All-optical extended focus imaging system

A lens in conjunction with a multiplexed set of Fresnel lenses (FL) can significantly reduce the sensitivity of an optical system to defocus aberrations. Each FL is considered as a corrective. lens with a slightly different focal length. Thus for a fixed detector plane, there is a set of object planes for which the composite lens provides perfect imaging. The various FLs are multiplexed using code division multiple access procedure. The resulting image is analyzed in this paper. One obtains a significant improvement of depth of field, albeit coupled with a reduction of resolution and image contrast.