An optical element (1) made of a material that is transparent to
wavelengths in the UV region, which optical element (1) includes an
oleophobic coating (6, 7) outside of its optically free diameter whose
disperse component of the surface energy is preferably 25 mN/m or less,
particularly preferably 20 mN/m or less, in particular 15 mN/m or less.
In addition or as an alternative, the optical element (1) within its
optically free diameter comprises an oleophilic coating (9b, 9c) that is
transparent to wavelengths in the UV region, with the disperse component
of the surface energy of this coating preferably being more than 25 mN/m,
particularly preferably more than 30 mN/m, in particular more than 40
mN/m. The optical element may be provided in an arrangement in which it
dips at least partially into an organic liquid.