scholarly journals Design of Symmetric Magnetic Lenses with Optimum Operational Conditions

2021 ◽  
Vol 24 (1) ◽  
pp. 30-38
Author(s):  
Basma Faiz Abd Alghane ◽  
◽  
Ahmad K. Ahmad ◽  
Keyword(s):  
Magnetic Properties ◽  
Optical Properties ◽  
Axial Magnetic Field ◽  
Focal Length ◽  
Optical Design ◽  
Air Gap ◽  
Magnetic Lens ◽  
Aperture Diameter ◽  
Operational Conditions ◽  
Chromatic Aberrations

In the present paper, the geometrical and optical object properties of symmetrical magnetic lens are designed and analyzed using the electron optical design (EOD) program. The effect of the axial aperture diameter (D), the air gap between the poles (s), the thickness of the poles (t), the excitation parameter NI of the lens are all studied for the best optical properties like the object focal length fo, the spherical and chromatic aberrations coefficients (Cs and Cc respectively). It was found that the optical properties of the object significantly improved with a decrease in the axial aperture diameter and width of the air gap of this lens. Upon our study, it was found that the best properties are achieved when the air gap width (S2 mm), and the axial hole diameter (D=6 mm). The effect of the electrode face thickness on the magnetic properties of the proposed magnetic lens is studied, it was found that the best magnetic properties and the highest value of magnetic flux and the lowest value of the axial magnetic field strength bandwidth were at electrode face thickness equal to (3 and 4 mm).Therefore, the best magnetic lens in our design with the best optical properties was S=2mm, D=6mm and t=3mm.

Design of objective lens for 200-kV high-resolution electron microscopes

1983 ◽  
Vol 41 ◽  
pp. 314-315
Author(s):  
K. Tsuno ◽  
T. Honda ◽  
Y. Harada ◽  
M. Naruse
Keyword(s):  
Optical Properties ◽  
Computer Technology ◽  
Axial Magnetic Field ◽  
Chromatic Aberration ◽  
Objective Lens ◽  
Resolution Electron ◽  
Correction Of Astigmatism ◽  
Three Stages ◽  
Electron Microscopes ◽  
Stage 1

Developement of computer technology provides much improvements on electron microscopy, such as simulation of images, reconstruction of images and automatic controll of microscopes (auto-focussing and auto-correction of astigmatism) and design of electron microscope lenses by using a finite element method (FEM). In this investigation, procedures for simulating the optical properties of objective lenses of HREM and the characteristics of the new lens for HREM at 200 kV are described.The process for designing the objective lens is divided into three stages. Stage 1 is the process for estimating the optical properties of the lens. Firstly, calculation by FEM is made for simulating the axial magnetic field distributions Bzc of the lens. Secondly, electron ray trajectory is numerically calculated by using Bzc. And lastly, using Bzc and ray trajectory, spherical and chromatic aberration coefficients Cs and Cc are numerically calculated. Above calculations are repeated by changing the shape of lens until! to find an optimum aberration coefficients.

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

The Reduction of Chromatic Aberrations Due to Instrumental Instabilities

1971 ◽  
Vol 29 ◽  
pp. 14-15
Author(s):  
J. S. Lally ◽  
R. Evans
Keyword(s):  
Electron Microscope ◽  
High Voltage ◽  
Focal Length ◽  
Chromatic Aberration ◽  
Objective Lens ◽  
Usual Practice ◽  
Voltage Electron ◽  
Short Focal Length ◽  
Chromatic Aberrations ◽  
Electron Microscopes

One of the instrumental factors often limiting the resolution of the electron microscope is image defocussing due to changes in accelerating voltage or objective lens current. This factor is particularly important in high voltage electron microscopes both because of the higher voltages and lens currents required but also because of the inherently longer focal lengths, i.e. 6 mm in contrast to 1.5-2.2 mm for modern short focal length objectives.The usual practice in commercial electron microscopes is to design separately stabilized accelerating voltage and lens supplies. In this case chromatic aberration in the image is caused by the random and independent fluctuations of both the high voltage and objective lens current.

A High Resolution Scanning Microscope

1968 ◽  
Vol 26 ◽  
pp. 356-357
Author(s):  
A. V. Crewe ◽  
J. Wall ◽  
L. M. Welter
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Spherical Aberration ◽  
Focal Length ◽  
Spot Size ◽  
Emission Source ◽  
Field Of View ◽  
Scanning Microscope ◽  
Magnetic Lens ◽  
High Quality

A scanning microscope using a field emission source has been described elsewhere. This microscope has now been improved by replacing the single magnetic lens with a high quality lens of the type described by Ruska. This lens has a focal length of 1 mm and a spherical aberration coefficient of 0.5 mm. The final spot size, and therefore the microscope resolution, is limited by the aberration of this lens to about 6 Å.The lens has been constructed very carefully, maintaining a tolerance of + 1 μ on all critical surfaces. The gun is prealigned on the lens to form a compact unit. The only mechanical adjustments are those which control the specimen and the tip positions. The microscope can be used in two modes. With the lens off and the gun focused on the specimen, the resolution is 250 Å over an undistorted field of view of 2 mm. With the lens on,the resolution is 20 Å or better over a field of view of 40 microns. The magnification can be accurately varied by attenuating the raster current.

scholarly journals Optical Design of a Shortwave Infrared Dual Camera CASSI Based on Improved Offner-Wynne Imaging Spectrometer

2021 ◽  
Vol 2112 (1) ◽  
pp. 012021
Author(s):  
Chong Song ◽  
Lipeng Huo ◽  
Yong Huang ◽  
Yangdong Yan ◽  
Gang Wang ◽  
...  
Keyword(s):  
Optical System ◽  
Imaging System ◽  
Optical Measurement ◽  
Focal Length ◽  
Optical Design ◽  
Optical Transmittance ◽  
Coded Aperture ◽  
Visual Axis ◽  
Imaging Spectrometer ◽  
Shortwave Infrared

Abstract Based on the optical system characteristics of coded aperture snapshot spectral imager (CASSI), an optimized optical system of shortwave infrared dual camera CASSI was designed based on improved Offner-Wynne imaging spectrometer. The operating wavelength of the optical system ranges from 900nm to 1700nm, and the focal length is 1200mm. It consists of two parts: the two dimensional imaging system and the multispectral CASSI imaging system. The key technical parameters of the two parts are the same and there is no visual axis difference. Therefore, the optimized optical system can effectively improve real-time performance, optical transmittance and compactness of the dual camera shortwave infrared CASSI, which is conducive to the application in optical measurement scenes in the shooting range.

Synergistic photo optical and magnetic properties of a hybrid nanocomposite consisting of a zinc oxide nanorod array decorated with iron oxide nanoparticles

2018 ◽  
Vol 6 (39) ◽  
pp. 10502-10512 ◽  
Author(s):  
Brandon Azeredo ◽  
Anne Carton ◽  
Cédric Leuvrey ◽  
Céline Kiefer ◽  
Dris Ihawakrim ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Magnetic Properties ◽  
Optical Properties ◽  
Iron Oxide ◽  
Iron Oxide Nanoparticles ◽  
Nanorod Array ◽  
Oxide Nanoparticles ◽  
Hybrid Nanocomposite ◽  
Optical And Magnetic Properties

A ZnO/PBA/Fe3−δO4 nanocomposite displays enhanced magnetic and optical properties as a result of dual synergy.

Optical and magnetic properties of Ba5(BO3)3F single crystals

2014 ◽  
Vol 16 (45) ◽  
pp. 24884-24891 ◽  
Author(s):  
A. P. Yelisseyev ◽  
Xingxing Jiang ◽  
V. P. Solntsev ◽  
T. B. Bekker ◽  
Zheshuai Lin
Keyword(s):  
Magnetic Properties ◽  
Optical Properties ◽  
Single Crystal ◽  
Single Crystals ◽  
Bulk Single Crystal ◽  
Optical And Magnetic Properties

The optical properties of Ba5(BO3)3F as a bulk single crystal are investigated experimentally and theoretically.

Microstructure and Magneto-Optical Properties of TbFeCo Films Prepared by Facing Targets Sputtering

1988 ◽  
Vol 132 ◽  
Author(s):  
H. Ito ◽  
T. Hirata ◽  
M. Naoe
Keyword(s):  
Magnetic Properties ◽  
Optical Properties ◽  
Rotation Angle ◽  
Perpendicular Magnetic Anisotropy ◽  
Columnar Structure ◽  
Torque Measurement ◽  
Amorphous Films ◽  
Kerr Rotation ◽  
Wide Range ◽  
Kerr Rotation Angle

ABSTRACTThe microstructure of TbFeCo amorphous films deposited by a facing targets type of sputtering (FTS) method varied with the change of deposition rate Rd. The films deposited at Rd of about 100–200 nm/min did not present any distinguishable columnar structure while the ones at Rd of about 50 nm/min revealed obvious columnar structure. The films with columnless structure exhibited Kerr rotation angle θk of 0.37 deg. of which the value was higher than that of the films with columnar structure over the wide range of Th content. The torque measurement implied that the presence of columnar structure was not mainly necessary for the occurrence of large perpendicular magnetic anisotropy. Under satisfactory confinement of plasma during sputtering, the dense, uniform and columnless TbFeCo films can be obtained on plasma-free substrate even at Rd as high as 200 nm/min, without destroying the excellent magnetic properties and magneto-optical characteristics.

Magnetic, electrochemical and optical properties of a sulfate-bridged Co(ii) imidazole dimer

2014 ◽  
Vol 38 (12) ◽  
pp. 5856-5860 ◽  
Author(s):  
Michael J. Murphy ◽  
Pavel M. Usov ◽  
Felix J. Rizzuto ◽  
Cameron J. Kepert ◽  
Deanna M. D'Alessandro
Keyword(s):  
Magnetic Properties ◽  
Optical Properties ◽  
High Spin ◽  
Antiferromagnetic Coupling ◽  
Optical And Magnetic Properties

The electrochemical, optical and magnetic properties of a sulfate-bridged high spin Co(ii) dimer, [Co2(DMIM)4(μ2-O2,O,O′-SO4)2]·2MeCN are reported. Antiferromagnetic coupling across the μ2-(O2-sulfato) bridging mode has been identified with J = −28 cm−1.

scholarly journals Splendid coloration of the peacock spider Maratus splendens

2016 ◽  
Vol 13 (121) ◽  
pp. 20160437 ◽  
Author(s):  
Doekele G. Stavenga ◽  
Jürgen C. Otto ◽  
Bodo D. Wilts
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Optical Properties ◽  
Air Gap ◽  
The Body ◽  
Structural Coloration ◽  
Optical Modelling ◽  
Jumping Spiders ◽  
Blue Coloration ◽  
Scanning Electron

Jumping spiders are well known for their acute vision and often bright colours. The male peacock spider Maratus splendens is richly coloured by scales that cover the body. The colours of the white, cream and red scales, which have an elaborate shape with numerous spines, are pigmentary. Blue scales are unpigmented and have a structural colour, created by an intricate photonic system consisting of two chitinous layers with ridges, separated by an air gap, with on the inner sides of the chitin layers an array of filaments. We have characterized the optical properties of the scales by microspectrophotometry, imaging scatterometry and light and scanning electron microscopy. Optical modelling revealed that the filament array constitutes a novel structural coloration system, which subtly fine tunes the scale reflectance to the observed blue coloration.

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