Precision of near-infrared laser spot detection on different skin tissues featuring an NDI stereo camera

Computer assisted surgery requires a registration process that identifies the position of the patient within the operating room. A common approach is to attach reflective markers to the patient which are illuminated and detected by a stereo camera. In order to reduce the logistic effort of operation planning, it is desirable to perform an automatically marker-less registration. In order to implement a reliable system for surface scanning the measurement precision may neither vary significantly throughout the scanning volume, nor be influenced by the angle of incidence. Moreover, the system precision should not depend on the skin pigmentation. Therefore, we assessed the influence of different parameters on the precision at which laser spots can be detected on skin tissue with an NDI stereo camera. In this paper, we present novel results of coupling an NDI stereo camera with an 850nm laser beam and the precision that can be achieved with this approach.