基于背景纹影技术的随机介质折射率场测量

针对光线通过复杂流场时产生的光传输效应问题，提出了基于背景纹影技术的复杂折射率场测量方法，给出了根据粒子图像偏移量求解折射率场分布的计算方法和推导过程，并对该方法的分辨率与灵敏度进行了理论分析。在此基础上，对火焰上方折射率场的分布进行了实验测量，利用粒子图像测量(PIV)技术对实验图像进行处理。结果表明:实验测量得到的空气折射率最大值为100029，最小值为100009，测量有效值小于00001。表明该方法具有较高的测量精度，能够有效实现复杂折射率场的实时精确测量。 

Refractive index field measurement of random medium based on background oriented schlieren

Targeting the problem of light propagation effect caused by complex flow field, a method for measuring the complex refractive index field based on the background image was proposed. The calculation method and derivation process of refractive index field distribution based on particle image offset were given, and the resolution and sensitivity of the method were analyzed theoretically. On this basis, experiments were carried out on the distribution of the refractive index field above the flame. The experimental image was processed by using the particle image velocimetry (PIV) method. Result showed that, the maximum and minimum refractive index of the air was 100029 and 100009, respectively, according to the experimental measurement, and the effective value was less than 00001. The experimental results showed that this method had high accuracy and can realize the real time accurate measurement of the complex refractive index field.