Mutifocal diffractive lenses are generally designed with concentric annular zones comprising blazed steps of equal area. Trifocal diffractive lenses differ in the intensity of light that they diffract into each of their three different powers. Usually, this light distribution has been adjusted by varying the step heights of the blazed steps within the annular zones. This invention discloses a trifocal diffractive lens wherein the equal area annular zones are further subdivided into two sub-zones wherein each sub-zone comprises a discrete blazed step. The sub-zones of this invention may be of unequal area. This allows the light distribution at its focal powers to be adjusted by varying not only the step heights of the blazed steps of the sub-zones, but also the relative areas of the sub-zones. The present invention allows for an increased flexibility in the design of multifocal diffractive lenses.
