With the development in freeform technology, it has now become more and more
feasible to use freeform surfaces in real system designs. While the freeform
surfaces helping optical designers achieve more and more challenging system
features, the methods for multiple freeform implementations are still
underdeveloped. We therefore investigate strategies to use freeform surfaces
properly in imaging optical systems with one Scheimpflug system and one
lithographic system. Based on the studies of the influences of the freeform
normalization radius, freeform order and system eccentricity, the methods of
determining the optimal location for implementing one freeform surface are
discussed. Different optimization strategies to optimize two freeform surfaces
are discussed to compare their resulting influences on the system performance.
On top of that, ways to implement more than one freeform surface in the optical
system is also investigated. In the end, a workflow is presented as guidance
for implementing multiple freeform surfaces with respect to system aberration
constitutions