MULTIFOCAL DIFFRACTIVE ELEMENTS

A method to compute diffractive elements focusing in a set of scaled l ines located in different focal planes along the optical axis is consi dered. A phase nonlinearity is applied to the phase function of a focu sator in a line. It is proved that the selection of the nonlinearity i s reduced to the problem of the phase diffraction grating with preset energy distribution in the orders. Multifocal elements to focus in a s et of scaled lines in a single plane are considered as well.