The field distribution in the focal plane of a paraboloidal reflector

1964 ◽  
Vol 12 (5) ◽  
pp. 561-569 ◽  
Author(s):  
W. Watson
Keyword(s):  
Field Distribution ◽  
Focal Plane

Quasi-Paraxial Acoustic Field Approximation for Phased Arrays

1989 ◽  
Vol 11 (4) ◽  
pp. 260-272
Author(s):  
Ke-Ou Peng ◽  
Marcel R. de la Fonteijne
Keyword(s):  
Field Distribution ◽  
Acoustic Field ◽  
Focal Plane ◽  
Phased Arrays ◽  
Computation Time ◽  
Acoustic Vibration ◽  
Field Approximation ◽  
Scanning Angle ◽  
Geometrical Characteristics ◽  
Special Element

The quasi-paraxial theory for phased arrays presented here can be used to estimate and analyze the acoustic field in the focal plane for a large scanning angle. The transient acoustic field is considered as the product of two terms that describe the time characteristics of the acoustic vibration over the array and the geometrical characteristics of the array, respectively. This method requires little computation time. The influence of special element shapes and functions that modulate the amplitude of the element vibration on the field distribution is also investigated.

scholarly journals Construction of a femtosecond laser for the study of aberrations in optical systems

2013 ◽  
Vol 23 ◽  
pp. 7-11
Author(s):  
Miguel Ángel González Galicia ◽  
M. Rosete-Aguilar ◽  
N. C. Bruce ◽  
J. Garduño-Mejía ◽  
R. Ortega-Martínez
Keyword(s):  
Femtosecond Laser ◽  
Electric Field ◽  
Field Distribution ◽  
Focal Plane ◽  
Electric Field Distribution ◽  
Laser System ◽  
Optical Systems ◽  
Sapphire Crystal ◽  
Field Curvature ◽  
Theoretical Results

We present the construction of a femtosecond laser, based on a titanium sapphire crystal. This laser produce pulses of 20 fs. We also present theoretical results for the electric field distribution near the focal plane of a lens for gaussian illumination under the influence of primary aberrations: spherical aberrations, coma, astigmatism and field curvature, for an achromatic doublet. The theoretical results are compared with results obtained with the laser system constructed.

scholarly journals О фокусировке широкополосных терагерцовых импульсов

2019 ◽  
Vol 127 (10) ◽  
pp. 667
Author(s):  
В.Л. Малевич ◽  
Г.В. Синицын ◽  
Н.Н. Розанов
Keyword(s):  
Field Distribution ◽  
Focal Plane ◽  
Amplitude Distribution ◽  
Beam Axis ◽  
Focal Distance ◽  
Spectral Maximum

AbstractThe particular features of the focusing of a broadband THz pulse with a Gaussian transverse amplitude distribution by a lens are investigated theoretically. The expressions for the spatiotemporal field distribution on the beam axis and in the focal plane of the lens are obtained in the quasi-optical approximation. It is shown that, for the focusing to be efficient, it is necessary to use lenses with a focal distance that is much shorter than the characteristic diffraction length at the frequency corresponding to the spectral maximum of the THz pulse.

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.

Field Distribution of Strongly Excited Magnetic Lenses

1975 ◽  
Vol 33 ◽  
pp. 140-141
Author(s):  
M. Strojnik
Keyword(s):  
Flux Density ◽  
Field Distribution ◽  
Optical Axis ◽  
Operating Point ◽  
Pole Piece ◽  
Partial Saturation ◽  
Axial Flux ◽  
The Stability

Magnetic lenses operating in partial saturation offer two advantages in HVEM: they exhibit small cs and cc and their power depends little on the excitation IN. Curve H, Fig. 1, shows that the maximal axial flux density Bz max of one of the lenses investigated changes between points (3) and (4) by 5% as the excitation varies by 40%. Consequently, the designer can relax the requirements concerning the stability of the lens current supplies. Saturated lenses, however, can only be used if (i) unwanted fields along the optical axis can be controlled, (ii) 'wobbling' of the optical axis due to inhomogeneous saturation around the pole piece faces is prevented, (iii) ample ampere-turns can be squeezed into the space available, and (iv) the lens operating point covers a sufficient range of accelerating voltages.

Tandem scanning reflected light microscopy: How it works and applications

1986 ◽  
Vol 44 ◽  
pp. 84-87
Author(s):  
Alan Boyde ◽  
Milan Hadravský ◽  
Mojmír Petran ◽  
Timothy F. Watson ◽  
Sheila J. Jones ◽  
...  
Keyword(s):  
Light Microscopy ◽  
Focal Plane ◽  
Central Symmetry ◽  
Single Line ◽  
Scanning Microscope ◽  
Reflected Light ◽  
Illuminating Light ◽  
Illuminating Beam

The principles of tandem scanning reflected light microscopy and the design of recent instruments are fully described elsewhere and here only briefly. The illuminating light is intercepted by a rotating aperture disc which lies in the intermediate focal plane of a standard LM objective. This device provides an array of separate scanning beams which light up corresponding patches in the plane of focus more intensely than out of focus layers. Reflected light from these patches is imaged on to a matching array of apertures on the opposite side of the same aperture disc and which are scanning in the focal plane of the eyepiece. An arrangement of mirrors converts the central symmetry of the disc into congruency, so that the array of apertures which chop the illuminating beam is identical with the array on the observation side. Thus both illumination and “detection” are scanned in tandem, giving rise to the name Tandem Scanning Microscope (TSM). The apertures are arranged on Archimedean spirals: each opposed pair scans a single line in the image.

Imaging sub-micron objects with light microscopy: Visualization of the T-4 bacteriophage

1989 ◽  
Vol 47 ◽  
pp. 834-835
Author(s):  
Malcolm Brown ◽  
Reynolds M. Delgado ◽  
Michael J. Fink
Keyword(s):  
Electron Microscopy ◽  
Light Microscopy ◽  
Focal Plane ◽  
Phase Contrast ◽  
Dark Field ◽  
E Coli ◽  
Polystyrene Beads ◽  
Television Camera ◽  
Transmission Electron ◽  
Universal Microscope

While light microscopy has been used to image sub-micron objects, numerous problems with diffraction-limitations often preclude extraction of useful information. Using conventional dark-field and phase contrast light microscopy coupled with image processing, we have studied the following objects: (a) polystyrene beads (88nm, 264nm, and 557mn); (b) frustules of the diatom, Pleurosigma angulatum, and the T-4 bacteriophage attached to its host, E. coli or free in the medium. Equivalent images of the same areas of polystyrene beads and T-4 bacteriophages were produced using transmission electron microscopy.For light microscopy, we used a Zeiss universal microscope. For phase contrast observations a 100X Neofluar objective (N.A.=1.3) was applied. With dark-field, a 100X planachromat objective (N.A.=1.25) in combination with an ultra-condenser (N.A.=1.25) was employed. An intermediate magnifier (Optivar) was available to conveniently give magnification settings of 1.25, 1.6, and 2.0. The image was projected onto the back focal plane of a film or television camera with a Carl Zeiss Jena 18X Compens ocular.

Microspectroscopy Using a Solid Immersion Lens

2001 ◽  
Vol 7 (S2) ◽  
pp. 148-149
Author(s):  
C.D. Poweleit ◽  
J Menéndez
Keyword(s):  
Spatial Resolution ◽  
Focal Plane ◽  
Numerical Aperture ◽  
Normal Incidence ◽  
Spot Size ◽  
Index Of Refraction ◽  
Objective Lens ◽  
Improvement Factor ◽  
Oil Immersion ◽  
Long Time

Oil immersion lenses have been used in optical microscopy for a long time. The light’s wavelength is decreased by the oil’s index of refraction n and this reduces the minimum spot size. Additionally, the oil medium allows a larger collection angle, thereby increasing the numerical aperture. The SIL is based on the same principle, but offers more flexibility because the higher index material is solid. in particular, SILs can be deployed in cryogenic environments. Using a hemispherical glass the spatial resolution is improved by a factor n with respect to the resolution obtained with the microscope’s objective lens alone. The improvement factor is equal to n2 for truncated spheres.As shown in Fig. 1, the hemisphere SIL is in contact with the sample and does not affect the position of the focal plane. The focused rays from the objective strike the lens at normal incidence, so that no refraction takes place.

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