Diffractive trifocal lens

A diffractive multifocal lens comprising an optical element having a first diffractive optical surface having a radial surface profile having a diffractive structure comprising a plurality of concentric annular zones concentric with a central zone and assignable, from the outer edge of the central zone to the edge of the lens, as alternating odd and even numbered zones each having a projected surface area that is equal, wherein the optical thickness of the lens changes monotonically within each zone, a distinct step in optical thickness occurs at the junction between the zones, the height of the steps differs between each adjacent zone, and a pattern of step height differences between two or more adjacent zones repeats periodically from the center to the edge of the lens so as to tailor the proportions of the diffraction order efficiencies of at least a zeroth, positive first, and positive second, diffractive order of the radial surface profile of the optical element, wherein the lens has a radial phase profile, of the optical phase change introduced by the diffractive structure, and elements of the radial phase profile within each of the concentric annular zones have a sawtooth shape, comprising a sharp peak having a leading edge that rises from a first value normalized to zero, gradually to a peak value, and a trailing edge that falls abruptly from the peak value back to the first value.