ACHROMATIC FOURIER TRANSFORMING PROPERTIES OF A SEPARATED DIFFRACTIVELENS DOUBLET - THEORY AND EXPERIMENT

The strong chromatic distortion associated with diffractive optical el ements is fully exploited to achieve an achromatic optical Fourier tra nsformation under broadband point-source illumination by means of an a ir-spaced diffractive lens doublet. An analysis of the system is carri ed out by use of the Fresnel diffraction theory, and the residual seco ndary spectrum (both axial and transversal) is evaluated. We recognize that the proposed optical architecture allows us to tune the scale fa ctor of the achromatic Fraunhofer diffraction pattern of the input by simply moving the diffracting screen along the optical axis of the sys tem. The performance of our proposed optical setup is verified by seve ral laboratory results. (C) 1998 Optical Society of America.