The optical system of the invention is comprised of a monolithic microlens
array assembly that consists of two groups of microlenses sub-assemblies
having different pitches between the adjacent lenses. A ratio between the
pitches of sub-assemblies is determined by a predetermined relationship
between the parameters of the optical system so that the microlenses of
the first sub-assembly create a plurality of individual intermediate
images arranged side-by-side in a common intermediate plane that are
transferred by the microlenses of the second sub-assembly to the final
image plane in the form of a plurality of identical and accurately
registered images interposed onto each other. This is achieved due to the
aforementioned ratio between the pitches.