John D. Stern

Effect of reduced stereoscopic camera separation on ring placement with a surgical telerobot

A custom, stereoscopic video camera was built to study the impact of decreased camera separation on a stereoscopically viewed, visual-manual task resembling some aspects of surgery. The camera’s field of view was matched to that of a stereoscopic laparoscope by adjusting focal length and viewing distance so that the viewer could see equivalent image content at a plane orthogonal to their view. This plane contained the point at which the left and right viewing axes converged. This geometry only exactly matches the images from both the laparoscope and the stereo-camera at this point. This condition was considered a useful approximation for a match between the two image sources. Twelve naive subjects and one of the experimenters were first trained in a ring placement task using the stereo-laparoscope and subsequently switched to the stereo-camera. It was used with differing camera separations ranging from 100% of the laparoscope’s separation to a biocular view corresponding to no separation. The results suggest that camera separation may be reduced 20-35% without appreciably degrading user performance. Even a 50% reduction in separation shows stereoscopically supported performance much better than the biocular condition. The results suggest that existing laparoscopes which use 5 mm camera separation may well be significantly miniaturized without causing substantial performance degradation.