Papers by Keyword: Phase Retardation

Abstract: As an electric coupling sensor, the D-dot voltage sensor can achieve non contact measurement of voltage. With the advantages of simple structure, a high dynamic range and measurement bandwidth, it can meet the needs of accurate measurement^[1][2]. Thus it has great application prospects in voltage on-line monitoring, relay protection or other fields in the power system. This paper considered the operation of the three-phase lines, and established the D-dot voltage sensor simulation model in the simulation platform of Ansoft Maxwell 3D. With the simulation of the sensor working conditions, we can get the distributed parameters of the system under three-phase lines in operation, construct an equivalent circuit of measurement and analyze the simulation results to get a voltage signal of input and output. The simulation results show that, with the equivalent circuit simulation of the three-phase D-dot voltage sensor, if we improve electrode capacitance parameter, there will be a good linear relationship between the input and output.

Abstract: The paper described a new magnetometer with cesium vapor in the spin-exchange-relaxation-free (SERF) regime. The variation behavior of phase retardation of the /4 wave plate (in the probing beam direction of this magnetometer) with temperature was introduced, which directly affected the sensitivity of the magnetometer. A detail theoretical analysis was expressed to give the temperature properties of a quartz wave plate. The retardation reduced 0.84 when the temperature increased 1°C for the wave plate with thickness of 2.24 mm and wavelength of 852 nm. According to the various phase retardations of wave plate in different temperatures, the relative intensity of the detection signal in this magnetometer was proposed.

Abstract: Based on liquid crystal electrically controlled birefringence, the paper theoretically deduces liquid crystal variable retarders’ (LCVRs) electrically controlled phase retardation characteristics, and establishes a mathematical analysis model which has been validated in experiment. With the fitting of research results and theoretical calculation of liquid crystal variable retarders’ electrically controlled phase retardation characteristics, a progress is made for us to further survey and understand LCVRs’ properties.

Abstract: This paper presents a new optical configuration for measuring the phase retardation of optical linear birefringent materials. Phase retardation is measured by a heterodyne light source, which is generated by a Zeeman laser. The measurement system has advantages as a simple optical setup, high stability, small size, and portable owing to the configuration and the use of a Zeeman laser. Using the ratio of amplitudes from two measured heterodyne signals, a simple algorithm can obtain the phase retardation directly. Moreover, we can extend dynamic range of the phase retardation measurement to be 0 180 successfully. According to the experimental results, the average absolute error for the phase retardation of λ / 4 -wave plate sample is determined to be only 2.7 %.