DESIGN OF DIFFRACTIVE PHASE ELEMENTS THAT PRODUCE FOCAL ANNULI - A NEW METHOD

A new optimization method based on the general theory of amplitude-pha se retrieval is proposed for designing the diffractive phase elements (DPE's) that produce focal annular patterns. A set of equations for de termining the phase distribution of the DPE is given. The profile of a surface-relief DPE can be designed with an iterative algorithm. Numer ical calculations are carried out for several examples. A comparison o f the performance of the DPE's designed with the Gerchberg-Saxton algo rithm and the new algorithm is presented. The effect of quantization o f the phase distribution of the DPE's on the results is also investiga ted. The results show that the new algorithm can successfully achieve the design of the DPE's that convert the uniform incident beam into th e focal annular patterns. (C) 1995 Optical Society of America