Application of digital image sensors in microscopy fpr traceable measurements of 2-dimensional structures: Problems and potential solutions

Digital image sensors are widely used in microscopy for quantitative measurements of the two-dimensional geometry of microstructures. In general, these measurements can be performed with very high precision, however, their traceability to the SI unit with uncertainties below 100 nm is insufficient. For this purpose it is necessary to know the magnification of the image formation by the microscope and its variations depending on the position of the object points. In addition, the digital sensor has to be characterized with regard to its linearity and image noise, and the model of the optical interaction of light with the two-dimensional object has to be understood. With the aid of selected standard measurement constellations we discuss the appearing problems and potential solutions. An experimental set-up has been realised. First results for Cr on Glass circles are presented.