The diffractive-phase axicon can convert the Gaussian-profile beam int
o axial uniform intensity distribution with long focal depth and high
lateral resolution. Two types of phase-retardation functions for the n
onuniform-illuminating axicon are derived in terms of the ray tracing
and the geometrical law of energy conservation. Based on the general t
heory of the amplitude-phase retrieval in optical system and the itera
tion algorithm, the optimization design of the phase distribution of t
he diffractive-phase axicon can be achieved. The simulation calculatio
ns show that the new approach may successfully offer the design of the
desired diffractive-phase axicon with long focal depth and high later
al resolution. A comparison of the performances of the holographic axi
con with the phase-retardation functions from the geometrical optics p
rediction and the diffractive-phase axicon designed by the new approac
h is also presented.