Coherent diffraction imaging methods enable imaging beyond lens-imposed
resolution limits. In these methods, the object can be recovered by minimizing
an error metric that quantifies the difference between diffraction patterns as
observed, and those calculated from a present guess of the object. Efficient
minimization methods require analytical calculation of the derivatives of the
error metric, which is not always straightforward. This limits our ability to
explore variations of basic imaging approaches. In this paper, we propose to
substitute analytical derivative expressions with the automatic differentiation
method, whereby we can achieve object reconstruction by specifying only the
physics-based experimental forward model. We demonstrate the generality of the
proposed method through straightforward object reconstruction for a variety of
complex ptychographic experimental models.Comment: 23 pages (including references and supplemental material), 19
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