【摘要】 基于面阵CCD(charge coupled device)的高温计由于存在光学系统渐晕,直接测量得到的温度场会发生严重畸变,大大降低了测温精度.因此,根据辐射测温及几何光学理论,建立了基于面阵CCD温度场测量的温度畸变数学模型.分析了光学参数对温度场测量精度的影响,并提出了一种基于图像邻域灰度梯度分布稀疏特性的渐晕系数估计方法.该方法与利用积分球标定方法相比,其渐晕系数估计的最大绝对误差为0.052,且其有效性在铸坯表面温度场校正实验中得到了进一步验证.更多还原

【Abstract】 Due to the existence of vignetting in the CCD-based pyrometer,there is serious photometric distortion in temperature field,resulting in the severely decreasing of the temperature measurement accuracy. So,a mathematical model for temperature distortion based on theories of radiation thermometry and geometrical optics w as built,and the influence of optical system parameters on the accuracy of temperature field measurement w as analyzed as w ell. Based on the sparsity of neighborhood gray gradient distribution( NGD),a method for the calibration of vignetting coefficient w as also proposed. Compared w ith the calibration method using a integrating sphere,its maximum absolute error for vignetting estimation is only 0. 052,and the effectiveness of this calibration method is validated by the experiment of temperature field correction for casting billets.更多还原