title: Wave-front design algorithm for shaping a quasi-far-field pattern.
abstract: To design a fully continuous wave-front distribution suitable for focused beam shaping by a deformable mirror, we modify the phase-retrieval algorithm by employing a uniformly distributed phase as a starting phase screen and spatial filtering for the near-field phase retrieved during the iteration process. A special phase unwrapping algorithm is not required to obtain a continuous phase distribution from the retrieved phase since the boundary of the 2pi-phase-jumped region in the designed phase distribution is perfectly closed. From the computational result producing a uniform square beam transformation from a circular defocused beam, this algorithm has provided a fully continuous wave-front distribution with a lower spatial frequency for a deformable mirror. The transformed square beam has a normalized intensity nonuniformity of varsigma(rms) = 0.14 with respect to a desired flat-topped square beam pattern. This beam-shaping method also provides a high energy-concentration rate of more than 98%.
authors.forename: G Y
authors.initials: GY
authors.lastname: Yoon
authors.forename: S
authors.initials: S
authors.lastname: Matsuoka
authors.forename: T
authors.initials: T
authors.lastname: Jitsuno
authors.forename: M
authors.initials: M
authors.lastname: Nakatsuka
authors.forename: Y
authors.initials: Y
authors.lastname: Kato