基于RGB数字滤光的CCD激光熔覆测温系统的标定  

Calibration of CCD temperature measurement system based on RGB digital filtering in laser cladding

作　　者：黄洁[1] 张轲[1] 朱晓鹏[1] 涂志强[1] 

机构地区：[1]上海交通大学激光制造与材料改性重点实验室,上海200240

出　　处：《光电子．激光》2013年第5期967-974,共8页Journal of Optoelectronics·Laser

基　　金：国家科技部(2009DFB50350);国家自然科学基金(50605044)资助项目

摘　　要：为提高基于彩色CCD比色测温的激光熔覆测温系统的精度和测温范围,提出了基于RGB数字滤光的温度标定方法。采用MIKON M390高温标准黑体炉,每隔50℃采集不同参数下黑体炉辐射图像,在1 000～1 800℃的测温范围内对彩色CCD相机采用比色测温法进行温度标定。提出将发射率归结到待定系数K值中,并基于最小二乘法建立K与灰度比之间的一一对应关系,减小发射率误差;提出先用外搭载RGB分色窄带滤光片进行图像采集和分色滤光处理,然后建立分色滤光后灰度与无分色滤光灰度之间的映射关系,对无RGB分色滤光片的灰度值进行数字滤光,实现光谱响应带宽的误差校正。本文方法将系统最大测温误差缩小至38.6℃,将原测温范围扩大近300℃。实验结果表明,基于RGB数字软滤波方法的彩色CCD测温标定方法,简单实用、精度较高,可以较大程度提高测温范围。To improve the precision and temperature range of the laser cladding temperature measurement system based on CCD colorimetric thermometry,a new method is proposed to perform temperature calibration by using RGB digital filtering. Take the temperature radiation image of the MIKON M390 high temperature standard blackbody furnace in each 50℃ under different parameters. Then calibrate the color-CCD from 1000℃ to 1800℃ by colorimetric thermometry. Emissivity is firstly included in the undetermined coefficient K and then the correspondence function relation between parameter K and gray ratio is built by least square method to reduce the error caused by emissivity. The idea of equipping with RGB narrowband filters is put forward to do image acquisition and color filtering processing, and then the mapping relationship between theRGB filter＇s gray level and no color filter＇s gray level is established, which can realize digital filtering of the no RGB filter＇s gray level, to achieve the error correction of spectral bandwidth response. Through this method,the maximum temperature error is deeply reduced to 38. 6 ℃ in measuring range,and the temperature measuring range is enlarged by about 300℃. The experiment results show that the method,which is based on RGB digital filtering to realize the calibration of color-CCD, is quite simple, practical, but high accuracy, and can largely improve the temperature range.

关 键 词：测量 温度标定 比色测温 数字滤光 激光熔覆 彩色CCD 

分 类 号：TN249[电子电信—物理电子学]