Internal Flaw Detection Of Materials And Shape Measurement Of Objects Based On Speckle Metrology

Speckle metrology is an optical measurement technique and is widely used in many areas due to itsadvantages of non-contact, high accuracy, real-time and full field measurement. According to thequestions which exist in some applications using speckle metrology for non-destructive testing andshape measurement, some researches and the relative resolvent methods are proposed in this paper.When we use speckle metrology to do some non-destructive testings, many deep depth flaws cannot be directly detected. To solve this problem, this paper proposes a method in which the secondderivative of displacement of the detected object to identify flaws is used. In addition, theoreticalderivation, numerical simulation and experiment are used to verify the validity of this method. Resultshows that the method can identify flaws very well. Meanwhile, the influence of shearing amount indigital shearography on flaw detection is also analyzed in the paper.Depth measurement is important and also complicate in flaw detection. In the most previous flawdetections, people detect the depth of a flaw on the basis of experience or by using some simplecalculation. These methods of detecting depth may cause a large error. Therefore, a new methodwhich combines the deflection equation of a plate and solution of equations is proposed in this paper.The experimental results show that the method has a higher accuracy than past methods.Digital image correlation is also a speckle metrology technique and has many applications on shapemeasurement. For example, shape information of an object can be acquired by measuring thedisplacement of each point using digital image correlation after translating the detected object.However, the method has a disadvantage that the detected object must be removable. Based on this, aplane mirror is added in the experiment and then the purpose of moving the detected object can beachieved by rotating the mirror. Result shows that this method not only is very simple but also has ahigh precision.