Inhomogeneity measurement is an important test of reference materials. In case of hardness reference blocks it consists of measurements at five distributed points on the surface with a test indenter. Unfortunately the test is destructive and it is not possible to use the same point for a new measurement. In this work we propose an optical method to measure the inhomogeneity of hardness standards. As we reported in a recent work, variations of hardness in a steel produces variations in their optical properties, this fact can be used to detect variations in the hardness of blocks with a non-destructive method.
In this work, the observation of phase delay changes between parallel and perpendicular components of an optical beam
reflected on a metal surface is reported. Those changes have been induced by electrically charging a metal with static
charge. A quasimonochromatic lineally polarized beam is directed to a piece of steel where the beam is reflected, the
polarization of the reflected beam is in general elliptical. The module of each polarization component and their
difference of phase are measured with an ellipsometer. For the experiments we have started by making ellipsometry
measurements on a grounded steel sample, then a second measurement has been carried out on the same sample after
inducing electrostatic charge, results indicate a rotation of the elliptical polarization in the beam reflected on the
electrically charged sample.
In a recent work we reported dependence between the hardness of steels and its refraction complex index, showing that
this optical property can be taken as a measure of the electronic interaction inside the molecular structure of metals. If
the molecular structure changes then the electronic interaction changes and it is observed as a modification of its
refraction index. In this work we present experimental results on steel pieces thermally treated and maintained in rest in
the laboratory for material stabilization. The refraction complex index showed variations through a several days period.
Variations are attributed to released stresses of the material. The steel sample is thermally treated with a tempering
process and tested with an optical setup. The refractive index of the sample is measured through several days, showing
variations. The ratio of changes is grater in the first days, showing an exponential decaying in subsequent periods of
The mechanical properties of the materials are related with the atomic arrangement of their constituent elements. Particularly, the electronic cloud at the surface of steels shows spatial properties of the charge distribution of the metallic crystals. In this work we report the conductivity properties of the electronic cloud in the directions normal and parallel to the surface. These conductivity features are studied through the interaction with an optical field. The reflectance components of the materials are measured and related with the conductivity in the respective directions. We show that for the different Steel samples that were measured, a relation between the hardness and the reflectance components is observed.