Achromatic imaging with combinations of holographic and conventional lenses

Abstract

Broadband imaging systems that utilize combinations of holographic lenses can be lightweight and have large apertures. Holographic lenses can be reproduced from a digital master using embossing techniques thus eliminating the high cost of polishing large glass elements. These features are attractive in the visible region and in the infrared where the size of optical elements is limited by available materials. We report a Fresnel-diffraction analysis of a broadband imaging system that consists of three lenses of arbitrary dispersion. A general solution is obtained for the wavelength dependence of the lenses that are required to correct both longitudinal and lateral paraxial chromatic aberration. The solution for the two-lens case is found as an intermediate step and is useful when correction for a single chromatic aberration is desired. From the general solution a specific system configuration is obtained that utilizes holographic elements to produce a well-corrected image in broadband light. An experimental system has been designed using conventional achromats and holographic lenses. Preliminary experiments are reported that demonstrate the performance of this imaging system in both laser and broadband illumination.