Visual Measurements at Small Scales: Guidelines to Reduce Uncertainties down to a Few Nanometers

Vision-based measurement is a widespread solution to characterize, classify and control micro and nano robotic systems. Achieving multi-degrees-of-freedom measurements with nanometer uncertainties using a common experimental setup has recently been demonstrated which appears highly interesting for many applications. Nevertheless, succeeding in setting the experimental set-up to reproduce such performances still appears not so easy, due to the difficulty to understand what are the influence quantities. To address this key issue, the paper firstly synthesizes the different approaches and good practices used in the literature where several influence quantities have mainly been investigated independently. Secondly, an experimental set-up is used to study the influence of several key quantities onto position uncertainties. These two kinds of investigations, conducted to propose practical guidelines to get position uncertainties down to 5 nm with typical experimental setups used for micro and nano robotics purposes. The experiments also show that measurement precision is experimentally estimated at a few nanometers by measurement reproducibility over several days.