irradiation is discussed.