Patent ID: 6517478
Filing Date: 2003-02-11
Classification: A61B

Abstract:
Apparatus for use in calibrating lens position and field of view in an endoscope having an elongate shaft and a distal-end lens, comprising:a plurality of tracking elements mounted at fixed positions on the endoscope's shaft, a pattern support having a feature pattern contained in a target region, positional elements mounted on the pattern support at known positions with respect to said pattern, a sensing device for sensing the tracking and positional elements, and a processor operably connected to the sensing device and a display device for carrying out the following operations: (i) determining the positions of the tracking and positional elements, with the endoscope placed at a selected position for viewing features in said pattern in three dimensions, (ii) using the determined positions of the tracking and positional elements to place the endoscope and the holder in a common frame of reference, (iii) determining the image coordinates of features in the pattern, as seen by the endoscope at the selected position, (iv) using a camera calibration algorithm to calculate from the image coordinates of the pattern features, and from the known positions of the pattern features in said common reference frame, the coordinates of the endoscopic lens with respect to said tracking elements and the lens' field of view.