1. A system for measuring a transparent object by fringe projection, measuring a profile or refractive index of an inspected transparent object, the system comprising: a long depth of focus (DO) image generating device configured to generate a long DOF image, wherein the long DOF image is emitted into the inspected transparent object; wherein the long DOF image is generated from a fringe image which has a sinusoidal distribution penetration ratio when the long DOF image is emitted into the inspected transparent object; and wherein the long DOF image generating device comprises: a two-dimensional amplitude grating; a light source configured to illuminate the two-dimensional amplitude grating, to generate a two-dimensional fringe image; and a wide-angle lens configured to receive the two-dimensional fringe image passing therethrough and generate the long DOF image; an image, capture device configured to receive a distorted image which is generated by the long DOF image emitted into the inspected transparent object and then refracted by the inspected transparent object; and an image processor electrically connected to the image capture device, wherein the image processor pre-stores the long DOF image, wherein the image processor analyzes the distorted image and compares the distorted image with the long DOF image, to identify the profile or refractive index of the inspected transparent object.