Novel tricyclic imidyl derivatives, for example those of the formula ##STR1## [n=1 or 2, Y=a bridge member and X=a functional group] are described. The novel tricyclic imidyl derivatives are suitable for the preparation of photocrosslinkable polymers by incorporation into existing polymer chains or by building up the polymer chain from tricyclic imidyl derivatives, according to the definition, with suitable functional groups X by polymerization or polycondensation. The photocrosslinkable polymers obtained by this means can be used, for example, to produce printing plates for the offset printing process and especially as photoresists.