An optical system comprises a three-mirror anastigmat including a primary mirror, a secondary mirror, and a tertiary mirror positioned to reflect a beam path. Such recording elements exhibit improved humidity keeping and smudge resistance, while maintaining good differential gloss. , by laser welding, to a welding platform. The reconstruction system reconstructs the detected data to generate an image of a subject in the volume of interest. The coating is made from a coating composition comprising solid particles of a release agent different from boron nitride and a binder comprising surface-modified nanoscale solid particles.