The optical element and optical arrangement so that

The invention relates to an optical element (1), comprising: a substrate (2), one on the substrate (2) applied coating (3, 9, 5), wherein the coating (3, 9, 5) comprises: a reflective coating (5b) for the reflection of radiation (4) with a used wavelength is formed (λ The invention also relates to an optical assembly comprising at least such an optical element (1) and at least one device for the thermal manipulation of the optical element (1) having at least one Heizlichtquelle (8) for generating thermal radiation (7).