Interferometric measurement of the optical phase distribution for Fresnel diffraction by a straightedge

Our analysis is based on the pure phase distribution equations of the Fresnel diffraction of an amplitude grating. Suppose P and M are positive integers which have no common divisor and 1/M is the opening ratio of the amplitude grating. Characteristics of the pure distributions are analysed. For instance at the fractional P/2M Talbot distance and (1-P/2M) Talbot distance, the amplitudes of the Fresnel diffraction field of the grating are the same while the phases are opposite. As an example we design two Talbot illuminators which phase distributions occur respectively at the fractional P/2M and (1-P/2M ) Talbot distance. Both phase distribution can carry out illumination behind them. Array illumination has important application in information optics

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Simulation of Reconstructed Holographic Images Considering Optical Phase Distribution in Small Liquid Crystal Pixels

IEICE Transactions on Electronics ◽

10.1587/transele.e100.c.1043 ◽

2017 ◽

Vol E100.C (11) ◽

pp. 1043-1046 ◽

Cited By ~ 2

Author(s):

Yoshitomo ISOMAE ◽

Yosei SHIBATA ◽

Takahiro ISHINABE ◽

Hideo FUJIKAKE

Keyword(s):

Liquid Crystal ◽

Phase Distribution ◽

Optical Phase

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Observation of Phase Contrast Images in STEM and CTEM Modes by Using 100 kV Field Emission Electron Gun

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100051967 ◽

1974 ◽

Vol 32 ◽

pp. 390-391

Author(s):

Y. Harada ◽

T. Goto ◽

H. Koike ◽

T. Someya

Keyword(s):

Field Emission ◽

Phase Contrast ◽

Image Formation ◽

Fresnel Diffraction ◽

Experimental Results ◽

Electron Gun ◽

Scanning Microscopy ◽

Emission Electron ◽

Lattice Images

Since phase contrasts of STEM images, that is, Fresnel diffraction fringes or lattice images, manifest themselves in field emission scanning microscopy, the mechanism for image formation in the STEM mode has been investigated and compared with that in CTEM mode, resulting in the theory of reciprocity. It reveals that contrast in STEM images exhibits the same properties as contrast in CTEM images. However, it appears that the validity of the reciprocity theory, especially on the details of phase contrast, has not yet been fully proven by the experiments. In this work, we shall investigate the phase contrast images obtained in both the STEM and CTEM modes of a field emission microscope (100kV), and evaluate the validity of the reciprocity theory by comparing the experimental results.

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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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Simulation of high-resolution annular dark field STEM images

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010013657x ◽

1995 ◽

Vol 53 ◽

pp. 40-41

Author(s):

E. J. Kirkland

Keyword(s):

Electron Beam ◽

Atomic Layer ◽

Fresnel Diffraction ◽

Dark Field ◽

Objective Lens ◽

Image Simulation ◽

Small Probe ◽

Annular Dark Field ◽

Stem Image ◽

Uniform Plane

In a STEM an electron beam is focused into a small probe on the specimen. This probe is raster scanned across the specimen to form an image from the electrons transmitted through the specimen. The objective lens is positioned before the specimen instead of after the specimen as in a CTEM. Because the probe is focused and scanned before the specimen, accurate annular dark field (ADF) STEM image simulation is more difficult than CTEM simulation. Instead of an incident uniform plane wave, ADF-STEM simulation starts with a probe wavefunction focused at a specified position on the specimen. The wavefunction is then propagated through the specimen one atomic layer (or slice) at a time with Fresnel diffraction between slices using the multislice method. After passing through the specimen the wavefunction is diffracted onto the detector. The ADF signal for one position of the probe is formed by integrating all electrons scattered outside of an inner angle large compared with the objective aperture.

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