沟槽轮廓的激光双三角测量

Laser Dual-Triangulation for Groove Profile

只有一个成像透镜的激光三角测量系统不适于测量沟槽轮廓。因为系统的投影光轴与成像光轴成一定角度，沟槽的陡峭边沿会遮挡物体表面照明点的漫反射光进入成像透镜，形成测量死角。为解决这个问题，在满足Scheimpflug条件的激光三角测量法基础上，开发了测量沟槽轮廓的激光双三角测量系统；讨论了像斑探测器积分时间的自动调节、像斑强度分布数据的数字滤波、像斑中心位置的提取和成像光束被凹槽边缘遮蔽的像斑的判别等问题；通过标定实验，确定了双三角测量映射关系。对轮胎胎面轮廓的静态受压变形测量实验表明本系统测量沟槽轮廓的有效性，其可测量的轮胎花纹沟槽轮廓深宽比达到1。

Laser triangulation system with single imaging lens is not suitable for measuring the groove profile. Diffuse reflected light of illumination point on object surface is blocked by steep groove edges and a measurement blind zone is formed, because the projection axis and the imaging axis are in a certain angle. To solve this problem, a laser dual-triangulation system based on the laser triangulation method with Scheimpflug condition is developed for groove profile measurement. The autoregulation of integral time of image spot detector and the digital filtering of image intensity data are discussed. Extraction of image spot center and discriminance of imaging point due to imaging beam shaded by groove edge are also studied. The dual-triangulation mapping relationship is determined by calibration experiment. The compressive deformation measurement of tread profile indicates the validity of this system and the measurable depth-to-width ratio of the groove profile is more than or equal to 5 mm.