Vision measurement error analysis for nonlinear light refraction at high temperature

For vision measurement at high temperature, pixel error from light refraction by high temperature is a problem that cannot be neglected. The refractive index distribution is nonlinear around the high-temperature component, leading to the light deflection. In this paper, the influence of measurement parameters on the deflection of imaging light and the accuracy after binocular reconstruction are systematically analyzed. The heat transfer theory is used to simulate the air temperature distribution near the measured component, and the corresponding refractive index distribution of air is obtained according to the refractive index formula. Then, the imaging measurement model of the nonlinear refractive index air medium for the high-temperature component is established to obtain the light deflection error. The binocular vision system reconstruction theory is applied to evaluate the measurement error between the theoretical reconstruction point and the object point. The influences of error sources, such as the temperature, optical wavelength, and camera parameters, are investigated systematically. It is found that temperature and base distance are the largest error sources on the final measurement error when the measured distance is fixed.