Disclosed are a system and method for monitoring total mercury within a gas sample in a substantially continuous manner and for calibrating for both elemental and oxidized mercury. The housing has an alternating arrangement of flights and spaces radially arrayed about its exterior dimensioned to be closely received within an endoscopic instrument channel so as to coaxially orient said housing with the instrument channel. Upon input of a first signal to an input node, an output node outputs a second signal. A new set of offsets of the damaged portion of the workpiece is then calculated.