99 ISSN 0020-4412, Instruments and Experimental Techniques, 2018, Vol. 61, No. 1, pp. 99–105. © Pleiades Publishing, Ltd., 2018. Single Camera 3D Digital Image Correlation Using a Polarized System 1 Junrui Li a , Boyang Zhang a , Xin Kang a, b , Wan Xu a , Guobiao Yang a , and Lianxiang Yang a, * a Department of Mechanical Engineering, School of Engineering and Computer Science, Oakland University, Rochester, USA b Department of Mechanical Engineering, School of Mechanical and Electrical Engineering, Putian University, Putian, China *e-mail: yang2@oakland.edu Received February 16, 2017 Abstract− In this paper, a novel single camera three dimensional digital image correlation (3D-DIC) system, using a polarized pseudo-stereo system, is proposed. Compared to traditional 3D-DIC systems using stereo- vision, it has a more compact structure and better vibration resistance. Compared to the conventional single camera pseudo-stereo system that splits the CCD sensor into two halves to capture the stereo views, the pro- posed system achieves both views using the entire CCD chip without reduction of the spatial resolution. In addition, the center of the two views stands in the center of the CCD chip, similarly to conventional 3D-DIC systems, thus minimizing the image distortion compared to the conventional pseudo-stereo system. The two overlapped views in the CCD sensor are separated using the different polarization states, and the standard 3D-DIC algorithm can be utilized directly to perform the evaluation. The principal and experimen- tal setup are described in detail, and multiple tests are performed to validate the system. DOI: 10.1134/S0020441218010050 1. INTRODUCTION Digital image correlation (DIC) is a non-contact, whole-field optical measurement method capable of measuring the contour, deformation and strain on a surface. This technique was proposed by Peters, [1], Sutton [2], and Yamaguchi, [3] in the 1980s. Starting in the mid-1990s, the three-dimensional digital image correlation (3D-DIC) technique was developed to obtain whole-field information, including the con- tour, deformation, and strain, in three dimensions [4]. In the 3D-DIC technique, the conventional DIC algorithm is integrated with a stereo-vision system to fulfill the 3D measurement. Two fixed cameras with an angle between them were placed in front of the test object, and the stereo-vision algorithm was applied to combine the information from these two cameras [5, 6]. In addtion, to determine the intrinsic and extrinsic parameters for the stereo-vision system, the 3D calibration technique for the DIC system was investigated at the same time [7–9]. Several problems currently exist in the 3D-DIC system. First, the conventional 3D-DIC system is sen- sitive to environmental vibration [10, 11]. Since the conventional 3D-DIC system uses two cameras to acquire the 3D information, the relative position between the cameras must be fixed to obtain accurate results after calibration. The environmental vibration could result in relative movement between the cam- eras, thus introducing error to the measurement. Sec- ond, the conventional 3D-DIC system has limitations with respect to high speed measurement. 3D-DIC requires that two images be captured at the same time for 3D measurement. However, this requires precise synchronization between the two high speed cameras, and the synchronization between the camera could change over the course of the measurement. Lastly, the conventional 3D-DIC has the difficulties with measuring small areas [12]. Through extension of the applications of 3D-DIC, 3D-DIC has been used for material testing within a small area. A long focus lens needs to be utilized to obtain good image resolution. However, the long focus lens is usually large in size, which results in a position conflict between the two lenses in the conventional system. To overcome the drawbacks of the conventional 3D-DIC system, K. Genovese proposed a single cam- era 3D-DIC setup utilizing the refraction-based pseudo-stereo system in 2013 [13]. A bi-prism, as a refractor, is used to split the scene into two equivalent lateral views in the two halves of the CCD chip. The single camera 3D-DIC system acheives the 3D-DIC 1 The article is published in the original. GENERAL EXPERIMENTAL TECHNIQUES