A sampling system for collecting a liquid sample, having at least one analytic auxiliary means is proposed. An analog-to-digital converter converts an analog input to a digital output, and a slicer maps the digital output to one of a plurality of predefined values. The measured distance is successively monitored and polishing is stopped when the distance has become a predetermined value corresponding to target amount of material removal from the work piece. The thermally isolation fins help reducing conduction of heat.