Understanding of the depth of focus evolution from an analysis of the iso-focal point

2005 ◽  
Author(s):  
S. Manakli ◽  
Y. Trouiller ◽  
P. Schiavone
Keyword(s):  
Focal Point ◽  
Depth Of Focus

scholarly journals Inverse-phase composite zone plate providing deeper focus than the normal diffraction-limited depth of X-ray microbeams

2019 ◽  
Vol 26 (1) ◽  
pp. 52-58
Author(s):  
Yasushi Kagoshima ◽  
Yuki Takayama
Keyword(s):  
Spatial Resolution ◽  
Optical Axis ◽  
Focal Point ◽  
Zone Plate ◽  
One Dimension ◽  
Depth Of Focus ◽  
Third Order ◽  
X Ray ◽  
Limited Depth ◽  
Focusing Properties

A novel type of zone plate (ZP), termed an inverse-phase composite ZP, is proposed to gain a deeper focus than the standard diffraction-limited depth of focus, with little reduction in spatial resolution. The structure is a combination of an inner ZP functioning as a conventional phase ZP and an outer ZP functioning with third-order diffraction with opposite phase to the inner ZP. Two-dimensional complex amplitude distributions neighboring the focal point were calculated using a wave-optical approach of diffraction integration with a monochromatic plane-wave illumination, where one dimension is the radial direction and the other dimension is the optical-axis direction. The depth of focus and the spatial resolution were examined as the main focusing properties. Two characteristic promising cases regarding the depth of focus were found: a pit-intensity focus with the deepest depth of focus, and a flat-intensity focus with deeper depth of focus than usual ZPs. It was found that twice the depth of focus could be expected with little reduction in the spatial resolution for 10 keV X-ray energy, tantalum zone material, 84 nm minimum fabrication zone width, and zone thickness of 2.645 µm. It was also found that the depth of focus and the spatial resolution were almost unchanged in the photon energy range from 8 to 12 keV. The inverse-phase composite ZP has high potential for use in analysis of practical thick samples in X-ray microbeam applications.

Integrating perspectives: How the development of second-personal competence lays the foundation for a second-personal morality

2020 ◽  
Vol 43 ◽  
Author(s):  
John Corbit ◽  
Chris Moore
Keyword(s):  
Empirical Evidence ◽  
Developmental Process ◽  
Focal Point ◽  
Personal Information ◽  
Personal Competence ◽  
Triadic Interactions ◽  
Personal Morality ◽  
Integrative Process

Abstract The integration of first-, second-, and third-personal information within joint intentional collaboration provides the foundation for broad-based second-personal morality. We offer two additions to this framework: a description of the developmental process through which second-personal competence emerges from early triadic interactions, and empirical evidence that collaboration with a concrete goal may provide an essential focal point for this integrative process.

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.

Record Wear Studies by Scanning Electron Microscopy

1968 ◽  
Vol 26 ◽  
pp. 364-365
Author(s):  
M.D. Coutts ◽  
E.R. Levin ◽  
J.G. Woodward
Keyword(s):  
Electron Microscopy ◽  
Constant Velocity ◽  
Peak Velocity ◽  
Great Depth ◽  
Depth Of Focus ◽  
Sweep Frequency ◽  
Transmission Electron ◽  
Test Record ◽  
Lateral Mode ◽  
Scanning Electron

While record grooves have been studied by transmission electron microscopy with replica techniques, and by optical microscopy, the former are cumbersome and restricted and the latter limited by lack of depth of focus and resolution at higher magnification. With its great depth of focus and ease in specimen manipulation, the scanning electron microscope is admirably suited for record wear studies.A special RCA sweep frequency test record was used with both lateral and vertical modulation bands. The signal is a repetitive, constant-velocity sweep from 2 to 20 kHz having a duration and repetitive rate of approximately 0.1 sec. and a peak velocity of 5.5 cm/s.A series of different pickups and numbers of plays were used on vinyl records. One centimeter discs were then cut out, mounted and coated with 200 Å of gold to prevent charging during examination. Wear studies were made by taking micrographs of record grooves having 1, 10 and 50 plays with each stylus and comparing with typical “no-play” grooves. Fig. 1 shows unplayed grooves in a vinyl pressing with sweep-frequency modulation in the lateral mode.

Electrostatic optics and aberration correction in the 1940s and today

1992 ◽  
Vol 50 (1) ◽  
pp. 6-7
Author(s):  
Gertrude F. Rempfer
Keyword(s):  
Electron Microscope ◽  
Focal Point ◽  
Focal Length ◽  
High Vacuum ◽  
Electron Optics ◽  
Applied Physics ◽  
Electrostatic Lenses ◽  
Commercial Instrument ◽  
The University ◽  
Theory And Experiment

I became involved in electron optics in early 1945, when my husband Robert and I were hired by the Farrand Optical Company. My husband had a mathematics Ph.D.; my degree was in physics. My main responsibilities were connected with the development of an electrostatic electron microscope. Fortunately, my thesis research on thermionic and field emission, in the late 1930s under the direction of Professor Joseph E. Henderson at the University of Washington, provided a foundation for dealing with electron beams, high vacuum, and high voltage.At the Farrand Company my co-workers and I used an electron-optical bench to carry out an extensive series of tests on three-electrode electrostatic lenses, as a function of geometrical and voltage parameters. Our studies enabled us to select optimum designs for the lenses in the electron microscope. We early on discovered that, in general, electron lenses are not “thin” lenses, and that aberrations of focal point and aberrations of focal length are not the same. I found electron optics to be an intriguing blend of theory and experiment. A laboratory version of the electron microscope was built and tested, and a report was given at the December 1947 EMSA meeting. The micrograph in fig. 1 is one of several which were presented at the meeting. This micrograph also appeared on the cover of the January 1949 issue of Journal of Applied Physics. These were exciting times in electron microscopy; it seemed that almost everything that happened was new. Our opportunities to publish were limited to patents because Mr. Farrand envisaged a commercial instrument. Regrettably, a commercial version of our laboratory microscope was not produced.

A confocal laser scanning microscope for fluorescence and reflection at video rates

1989 ◽  
Vol 47 ◽  
pp. 134-135
Author(s):  
P.M. Houpt ◽  
A. Draaijer
Keyword(s):  
Light Source ◽  
Laser Scanning ◽  
Focal Point ◽  
Confocal Laser Scanning Microscope ◽  
Confocal Laser ◽  
Point Light Source ◽  
Volume Of Interest ◽  
Ion Laser ◽  
Point Light ◽  
Point Detector

In confocal microscopy, the object is scanned by the coinciding focal points (confocal) of a point light source and a point detector both focused on a certain plane in the object. Only light coming from the focal point is detected and, even more important, out-of-focus light is rejected.This makes it possible to slice up optically the ‘volume of interest’ in the object by moving it axially while scanning the focused point light source (X-Y) laterally. The successive confocal sections can be stored in a computer and used to reconstruct the object in a 3D image display.The instrument described is able to scan the object laterally with an Ar ion laser (488 nm) at video rates. The image of one confocal section of an object can be displayed within 40 milliseconds (1000 х 1000 pixels). The time to record the total information within the ‘volume of interest’ normally depends on the number of slices needed to cover it, but rarely exceeds a few seconds.

Do Work Characteristics Mediate the Negative Effect of Transformational Leadership on Impaired Well-Being?

2017 ◽  
Vol 61 (4) ◽  
pp. 167-180 ◽  
Author(s):  
Sylvie Vincent-Höper ◽  
Sabine Gregersen ◽  
Albert Nienhaus
Keyword(s):  
Transformational Leadership ◽  
Focal Point ◽  
Leadership Behavior ◽  
Workplace Health Promotion ◽  
Well Being ◽  
Mediating Effect ◽  
Equation Modeling ◽  
Related Factor ◽  
Work Characteristics ◽  
Role Clarity

Abstract: In recent years, transformational leadership as a health-related factor has become a focal point of interest in research and practice. However, the pathways and mechanisms underlying this association are not yet well understood. In order to gain knowledge on how or why transformational leadership and employee well-being are associated, we investigated the mediating effect of the work characteristics role clarity and predictability. The study was carried out on 618 employees working in the health-care sector in Germany. We tested the mediator effect using structural equation modeling. The results indicate that role clarity and predictability fully mediate the relation between transformational leadership and negative indicators of well-being. These results give credit to the notion that work characteristics play an important role in identifying health-relevant aspects of leadership behavior. Our findings advance the understanding of how to enhance employee well-being and have implications for the design of leadership-related interventions of workplace health promotion.

Climate Research: a focal point for the climate and ecosystem-impact research communities

2008 ◽  
Vol 37 ◽  
pp. 1-outline
Author(s):  
NC Stenseth ◽  
MA Semenov
Keyword(s):  
Focal Point ◽  
Climate Research ◽  
Impact Research ◽  
Research Communities

Probing the Versatility of Shape-Persistent Tetraphenylmethane Dendrimers by Modification of the Skeleton

2019 ◽  
Author(s):  
Julio Ignacio Urzúa ◽  
Sandra Campana ◽  
Massimo Lazzari ◽  
Mercedes Torneiro
Keyword(s):  
Design Principle ◽  
Focal Point ◽  
Sonogashira Coupling ◽  
Terminal Alkyne ◽  
Double Phase ◽  
Rigid Rod ◽  
Convergent Approach ◽  
First And Second Generation ◽  
Oxidative Homocoupling ◽  
Hypercrosslinked Polymers

Tetraphenylmethane has emerged as a recurrent building block for advanced porous materials such as COFs, PAFs and hypercrosslinked polymers. Guided by a similar design principle, we have previously synthesized shape-persistent dendrimers with tetraphenylmethane nodes and ethynylene linkers. Here we report the generality of our approach by describing new dendritic architectures built from tetraphenylmethane. First, we prepared expanded dendrimers where the tetrahedral units are bonded through larger rigid rod spacers. Among the different synthetic strategies tested, the convergent route, with alternating steps of Pd-catalyzed Sonogashira coupling and alkyne activation by removal of TMS masking groups, efficiently afforded the first- and second-generation dendrimers. A second type of compounds having a linear diyne at the core is also described. The dendrimers of generations 1-2 were also synthesized by a convergent approach, with the diyne being assembled in the last step of the synthesis by a Glaser oxidative homocoupling of the corresponding dendrons bearing a terminal alkyne at the focal point. A third-generation dendrimer was also successfully prepared by a double-phase strategy.<br>

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