United States Patent  [ii] Patent Number: 5,999,837
Messner et al.  Date of Patent: Dec. 7,1999
U.S. Patent Dec. 7,1999 sheet 1 of 4 5,999,837
A microscope calibrator probe includes a handle, a tool head connected to the handle, a viewable target connected to an end of the tool head opposite the handle, and three or more position signaling devices disposed on the handle for tracking the probe in an image guided surgery system. The tool head includes a bend of approximately 90 degrees to provide easy placement of the viewable target on an object being viewed below a microscope. Other angles for the bend are also acceptable. A precise location of the object being viewed is determined by sensing a location the three or more position signaling devices disposed on the handle with respect to an operating room reference frame and knowing an offset between the position signaling devices and a bottom surface of the viewable target in contact with the object. Additionally, the viewable target includes a viewable aperture for calibrating a line of sight of the microscope and a means for indicating a rotational sense of the viewable target.
30 Claims, 4 Drawing Sheets