R. Liu et al., DESIGN OF DIFFRACTIVE PHASE ELEMENTS THAT REALIZE AXIAL-INTENSITY MODULATION BASED ON THE CONJUGATE-GRADIENT METHOD, Journal of the Optical Society of America. A, Optics, image science,and vision., 15(3), 1998, pp. 689-694
We employ the conjugate-gradient method to design diffractive phase el
ements (DPE's) that implement the predefined axial-intensity modulatio
n over a given axial region. We introduce an error function for guidin
g the design of DPE's and for evaluating their performance. Numerical
simulations are carried out for several examples, for instance, the de
sign of the DPE that generates four foci with equal or unequal spacing
between the consecutive foci along the optical axis and the DPE that
produces a sinusoidlike axial-intensity modulation. The obtained resul
ts show that the designed DPE's can satisfactorily match practical req
uirements. (C) 1998 Optical Society of America.