#$%^&*AU2016277626A120170720.pdf#####ABSTRACT A surgical apparatus includes a rotatable shaft and a hollow insertion tube. The shaft includes at least one optical marker located thereon. The insertion tube is configured for insertion into a patient body, and is coaxially disposed around the shaft. One or more optical devices are coupled around an inner perimeter of the insertion tube and are configured to detect the marker and output one or more signals indicative of an angular position of the detected marker.2/2 LC)L 000 (0D LO CD m r-(0 (0m m N0 114- 114 CD C,4O Ln n C 1
