A surgical system used to determine a size of a vessel within a region proximate to a working end of a surgical instrument includes at least one light emitter disposed at the working end, an array of light sensors disposed opposite the at least one light emitter, the array comprising a least one row of light sensors, individual light sensors in the row adapted to generate a signal comprising a pulsatile and a non-pulsatile component, and a controller coupled to the array, the controller comprising a splitter to separate the pulsatile component from the non-pulsatile component, and an analyzer to determine the magnitudes of the pulsatile and non-pulsatile components at the individual light sensors, to determine a first peak magnitude and a second peak magnitude of the pulsatile components, and to determine a resting outer diameter of the vessel based on the first and second peak magnitudes.
