Considering the effectiveness of 3rd order aberration theory from the view point of sine condition in the presence of spherical aberration

Optik ◽  
2013 ◽  
Vol 124 (20) ◽  
pp. 4159-4163
Author(s):  
Masato Shibuya
Keyword(s):  
Spherical Aberration ◽  
View Point ◽  
Aberration Theory

Application of a Superconducting Cryo-Electron Microscope to the Physics and Material Science of Ceramics

1990 ◽  
Vol 48 (1) ◽  
pp. 82-83
Author(s):  
Masaaki Sugiyama ◽  
Hiroshi Kubo ◽  
Kurio Fukushima
Keyword(s):  
Electron Microscope ◽  
Material Science ◽  
Spherical Aberration ◽  
Microstructural Characterization ◽  
West Germany ◽  
Objective Lens ◽  
View Point ◽  
Cross Sectional ◽  
New Type ◽  
Free Environment

Superconducting cryo-electron microscope (SCM) has been mainly applied to the biological field, due to the advantages such as reduction of radiation damage and the possibility of a perfectly contamination-free environment. From the material science view point, microstructural characterization at liquid helium temperature is an attractive technique. In this presentation, some topics concerning the low temperature physics of ceramics will be discussed on the basis of the data obtained using high resolution SCM.The principle of the superconducting lens (SCL) was first described by the Dietrich Group of Siemens AG, West Germany in 1966, following this by fitting a SCL as the objective lens of a 200kV electron microscope, a new type of electron microscope, the JEM-2000SCM, was developed by JEOL LTD, Japan. A detailed cross-sectional diagram of the SCL is shown in Fig.1. A spherical aberration coefficient of 1.2mm was obtained.

The Design and Implementation of Matlab Simulation in Optical Aberration

2014 ◽  
Vol 575 ◽  
pp. 541-544
Author(s):  
Zhen Hua Lao
Keyword(s):  
Programming Language ◽  
Spherical Aberration ◽  
Simulation Algorithm ◽  
Matlab Simulation ◽  
Parametric Variation ◽  
Design And Implementation ◽  
Optical Aberration ◽  
Aberration Theory

In the teaching of optical courses, the aberration knowledge is abstract and students often feel it difficult to understand. According to this phenomenon, a new simulation algorithm, which is based on the analysis of chromatic and spherical aberration theory, is described in this paper; with Matlab as the programming language, the emulation programs of chromatic and spherical aberration are designed and the simulation figures are presented, from which the effect of parametric variation on aberration can be shown vividly and intuitively. And for students, this will be helpful in the mastery of aberration knowledge.

scholarly journals Geometric Aberration Theory of Offner Imaging Spectrometers

Sensors ◽  
2019 ◽  
Vol 19 (18) ◽  
pp. 4046 ◽  
Author(s):  
Meihong Zhao ◽  
Yanxiu Jiang ◽  
Shuo Yang ◽  
Wenhao Li
Keyword(s):  
Ray Tracing ◽  
Diffraction Grating ◽  
Spherical Aberration ◽  
Image Plane ◽  
Third Order ◽  
Commercial Software ◽  
Extended Source ◽  
Imaging Spectrometer ◽  
High Degree ◽  
Aberration Theory

A third-order aberration theory has been developed for the Offner imaging spectrometer comprising an extended source; two concave mirrors; a convex diffraction grating; and an image plane. Analytic formulas of the spot diagram are derived for tracing rays through the system based on Fermat’s principle. The proposed theory can be used to discuss in detail individual aberrations of the system such as coma, spherical aberration and astigmatism, and distortion together with the focal conditions. It has been critically evaluated as well in a comparison with exact ray tracing constructed using the commercial software ZEMAX. In regard to the analytic formulas, the results show a high degree of practicality.

A multislice approach to the spherical aberration theory in electron optics

1996 ◽  
Vol 43 (11) ◽  
pp. 2367-2379 ◽  
Author(s):  
Annamaria Di Sebastiano ◽  
Giulio Pozzi
Keyword(s):  
Spherical Aberration ◽  
Electron Optics ◽  
Aberration Theory

CBED Shadow Images and Cs:Aberration Measurement

1982 ◽  
Vol 40 ◽  
pp. 696-697
Author(s):  
R. W. Carpenter ◽  
I.Y.T. Chan ◽  
J. M. Cowley
Keyword(s):  
Focal Point ◽  
Spherical Aberration ◽  
Optic Axis ◽  
Wide Angle ◽  
Caustic Surface ◽  
Convergent Beam

Wide-angle convergent beam shadow images(CBSI) exhibit several characteristic distortions resulting from spherical aberration. The most prominent is a circle of infinite magnification resulting from rays having equal values of a forming a cross-over on the optic axis at some distance before reaching the paraxial focal point. This distortion is called the tangential circle of infinite magnification; it can be used to align and stigmate a STEM and to determine Cs for the probe forming lens. A second distortion, the radial circle of infinite magnification, results from a cross-over on the lens caustic surface of rays with differing values of ∝a, also before the paraxial focal point of the lens.

Resolution Attainable With the Present Day STEM

1973 ◽  
Vol 31 ◽  
pp. 230-231 ◽  
Author(s):  
J. S. Wall ◽  
J. P. Langmore ◽  
H. Isaacson ◽  
A. V. Crewe
Keyword(s):  
Spherical Aberration ◽  
Focal Length ◽  
Incident Beam ◽  
Scanning Transmission Electron Microscope ◽  
Aperture Size ◽  
Magnetic Lens ◽  
Peak Intensity ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Half Angle

The scanning transmission electron microscope (STEM) constructed by the authors employs a field emission gun and a 1.15 mm focal length magnetic lens to produce a probe on the specimen. The aperture size is chosen to allow one wavelength of spherical aberration at the edge of the objective aperture. Under these conditions the profile of the focused spot is expected to be similar to an Airy intensity distribution with the first zero at the same point but with a peak intensity 80 per cent of that which would be obtained If the lens had no aberration. This condition is attained when the half angle that the incident beam subtends at the specimen, 𝛂 = (4𝛌/Cs)¼

Experiments with a Quadrupole Octopole Corrector in a STEM

1977 ◽  
Vol 35 ◽  
pp. 90-91 ◽  
Author(s):  
V. Beck
Keyword(s):  
Lower Order ◽  
Spherical Aberration ◽  
Mechanical Alignment

Recently a number of experiments have been carried out on a STEM which included a multipole corrector for primary spherical aberration. The results of these experiments indicate that the correction of primary spherical aberration with magnetic multipoles is beset with very serious difficulties related to hysteresis.The STEM and corrector have been described previously. In theory, the corrector should cancel primary spherical aberration so that other aberrations limit the resolution. For this instrument, secondary spherical aberration should limit the resolution to 1 A at 50 kV. A thorough study of misalignment aberrations was made. The result of the study indicates that the octopoles must be aligned to 1000 A. Since mechanical alignment cannot be done to this accuracy, trim coils were built into the corrector in order to achieve the required alignment electrically. The trim coils are arranged to excite all the lower order moments of an element.

High Resolution Specimen Area Imaged Under Negligible Field Aberrations

1970 ◽  
Vol 28 ◽  
pp. 540-541 ◽  
Author(s):  
T. Yanaka ◽  
K. Shirota
Keyword(s):  
High Resolution ◽  
Field Distribution ◽  
Image Space ◽  
Beam Deflection ◽  
Objective Lens ◽  
Resolution Limit ◽  
Leakage Flux ◽  
Specimen Area ◽  
Points Of View ◽  
Aberration Theory

It is significant to note field aberrations (chromatic field aberration, coma, astigmatism and blurring due to curvature of field, defined by Glaser's aberration theory relative to the Blenden Freien System) of the objective lens in connection with the following three points of view; field aberrations increase as the resolution of the axial point improves by increasing the lens excitation (k2) and decreasing the half width value (d) of the axial lens field distribution; when one or all of the imaging lenses have axial imperfections such as beam deflection in image space by the asymmetrical magnetic leakage flux, the apparent axial point has field aberrations which prevent the theoretical resolution limit from being obtained.

Improvements in the electron probe forming capabilities and x-ray hole counts in the Philips TEM

1983 ◽  
Vol 41 ◽  
pp. 376-377
Author(s):  
Richard L. McConville
Keyword(s):  
Field Strength ◽  
Electron Probe ◽  
Spherical Aberration ◽  
Focal Length ◽  
Objective Lens ◽  
Parallel Beam ◽  
Tilt Axis ◽  
X Ray ◽  
Small Probe ◽  
Specimen Height

A second generation twin lens has been developed. This symmetrical lens with a wider bore, yet superior values of chromatic and spherical aberration for a given focal length, retains both eucentric ± 60° tilt movement and 20°x ray detector take-off angle at 90° to the tilt axis. Adjust able tilt axis height, as well as specimen height, now ensures almost invariant objective lens strengths for both TEM (parallel beam conditions) and STEM or nano probe (focused small probe) modes.These modes are selected through use of an auxiliary lens situ ated above the objective. When this lens is on the specimen is illuminated with a parallel beam of electrons, and when it is off the specimen is illuminated with a focused probe of dimensions governed by the excitation of the condenser 1 lens. Thus TEM/STEM operation is controlled by a lens which is independent of the objective lens field strength.

Sign in / Sign up

Export Citation Format

Share Document