The article considers the effect of pairing on improving the quality of navigation measurements. It is shown that when performing navigation measurements, pairing provides the ability to compare the results obtained at all stages of the measurement process, ensuring their reliability and the possibility of their geometric analytical description, increasing and supplementing the accuracy parameters.

Possible difference in values of linewidth which can be obtained at measurements of a protrusion by scanning and transmission electron microscopes is produced. Contribution of potential sources of errors capable to induce a possible value difference is evaluated for the both instruments. The most important source of value difference is occurs to be discrepancies of the model of the linear measurements used for a scanning electron microscope. Its further enhance is limited so calibration of these measurements with use of a transmission microscope is needed. Linewidth measurements with use of a transmission microscope are lead to an error also. They are resulting due to a multitude of details of a real form of protrusion profile that affect the linewidth size so that consideration of its influence is complicated. An application of simplified model of profile form leads to an error also. As a result the overall size difference of a protrusion linewidth due to the both model shortcomings can be 1-20 nanometers.

The new approach to the improving of the accuracy of the electrical impedance measurements is described. This approach uses the variation of the influence of uncertainty sources on the result of measurement. Using these well known variations we provide the additional number of measurements, equal to the number of the uncertainty sources. System of equations describes these measurements. Solution of this system and gets us accurate result of impedance measurement. This approach was used for the development of the impedance meters in different areas. Article shortly describes some results of these developments.

First part of this article described fundamentals of the variational method of the impedance meters error correction. Second part describes the realization of the variational method in specific measuring circuits, in particular, in transformer bridges with closely coupled arms and in logometric bridges, based on the Op Amp with high gain. In transformer bridges variational method eliminates influence of main error sources - impedances of the connecting cables and transformer windings. In logometric bridges variational method eliminates influence on the result of measurement of the finite OP Amp gain and input admittance. Theoretical and experimental investigations have shown that variational method decreases the error of measurement on hundreds or thousands times. The metrological data of the impedance meters, developed using variational methods, are given.