Theoretical studies on Stokes polarimeter made of one twisted nematic crystal (TNLC) and one linear polarizer were carried out. Approaching the description of the TNLC theoretically, a model of Stokes polarimeter was created and its behavior was investigated in a numerical way. The minimization criterion of the condition number of the matrix describing the setup’s behavior was applied leading to the conclusion concerning the extension of the introduced by TNLC phase difference range up to 4π.
A new high sensitivity polarimeter has been established based on a fast change of the geometrical phase caused by a small change of an examined medium birefringence. In this setup sensitivity and measurement range can be controlled. The obtained sensitivity amounts up to 800 with regard to classical polariscopes. The proposed setup enables carrying out real time measurements. Stability and measurements resolution have been examined. Numerical simulations and measurements were performed.
We present a new method for the measurement of a residual birefringence in a polariscopic interferometer. Measured
medium inserted into the setup can cause the changes in the polarization state of the propagated beam. Specific
orientation of the elements (i.e. the analyzer and the phase retarder) modifies the setup response to the small changes of
the azimuth and ellipticity angles of the propagated beam - the sensitivity of the setup is highly increased within the
limited measuring range. The sensitivity and the measuring range of the setup can be adjusted by proper mutual
orientation of the setup elements. Even though the measurement requires the analysis of the low contrast interferograms,
what can be difficult, the application of the Fourier analysis allows the calculations for the interferogram contrast lower
than in case of classical interference pattern shift tracking. In the present paper both theoretical considerations and
experimental results taken from the experimental model setup are presented. Hundredfold increase in sensitivity was
obtained in the presented experiments, which allowed the measurement of phase difference introduced by the
birefringent medium with an accuracy of one hundredth degree.
The device for the measurements of light polarization state parameters distributions has been presented. It consists of two
Wollaston like prisms (acting as spatial frequency generators), a linear analyzer, a CCD camera and a computer with the
specific software. The 2D Fourier transform of the recorded output intensity distribution contains two nonzero carrier
frequencies. The areas around these frequencies carry the information about the azimuth and the ellipticity angles
distributions of the examined light assuming that the variations of these parameters are with the frequency much lower
than the analyzer's carrier frequencies. Applying the Fourier transform methods of masking, shifting and inverse Fourier
transform with regard to these two areas, one can receive the wanted light polarization state distributions. The main
merits of this technique are: (1) the reconstruction of the polarization parameters distributions from one recorded output
image only, (2) the setup's compactness and no movable or electronically driven components. The paper presents the
setup details, critical points of adjusting setup procedure and numerical analysis, as well as the theoretical and
experimental results for uniform and non-uniform examined waves. The accuracy of the tests was estimated as λ/100.
We present a setup established to measure the light polarization state based on the general concept of Stokes
polarimeter. This setup consists of two liquid crystal modulators (LCMs), linear analyzer and CCD camera connected to
PC computer. Using this polarimeter all two-dimensional distributions of main polarized light parameters can be
measured. The measurement process consists of six fast intensity distributions measurements. In addition to the setup
description we discuss also the ways of the angular justification of both LCMs elements as well as the proper selection of
the LCMs' input voltages. The results of the measurement of some exemplary uniform and non-uniform polarized light
distributions are presented.
We propose a new setup established to measure the light polarization state and the birefringent media parameters. This
setup consists of two pairs of the linear Wollaston compensators and special circular compensators which form a set of
two spatially modulated elliptical compensators. These compensators can be used separately as a spatial generator of all
polarization states and as an elliptical spatial analyzer. When analyzing the light polarization state the singular minimum
points in the output light intensity appear. The coordinates of these points depend linearly on the azimuth and ellipticity
angles of the examined light. When combining both elements (generator and compensator) we can obtain a special
spatial elliptical polariscope. It allows measuring the main birefringent media parameters: the azimuth and the ellipticity
angle of its both eigenvectors as well as the phase difference, introduced by this medium. All desired quantities could be
obtained by some simple intensity measurements and neither movable parts nor active elements are needed and no
complicated analysis of output light should be made. We propose also a modification of described setup by using
different shearing angles in Wollaston compensators used in generator and analyzer. This should allow using Fourier
analysis of the output intensity distribution and makes our devices more suitable to real time measurements.
We present the results of birefringent media properties measurement using two different interferometers with polarizing
elements. These setups allow to generate regular and stable lattice of optical vortices (OVs) and to record the lattice
deformations caused by introduced birefringent plate. The first setup is a polariscope arrangement with two Wollaston
compensators placed between crossed polarizers. The shape of lattice basic cell is determined by the Wollaston's
shearing angle and examined birefringent medium causes only the shift of the whole OVs lattice. The calculated
displacement vector allows determining at least two parameters of measured medium simultaneously. This setup was
used also to measure the absolute value of the phase shift introduced by examined birefringent sample by using two light
sources with slightly different wavelength. We manage to determine the phase retardance order by tracking the center of
two interferograms made with and without sample. The second setup is based on modified Mach-Zehnder interferometer
in which the Wollaston compensator is inserted into the one of interferometer's arm. The measured birefringent medium
placed in another interferometer's arm causes the mutual displacement of two OVs sublattices with different topological
signs. Calculated displacements vectors between those two sublattices allows to determine birefringent sample
The optical vortices were intensively studied during last decade. In the literature there are papers presenting application of the optical vortices. The regular net of optical vortices generated by the three plane waves interference allows for the new kind of the interferometer - the Optical Vortex Interferometer (OVI). The precision of the OVI depends on the localization accuracy and the phase reconstruction. The localization methods give errors if we use beamsplitters with coatings changing the polarization state of the light. There are six beamsplitters used in this interferometer. In the setup we used non-polarizing coatings. We observed pleochroism effect, which occurs in these coatings. It is the cause of errors in the localization of optical vortices. In this paper we study the effect of pleochroism and we show the way to avoid errors in the localization of optical vortices in the OVI.
The rule for both known magneto-optic effects in isotropic media is presented. It is a generalization of Faraday and Cotton-Mouton effects. This generalization includes any orientation of external magnetic field with regard to the light wave propagation direction. Also the formulae for total birefringence in medium placed within magnetic field has been given.
The first purpose of the article is to discuss the Senarmont method of the measurement of the phase difference of the birefringence medium, which is effective even if the quarter wave plate with the phase shift different from 90 degrees is used in the measurement setup. And also the modification of the Senarmont compensator is presented in the second part of this paper. It uses standard simple and reverse Senarmont setups, however, the phase retardances of unknown medium as
well as the element used as a quarter wave plate in classical setups could be measured.
The practical problem of the lack of quarterwave plate for arbitrary wavelength has been solved. It has been shown that is possible to substitute this plate with a combination of two phase plates with phase shift different from 90 degrees. Some formulae have been derived for several of the most important cases of wave plates application in measurement setup. All the formulae are valid for arbitrary phase difference of component plates.
Side-hole fibers are one of the most hopeful types of fibers applied in pressure measurements. They have high sensitivity to pressure due to the presence of two air channels placed symmetrically near the circular or cylindrical core. In this paper, results of research of side-hole fibers with elliptical core are presented. The beat lengths of these fibers as well as the pressure and temperature sensibility were measured. The pressure sensibility reached 150 rad/MPa(DOT)m for the most sensitive fiber; that is a value 15 times greater than the sensitivity of standard birefringent fibers. Relation between the pressure and temperature sensitivity seems to be hopeful also, because their quotient was about 100 K/MPa for most of examined fibers.
The theory of elliptic retardation plates that takes into account a phenomenon of multiple reflections is presented. An analytical form of transition matrix for the normally incident plane wave is shown. Sample calculations of phase shift introduced by quartz retardation plates and of the output beam parameters as a function of plate thickness and optical axis orientation were done.
In recent 25 years a new kind of optical elements - gradient-index lenses, especially these of SELFOC type - meet with wide applications in many devices (photocopiers, compact disc players). Regardless of used in manufacturing of these lenses kind of technology, the nonuniformity of material (different doping concentration) and differences between the coefficients of linear expansion in the particular regions of the lens causes the internal stresses. Due to these stresses the gradient-index lens have to be considered as a birefringent medium. Anisotropy evoked by these stresses causes the splitting of the incident wavefront into two orthogonally polarized wavefronts and as a result: changing the image quality. The results of measurements of internal stresses and anisotropy for a few lenses are shown. The estimation of the split of the ordinary and extraordinary rays in these lenses and the numerical investigation of their diffraction image quality are presented.
Two measuring systems are presented enabling determination of the refractive index profile and its anisotropy as well as principal stress components in optical fibers and preforms, respectively. The system for optical fibers is a scanning-type, differentiating interferometer used to measure directly the wavefront derivative, from which, after the inverse Abel transformation, the index profile is obtained. The required high sensitivity of measurement is achieved by applying the sinusoidal modulation of the input beam ellipticity and the homodyne detection of the first harmonic component of the output intensity. After removing the Wollaston prism, the system can be used to measure the retardation function that is related to the fiber residual birefringence. The dynamic spatial-filtering technique, used until now to measure the ray deflection function, has been modified for testing the preforms. An optionally applied linear modulator of ellipticity of the input beam was added, to enable the measurement of the retardation function also. The system can be easily switched from the measurement of the ray deflection function to the measurement of the retardation function by moving only a single element.