基于激光视觉原理测量玻璃中气泡的尺寸

为了实现玻璃中气泡尺寸的在线测量,基于激光视觉原理,采用线结构激光器、线阵CCD相机和运动控制系统在实验室搭建玻璃气泡的动态测量系统。投射到玻璃表面的线结构激光光斑经变焦镜头成像在相机的光敏阵列上,相机的横向扫描与运动平台的纵向扫描配合,利用Sapera CamExpert图像采集软件获得玻璃气泡的灰度图像;理论上讨论了图像的纵向和横向精度,给出了气泡图像失真的判断依据及工作像素时钟频率与玻璃板纵向运动速率之间的匹配关系;采集了不同纵向运动速率下气泡的灰度图像,利用Sapera Architect软件测量气泡图像的横向和纵向像素数,通过理论计算得出气泡的横向和纵向尺寸,并与直尺测量结果比较,发现纵向尺寸相对误差为0.18,横向尺寸相对误差为0.05。结果表明,在相机工作距离、焦距和像元尺寸确定的情况下在误差允许的范围内该系统可以用来测量气泡的横向尺寸。

Measurement of glass bubble size based on laser vision principle

In order to measure glass bubble size in real time, a dynamic system for measuring glass bubble was built in laboratory with a linear laser diode, a linear CCD and a movement control system based on the laser vision principle. The laser spot projected onto the glass surface was imaged on the photosensitive array of the camera through its zoom lens. Gray images of glass bubbles were grabbed by Sapera CamExpert software with the combination of the transverse scanning of the camera and the longitudinal scanning of the movement platform. The transverse and longitudinal precision of gray images was discussed in theory. The criterion for distinguishing the bubble images from distortion was confirmed and the matching relationship between the clock frequency of work pixels and the longitudinal velocity of the float glass was deduced. Bubble gray images were grabbed at the different longitudinal velocities. The transverse and longitudinal pixel number of glass bubbles was measured by the Sapera Architect. The transverse and longitudinal size of bubbles was acquired by theoretical calculation. Comparing with bubble size measured with a ruler, the relative error of the longitudinal size is 0.18 and of the transverse size is 0.05. The results show that in the case that camera work distance, focal length and pixel cell size are fixed, the transverse size of glass bubbles can be measured by this system in the range of permitted errors.