Active polarization compensation and goniometer for angularly resolved light scattering measurements (original) (raw)
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Measurement of Polarized Light Scattering via the Mueller Matrix
1979
A new instrument for rapid and accurate measurement of the Mueller matrix is described. Distinct measurements of all, sixteen en elements are made simultaneously and with an absolute accuracy of ,1% to 5%. The instrument employs electro-optic modulators. Results are presented for several snimple optical devices and systems.
Degree of polarization as an objective method of estimating scattering
Journal of the Optical Society of America A, 2004
A new method of determining objectively the amount of scattered light in an optical system has been developed. It is based on measuring the degree of polarization of the light in images formed after a double pass through the system. A dual apparatus composed of a modified double-pass imaging polarimeter and a wavefront sensor was used to measure polarization properties and aberrations of the system under test. We studied the accuracy of the procedure in a system that included a lanthanum-modified lead zirconate titanate (PLZT) ceramic plate able to generate variable amounts of scattered light as a function of the applied voltage. Changes in the voltage applied to the ceramics plate modified significantly the scattering contribution while hardly altering the wave-front aberration. The degree of polarization was well correlated with the level of scattering in the system as determined by direct-intensity measurements at the tails of the double-pass images. This indicates that this polarimetric parameter provides accurate relative estimates of the amount of scattering generated in a system. The technique can be used in a number of applications, for example, to determine objectively the amount of scattered light in the human eye.
Modelling and instrumentation for polarized light imaging and spectroscopy of scattering media
Extracting light that has maintained its original polarization state can be used to improve the image resolution in imaging or localize the volume probed in spectroscopy. This paper describes polarization dependent instrumentation and modelling methods used in the imaging and spectroscopy of scattering media. The use of integrated optical sensors in imaging the polarization difference signal is also demonstrated.
Polarization sensitive and Mueller matrix OCT measurements and data analysis
Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XV, 2011
The present work developed a Polarization Sensitive Optical Coherence Tomography system capable of perform birrefringence images and also determine completely the Mueller Matrix of a sample, in depth. In this way many measurements were needed to be done, with different combinations of polarization states of the incident beam on the sample and the reference arm of the interferometer. After calibrating the system, a roll of adhesive tape was used as sample for two main reasons: presents birrefringent and has a periodic structure. Firstly the system was set to gather data about the horizontal polarization state and then vertical polarization state of light to construct a birrefringence image. The birrefringence (δn) of ordinary adhesive tape was evaluated as 4.03(26)x10-4. Latter a system capable of measure any polarization state was implemented and 16 scattering profiles for different polarizations were collected. Software also was developed to solve a linear equations system. As a result a 4x4 matrix of images were calculated. Some of the features, as birefringence were easily indentified in some elements of this matrix, others, more subtle, can be founded in the literature. We also decomposed the matrix as linear combinations of other known optical elements.
Astronomy & Astrophysics, 2014
With the forthcoming release of high precision polarization measurements, such as from the Planck satellite, the metrology of polarization needs to be improved. In particular, it is important to have full knowledge of the noise properties when estimating polarization fraction and polarization angle, which suffer from well-known biases. While strong simplifying assumptions have usually been made in polarization analysis, we present a method for including the full covariance matrix of the Stokes parameters in estimates of the distributions of the polarization fraction and angle. We thereby quantified the impact of the noise properties on the biases in the observational quantities and derived analytical expressions for the probability density functions of these quantities that take the full complexity of the covariance matrix into account, including the Stokes I intensity components. We performed Monte Carlo simulations to explore the impact of the noise properties on the statistical variance and bias of the polarization fraction and angle. We show that for low variations (<10%) of the effective ellipticity between the Q and U components around the symmetrical case the covariance matrix may be simplified as is usually done, with a negligible impact on the bias. For S/Ns with intensity lower than 10, the uncertainty on the total intensity is shown to drastically increase the uncertainty of the polarization fraction but not the relative bias of the polarization fraction, while a 10% correlation between the intensity and the polarized components does not significantly affect the bias of the polarization fraction. We compare estimates of the uncertainties that affect polarization measurements, addressing limitations of the estimates of the S/N, and we show how to build conservative confidence intervals for polarization fraction and angle simultaneously. This study, which is the first in a set of papers dedicated to analysing polarization measurements, focuses on the basic polarization fraction and angle measurements. It covers the noise regime where the complexity of the covariance matrix may be largely neglected in order to perform further analysis. A companion paper focuses on the best estimators of the polarization fraction and angle and on their associated uncertainties.
Effect of the structure of polarimeter characteristic matrix on light polarization measurements
Semiconductor physics, quantum electronics and optoelectronics, 2009
In the paper, we carried out the comparative analysis of three polarimeters among the most usable their variants: (i) Stokes polarimeter based on phenomenological definition of Stokes parameters; (ii) Stokes polarimeter based on the method of four intensities; (iii) Stokes dynamic polarimeter. We show that, since the accuracy in determination of individual Stokes parameter is different for different types of polarimeters, and, therewith, it depends on polarization of input light. All that strongly motivates the choice of type of polarimeter to provide minimum errors in determination of polarization parameters (ellipticity angle ε, azimuth β, and degree of polarization P).
Wavelength-scanning polarization-modulation ellipsometry: some practical considerations
Applied Optics, 1978
A discussion is presented of the practical considerations involved in wavelength-scanning polarization-modulation ellipsometry. Emphasis is placed on factors affecting accuracy and precision and on the alignment of the optical elements. The system described is used to measure the optical properties of air-cleaved KCI and of clean and tarnished Ag surfaces in ultrahigh vacuum in the 250-650-nm range.
2014
We have described a novel way to determine the Mueller matrix of any optical element by using projection method. For this purpose, we have used two universal SU(2) gadgets for polarization optics to obtain projection matrix directly from the experiment. Mueller matrix has been determined using the experimentally obtained projection matrix for three known optical elements namely free space, half wave plate and quarter wave plate. Experimental matrices are in good agreement with the corresponding theoretical matrices. The error is minimized as the experimental conditions remains same for all measurements since we have used a fixed set of polarization optics i.e. there is no removal or insertion of an optical component during the experiment.