The Distribution of Light from Optical Systems

1949 ◽  
Vol 2 (3) ◽  
pp. 335
Author(s):  
WH Steel
Keyword(s):  
Point Source ◽  
Optical System ◽  
Optical Axis ◽  
Spherical Aberration ◽  
Light Distribution ◽  
Optical Systems ◽  
Geometrical Method ◽  
Plane Normal ◽  
Finite Source

A geometrical method is developed for calculating the distribution of intensity with angle of the light leaving an optical system, when the angle at which a ray from a point on the optical axis leaves the system is known as a function of the aperture. The case of a point source on the axis of the system is treated exactly, and an approximation is given for that of a small finite source ; the method is applicable to systems with spherical aberration. The distribution of illumination across any plane normal to the axis is treated by analogous methods. The results are compared with measurements of the light distribution from an optical system possessing considerable spherical aberration.

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.

scholarly journals Current Status of the Astrometric Capabilities of the Hubble Space Telescope Fine Guidance Sensors

1991 ◽  
Vol 127 ◽  
pp. 68-76
Author(s):  
W.H. Jefferys ◽  
G.F. Benedict ◽  
R.L. Duncombe ◽  
O.G. Franz ◽  
L.W. Fredrick ◽  
...  
Keyword(s):  
Optical System ◽  
Reference Frames ◽  
Optical Axis ◽  
Hubble Space Telescope ◽  
Current Knowledge ◽  
Spherical Aberration ◽  
Radial Distance ◽  
Current Status ◽  
Space Telescope ◽  
Wavefront Error

AbstractThe Fine Guidance Sensors (FGSs) are the instrument of choice for most astrometric measurements with the Hubble Space Telescope (HST). The observed amount of spherical aberration in the Ritchey Chretien optical system does not affect positional measurements with perfectly aligned FGSs because they are interferometers. The FGSs combine wavefronts from points in the exit pupil with other points which are at the same radial distance from the optical axis. Asymmetric aberrations such as coma and astigmatism do affect the measured positions. The current knowledge of the HST wavefront error, the FGS operation and the implications for milliarcsecond relative astrometry are discussed. It is still planned to use the HST to tie the HIPPARCOS and VLBI Reference Frames together at the few milliarcsecond level.

A Novel High Concentration Fresnel Lens as a Solar Concentrator

2021 ◽  
pp. 1-29
Author(s):  
Kuldeep Awasthi ◽  
Desireddy Shashidhar Reddy ◽  
Mohd. Kaleem Khan
Keyword(s):  
Optical Axis ◽  
Spherical Aberration ◽  
Spherical Surface ◽  
Fresnel Lens ◽  
High Concentration ◽  
Aperture Diameter ◽  
Convex Lens ◽  
Flat Base ◽  
Fresnel Lenses ◽  
Outer Vertex

Abstract This paper describes the design methodology for a novel Fresnel lens. The original Fresnel lens is obtained from a plano-convex lens, whose spherical surface is split into a number of divisions (called facets), collapsed onto the flat base. Thus, all the facets of the original Fresnel lens have the same radius as that of the plano-convex lens. The proposed design aims to achieve better ray concentration and reduced spherical aberration than the original Fresnel lens by constructing spherical facets with unequal radii. The centers and radii of facets are constrained so that the ray refracted from the bottom vertex of each facet on one side of the optical axis and the ray refracted from the outer vertex of the corresponding facet on the other side of the optical axis must intersect at the focal plane. The proposed lens design has resulted in a 275% gain in the concentration ratio and a 72.5% reduction in the spherical aberration compared to the original lens of the same aperture diameter and number of facets. The performance of both novel and original Fresnel lenses when used as solar concentrators with a conical coil receiver is evaluated. The novel Fresnel lens led to increased heat gain and resulted in a compact solar collector design.

Modelling of influence of spherical aberration coefficients on depth of focus of optical systems

2017 ◽  
Author(s):  
Petr Pokorný ◽  
Filip Šmejkal ◽  
Pavel Kulmon ◽  
Antonín Mikš ◽  
Jiří Novák ◽  
...  
Keyword(s):  
Spherical Aberration ◽  
Optical Systems ◽  
Depth Of Focus

scholarly journals Optical axes of catadioptric systems including visual, Purkinje and other nonvisual systems of a heterocentric astigmatic eye

2010 ◽  
Vol 69 (3) ◽  
Author(s):  
W. F. Harris
Keyword(s):  
Visual System ◽  
Optical Axis ◽  
The Other ◽  
Optical Systems ◽  
Numerical Examples ◽  
Straight Line ◽  
Optical Axes ◽  
Catadioptric Systems ◽  
Reflecting Surfaces ◽  
Special Case

For a dioptric system with elements which may be heterocentric and astigmatic an optical axis has been defined to be a straight line along which a ray both enters and emerges from the system.  Previous work shows that the dioptric system may or may not have an optical axis and that, if it does have one, then that optical axis may or may not be unique.  Formulae were derived for the locations of any optical axes.  The purpose of this paper is to extend those results to allow for reflecting surfaces in the system in addition to refracting elements.  Thus the paper locates any optical axes in catadioptric systems (including dioptric systems as a special case).  The reflecting surfaces may be astigmatic and decentred or tilted.  The theory is illustrated by means of numerical examples.  The locations of the optical axes are calculated for seven optical systems associated with a particular heterocentric astigmatic model eye.  The optical systems are the visual system, the four Purkinje systems and two other nonvisual systems of the eye.  The Purkinje systems each have an infinity of optical axes whereas the other nonvisual systems, and the visual system, each have a unique optical axis. (S Afr Optom 2010 69(3) 152-160)

A NEW METHOD OF LENS CENTERING IN THE OPTICAL SYSTEM BY USING SPECIAL MOUNT

2021 ◽  
pp. 137-144
Author(s):  
Bao Bui Dinh
Keyword(s):  
Optical System ◽  
Optical Axis ◽  
Assembly Process ◽  
Optical Surface ◽  
Lens System ◽  
High Quality ◽  
Manufacturing Equipment ◽  
Influence Coefficients ◽  
Process Solutions

Decentration in lens systems (for example objectives) significantly degrades the quality of image, such as the coma. In order to reduce lens decentration, the lenses are centered while manufacturing, while gluing, while attachment in the mounts. Significant decrease in the lenses decentering in the mounts is achieved by using a special manufacturing equipment, which allow combining the optical axis of the lens with the base axis of the mount in assembly process. Solutions for coma's alignment by shifting, tilting and rotation their components are also provided in the construction of high-quality objectives (microscopes [1-7], photolithographic, aerophotographic). For optimization of methods for such adjustment the influence coefficients of decentering of each optical surface of the lens system on the value and sign of coma must be calculated and taken into account. In this paper, we propose a special mounting which combined with the Opticentric of Trioptics device to center the lenses. The results show that the decentering is significantly reduced (0.9µm) compared to (44.2µm) with using a reference mount.

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