The challenge was to sample a pond wall from above, in a situation where it was not possible to use a robot. The answer was an extendable pole that was lowered down to the sampling point. The question was ‘how will we know the sampling head is in contact with the wall when we are sampling?’ The answer is easy. The sampling head has proximity sensors designed to control the laser power for safety reasons: if the head moves away from the surface, the laser cuts out. So, unless the head is in...