Application of Optical Flow Field in Out-of-plane Displacement Measurement for Optical Fiber Material

In order to monitor the micro-scale deformation of opticalfiber material during industrial production, image wedge model is built and then a out-of-plane displacement measurement technique based on optical flow field is proposed. The experimental apparatus consists of an optical microscope with an industrial camera and a holder with a fixed image inverter and the deformation can be loaded by tilting the holder. First, 2D images before and after deformation are captured through microscope with CCD camera. Subsequently, the optical flow field between two images is obtained by Brox optical flow algorithm. Finally, according to the image wedge model, the out-of-plane displacement field between two images is extracted from the optical flow field and the results of experiment are analysed as well. The experimental results indicate that the absolute errors and the relative errors of the measurement by optical microscope with magnification of 50X are less than 0.1 mu m and 1.5%, respectively. The displacement measurement can be completed by two consecutive frames which obtained by only one optical microscope with a industrial camera. The proposed method is appropriate for dynamic deformation monitoring and industrial in-situ detection and it neither need conversion of the images to frequency domain, also do riot need phase envelope operation during the out-of-plane displacement extraction process. Due to the low errors, it has been applied to the industrial uniformity and micro-nano-scale deformation monitoring of optical fiber image transmission materials.