Abstract

This study has enabled an analysis of the influence of the depth of field and the configuration parameters, frequency (F) and power (P), on the quality of measurements performed using a conoscopic holography (CH) sensor. To this end, tests were carried out on a stepped AISI 316 specimen, evaluating different combinations of F and P across the sensor’s entire working range (WR).

Based on the results obtained, a Confidence Area (CA) was defined, comprising the parameter combinations that enable an adequate geometric reconstruction throughout the WR. The analysis using different metrological indicators showed that these combinations ensure a high reconstruction quality, with a mean value of the η indicator above 82%.

The analysis of the distance measurements showed that the error increases as the surfaces move away from the theoretical stand-off position, following an approximately linear relationship. The slope of this relationship depends on the F and P combination; therefore, an appropriate selection of these parameters can reduce the mean error. However, this reduction leads to an increase in the standard deviation and, consequently, a deterioration in repeatability, particularly at positions further away from the stand-off.

On the other hand, distance measurements between adjacent surfaces exhibit behaviour that is largely independent of their position within the WR and of the selected F and P combination. This indicator provides better repeatability, with standard deviations generally below 5 µm, demonstrating a homogeneous measurement quality throughout the WR. Nevertheless, the best results are obtained in the vicinity of the theoretical stand-off position.