Determination of probe non-linearity and error due to measurement position for direct measurement type of gauge block comparator and its measurement uncertainty

The non-linearity of probes is one of the important components in gauge block calibration by the mechanical comparative method of two gauges blocks at the same nominal length. However, an advanced method for gauge block calibration is a mechanical direct measurement method of two gauge blocks showing the greatest difference in nominal length of 25 mm. This method uses a special probe based on the interferential scanning principle to produce the signals to measure the displacement. In this paper, non-linearity and error due to measurement position were investigated as they related to the accuracy of measurement results. The differences in central length of pairs of standard gauge blocks made of steel were measured by optical interferometry with the measurement uncertainty (k=2) 23 nm. Length in the range of 5 μm to 25 mm was used in the experiment. Non-linearity of the probe was evaluated by the simple linear regression model. Various factors such as origin setting point, temperature, and vibration have been analysed. In the preliminary experiment, the non-linearity, position error, repeatability and retrace error over the measuring range 25 mm are 13 nm, -18 nm, 15 nm, and 10 nm respectively. The standard uncertainty of direct measurement type caused by non-linearity is 4 nm.

Using a Gauge Block for Derivation of Parameters of Four Laser Triangulation Sensors in a Local Coordinate System

The paper discusses the derivation of an accurate coordinate measuring system consisting of two, three, or four sensors based on the records of four fixed laser triangulation sensors done for a gauge block in movement. Three-dimensional case is considered. In the simulations, using a set of distances quadruplets, parameters of sensors in a local sensors coordinate system are determined through a least squares minimization process using the Differential Evolution approach. The influence of the measurement and rounding inaccuracy on the identification accuracy using numerical simulation methods are assessed.

Algorithmization of calculation of fractal parameters of rough surface relief according to GOST R ISO 25178-2-2014

Russian version of the ISO 25178-2:2012 standard is commented. The functions provided by the standard for calculating fractal dimension are considered, and the algorithms for calculating them in the Mathcad environment are described. An example of calculations based on the results of measurements of the height of the surface irregularities of the gauge block obtained using an atomic force microscope is given.

Thermal imaging observations of the surface of a gauge block

This paper proposes a method for determining the time at which the temperature of surface of a gauge block will be established. The relationship between the temperature of a gauge block, its length and the value of uncertainty of measurement when calibrating using this block was explained. Attention was paid to problems resulting from the applied measurement method. Particular attention was paid to thermal imaging observations of the lateral surface of a gauge block