The thickness of the helium film

1951 ◽  
Vol 205 (1081) ◽  
pp. 270-285 ◽  
Keyword(s):  
Stainless Steel ◽  
Liquid Helium ◽  
Polarized Light ◽  
Angle Of Incidence ◽  
Helium Film ◽  
Helium Ii ◽  
Reflected Light ◽  
Linearly Polarized ◽  
Barium Stearate

A description is given of an optical method for the determination of the thickness of the helium II film. Linearly polarized light is reflected from a stainless steel mirror, the upper part of which is coated with a layer of barium stearate one molecule thick and the lower part with a similar layer three molecules thick. The reflected light passes through a mica compensating plate and a nicol prism. Adjustment of the mica plate and nicol gives equality of illumination on the ‘1’ and ‘3’ areas. If now a film of helium II covers the mirror the nicol must be rotated to restore equality of illumination. The rotation is a measure of the thickness of the helium film, the relation between the two quantities being calculated in terms of the angle of incidence and the optical constants of liquid helium, barium stearate and stainless steel. The observed thickness at any given height above the liquid helium was found to be nearly independent of the temperature between 1⋅1 and 2⋅18° K but then decreased rapidly to zero at the λ -point. In the formula d = k / h 1/ z for the thickness d at height h cm. for any given temperature, the value of z varies from 3⋅5 at 1⋅1° K to 2⋅5 at 2⋅1° K. The thickness at 1 cm. and 1⋅5° K is provisionally given as 1⋅9 x 10 -6 cm.

THE THICKNESS OF MOVING HELIUM II FILM

1963 ◽  
Vol 41 (7) ◽  
pp. 1047-1055 ◽  
Author(s):  
P. W. F. Gribbon ◽  
L. C. Jackson
Keyword(s):  
Stainless Steel ◽  
Liquid Helium ◽  
Polarized Light ◽  
Helium Ii ◽  
The Difference ◽  
Stainless Steel Beaker ◽  
Moving Liquid

The thickness of moving liquid helium II films has been measured using the polarized light method developed by Burge and Jackson. The moving film was that on the outside of a cylindrical stainless steel beaker emptying by creep at the rate corresponding to the temperature for the two cases 1.68° K and 1.83° K. Measured at a height of 1 cm above the outer level of the liquid the thicknesses were 5.6% and 4.5% less than those of the stationary film at 1.68° K and 1.83° K respectively. The observations are compared with the theoretical expressions for the difference in thickness of stationary and moving films derived by Kontorovich and by Franchetti.

scholarly journals Problems of Menotactic Orientation According to the Polarized Light of the Sky

1975 ◽  
Vol 30 (1-2) ◽  
pp. 88-90 ◽  
Author(s):  
Kuno Kirschfeld ◽  
M. Lindauer ◽  
H. Martin
Keyword(s):  
Infinite Number ◽  
Polarized Light ◽  
The Sun ◽  
Number Of Solutions ◽  
Special Cases ◽  
Linearly Polarized ◽  
Vector Direction

Abstract It is shown that the knowledge of the E-vector direction of the linearly polarized light at any point of the sky alone is insufficient for the determination of the position of the sun. If the E-vector direction of a second point is not known the knowledge of at least one other parameter is necessary. This parameter might be the height of the sun over the horizon. With the knowledge of the height the infinite number of solutions for the sun’s position becomes reduced to two, or in special cases to one. These cases are derived.

scholarly journals Analysis of ellipsometric parameters in the reflection of circularly polarized light from a thin anisotropic plate

2021 ◽  
Vol 2094 (2) ◽  
pp. 022071
Author(s):  
V V Yatsyshen
Keyword(s):  
Anisotropic Plate ◽  
Plate Boundary ◽  
Polarized Light ◽  
High Sensitivity ◽  
Incident Radiation ◽  
Angle Of Incidence ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
Left Handed ◽  
Reflected Light

Abstract The article presents the results of the analysis of the angular spectra of the ellipsometric parameters of the reflected wave when a circularly polarized light wave is incident on an anisotropic plate. The given dependences show a very high sensitivity of the ellipsometric parameters of the reflected light on the angle of incidence and the angle between the optical axis and the normal to the plate boundary. The energy reflection spectra themselves show much less variability when these parameters change. It should be especially emphasized the nature of the change in the ellipsometric angle Δ, which is responsible for the type of elliptical polarization - when Δ> 0, the polarization is left-handed, and when Δ <0, it is right-handed. It is shown that a thin anisotropic plate at certain angles can serve as a polarization converter of the incident radiation. The ellipsometry parameter ρ characterizes the degree of compression of the ellipse - when ρ = 1, the ellipse is transformed into a circle, and the light is circularly polarized in this case. Thus, a thin anisotropic plate can not only convert left-handed polarization to right-handed, but it can also control the very shape of the polarization ellipse. Such a plate can be used in conjunction with a layered medium, for example, a one-dimensional photonic crystal, to control the polarization of the incident circularly polarized light.

scholarly journals A theory of the film phenomena of liquid helium II

1949 ◽  
Vol 198 (1054) ◽  
pp. 438-446 ◽  
Keyword(s):  
Film Thickness ◽  
Liquid Helium ◽  
Helium Film ◽  
Helium Atoms ◽  
Helium Ii ◽  
Order Of Magnitude ◽  
New Interpretation

A theory of the liquid helium film on the general lines of that due to Schiff (1941) is proposed, the attraction between the walls of the container and the helium atoms being balanced against gravity, but the wave-like nature of the helium atoms and their mutual attractions are now considered. The predictions of the variation of film thickness with height agree with experiment in order of magnitude. A start is made on the problem of calculating the variation of film thickness with temperature, and a new interpretation of the rate of transfer of helium by the film is suggested.

Variable Angle Spectroscopic Ellipsometry (VASE) for the Study of Ion-Beam and Growth-Modified Solids

1987 ◽  
Vol 93 ◽  
Author(s):  
John A. Woollam ◽  
Paul G. Snyder ◽  
M. C. Rost
Keyword(s):  
Ion Beam ◽  
Polarized Light ◽  
Stepper Motor ◽  
Angle Of Incidence ◽  
Wide Range ◽  
State Of Polarization ◽  
Linearly Polarized ◽  
Variable Angle Spectroscopic Ellipsometry ◽  
The University ◽  
Elliptically Polarized

In the most commonly used form of ellipsometry, a monochromatic collimated linearly polarized light beam is directed at an angle φ to the normal of a sample under study. The specularly reflected beam is, in general, elliptically polarized, and the state of polarization is analyzed using a second polarizer and photodetector.1 Figure 1 shows a schematic of the rotating analyzer automated spectroscopic ellipsometer used at the University of Nebraska. The angle of incidence can be set over a wide range of angles, with a precision and repeatability of ±0.01 angular degrees. A computer controls the monochromator, the azimuth of a stepper motor driven polarizer, a shutter, and the digitization of the detector signal. There are several other schemes used for acquiring ellipsometric data, and these are discussed in several sources.

scholarly journals Polarization photo absorption spectroscopy of ZnO/CdS/Cu(In, Ga)Se2 thin film solar cells

2019 ◽  
pp. 97-103
Author(s):  
Vasilii Yu. Rud
Keyword(s):  
Solar Cells ◽  
Polarized Light ◽  
Optical Quality ◽  
Thin Film Solar Cells ◽  
Polycrystalline Film ◽  
Zno Films ◽  
Angle Of Incidence ◽  
Linearly Polarized ◽  
Different Thickness

The photosensitivity of polycrystalline-film Cu(ln,Ga)Se2/CdS/ZnO solar cells with different thickness of CdS and ZnO films have been studied. These structures exhibit a conversion efficiency 11-12% in the spectral region from 1.2 to 2.4 eV at T= 300 K. Polarization photosensitivity was observed for oblique incidence of linearly polarized light on the ZnO surface of these structures. The induced photopleochroism and an increase of the photocurrents as a result of a decrease of reflection losses were found. The induced photopleochroism 82 coefficient P1 increases with the angle of incidence E> as P1- and its value isfound to be 10-17% at E>= 75e°. The results of these polarization investigations demonstrate the sensitivity of the photoelectric processes to the optical quality of the ZnO films. Such polycrystalline-film solar cells can be employed as polarization-photosensitive devices.

On resolving fine periodic microstructures in the optical microscope

1989 ◽  
Vol 47 ◽  
pp. 364-365
Author(s):  
W.S. Putnam ◽  
C. Viney
Keyword(s):  
Liquid Crystalline ◽  
Numerical Aperture ◽  
Polarized Light ◽  
Normal Incidence ◽  
Optical Microscope ◽  
Angle Of Incidence ◽  
Resolution Limit ◽  
Crystalline Materials ◽  
Periodic Microstructures ◽  
Liquid Crystalline Materials

Many sheared liquid crystalline materials (fibers, films and moldings) exhibit a fine banded microstructure when observed in the polarized light microscope. In some cases, for example Kevlar® fiber, the periodicity is close to the resolution limit of even the highest numerical aperture objectives. The periodic microstructure reflects a non-uniform alignment of the constituent molecules, and consequently is an indication that the mechanical properties will be less than optimal. Thus it is necessary to obtain quality micrographs for characterization, which in turn requires that fine detail should contribute significantly to image formation.It is textbook knowledge that the resolution achievable with a given microscope objective (numerical aperture NA) and a given wavelength of light (λ) increases as the angle of incidence of light at the specimen surface is increased. Stated in terms of the Abbe resolution criterion, resolution improves from λ/NA to λ/2NA with increasing departure from normal incidence.

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