scholarly journals Experimental Mueller matrix polarimetry with full Poincaré beams and a CCD camera

2021 ◽  
Vol 255 ◽  
pp. 12005
Author(s):  
Juan Carlos Suárez-Bermejo ◽  
J. Carlos González de Sande ◽  
Massimo Santarsiero ◽  
Gemma Piquero
Keyword(s):  
Polarization State ◽  
Linear Equations ◽  
Ccd Camera ◽  
Mueller Matrix ◽  
Phase Plate ◽  
Overdetermined System ◽  
Mathematical Methods ◽  
Quarter Wave ◽  
Optimum Solution ◽  
Linear Polarizer

Recently, the use of full Poincaré beams for extracting the Mueller matrix of a sample has been proposed. These beams present all possible polarization states across their transverse section. By placing a CCD camera behind a simple polarization analyzer formed by a quarter wave phase plate and a linear polarizer, a polarization map of the beam cross section can be obtained. This polarization map is modified when a sample is inserted before the polarization state analyzer. Comparison of these two polarization maps allows to obtain the Mueller matrix of the sample. An overdetermined system of linear equations (thousands of equations) can be written from this comparison. Standard mathematical methods are used to find optimum solution of this overdetermined system of equations. Some experimental results will be presented to check the performance of the proposed polarimetric method.

A SPINNING POLARIZER AND SPINNING ANALYZER METHOD FOR VISUALIZING THE ISOCHROMATES IN CONOSCOPIC INTERFEROMETERS

2013 ◽  
Vol 27 (30) ◽  
pp. 1350175
Author(s):  
OLUWATOBI OLORUNSOLA ◽  
OLUWASEYE DADA ◽  
PENGQIAN WANG
Keyword(s):  
Lithium Niobate ◽  
Electric Field ◽  
Polarization State ◽  
Direct Visualization ◽  
Simple Method ◽  
Circular Polarizer ◽  
Isochromatic Fringes ◽  
Quarter Wave ◽  
Viewing Screen ◽  
Linear Polarizer

We have developed a spinning polarizer and spinning analyzer (SPSA) method to visualize the whole isochromatic fringes in conoscopic interferometers for the study of optically anisotropic materials. This simple method completely eliminates the broad and dark isogyre fringes appearing in a conventional conoscopic interferometer where a linear polarizer and a linear analyzer (LPLA) are used. Our method allows the direct visualization of the isochromates on the viewing screen by eyes in real time, without the need of additional optics or detectors other than those used in a conventional conoscopic interferometer, and no additional computation is required. This method works at any polarization state of the input light, and at any wavelength permitted by the polarizers. In the case of polychromatic illumination our method reveals the isochromates of all colors indiscriminatively, in comparison to the method of circular polarizer and circular analyzer (CPCA), which is considerably subject to spectrum modulation due to the dispersion in the retardation of the quarter-wave plates. The proposed method is demonstrated in a lithium niobate ( LiNbO 3) crystal driven by an external electric field.

scholarly journals High-Contrast and Scattering-Type Transflective Liquid Crystal Displays Based on Polymer-Network Liquid Crystals

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 739 ◽  
Author(s):  
Cheng-Kai Liu ◽  
Wei-Hsuan Chen ◽  
Chung-Yu Li ◽  
Ko-Ting Cheng
Keyword(s):  
Liquid Crystal ◽  
Polymer Network ◽  
Liquid Crystal Displays ◽  
Quarter Wave Plate ◽  
High Contrast ◽  
Trade Off ◽  
Twisted Nematic ◽  
Quarter Wave ◽  
The Common ◽  
Linear Polarizer

The methods to enhance contrast ratios (CRs) in scattering-type transflective liquid crystal displays (ST-TRLCDs) based on polymer-network liquid crystal (PNLC) cells are investigated. Two configurations of ST-TRLCDs are studied and are compared with the common ST-TRLCDs. According to the comparisons, CRs are effectively enhanced by assembling a linear polarizer at the suitable position to achieve better dark states in the transmissive and reflective modes of the reported ST-TRLCDs with the optimized configuration, and its main trade-off is the loss of brightness in the reflective modes. The PNLC cell, which works as an electrically switchable polarizer herein, can be a PN-90° twisted nematic LC (PN-90° TNLC) cell or a homogeneous PNLC (H-PNLC) cell. The optoelectric properties of PN-90° TNLC and those of H-PNLC cells are compared in detail, and the results determine that the ST-TRLCD with the optimized configuration using an H-PNLC cell can achieve the highest CR. Moreover, no quarter-wave plate is used in the ST-TRLCD with the optimized configuration, so a parallax problem caused by QWPs can be solved. Other methods for enhancing the CRs of the ST-TRLCDs are also discussed.

scholarly journals Longitudinal Component Properties of Circularly Polarized Terahertz Vortex Beams

2021 ◽  
Vol 9 ◽  
Author(s):  
Miao Wang ◽  
Xinke Wang ◽  
Peng Han ◽  
Wenfeng Sun ◽  
Shengfei Feng ◽  
...  
Keyword(s):  
Spot Size ◽  
Longitudinal Component ◽  
Transverse Component ◽  
Quarter Wave Plate ◽  
Phase Plate ◽  
Vortex Beam ◽  
Circularly Polarized ◽  
Left Hand ◽  
Quarter Wave ◽  
Focusing Properties

A circularly polarized vortex beam possesses similar focusing properties as a radially polarized beam. This type of beam is highly valuable for developing optical manufacturing technology, microscopy, and particle manipulation. In this work, a left-hand circularly polarized terahertz (THz) vortex beam (CPTVB) is generated by utilizing a THz quarter wave plate and a spiral phase plate. Focusing properties of its longitudinal component Ez are detailedly discussed on the simulation and experiment. With reducing the F-number of the THz beam and comparing with a transverse component Ex of a general circularly polarized THz beam, the simulation results show that the focal spot size and intensity of its Ez component can reach 87 and 50% of Ex under a same focusing condition. In addition, the experimental results still demonstrate that the left-hand CPTVB can always maintain fine Ez focusing properties in a broad bandwidth, which manifest the feasibility of this class of THz beams.

scholarly journals Imaging Mueller matrix determination of transparent, unpolarizing samples using a classically entangled polarization state

2018 ◽  
Vol 64 (4) ◽  
pp. 407
Author(s):  
Jacqueline Isamar Muro-Ríos ◽  
R. Espinosa-Luna
Keyword(s):  
Open Space ◽  
Polarization State ◽  
Theoretical Work ◽  
Mueller Matrix ◽  
Experimental Setup ◽  
Wave Plate ◽  
Recent Theoretical Work ◽  
Study Results ◽  
Theoretical Proposal

Inspired in a recent theoretical work for the determination of the Mueller matrix, using as incidence a single classically entangled polarization state (F. Töppel et al., New J. Phys. 16 (2014) 073019), an experimental setup is proposed and tested.  The open space and two wave plate retarders are used as the transparent, nondepolarizing samples under study. Results show some experimental improvements are necessary in order to implement accurately the theoretical proposal in which this work is based.

scholarly journals Minimization of Deviations of Gear Real Tooth Surfaces Determined by Coordinate Measurements

1993 ◽  
Vol 115 (4) ◽  
pp. 995-1001 ◽  
Author(s):  
F. L. Litvin ◽  
C. Kuan ◽  
J. C. Wang ◽  
R. F. Handschuh ◽  
J. Masseth ◽  
...  
Keyword(s):  
Linear Equations ◽  
Least Square Method ◽  
Least Square ◽  
Tooth Surface ◽  
Hypoid Gear ◽  
Overdetermined System ◽  
Entire Surface ◽  
First Order ◽  
Tooth Surfaces ◽  
Coordinate Measurements

The deviations of a gear’s real tooth surface from the theoretical surface are determined by coordinate measurements at the grid of the surface. A method has been developed to transform the deviations from Cartesian coordinates to those along the normal at the measurement locations. Equations are derived that relate the first order deviations with the adjustment to the manufacturing machine tool settings. The deviations of the entire surface are minimized. The minimization is achieved by application of the least-square method for an overdetermined system of linear equations. The proposed method is illustrated with a numerical example for hypoid gear and pinion.

scholarly journals A novel interpretation of least squares solution

1992 ◽  
Vol 15 (1) ◽  
pp. 41-46
Author(s):  
Jack-Kang Chan
Keyword(s):  
Least Squares ◽  
Source Localization ◽  
Convex Combination ◽  
Linear Equations ◽  
Singular Values ◽  
Statistical Interpretation ◽  
System Of Linear Equations ◽  
Overdetermined System ◽  
The Matrix ◽  
Cramer’S Rule

We show that the well-known least squares (LS) solution of an overdetermined system of linear equations is a convex combination of all the non-trivial solutions weighed by the squares of the corresponding denominator determinants of the Cramer's rule. This Least Squares Decomposition (LSD) gives an alternate statistical interpretation of least squares, as well as another geometric meaning. Furthermore, when the singular values of the matrix of the overdetermined system are not small, the LSD may be able to provide flexible solutions. As an illustration, we apply the LSD to interpret the LS-solution in the problem of source localization.

scholarly journals L1 Norm Solution of Overdetermined System of Linear Equations

2019 ◽  
Vol 1 (1) ◽  
pp. 19-30
Author(s):  
Bijan Bidabad
Keyword(s):  
Linear Equations ◽  
Computer Programs ◽  
System Of Linear Equations ◽  
Overdetermined System ◽  
L1 Norm ◽  
Weighted Median

In this paper, three algorithms for weighted median, simple linear, and multiple m parameters L1 norm regressions are introduced. The corresponding computer programs are also included.   

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