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In this study, an interferometric method was proposed for the simultaneous measurement of phase retardation and fast-axis azimuth angle of a wave plate by using a Mach–Zehnder interferometer. The wave plate to be tested is placed in one of the light passages in the interferometer, and two analyzers with transmission axes at horizontal and vertical orientations are arranged at the two output regions. When a linearly polarized laser light beam is passed through the interferometer, two interference light beams are simultaneously generated. Through an analysis of the intensities of the two light beams, the phase retardation and fast-axis azimuth angle of the tested wave plate can be simultaneously determined using specially derived equations. The feasibility of the proposed method was demonstrated using measurements of zero-order half-wave and zero-order quarter-wave plates. The proposed method is easy to operate, enables rapid measurement, and has high stability and accuracy. [ABSTRACT FROM AUTHOR]

In this study, an optical scheme based on the measurement of light intensity and a proper orientation of the Fresnel Rhomb is successfully developed for simultaneous determination of the phase retardation and fast axis of a wave plate. The theoretical analysis of the principle of measuring the reflection-induced retardance of the Fresnel Rhomb and the phase retardation of a wave plate is given taking Stokes–Mueller Formalism as a mathematical tool. In this method, the fast axis position of the wave plate need not be determined in advance. In addition, the measured result is free of the intensity fluctuation of light source. An application example is also demonstrated. The measured result of the example is verified with an experiment. Some of the merits of the method, such as, a simple optical set-up, high stability and high accuracy, low cost and easier operation, are presented, and the validity of the method is demonstrated. [ABSTRACT FROM PUBLISHER]

We present an experimental and post-processing scheme that allows ultrasound surface wave detection by means of an unstabilized homodyne interferometric technique. We register interference signals for a set of uncalibrated phase shifts and, from them, we are able to retrieve the normal surface displacement of a thin aluminium plate. The results obtained with this technique are then compared to robust and more traditional phase recovery methods such as the Carré algorithm and the 11-step windowed discrete Fourier transform algorithm. For both algorithms, we found a correlation superior to 99.9%, when compared to the results of the proposed technique. This non-destructive testing scheme represents a simpler and less-expensive alternative to other existing laser ultrasonic techniques. [ABSTRACT FROM PUBLISHER]

The system estimation by least squares optimization is employed to obtain physical polarization parameters of optical devices. The method is proved flexible and convenient for measuring polarization parameters in different systems where the input state of polarization (SOP) of the devices is either measurable or not, providing the analytical estimation equations and adequate measurements are available. The estimation error for the measurement system with a rotating wave-plate (WP) as the polarization state generator is analyzed and simulated. Better estimation precision can be obtained by involving more SOP measurements in estimations and choosing a WP with retardance around 3/4. Two experiments are demonstrated. One is to estimate the polarization parameters of a fiber polarization controller with measurable input SOP, and the other is to measure the retardance of a glass quarter-wave plate whose input SOP is immeasurable. The standard deviations of estimated polarization parameters are within 0.0011–0.0103. [ABSTRACT FROM PUBLISHER]

Fiber optic quarter waveplate (QWP) is widely used in all kinds of optical fiber systems such as fiber sensing systems. Specifically, in fiber optic current sensor (FOCS) system, which is now applied in power grids to measure current and monitor operation, fiber optic QWP is a key device and has serious impact on temperature stability and accuracy of the system. We fabricated a QWP using polarization-maintaining photonic crystal fiber (PM PCF), and studied its impact on the temperature characteristic of a home-made FOCS system. We also made a QWP with conventional polarization-maintaining fiber (PMF) for comparison purposes. The measured system error of the FOCS prototype using a QWP made of PM PCF between −40°C and 70°C was 8.45‰, which is five times smaller than with a QWP made of conventional PMF. [ABSTRACT FROM AUTHOR]

An optical system is proposed for the controlled focus shaping of generalized cylindrical vector beams by a high-numerical-aperture lens. A segmented electro-optical filter with four concentric belts is introduced and works with a double-λ/2-plate. By controlling the rotational angle of the plate and the voltage applied to the filter with proper azimuth angle, a three-dimensional engineered focusing field, such as an electrically controlled axial-shifted focus, extended depth of focus, and a diffraction-limited optical tube, can be achieved. The main advantage of this focusing system is that the focused field can be adjusted and formed by the applied voltage and the rotational angle of the half-wave plates. It can provide a new focus shaping technique with free adjustability and flexibility. [ABSTRACT FROM AUTHOR]