| 摘要 |
An optical element comprising a plurality of optical zones 10, 20, where at least one of the zones includes at least one noise introducing feature 30, which acts to modulate. The diffractive Fresnel lens may have chromatic homogenising features in one of the rings to reduce chromatic aberration and/or directional homogenising features in one of the zones to improve directional homogeneity. Also claimed is: a method of forming a zone plate with a noise introducing feature 30; a method of adding noise to a zonal optical element with a noise introducing feature 30; a method of homogenising light using a zonal optical element; a method of suppressing or reducing chromatic aberration of non-monochromatic light using a zonal optical element; and a method of modifying the angular and/or intensity characteristics of light with a zonal optical element; where the latter three methods include at least one chromatic homogenising and/or direction homogenising feature. |
