An optical arrangement, in particular a microlithographic projection
printing installation, has in particular a slot-shaped image field or
rotationally non-symmetrical illumination. An optical element (1) is
therefore acted upon in a rotationally non-symmetrical manner by the
radiation of the light source. A compensating light supply device (11, 14
to 19) is optically coupled via the peripheral surface (13) of the optical
element (1) to the latter. It supplies compensating light (16, 12) to the
optical element (1) in such a way that the temperature distribution in the
optical element (1), which arises as a result of cumulative heating of the
optical element (1) with projection light (2) and compensating light (12),
is at least partially homogenized. In said manner image defects induced by
the projection light are corrected.