ABERRATION CORRECTION USING OFF-AXIS HOLOGRAPHY .1. ABERRATION ASSESSMENT

被引：10

作者：

ISHIZUKA, K ^{[1
]}

TANJI, T ^{[1
]}

TONOMURA, A ^{[1
]}

OHNO, T ^{[1
]}

MURAYAMA, Y ^{[1
]}

机构：

[1] HITACHI LTD, ADV RES LAB, JRDC, TONOMURA ELECTRON WAVEFRONT PROJECT, HATOYAMA, SAITAMA 35003, JAPAN

来源：

ULTRAMICROSCOPY | 1994年 / 53卷 / 04期

关键词：

D O I：

10.1016/0304-3991(94)90049-3

中图分类号：

TH742 [显微镜];

学科分类号：

摘要：

In order to carry out aberration correction, the aberration working on each hologram must be estimated. Since it is rather difficult to precisely control aberration coefficients in the experimental stage, we developed a procedure to estimate the working aberration from the hologram itself. In this procedure, the specimen is assumed to be an approximate phase object. Therefore, the amplitude variation of the restored wave should be minimized when the aberration is corrected. We assume a symmetrical aberration function parametrized only by a spherical aberration coefficient and a defocus value. A normalized standard deviation is then calculated from the restored wave for each combination of these parameters. The working aberration is determined from the combination of the parameters giving the smallest standard deviation. This procedure is applied to holograms taken of an amorphous carbon film which can be considered as an approximate phase object. The side-bands of the hologram have information of up to 3.3 nm(-1), and the aberration correction is carried out over this range. The same procedure can be applied in order to correct aberration beyond the Scherzer limit when using crystal specimens.

引用

页码：361 / 370

页数：10

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