Microscale tracking of surgical instrument motion

Abstract

An apparatus for accurate three-dimensional tracking of the tip of a microsurgical instrument has been developed for laboratory use. The system is useful for evaluation of microsurgical instrument designs and devices for accuracy enhancement (both robotic devices and active hand-held instruments), as well as for assessment and training of microsurgeons. It can also be used as a high-precision input interface to microsurgical simulators. The system involves illumination of the workspace and optical sensing of the position of a small reflective ball at the instrument tip, and therefore requires no wiring connection to the instrument being tracked. Sensing is performed by two position-sensitive photodiodes, placed orthogonally. The rms noise per coordinate is presently 7 microns. Preliminary results are presented. The photodiodes exhibit some degree of nonlinearity, which can be calibrated. The goal is to achieve an rms noise level of 1 micron. This is expected to be attainable via a synchronous detection scheme which has not yet been implemented.