双远心影像系统在微小结构测量中的应用

Application of bilateral telecentric image system in mini structure measurement

为适应精密元器件微小结构测量的需求,建立一种基于线结构光扫描的影像测量系统。系统采用自行研制的低畸变(优于0.02%)、大景深(大于5 mm)双远心光学镜头,在景深范围内,物像映射矩阵呈现良好的线性关系。对测量图像噪声抑制方法及结构光图像中线提取算法进行研究,用线性映射算法还原工件轮廓,实现微小结构的快捷测量。为保证测量的稳定,系统选择线激光光源并引入窄带滤光片,有效抑制背景噪声,在5 mm量程内,一阶误差补偿后的测量误差控制在-10~10μm内。测量系统对工件定位要求低,适用于精密零件台阶、倾角及微小异型面的常规测量,可满足基本的工业及计量检测要求。

In order to meet requirements of the precise measurement of the mini structure, an image measurement system based on line-structured laser scanning was established. In the system, a self-developed bilateral telecentric lens of low distortion （better than 0.02%） and large depth of field （greater than 5 mm） was used.In the depth of field, the matrix of imaging showed a good linearity. The noise suppression method and the midline extraction algorithm of structured light image were studied and the linear mapping algorithm was used to restore the contour of the workpiece, so as to realize the fast measurement of the mini structure. In order to ensure the stability of the measurement, the laser light was chosen and the narrow band filter was introduced, which effectively restrained the background noise. In the range of 5 mm,the measurement accuracy is between -10-10μm after the first -order error compensation. The system has low requirement for the positioning of the workpiece and it is applicable to the conventional measurement of the chamfer, inclination and small irregular surface of the precision parts, which can meet the require-ment of the basic industrial and metrological testing.