基于4f的大视角剪切散斑干涉系统设计

Design of digital shearography with wide angle of view based on 4f system

数字剪切散斑干涉技术在工业无损检测领域有广阔的应用前景,传统的迈克尔逊型数字剪切散斑干涉仪由于结构的限制,视场角很小,这限制了其在工程上的应用。介绍一种新型的大视角剪切散斑干涉系统,通过在成像镜头和CCD传感器之间嵌入4f光学系统来扩大其视场角,并实现镜头的外置。理论分析证明,视场角不再受到迈克尔逊结构的限制,仅仅取决于镜头的焦距和CCD传感器的靶面尺寸。设计并组建了一个大视场角迈克尔逊剪切散斑干涉系统,对比实验表明,在短的工作距离下实现了大视场的全场检测,在1m的测距下,新系统测量面积可达800mm×600mm,而传统的系统测量面积只有250mm×200mm。

Digital shearography has broad application prospects in the field of industrial non-destructive inspection. However, the traditional Michelson-interfero-meter-based digital shearography suffers from the small angle of view due to the structure,which limits its employments in industrial application.We demonstrated a novel digital shearography system with a large angle of view by embedding a 4foptical system between the separate lens and camera,achieving the lens outside of the instrument housing.Theoretical analysis shows that the angle of view has no limit to the setup but it is based on the focus length of the imaging lens and the size of the imaging sensor inside the camera.A novel digital shearography system was built and experimental results prove that the new shearography system is a good tool to conduct the full field inspection of a big size sample at a short working distance.At a working distance of 1m,the measuring area of the novel shearography system is 800 mm × 600 mm,compared with only 250mm×200mm of the traditional one.