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Linear birefringence is one of the most important parameters of optical (fibre-optic) current-sensing heads, which can obviously affect the performance of optical current sensors. Therefore, it is of great importance to measure the linear birefringence inside the optical current-sensing head to enhance the properties of sensors. A novel method to measure the linear birefringence inside bulk glass current-sensing heads is reported in this paper, which gives a theoretical analysis of the principle, the measurement uncertainty analysis—using the Jones matrix as a mathematical tool—and an applied example. This method overcomes the shortcomings of the two methods reported before which cannot uniquely determine the value of the linear birefringence or introduce large measurement uncertainty. The experimental result shows that this method can certainly enhance the measurement precision.

Verdet constant is one of the prominent parameter showing the magneto-optical property of magneto-optical materials. There will be a wavelength accumulation effect in the systems employing broad-band optical sources, because of the dispersion property of Verdet constant. It is not proved, however, how much this effect can affect the broad-band system up till now. Therefore it is necessary to research into it, because the question whether it is reasonable and feasible to use a monochromatic light model for the describing of broad-band systems is concerned. The dispersion formula of the Verdet constant of ZF-7 glass is calculated first, and then, its wavelength accumulation effect upon an optical current sensor is theoretically analyzed and digitally simulated, in this paper. The results show that the wavelength accumulation effect of the Verdet constant of ZF-7 glass is less enough and the treatment of using monochromatic model to describe broad-band optical current sensing systems is reasonable and feasible, if the wavelength accumulation effects of the other optical parameters of the sensing head are not considered. The results might be a reference to the colleagues working in the optical current sensing techniques area.

Linear birefringence inside the sensing head can obviously affect the performances of optical (fiber-optic) current transformers. Therefore, it is important to measure the linear birefringence for the design and the property enhancement of optical current transformers. A method employing a retarder to measure the linear birefringence inside the bulk glass current sensing head is reported. The theoretical analyses of the principle and the measurement uncertainty of the method are given using Jones Matrix as a mathematical tool. An applied example is also given. The main advantage of this method is that it can uniquely determine the value of the linear birefringence inside the sensing head, which overcomes the shortcoming of that only a trigonometric function value of the birefringence can be determined by the method reported before. Furthermore, there are some other advantages such as simple structured, practical and that the devices needed are easy to obtain.