Device and method for linearly and rapidly measuring half-wave voltage of linear electro-optical crystal

Abstract

The invention discloses a device and a method for linearly and rapidly measuring half-wave voltage of linear electro-optical crystal. The method comprises the following steps: a phase delay introduced by the electro-optical crystal under an external voltage is converted into the movement of interference fringes by utilizing a polarization interference principle; the movement of the fringes is measured by adopting a high-speed camera so as to obtain a phase delay amount; when the applied voltage makes the phase delay introduced by the electro-optical crystal be 180 degrees, the corresponding voltage is the half-wave voltage. According to the invention, the method belongs to the linear measurement, so that the result is not affected by the light source power fluctuation, the measurement precision is high; the measurement time of the phase delay amount is determined by the acquisition frequency of the high-speed camera and is up to microsecond level.

Description

technical field [0001] The invention relates to the application field of electro-optic crystals, in particular to a linear electro-optic crystal half-wave voltage fast measuring device and a method thereof. Background technique [0002] Electro-optic crystals are crystal materials with electro-optic effects. The phenomenon that the refractive index of crystals changes when an external electric field is applied is called the electro-optic effect. The change of the refractive index of the electro-optic crystal will generate a new main axis of the refractive index, resulting in a change in the phase difference between the polarization components of the incident light on the new main axis of the refractive index. When the phase difference is 180°, which is half the optical path difference, the corresponding applied voltage is called the half-wave voltage of the electro-optic crystal. Half-wave voltage is an important physical parameter of electro-optic crystals, which determine...

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Problems solved by technology

This method is greatly affected by the modulation signal, and the modulation signal needs to be selected near the half-wave voltage, which is difficult to achieve for the measurement of the high-value half-wave voltage.

Other methods include using phase-locked circuits to increase test accuracy, etc., but generally speaking, all current methods are based on light intensity measurement. Due to the nonlinear relationship between light intensity and phase difference, the phase difference measurement near the extreme value of light intensity Errors are magnified and are susceptible to laser power fluctuations

Although the modulation method can reduce the influence of power fluctuations, the required modulation circuit is complex and easily introduces additional errors, resulting in the inability to further improve the accuracy and speed of half-wave voltage measurement

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