A process for making a microlens array or a microlens array masterform
comprises (a) providing a photoreactive composition, the photoreactive
composition comprising (1) at least one reactive species that is capable
of undergoing an acid- or radical-initiated chemical reaction, and (2) at
least one multiphoton photoinitiator system; and (b) imagewise exposing
at least a portion of the composition to light sufficient to cause
simultaneous absorption of at least two photons, thereby inducing at
least one acid- or radical-initiated chemical reaction where the
composition is exposed to the light, the imagewise exposing being carried
out in a pattern that is effective to define at least the surface of a
plurality of microlenses, each of the microlenses having a principal axis
and a focal length, and at least one of the microlenses being an
aspherical microlens.