Probe position recovery for ptychographical imaging

Hurst, A C; Edo, T. B.; Walther, T.; Sweeney, F.; Rodenburg, J. M.

doi:10.1088/1742-6596/241/1/012004

Cited by 21 publications

(11 citation statements)

References 5 publications

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“…It may not be possible for Steps 6-8 to converge to a good joint estimate for the linear phase and subaperture translations from the estimates for exit pupil phase and amplitude derived from the earlier steps. Noise in the detected PSFs alters the location of global minimum of the error metric and may add new local minimums, as in [44]. It is also possible to have a PSF whose subaperture translation from its neighbor is so great that the optimizer would have to go up in error metric value before finding this better minimum of the error metric.…”

Section: A Discussionmentioning

confidence: 99%

Ptychography for optical metrology with limited translation knowledge

Moore

Fienup

2016

Appl. Opt.

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We introduce unknown-transverse translation diversity phase retrieval: a ptychographic algorithm for optical metrology when a subaperture is translating through a plane conjugate to the exit pupil in a very poorly known fashion. The algorithm estimates the direction of translation and the distance traveled by the subaperture from one point spread function (PSF) to the next. It also estimates unknown point target motion and rotations of the subaperture between PSF acquisitions from the PSF data.

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Section: A Discussionmentioning

confidence: 99%

Ptychography for optical metrology with limited translation knowledge

Moore

Fienup

2016

Appl. Opt.

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“…Indeed, it is known that cCDI reconstructions are improved in this Fresnel mode [98]. If there are errors in the probe positions, this is very obvious in the Ronchigram, and can be used to coarsely adjust probe position errors, provided only defocus (and not higher order aberrations) are present [99]: in this case the Ronchigram is an undistorted near-field image of the object.…”

Section: Nmmentioning

confidence: 99%

Ptychography

Rodenburg

Maiden

2019

Springer Handbooks

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Ptychography is a computational imaging technique. A detector records an extensive data set consisting of many inference patterns obtained as an object is displaced to various positions relative to an illumination field. A computer algorithm of some type is then used to invert this data into an image. It has three key advantages: it does not depend upon a good-quality lens, or indeed on using any lens at all; it can obtain the image wave in phase as well as in intensity; and it can self-calibrate in the sense that errors that arise in the experimental set-up can be accounted for and their effects removed. Its transfer function is in theory perfect, with resolution being wavelength-limited. Although the main concepts of ptychography were developed many years ago, it has only recently (over the last ten years) become widely adopted. This chapter surveys visible light, X-ray, electron, and EUV ptychography as applied to microscopic imaging. It describes the principal experimental arrangements used at these various wavelengths. It reviews the most common inversion algorithms that are nowadays employed, giving examples of meta code to implement these. It describes, for those new to the field, how to avoid the most common pitfalls in obtaining good quality reconstructions. It also discusses more advanced techniques such as modal decomposition and strategies to cope with 3D multiple scattering. 'STE/XM'. This is because, being optically equivalent to one another, ptychography treats them both identically.Ronchigram: This term is used in the electron literature but rarely in the X-ray imaging literature. It refers to the unscattered beam created by a convergent focused beam in the far-field. This is usually circular in electron microscopy (being the shadow image cast by the condenser aperture). For an X-ray Fresnel zone plate lens it is usually doughnut-shaped because of the central stop required to block undiffracted intensity. If Kirkpatrick-Baez (KB) mirrors are used, it is rectangular. When the probe is defocused from the object plane, it is equivalent to a Gabor in-line hologram.Circles: As a warning to the reader, we remark that the science of ptychography involves lots of diagrams of circles. The probe function (in real space) is often circular, or represented by a circle. Diffraction disks (in reciprocal space) from a crystalline object are circular when a focused lens with an aperture in its back focal plane is used to form the probe. The Fat-H and the trotters are made out of parts of circles. Fourier ptychography and SAP ptychography have their own circular apertures. The modulus constraint in the complex plane is circular. Know which circle is which: they are not all the same! 2) A Brief HistoryThis Chapter is not an historical review. However, for the benefit of those new to the subject, we now make one or two non-essential observations about its history.First -where did the name come from? Ptychography derives from the Greek 'ptycho', meaning to fold. Hoppe and Hegerl [1] introduced it to describe a method ...

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“…Some probe position correction methods were explored. 15,16 These methods require human intervention and are computationally expensive. If the model of positioning error is known, one can use a method developed by Beckers at al., 18 whereas the "annealing approach" 17 uses the trial and error method.…”

Section: Introductionmentioning

confidence: 99%

New method for probe position correction for Ptychography

et al. 2017

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For high resolution imaging, X-rays and electron beams are being used. However, for such a short wavelength, imaging with lenses becomes difficult as lenses absorb a part of radiation and lenses with very low aberrations must be used. Ptychography is a lens-less imaging technique which uses intensity information of the multiple diffraction patterns in the far field. These multiple far field diffraction patterns are generated by an unknown object which is scanned by a localized illuminated spot (probe).Accurate knowledge of initial parameters is important for a good reconstruction of the object. Robustness of the Ptychography Iterative Engine (PIE) has already been studied for inaccurately known initial parameters, where the success of the algorithm was found to be sensitive to the accuracy of the estimate of lateral positions of the probe.We present here a new method to correct the lateral position of the probe with respect to the object. This method is more straightforward to implement than other existing algorithms while comparable accuracy for the lateral position is achieved. Being able to correct the probe positions has positive implication in experiments, in particular at the short wavelength cases. It relaxes the requirement for the experimental set-up.

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Probe position recovery for ptychographical imaging

Cited by 21 publications

References 5 publications

Ptychography for optical metrology with limited translation knowledge

Ptychography for optical metrology with limited translation knowledge

Ptychography

New method for probe position correction for Ptychography

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