GENERAL ASPHERE-CONIC CONFORMAL OPTICAL WINDOWS

摘要

An optical system (26) includes a window (24) made of a curved piece of a transparent material having an inner surface (28) and an outer surface (30). The inner surface (28) has a nominal inner surface shape defined by a first conicoidal relationship, and the outer surface (30) has a nominal general aspheric surface shape. The optical system (26) also typically includes a sensor (32) and an optical train (36) on the side of the inner surface (28) of the window (24). The accuracy of the shape of the inner surface (28) is tested by directing a coherent light beam through a remote focus (54) of the inner surface (28), reflecting the light beam from the inner surface (28) toward an adjacent focus (52) of the inner surface (28), reflecting the light beam from a spherical reflector (60) at the adjacent focus (52) of the inner surface (28) and back toward the inner surface (28), reflecting the light beam from the inner surface (28) back toward the remote focus (54), and interferometrically comparing the reflected beam arriving at the remote focus (54) with a reference beam.