| 摘要 |
<p>The invention provides in particular for an achromatic diffractive diffuser comprising a surface relief diffractive device (180) arranged such that, under illumination by ambient light (6), the diffractive effect serves to provide a uniform achromatic diffuser reflection into a defined viewing zone (14) for observation by an observer (11), and also such that the achromatic diffractive replay of the device has a non-symmetric distribution of diffractive light intensity between positive and negative diffractive order such that the diffractive efficiency in the desired diffractive order is enhanced over that of the undesired order to provide an enhanced brightness achromatic device.</p> |
