数字散斑干涉面内变形内窥测量方法研究

Research on method of endoscopic measurement of in-plane deformation using digital speckle pattern interferometry

针对现阶段数字散斑干涉内窥测量技术只能间接测量物体面内变形的问题,提出了一种双路照明的内窥式数字散斑干涉面内变形直接测量的方法,避免了离面变形对面内变形测量的影响。通过在相移式数字散斑干涉技术中结合内窥镜进行测量,并且使用对称分布的多模光纤形成双光路照明,实现了对空腔、深孔或被遮掩物面内形变的高精度测量。实验实现了入口直径为40 mm的空腔内部面内变形直接测量,当工作距离为20 mm时,测量面积可达到300 mm^2,测量分辨率达到68 nm。

In view of the problem that the traditional endoscopic digital speckle pattern interferometry(DSPI)can only measure the in-plane deformation indirectly,a method of direct measurement of the in-plane deformation using a dual-beam-illumination endoscopic DSPI is proposed to avoid the influence of the out-of-plane deformation on the in-plane deformation.High-accuracy measurement of the in-plane deformation of surface inside cavity,deep hole,or hidden object is achieved by combining the phase-shifting DSPI with an endoscope and using symmetrically distributed multimode fibres to generate a dual-beam illumination.In the experiment,a direct measurement of the in-plane deformation inside a cavity with inlet diameter of 40 mm is realized.The measuring area can reach 300 mm2 at a working distance of 20 mm and the measurement resolution reaches 68 nm.