In this paper, absolute-phase total internal reflection heterodyne interferometry is proposed for measuring a full-field refractive index. In this method, an optical configuration of prism-based total internal reflection is used. If an electro-optical modulator is driven by a sawtooth wave with an amplitude lower than the half-wave voltage, heterodyne interferometric signals can be generated in segment mode. After a camera has captured these discrete interferometric signals, the optimum signal segment can be analyzed; a specific time segment can be inserted so that the interferometric signals of every pixel can be fitted as a continuous sinusoidal wave; a least-squares sine-fitting algorithm can extract the initial phase. Finally, the absolute phase can be calculated by subtraction of the characteristic phase, and the full-field refractive index can be obtained. To prove the feasibility of the proposed method, the different combinations of specimens were measured, including air, water, glycerol, and castor oil. The experimental data correspond well with the theoretical values. This method features simple operation, low influence of environmental disturbance, rapid measurement, and high resolution.

中文翻译：

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使用绝对相位全内反射外差干涉法进行全场折射率测量

在本文中，提出了用于测量全场折射率的绝对相位全内反射外差干涉法。在该方法中，使用了基于棱镜的全内反射的光学配置。如果电光调制器由幅度低于半波电压的锯齿波驱动，则可以在分段模式下产生外差干涉信号。在相机捕捉到这些离散干涉信号后，可以分析最佳信号段；可以插入特定的时间段，使每个像素的干涉信号可以拟合为连续的正弦波；最小二乘正弦拟合算法可以提取初始相位。最后，可以通过减去特征相位来计算绝对相位，并且可以得到全场折射率。为了证明所提出方法的可行性，测量了样品的不同组合，包括空气、水、甘油和蓖麻油。实验数据与理论值吻合良好。该方法操作简单，受环境干扰影响小，测量速度快，分辨率高。