Depth Resolution in Ptychography

Session

Stream 3: 3D+ Image Analysis

Authors

Mr Shengbo You (1)

Affiliations

1. The University of Sheffield

Keywords

Depth Resolution, Ptychography, Multislice

Abstract text

Ptychography processes multiple diffraction patterns collected from adjacent areas of a transmission specimen to obtain the complex transfer function of the specimen. The advantages of ptychography over conventional imaging methods are now widely appreciated [1]. Ptychography has further been extended in order to solve the multiple scattering problem in thick, strongly scattering specimens [2], a method which has been demonstrated at visible light [3], X-ray [4] and electron wavelengths[5]. However, many questions still remain regarding this ‘reverse multislice’ approach. First, there is simply the amount of information that can be reasonably recovered from a single ptychography data set: if we plan to solve for 20 layers of a specimen, each of which we recover in modulus and phase, then our data must be sufficiently diverse to solve for 40 independent greyscale images. A simple ‘number or numbers’ calculation puts a definite limit on this, dependent on the sampling of the ptychographical data set. Secondly, we may wonder whether the conventional depth resolution relationship applies (i.e. that depth resolution should scale proportionally with, where is the semi angle of the probe on the specimen). Thirdly, we may suppose that layers of the specimen that scatter strongly will themselves alter the range of incident angles on layers deeper down into the specimen, thus changing both the lateral and depth resolution in a complicated manner. In this paper, we investigate these relationships via model calculations at various wavelengths. We indicate the limit of the multislice approach at different wavelengths and related specimen scattering strengths.

References

1. Rodenburg, J. and A. Maiden, Ptychography, in Springer Handbook of Microscopy, P.W. Hawkes and J.C.H. Spence, Editors. 2019, Springer International Publishing: Cham. p. 2-2.

2. Maiden, A.M., M.J. Humphry and J. Rodenburg, Ptychographic transmission microscopy in three dimensions using a multi-slice approach. JOSA A, 2012. 29(8): p. 1606-1614.

3. Godden, T., R. Suman, M. Humphry, J. Rodenburg and A. Maiden, Ptychographic microscope for three-dimensional imaging. Optics express, 2014. 22(10): p. 12513-12523.

4. Suzuki, A., S. Furutaku, K. Shimomura, K. Yamauchi, Y. Kohmura, T. Ishikawa and Y. Takahashi, High-Resolution Multislice X-Ray Ptychography of Extended Thick Objects. Physical Review Letters, 2014. 112(5).

5. Gao, S., P. Wang, F. Zhang, G.T. Martinez, P.D. Nellist, X. Pan and A.I. Kirkland, Electron ptychographic microscopy for three-dimensional imaging. Nature Communications, 2017. 8(1): p. 163.