Modification of diffraction pattern of a slit using polarized light having variable state of polarization

A planar liquid crystal (LC) cell is developed in which two photo-alignment layers have been illuminated with respectively a horizontal and a vertical diffraction pattern of interfering left- and right-handed circularly polarized light.

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Variable Angle Spectroscopic Ellipsometry (VASE) for the Study of Ion-Beam and Growth-Modified Solids

MRS Proceedings ◽

10.1557/proc-93-203 ◽

1987 ◽

Vol 93 ◽

Cited By ~ 12

Author(s):

John A. Woollam ◽

Paul G. Snyder ◽

M. C. Rost

Keyword(s):

Ion Beam ◽

Polarized Light ◽

Stepper Motor ◽

Angle Of Incidence ◽

Wide Range ◽

State Of Polarization ◽

Linearly Polarized ◽

Variable Angle Spectroscopic Ellipsometry ◽

The University ◽

Elliptically Polarized

In the most commonly used form of ellipsometry, a monochromatic collimated linearly polarized light beam is directed at an angle φ to the normal of a sample under study. The specularly reflected beam is, in general, elliptically polarized, and the state of polarization is analyzed using a second polarizer and photodetector.1 Figure 1 shows a schematic of the rotating analyzer automated spectroscopic ellipsometer used at the University of Nebraska. The angle of incidence can be set over a wide range of angles, with a precision and repeatability of ±0.01 angular degrees. A computer controls the monochromator, the azimuth of a stepper motor driven polarizer, a shutter, and the digitization of the detector signal. There are several other schemes used for acquiring ellipsometric data, and these are discussed in several sources.

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Instantaneous Spatial Phase-Stepping Methods for Phase-Measuring Interferometry and Photoelasticity

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.326-328.39 ◽

2006 ◽

Vol 326-328 ◽

pp. 39-42

Author(s):

Satoru Yoneyama ◽

M. Mizuhara ◽

H. Kikuta ◽

K. Moriwaki

Keyword(s):

Polarized Light ◽

Stokes Parameters ◽

Single Camera ◽

Single Image ◽

Optical Elements ◽

Multiple Exposures ◽

Phase Stepping ◽

State Of Polarization ◽

Polarization Interferometer ◽

Subsequent Phase

This paper demonstrates instantaneous phase-stepping and subsequent phase analysis methods for interferometry and two-dimensional photoelasticity. The camera that has a pixelated form-birefringent micro-retarder array acquires phase-stepped fringes in a single camera frame. Then, the distributions of Stokes parameters that represent the state of polarization are calculated from a single image. In the case of the polarization interferometer, the phase difference of the two orthogonally polarized light beam can be easily determined from the Stokes parameters. On the other hand, the phase distributions of the isochromatics and the isoclinics are obtained in the case of the photoelasticity. It is emphasized that this method is applicable to real-time inspection of optical elements as well as the study of the mechanics of time-dependent materials because multiple exposures are unnecessary for sufficient data acquisition in the completion of data analysis.

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High Voltage Electron Microscopy of Ion-Milled Dental Enamel

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100050317 ◽

1974 ◽

Vol 32 ◽

pp. 60-61

Author(s):

L. D. Ackerman ◽

S. H. Y. Wei

Keyword(s):

Electron Microscopy ◽

High Voltage ◽

Third Molar ◽

Polarized Light ◽

Dental Enamel ◽

Longitudinal Section ◽

Ion Milling ◽

High Voltage Electron Microscopy ◽

Voltage Electron ◽

High Voltage Electron

Mature human dental enamel has presented investigators with several difficulties in ultramicrotomy of specimens for electron microscopy due to its high degree of mineralization. This study explores the possibility of combining ion-milling and high voltage electron microscopy as a means of circumventing the problems of ultramicrotomy.A longitudinal section of an extracted human third molar was ground to a thickness of about 30 um and polarized light micrographs were taken. The specimen was attached to a single hole grid and thinned by argon-ion bombardment at 15° incidence while rotating at 15 rpm. The beam current in each of two guns was 50 μA with an accelerating voltage of 4 kV. A 20 nm carbon coating was evaporated onto the specimen to prevent an electron charge from building up during electron microscopy.

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Analysis of electron-diffraction intensity profiles using a photodiode-array detection system

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100075403 ◽

1983 ◽

Vol 41 ◽

pp. 322-323

Author(s):

J. B. Warren

Keyword(s):

Electron Diffraction ◽

Diffraction Pattern ◽

Detection System ◽

High Energy ◽

Photographic Emulsion ◽

Diffraction Intensity ◽

Silicon Photodiode ◽

Photodiode Array Detection ◽

Analog To Digital ◽

Photodiode Array

Electron diffraction intensity profiles have been used extensively in studies of polycrystalline and amorphous thin films. In previous work, diffraction intensity profiles were quantitized either by mechanically scanning the photographic emulsion with a densitometer or by using deflection coils to scan the diffraction pattern over a stationary detector. Such methods tend to be slow, and the intensities must still be converted from analog to digital form for quantitative analysis. The Instrumentation Division at Brookhaven has designed and constructed a electron diffractometer, based on a silicon photodiode array, that overcomes these disadvantages. The instrument is compact (Fig. 1), can be used with any unmodified electron microscope, and acquires the data in a form immediately accessible by microcomputer.Major components include a RETICON 1024 element photodiode array for the de tector, an Analog Devices MAS-1202 analog digital converter and a Digital Equipment LSI 11/2 microcomputer. The photodiode array cannot detect high energy electrons without damage so an f/1.4 lens is used to focus the phosphor screen image of the diffraction pattern on to the photodiode array.

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Light Optical Diffraction Studies of Macromolecular Ultrastructure

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010006828x ◽

1970 ◽

Vol 28 ◽

pp. 258-259

Author(s):

Glen B. Haydon

Keyword(s):

High Resolution ◽

Diffraction Analysis ◽

Diffraction Pattern ◽

Electron Micrographs ◽

Optical Diffraction ◽

Electron Micrograph ◽

Its Analysis ◽

Resolution Electron ◽

Diffraction Patterns

Analysis of light optical diffraction patterns produced by electron micrographs can easily lead to much nonsense. Such diffraction patterns are referred to as optical transforms and are compared with transforms produced by a variety of mathematical manipulations. In the use of light optical diffraction patterns to study periodicities in macromolecular ultrastructures, a number of potential pitfalls have been rediscovered. The limitations apply to the formation of the electron micrograph as well as its analysis.(1) The high resolution electron micrograph is itself a complex diffraction pattern resulting from the specimen, its stain, and its supporting substrate. Cowley and Moodie (Proc. Phys. Soc. B, LXX 497, 1957) demonstrated changing image patterns with changes in focus. Similar defocus images have been subjected to further light optical diffraction analysis.

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Electron Diffraction Analysis of Microtwin Structures in Regrown (III) Silicon

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100054765 ◽

1982 ◽

Vol 40 ◽

pp. 460-461

Author(s):

P. Ling ◽

R. Gronsky ◽

J. Washburn

Keyword(s):

Electron Diffraction ◽

Ion Implantation ◽

Diffraction Analysis ◽

Diffraction Pattern ◽

Direct Consequence ◽

The Other ◽

Electron Diffraction Analysis ◽

Defect Microstructures ◽

Ion Implanted

The defect microstructures of Si arising from ion implantation and subsequent regrowth for a (111) substrate have been found to be dominated by microtwins. Figure 1(a) is a typical diffraction pattern of annealed ion-implanted (111) Si showing two groups of extra diffraction spots; one at positions (m, n integers), the other at adjacent positions between <000> and <220>. The object of the present paper is to show that these extra reflections are a direct consequence of the microtwins in the material.

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Video-Enhanced Microscopy--Better Visibility of Plant Cell Structures

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100053589 ◽

1982 ◽

Vol 40 ◽

pp. 182-185

Author(s):

N.S. Allen ◽

R.D. Allen

Keyword(s):

Diffraction Pattern ◽

Theoretical Basis ◽

Numerical Aperture ◽

Gain Control ◽

Control Unit ◽

Camera Control ◽

Variable Gain ◽

Contrast Method ◽

Fine Detail ◽

Cell Structures

Various methods of video-enhanced microscopy combine TV cameras with light microscopes creating images with improved resolution, contrast and visibility of fine detail, which can be recorded rapidly and relatively inexpensively. The AVEC (Allen Video-enhanced Contrast) method avoids polarizing rectifiers, since the microscope is operated at retardations of λ/9- λ/4, where no anomaly is seen in the Airy diffraction pattern. The iris diaphram is opened fully to match the numerical aperture of the condenser to that of the objective. Under these conditions, no image can be realized either by eye or photographically. Yet the image becomes visible using the Hamamatsu C-1000-01 binary camera, if the camera control unit is equipped with variable gain control and an offset knob (which sets a clamp voltage of a D.C. restoration circuit). The theoretical basis for these improvements has been described.

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Convergent Beam Electron Diffraction

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100070072 ◽

1978 ◽

Vol 36 (3) ◽

pp. 304-315

Author(s):

G. Lehmpfuhl

Keyword(s):

Electron Diffraction ◽

Diffraction Pattern ◽

Crystal Surface ◽

Diffraction Spot ◽

Crystal Thickness ◽

Large Area ◽

Electron Microscopic ◽

Additional Information ◽

Microscopic Investigations

Introduction In electron microscopic investigations of crystalline specimens the direct observation of the electron diffraction pattern gives additional information about the specimen. The quality of this information depends on the quality of the crystals or the crystal area contributing to the diffraction pattern. By selected area diffraction in a conventional electron microscope, specimen areas as small as 1 µ in diameter can be investigated. It is well known that crystal areas of that size which must be thin enough (in the order of 1000 Å) for electron microscopic investigations are normally somewhat distorted by bending, or they are not homogeneous. Furthermore, the crystal surface is not well defined over such a large area. These are facts which cause reduction of information in the diffraction pattern. The intensity of a diffraction spot, for example, depends on the crystal thickness. If the thickness is not uniform over the investigated area, one observes an averaged intensity, so that the intensity distribution in the diffraction pattern cannot be used for an analysis unless additional information is available.

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