提出一种基于切口特征自动识别的五轴三维激光切割轨迹自动生成方法。采用STL模型,通过切口特征自动识别实现了切口特征的自动选取,并通过对切口边环的偏置实现了激光束半径补偿;利用切口边环的离散点确定了激光束入射点位置,并利用激光束入射点所在三角面片的法向量确定了激光头姿态;算法应用实例表明,该方法能够实现切口特征的自动选取和激光束半径补偿,并能保证激光头始终与工件表面保持垂直,软件系统运行稳定可靠。

提出了一种在五轴激光切割中激光头与工件干涉检查并对激光头姿态进行修正的方法。采用STL模型对激光头进行模型化,并将其分为凸型和凹型两种类型;利用工件STL模型的离散点与激光头各三角面片法向量位置关系找出干涉区域;给出了通过旋转激光头来消除干涉并利用一系列切平面切割激光头来计算临界旋转角的方法;采用VC++和OpenGL完成了算法的系统实现。算法应用实例表明,该方法能够很好地检查出激光头和工件的干涉区域,并能够修正激光头的姿态以避免干涉,整个检查与修正过程稳定可靠。

Optical coherence tomography (OCT) is a noninvasive cross-sectional imaging modality capable of measuring tissue morphology and function with high spatial resolution. Both the amplitude and the phase of the interometric heterodyne signal can be exploited to obtain the profile of sample reflectivity related to its microstructure and the bi-directional blood flowing velocity information. The fact that the skin and human mucosa have a layer structure suggests that the backscattered signal from tissue arises from two sources. The first is the scattering particles within the tissue. The second is the Fresnel refraction on the interface between two layers. However, the analysis available only considers one aspect of the backscattering sources. In this paper, we report an analysis that is based on the combination of both the particle scattering within the tissue and the Fresnel reflection on the interfaces between two layers. The new model is more reasonable for establishing the relationship between the signal detected by OCT scanner and tissue structures.