The paper presents the results of research on the plastic zones formation in thin (3.51 [mm]) shields made of steel C45 with holes of 4, 10 and 20 diameters. The authorship method of identifying plastic macro-strains utilizing optical interference phenomenon was used in the experiments. The basic idea of the method is summarized below as being: “The occurrence of plastic deformations in the active process of loading is testified by a loss of the interference fringes that were previously present or by a clear and rapid change in their character”. In the experiments, the values of the stress initiating the first plastic deformation were determined. In order to explain the processes of plastic deformation appearance a detailed stress state analysis in the holes surrounding area was realized with the use of Finite Element Method. Comparison of experimental results with the results of FEM calculations indicates that there are significant quantitative as well as qualitative differences. Namely stresses initiating plastic deformations clearly exceed the value of ReH, and plastic deformation are of local plastic slides character. Similar results were previously obtained in studies on the shields made of steel 15CrMo with holes.

A contactless laser hygrometer based on light absorption by H2O molecules at 1392.5 nm is described. However, measurement results can be affected by optical noise when applied to an atmospheric tunnel or glass cuvette. The noises (occurring in the form of periodic fringes in the recorded spectrum) come from unexpected interference of the light beams reflected from surfaces of the windows or other optical elements. The method of their suppression is described in this article. It is based on wavelength modulation and signal averaging over the fringes period. Also, an experiment confirming the usefulness of this method is described here.