Abstract
An infrared imaging lens that produces beams with long focal depth whilst preserving the entire aperture for full light capturing and high transverse resolution is presented. It is a diffractive optical element that generates a long range of pseudo-non-diffractive rays. The design technique is based on the conjugate-gradient algorithm. The surface relief pattern was generated on a thick film photoresist and then the pattern was transferred to germanium substrate. Preliminary experimental results demonstrated four times improvement in depth of focus at 10.6 m wavelength.
