Displacement Measurement of Interior Wall of Hollow Cylinder by Digital Image Correlation Method Using Fisheye Lens

In this paper we present a method to inspect the interior wall displacement and strain of hollow cylinder by digital image correlation (DIC) method using fisheye lens. The fisheye lens provides a long depth of field and wide angle of view that make it suitable for our work. We also present the relationship between incident ray from object space and image position on the image plane. We transform omnidirectional image into real size panoramic image. The real size panoramic image can be analyzed by the DIC method to extract the in-plane deformation and strain field. The displacement can also be computed from contour maps obtained before and after the rigid body rotation or translation. Furthermore the experimental setup is simple and compact size which makes it possible to use this method into automotive optical inspection and nondestructive testing.