A scanning fiber endoscope for optical imaging and diagnosis has been developed at the Mechanical Engineering Department at the University of Washington.  This novel design contains a micro-optical scanner at the distal end with less than a 2mm outer diameter and can produce a significantly smaller, cheaper, and flexible endoscope or catherscope which is mechanically like a catheter but with high resolution imaging capability.  Applications of an ultrathin scanning fiber endoscope, which is inserted from a standard flexible scope, include imaging of the main pancreatic duct, peripheral lung or any smaller body cavities such as the sinuses.  The scanning fiber endoscope, referred to as the catheterscope, uses a vibrating single mode fiber to scan a laser beam over the object surface and detectors to record the backscattered signal.  A prototype that uses a 1.6 mm diameter scanner, resulting in a 13 mm rigid tip length that includes the imaging system, followed by a soft, flexible shaft has been developed. A second endoscope prototype with a 1.0 mm diameter is currently under development.