1. An optical imaging system for obtaining a high-resolution image of an observation area from a plurality of low-resolution images thereof, said system comprising: a Cassegrain-type objective for forming said low-resolution images, said objective comprising a primary mirror defining a concave optical surface and a secondary mirror disposed coaxially with said primary mirror, said secondary mirror having a mirror plane and defining a convex optical surface therealong; a focal plane array generally disposed at a focal plane of said Cassegrain-type objective for detecting said low-resolution images therefrom; and a microdisplacement mechanism for pivoting said secondary mirror about first and second orthogonal axes in said mirror plane to displace in a leveraged manner said low-resolution images along the focal plane array, so that combining said low-resolution images yields said high-resolution image.