A plasma-optical System modelled using particles

1987 ◽  
Vol 38 (1) ◽  
pp. 87-94 ◽  
Author(s):  
W. N. G. Hitchon
Keyword(s):  
Optical System ◽  
Particle Method ◽  
Optical Systems ◽  
Particle Model ◽  
Integration Step ◽  
Electron Motion ◽  
Efficient Treatment ◽  
Neutral Particles ◽  
Rf Discharges ◽  
Background Gas

A ‘particle’ model of plasma behaviour, suitable for application to the study of plasma-optical Systems, has been developed. A plasma-optical System which removes macroscopic droplets from a neutralized beam of ions and electrons, produced by an arc, has been modelled and its performance has been analysed. The particle model employs an extremely efficient treatment of the electron motion through a background gas, which in this case consists of neutral particles. The distribution of distances travelled by electrons in the course of many collisions with the neutral background is generated using a Monte Carlo method and samples from the distribution are used to determine the electron motion at each integration step. In sheath regions, for instance, direct integration is still necessary, but for most electrons the simulation is very fast, largely removing the numerical ‘stiffness’ of the particle method. This method will be equally effective for time-dependent fields such as occur in RF discharges used in ‘plasma processing’. The variation in ion current to a substrate, where the ions deposit as a thin film, has been studied. The objective is to maximize the deposition rate whilst preventing macroscopic particles which arise at the are from striking the film. An alternative System whose calculated transmittal rate from source to target is higher, for long mean-free-paths, is also examined.

Atomic Resolution in Crystal Aperture Stem

1990 ◽  
Vol 48 (1) ◽  
pp. 236-237
Author(s):  
J T Fourie
Keyword(s):  
Optical System ◽  
Spherical Aberration ◽  
Three Dimensional ◽  
Transmission Function ◽  
Optical Systems ◽  
Bragg Angle ◽  
Electron Optical System ◽  
Intimate Contact ◽  
Diffraction Effects ◽  
Design Aspect

The attempts at improvement of electron optical systems to date, have largely been directed towards the design aspect of magnetic lenses and towards the establishment of ideal lens combinations. In the present work the emphasis has been placed on the utilization of a unique three-dimensional crystal objective aperture within a standard electron optical system with the aim to reduce the spherical aberration without introducing diffraction effects. A brief summary of this work together with a description of results obtained recently, will be given.The concept of utilizing a crystal as aperture in an electron optical system was introduced by Fourie who employed a {111} crystal foil as a collector aperture, by mounting the sample directly on top of the foil and in intimate contact with the foil. In the present work the sample was mounted on the bottom of the foil so that the crystal would function as an objective or probe forming aperture. The transmission function of such a crystal aperture depends on the thickness, t, and the orientation of the foil. The expression for calculating the transmission function was derived by Hashimoto, Howie and Whelan on the basis of the electron equivalent of the Borrmann anomalous absorption effect in crystals. In Fig. 1 the functions for a g220 diffraction vector and t = 0.53 and 1.0 μm are shown. Here n= Θ‒ΘB, where Θ is the angle between the incident ray and the (hkl) planes, and ΘB is the Bragg angle.

Image Distortion, between Unwanted Geometric Aberration and the Tool Used to Improve Observation Equipment Performance

2014 ◽  
Vol 555 ◽  
pp. 751-758 ◽  
Author(s):  
Nicolae Guzulescu ◽  
Cornel Todirică ◽  
Daniel Lăpădat
Keyword(s):  
Optical System ◽  
Measurement Errors ◽  
Optical Measurement ◽  
Image Distortion ◽  
Field Of View ◽  
Optical Systems ◽  
Object Appearance ◽  
And Control ◽  
Measurement And Control ◽  
Equipment Performance

An distortion aberration free optical system forms an orthoscopic image mean that is similar to original object, undeformed. Naturally imply that most optical systems are designed so that the image distortion is minimal, not to cause inconvenience to the user about either the object appearance – when it comes to a camera or camcorder, or the deformities that may cause measurement errors – when it comes to optical measurement and control equipment. However there are situations when distortion is desired to improve some performances of the observation optical system. In this article we present how distortion is used to increase the field of view, and also how distortion is used to optimize the field of view – resolution compromise.

Probing the spatial coherence of wide X-ray beams with Fresnel mirrors at BL25SU of SPring-8

2019 ◽  
Vol 26 (3) ◽  
pp. 756-761
Author(s):  
Yoko Takeo ◽  
Hiroto Motoyama ◽  
Yasunori Senba ◽  
Hikaru Kishimoto ◽  
Haruhiko Ohashi ◽  
...  
Keyword(s):  
Optical System ◽  
Spatial Coherence ◽  
Optical Systems ◽  
X Rays ◽  
X Ray ◽  
Interference Fringes ◽  
Radiation Sources ◽  
Wide Wavelength Range ◽  
Valuable Method ◽  
The Relationship

Probing the spatial coherence of X-rays has become increasingly important when designing advanced optical systems for beamlines at synchrotron radiation sources and free-electron lasers. Double-slit experiments at various slit widths are a typical method of quantitatively measuring the spatial coherence over a wide wavelength range including the X-ray region. However, this method cannot be used for the analysis of spatial coherence when the two evaluation points are separated by a large distance of the order of millimetres owing to the extremely narrow spacing between the interference fringes. A Fresnel-mirror-based optical system can produce interference patterns by crossing two beams from two small mirrors separated in the transverse direction to the X-ray beam. The fringe spacing can be controlled via the incidence angles on the mirrors. In this study, a Fresnel-mirror-based optical system was constructed at the soft X-ray beamline (BL25SU) of SPring-8. The relationship between the coherence and size of the virtual source was quantitatively measured at 300 eV in both the vertical and horizontal directions using the beam. The results obtained indicate that this is a valuable method for the optimization of optical systems along beamlines.

Method of calculating the aberrations of soft X-ray and vacuum ultraviolet optical systems

2019 ◽  
Vol 26 (5) ◽  
pp. 1558-1564
Author(s):  
Yiqing Cao ◽  
Zhijuan Shen ◽  
Zhixia Zheng
Keyword(s):  
Optical System ◽  
Vacuum Ultraviolet ◽  
Optical Systems ◽  
Third Order ◽  
Order Accuracy ◽  
X Ray ◽  
Plane Symmetric ◽  
The Third ◽  
Aberration Theory ◽  
Ray Coordinates

Based on the the third-order aberration theory of plane-symmetric optical systems, this paper studies the effect on aberrations of the second-order accuracy of aperture-ray coordinates and the extrinsic aberrations of this kind of optical system; their calculation expressions are derived. The resultant aberration expressions are then applied to calculate the aberrations of two design examples of soft X-ray and vacuum ultraviolet (XUV) optical systems; images are compared with ray-tracing results using SHADOW software to validate the aberration expressions. The study shows that the accuracy of the aberration expressions is satisfactory.

Electromagnetic diffraction in optical systems - I. An integral representation of the image field

1959 ◽  
Vol 253 (1274) ◽  
pp. 349-357 ◽  
Keyword(s):  
Electromagnetic Field ◽  
Integral Representation ◽  
Optical System ◽  
Plane Waves ◽  
Angular Spectrum ◽  
Optical Systems ◽  
Angular Aperture ◽  
Spherical Waves ◽  
Simple Physical Interpretation ◽  
Electromagnetic Diffraction

An integral representation is obtained for the electromagnetic field in the image space of an optical system . This representation, which is not restricted to systems of low angular aperture, is in the form of an angular spectrum of plane waves, and is closely related to that introduced by Luneberg (1944) as a vector generalization of well-known formulae of Debye (1909) and Picht (1925). It is shown that the representation has a simple physical interpretation in terms of a modified Huygens—Fresnel principle which operates with secondary plane waves rather than with secondary spherical waves.

Comparison of Design and Spatial Stability of Two Kinds of Optical Systems for Stereoscopic Mapping Camera

2013 ◽  
Vol 760-762 ◽  
pp. 368-372
Author(s):  
Tian Jin Tang ◽  
Wei Jun Gao
Keyword(s):  
Optical System ◽  
Linear Array ◽  
Focal Length ◽  
Optical Systems ◽  
Modulation Transfer ◽  
Working Temperature ◽  
Edge Field ◽  
Performance Requirements ◽  
And Performance ◽  
Structure Layout

To achieve a certain precision when mapping in accord with a particular proportion or scale with stereo mapping camera, the change of chief ray height of the edge field due to the fluctuation of working temperature is required to be within the range of microns, and at the meantime the size and structure layout of three-linear array stereo mapping camera are determined directly by the configuration of optical system. Based on the requirements of refractive optical system with long focal length, academic calculation and actual optical designs based on two typical configurations for stereoscopic mapping camera are made,the actual working temperature and performance requirements are also taken into consideration, the results including the modulation transfer function, distortion and stability comparison are also given.

scholarly journals Generalized algorithm for finding the catacaustics of an optical system

2020 ◽  
pp. 40-48
Author(s):  
Evgenii Vladimirovich Lyubchinov
Keyword(s):  
Optical System ◽  
Computer Aided Design ◽  
Optical Radiation ◽  
Optical Systems ◽  
Direct Light ◽  
Geometric Objects ◽  
Design Systems ◽  
Aided Design ◽  
Applied Fields ◽  
Scattered Beam

The author of the work has proposed an algorithm for determining catacaustics in a “source-reflector” optical system on a plane. Katakaustika is called the envelope of reflected rays from a given curve and the study of catacaustics in the design of optical systems is one of the main tasks. The paper gives examples of solving this problem and presents the corresponding visualization. Particular attention is paid to problems where the source and reflector are curved, because these tasks in the scientific literature have not been previously considered. The presented algorithm is based on the cyclographic projection of the spatial curve of the line and its optical property. It is versatile and suitable for all tasks where the source of optical radiation is given in the form of a central (point), parallel or scattered beam of direct (light rays). The main advantage of the algorithm is that in the end it turns out analytical, i.e. exact solution to the problem of determining catacaustics. The results of the study can be used in applied fields of geometric optics, as well as in various computer-aided design systems specializing in modeling lighting of geometric objects.

scholarly journals Transient Dynamical-Thermal-Optical System Modeling and Simulation

2020 ◽  
Vol 238 ◽  
pp. 12001
Author(s):  
Luzia Hahn ◽  
Peter Eberhard
Keyword(s):  
Optical System ◽  
High Performance ◽  
System Modeling ◽  
Computational Cost ◽  
Order Reduction ◽  
Optical Systems ◽  
Model Order ◽  
Transient Simulations ◽  
Reduction Methods ◽  
Low Computational Cost

In this work, methods and procedures are investigated for the holistic simulation of the dynamicalthermal behavior of high-performance optics like lithography objectives. Flexible multibody systems in combination with model order reduction methods, finite element thermal analysis and optical system analyses are used for transient simulations of the dynamical-thermal behavior of optical systems at low computational cost.

scholarly journals Aсtive electro-optical system of targets detection with dynamic spectral processing of optical radiation

2021 ◽  
Vol 24 (02) ◽  
pp. 218-226
Author(s):  
L.F. Kupchenko ◽  
◽  
V.D. Karlov ◽  
A.S. Rybiak ◽  
О.А. Goorin ◽  
...  
Keyword(s):  
Optical System ◽  
Optical Radiation ◽  
Block Diagram ◽  
Imaging Spectroscopy ◽  
Optical Signal ◽  
Optical Systems ◽  
Spectral Processing ◽  
Mathematical Operation ◽  
Radiation Fields ◽  
Laser Vision

The issues discussed in this paper provide for further development of studies in the sphere of imaging spectroscopy and laser vision. In terms of forming the information fields (radiation fields), the electro-optical systems are subdivided into the passive and active ones. Passive electro-optical systems use the information fields formed by natural radiation sources, whereas the active ones suggest using artificial sources. Comparative analysis of mathematical and physical issues of designing the electro-optical systems with dynamic spectral processing of optical radiation of the passive and active types has been performed. It has been shown that the controlled dynamic spectral processing of optical radiation can be implemented within the passive and active electro-optical systems on the basis of the same algorithm that represents operation of the optical processor performing the mathematical operation of dot product. The authors have developed the block diagram of an active electro-optical system with dynamic spectral processing. The algorithm for optimal detection of optical signals has been developed using basics of the signal detection theory. Mathematical modeling of target detection against an inhomogeneous background has been performed. It has been shown that the optimal dynamic spectral processing of optical radiation in active electro-optical system enables to separate the desired optical signal by suppressing the background signal.

Third-order aberration of soft X-ray optical systems with orthogonal and coplanar arrangement of the main planes of elements

2020 ◽  
Vol 27 (6) ◽  
pp. 1477-1484
Author(s):  
Yiqing Cao ◽  
Zhijuan Shen ◽  
Haihe Xie
Keyword(s):  
Optical System ◽  
Optical Systems ◽  
Analysis Method ◽  
Third Order ◽  
Optical Elements ◽  
Analytical Analysis ◽  
X Ray ◽  
Plane Symmetric ◽  
Design And Optimization ◽  
Aberration Theory

A third-order aberration analytical analysis method of soft X-ray optical systems with orthogonal and coplanar arrangement of the main planes of elements is proposed. Firstly, the transfer equations of the aperture ray and the principle ray are derived; then, based on the third-order aberration theory with the aperture-ray coordinates on the reference exit wavefront of a plane-symmetric optical system, the aberration expressions contributed by the wave aberration and defocus of this kind of optical system are studied in detail. Finally, the derived aberration calculation expressions are applied to calculate the aberration of two design examples of such types of optical systems; the images are compared with ray-tracing results obtained using the Shadow software to validate the aberration expressions. The study shows that the accuracy of the aberration expressions is satisfactory. The analytical analysis method of aberration is helpful in the design and optimization of the soft X-ray optical systems with orthogonal and coplanar arrangement of the main planes of optical elements.

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