Patent ID: 7110657
Filing Date: 2006-09-19
Classification: G02B

Abstract:
1. A method of characterizing distortion introduced by an imaging system that comprises imaging optics and a detector, the method comprising: providing a generally cylindrical object having a peripheral surface, an end face and a longitudinal axis, positioning the object with the longitudinal axis substantially coinciding with an axis of rotation, the object and the imaging optics being in a first relative angular position about the axis of rotation, employing the imaging optics to image the end face of the object on the detector, extracting a first definition of the shape of the image of the periphery of the end face of the object from image data provided by the detector when the object and the imaging optics are in the first relative angular position, effecting relative rotation of the imaging optics and the object about the axis of rotation to a second relative angular position, extracting a second definition of the shape of the image of the periphery of the end face of the object from image data provided by the detector when the object and the imaging optics are in the second relative angular position, calculating a function that characterizes measurement distortion introduced by the imaging system, and applying said function to at least one of the first and second definitions to determine physical distortion of the peripheral surface of the cylindrical object.