zPIE: an autofocusing algorithm for ptychography

Lars Loetgering*, Mengqi Du, Kjeld S.E. Eikema, Stefan Witte

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


An autofocusing algorithm for ptychography is proposed. The method optimizes a sharpness metric that would be observed in a differential interference microscope and is valid for both amplitude and phase modulating specimens. We experimentally demonstrate that the algorithm, based on the extended ptychographic iterative engine (ePIE), calibrates the sample-detector distance with an accuracy within the depth of field of the ptychographic microscope. We show that the method can be used to determine slice separation in multislice ptychography, provided there are isolated regions on each slice of the specimen that do not axially overlap.

Original languageEnglish
Pages (from-to)2030-2033
Number of pages4
JournalOptics Letters
Issue number7
Early online date30 Mar 2020
Publication statusPublished - 1 Apr 2020


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