THE SPACE-GROUP OF POTASSIUM DITHIONATE

1931 ◽  
Vol 4 (6) ◽  
pp. 565-569 ◽  
Author(s):  
W. H. Barnes ◽  
G. V. Helwig
Keyword(s):  
Polarized Light ◽  
Rotatory Power ◽  
Quarter Wave Plate ◽  
Double Refraction ◽  
Space Group ◽  
X Ray ◽  
Single Cross ◽  
Quarter Wave ◽  
Crystal Class ◽  
Axis Rotation

An X-ray investigation of the space-group of potassium dithionate is described.Approximate measurements of refractive indices and specific rotatory power were in harmony with those obtained by Groth. From Laue photographs and the fact of optical activity, the crystal class is trigonal trapezohedral, in agreement with crystallographic data.The crystals showed the single cross and circular concentric rings characteristic of uniaxial crystals when plates perpendicular to the c axis were examined under crossed Niçois in convergent polarized light. The sign of the double refraction as determined with a quarter-wave plate was positive.The primitive translations of the unit cell, determined from the a axis and c axis rotation photographs were: a0, 9.77 Å; c0, 6.28 Å, and a:c = 1:0.644. The number of molecular units per cell was found to be three. It is deduced that the lattice must be hexagonal (Γh.) From the fact that no abnormal spacings of {0001} were observed, the space-group of potassium dithionate is shown to be either [Formula: see text] or [Formula: see text].

Experimental Investigation into High Speed FD-OCT Imaging Based on Orthogonally Polarized Light

2011 ◽  
Vol 65 ◽  
pp. 315-318
Author(s):  
Hsu Chih Cheng ◽  
Ming Shiuan Shiu
Keyword(s):  
High Speed ◽  
Full Range ◽  
Polarized Light ◽  
Simple Wave ◽  
Phase Shifting ◽  
Quarter Wave Plate ◽  
Quarter Wave ◽  
Scanning Frequency ◽  
Oct Imaging ◽  
The One

A phase shifting method based on orthogonal polarized light is proposed over complex Fourier domain optical coherence tomography (FD-OCT) to enhance the speed of OCT image scanning and to resist the environmental disturbance such as vibration. In the proposed approach, one simple wave plates (a quarter-wave plate ) are inserted into the system with appropriate rotational angles, the one interference data on orthogonal polarized directions will then manipulate with π/2 phase-shifting algorithm to reduce the scanning frequency. In other words, the proposed approach enables one-shot and full-range FD-OCT.

Measurement of Stokes Parameters by Quarter-Wave Plate and Polarizer

2006 ◽  
Vol 3-4 ◽  
pp. 235-242 ◽  
Author(s):  
T. Kihara
Keyword(s):  
Wavelength Range ◽  
Relative Phase ◽  
Monochromatic Light ◽  
Polarized Light ◽  
Stokes Parameters ◽  
Quarter Wave Plate ◽  
Phase Retardation ◽  
Wave Plate ◽  
Wide Wavelength Range ◽  
Quarter Wave

Formulations of the theory of automated photoelasticity are expressed simply by use of the Stokes parameters. In the automated photoelasticity, the measurement of the total relative phase retardation must often be performed over a wide wavelength range. The Stokes parameters (S0, S1, S2 and S3) need to be measured over a wide wavelength range. The Stokes parameters of monochromatic light can be measured by the adjustable azimuth settings of a retarder and analyzer (ARA) method. When undertaking the measurement of the Stokes parameters of light of an arbitrary wavelength over a wide wavelength range, the measurement of S3 by the conventional ARA method is dependent on the phase difference error ρ i of a quarter-wave plate mismatch as well as Stokes parameter S2. The measurement of S3 by a judicious choice of azimuth settings of a quarter-wave plate and a polarizer (JCAQP) as in the method proposed can be obtained by considering ρ I . The JCAQP method is clarified by employing the Poincaré sphere. It is shown that application of the JCAQP method yields the principal axis and the relative phase retardation of the birefringent plate free from the ρ i of the quarter-wave plate for incident elliptically polarized light of an arbitrary wavelength.

X-ray quarter wave plate for magnetic dichroism

2016 ◽  
Author(s):  
EDUARDO HENRIQUE DE TOLEDO POLDI ◽  
NARCIZO MARQUES SOUZA NETO ◽  
CARLOS AUGUSTO ESCANHOELA JÚNIOR ◽  
JAIRO FONSECA JÚNIOR
Keyword(s):  
Quarter Wave Plate ◽  
X Ray ◽  
Wave Plate ◽  
Magnetic Dichroism ◽  
Quarter Wave

Nanosecond-resolved XMCD on ID24 at the ESRF to investigate the element-selective dynamics of magnetization switching of Gd–Co amorphous thin film

1998 ◽  
Vol 5 (3) ◽  
pp. 750-752 ◽  
Author(s):  
M. Bonfim ◽  
K. Mackay ◽  
S. Pizzini ◽  
A. San Miguel ◽  
H. Tolentino ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Thin Film ◽  
Magnetic Circular Dichroism ◽  
Quarter Wave Plate ◽  
Amorphous Thin Film ◽  
X Ray ◽  
Parallel Data ◽  
Quarter Wave ◽  
Left And Right ◽  
The One

The one-bunch filling mode of the ESRF is combined with a microcoil to generate a pulsed-magnetic-field pump phased with respect to the probe that is given by the bunch of photons emitted each turn (357 kHz). Nanosecond-resolved X-ray magnetic circular dichroism (XMCD) is carried out. Besides the microcoil, the two other key-elements are the energy-dispersive XAS spectrometer, which yields parallel data acquisition, and the diamond-based quarter-wave plate, which tunes the helicity of the photon alternatively left and right.

Development of Polarization Modulation Near-Field Scanning Optical Microscope and its Application to Mapping Defect-Induced Birefringence in SrTiO3 Bicrystals

1998 ◽  
Vol 4 (S2) ◽  
pp. 314-315
Author(s):  
Julia W. P. Hsu ◽  
E. B. McDaniel ◽  
S. C. McClain
Keyword(s):  
Modulation Frequency ◽  
Near Field ◽  
Polarized Light ◽  
Optical Microscope ◽  
Quarter Wave Plate ◽  
Polarization Modulation ◽  
Polarization Component ◽  
Wave Plate ◽  
Submicron Scale ◽  
Quarter Wave

Photoelastic measurement is a sensitive optical technique to map strain fields in otherwise isotropic materials. To extend this method to the submicron scale, we combine dynamic polarimetry with nearfield scanning optical microscopy (NSOM) and construct a polarization modulation NSOM (PMNSOM). The 670 nm laser light passes first through a linear polarizer (oriented at 90°), and then through a photoelastic modulator (PEM), and finally through a quarter wave plate. The PEM introduces a sinusoidally time varying phase shift δ0sin(2πft) into the +45° polarization component, where the modulation frequency/is the resonant frequency (50 kHz) of the PEM quartz element. The quarter wave plate (oriented at 0°) transforms this elliptically polarized light into linearly polarized light with its orientation varying sinusoidally at the modulation frequency. This polarized light is then coupled into a single-mode optical fiber leading to the NSOM tip.

scholarly journals Sharp focus of a circularly polarized optical vortex at the output of a metalens illuminated by linearly polarized light

2019 ◽  
Vol 43 (4) ◽  
pp. 528-534
Author(s):  
A.G. Nalimov ◽  
V.V. Kotlyar
Keyword(s):  
Silicon Film ◽  
Polarized Light ◽  
Optical Vortex ◽  
Quarter Wave Plate ◽  
Phase Plate ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
Subwavelength Gratings ◽  
Linearly Polarized ◽  
Quarter Wave

A three-level spiral metalens in an amorphous silicon film is designed. The metalens relief consists of two subwavelength gratings with a 220-nm period (for 633 nm wavelength) and depths of 90 and 170 nm. The metalens forms a left-hand circular polarized optical vortex with topological charge 2 when illuminated by a linearly polarized plane wave. The intensity distribution at a distance of 633 nm is in the form of a subwavelength circle, whereas the longitudinal projection of the Pointing vector has negative values on the optical axis, meaning that a backward energy flow occurs. Two subwavelength gratings with different depth act as quarter-wave plates, transforming linearly polarized light into circularly polarized light with a phase delay of (lambda)/2. This metalens combines functionalities of three optical elements: a quarter-wave plate, a spiral phase plate, and a high-NA diffraction metalens (NA close to unity).

Liquid Crystal Variable Retarders’ Phase Retardation Measurement with Quarter-Wave Plate and the Validation

2011 ◽  
Vol 181-182 ◽  
pp. 297-300
Author(s):  
Lin Ling Bai ◽  
Dai Li ◽  
Zi Qiang Huang
Keyword(s):  
Liquid Crystal ◽  
Polarized Light ◽  
Optical Systems ◽  
Quarter Wave Plate ◽  
Phase Retardation ◽  
Measurement Systems ◽  
Wave Plate ◽  
Relative Value ◽  
Optical Retardation ◽  
Quarter Wave

Liquid crystal variable retarders (LCVRs) are starting to be widely used in optical systems because of their capacity to provide a controlled variable optical retardation – an important technical parameter for LCVRs. In this paper, using polarization condition change of polarized light, a set of measurement systems is built. Through the measurement of the relative value of luminous intensity instead of the absolute value which can be easy affected by ambient light and the illuminant instability, it can comparative accurately acquire electrically controlled phase retardation of LCVRs. With the light source of He-Ne laser with the wave 632.8 nm, at temperature 25 °C, a standard quarter-wave plate has been measured, with the relative error less than 1 %.

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