We report on the design and fabrication of novel diffractive phase elements that reconstruct distinct intensity patterns in the far-field on illumination with two specific wavelengths. The elements contain deep surface-relief structures that represent phase-delays of greater than 2p radians. The design process incorporates a modified version of the iterative Fourier transform algorithm. A 16 phase-level element for dual wavelength (blue and red) operation, with high diffraction efficiency, is demonstrated experimentally. © 1997 Optical Society of America.
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|Published - Jul 1997