Computer-Free, All-Optical Reconstruction of Holograms Using Diffractive Networks

Aposteriori deblurring of high resolution electron micrographs of weak phase objects can be performed by holographic filters [1,2] which are arranged in the Fourier domain of a light-optical reconstruction set-up. According to the diffraction efficiency and the lateral position of the grating structure, the filters permit adjustment of the amplitudes and phases of the spatial frequencies in the image which is obtained in the first diffraction order.In the case of bright field imaging with axial illumination, the Contrast Transfer Functions (CTF) are oscillating, but real. For different imageforming conditions and several signal-to-noise ratios an extensive set of Wiener-filters should be available. A simple method of producing such filters by only photographic and mechanical means will be described here.A transparent master grating with 6.25 lines/mm and 160 mm diameter was produced by a high precision computer plotter. It is photographed through a rotating mask, plotted by a standard plotter.

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Correlation analysis of radiation damage

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100108210 ◽

1978 ◽

Vol 36 (1) ◽

pp. 214-215

Author(s):

R. Hegerl ◽

A. Feltynowski ◽

B. Grill

Keyword(s):

Electron Microscopy ◽

Independent Random Variables ◽

Optical Parameters ◽

Bright Field Image ◽

Bright Field ◽

Expectation Value ◽

All Optical ◽

Image Element ◽

Stochastic Series ◽

The Common

Till now correlation functions have been used in electron microscopy for two purposes: a) to find the common origin of two micrographs representing the same object, b) to check the optical parameters e. g. the focus. There is a third possibility of application, if all optical parameters are constant during a series of exposures. In this case all differences between the micrographs can only be caused by different noise distributions and by modifications of the object induced by radiation.Because of the electron noise, a discrete bright field image can be considered as a stochastic series Pm,where i denotes the number of the image and m (m = 1,.., M) the image element. Assuming a stable object, the expectation value of Pm would be Ηm for all images. The electron noise can be introduced by addition of stationary, mutual independent random variables nm with zero expectation and the variance. It is possible to treat the modifications of the object as a noise, too.

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Digital phase analysis in interference electron microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100106272 ◽

1988 ◽

Vol 46 ◽

pp. 842-843

Author(s):

S. Hasegawa ◽

T. Kawasaki ◽

J. Endo ◽

M. Futamoto ◽

A. Tonomura

Keyword(s):

Magnetic Field ◽

Electron Microscopy ◽

Phase Distribution ◽

Magnetic Recording Media ◽

Electron Wave ◽

Vector Potentials ◽

Weak Magnetic Fields ◽

Leakage Magnetic Field ◽

Optical Reconstruction ◽

Processing Techniques

Interference electron microscopy enables us to record the phase distribution of an electron wave on a hologram. The distribution is visualized as a fringe pattern in a micrograph by optical reconstruction. The phase is affected by electromagnetic potentials; scalar and vector potentials. Therefore, the electric and magnetic field can be reduced from the recorded phase. This study analyzes a leakage magnetic field from CoCr perpendicular magnetic recording media. Since one contour fringe interval corresponds to a magnetic flux of Φo(=h/e=4x10-15Wb), we can quantitatively measure the field by counting the number of finges. Moreover, by using phase-difference amplification techniques, the sensitivity for magnetic field detection can be improved by a factor of 30, which allows the drawing of a Φo/30 fringe. This sensitivity, however, is insufficient for quantitative analysis of very weak magnetic fields such as high-density magnetic recordings. For this reason we have adopted “fringe scanning interferometry” using digital image processing techniques at the optical reconstruction stage. This method enables us to obtain subfringe information recorded in the interference pattern.

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