title: Development of the Endo-Periscope.
abstract: The indirect method of observing and manipulating impairs the depth perception and eye-hand coordination of a laparoscopic surgeon. Important factors that impair depth perception are absence of shadows in endoscopic camera pictures and a restricted ability to observe organs from different sides. One important factor that impairs eye-hand coordination is the unnatural endoscopic line-of-sight, which results in a misorientation between the surgeon's hand movements and the instrument movements on the screen. In order to solve these problems, a new type of steerable endoscope was developed by close cooperation between the Delft University of Technology and the Tokyo Institute of Technology. The endoscope, called Endo-Periscope, is designed for use in combination with a miniature camera on the tip. Shadows are introduced by a light source on the shaft. The steerable tip, which can move in six degrees of freedom (DoF), can be used to observe anatomic structures from the side and to eliminate misorientations. The steerable tip is controlled by the handgrip via a spatial parallelogram mechanism. The handgrip contains an arrow that points always in the direction of the camera's line-of-sight. This provides intuitive control of the tip, showing how the camera is oriented in the abdominal cavity. The tip contains a new kind of spring that enables the tip to bend over 180&#176; within a very small bending radius. We have applied for two international patents to cover the construction of the Endo-Periscope and the spring in the tip.