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Laser beam used to measure and highlight the transparency changes in gamma irradiated borosilicate glass

M. R. IOAN1, I. GRUIA2,* , G. V. IOAN1, L. RUSEN2,3, P. IOAN1

Affiliation

  1. "Horia Hulubei" National Institute of Physics and Nuclear Engineering - IFIN HH, 30 Reactorului Str., 077125 Magurele - Bucharest, Romania
  2. Physics Department, University of Bucharest, 405 Atomistilor Str., 077125 Magurele - Bucharest, Romania
  3. ISOTEST Laboratory, National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 077125 Magurele - Bucharest, Romania

Abstract

The optical windows are the bridges of connection between the laser systems and the real environment and therefore are often subjected to hostile conditions which they can affect the optical and mechanical performances. The purpose of this paper is that by applying special diagnostic techniques through a low laser power to be able to investigate the transparency changes of the glass made optical windows, caused by exposure to indirectly ionizing radiation (e.g. X, gamma radiation). Basically, we investigated the changes due to the colour centres or other defects produced by rradiating borosilicate glass with 60Co, as a source of gamma radiation. In principle, we can expect to changes in the transmittance properties of these glasses and for larger-size induced defects even to an increase in their scattering properties, or a change in the spatial profile of the laser beam used as a test beam. In addition, we used optical anisotropy (linear dichroism) as a technique for highlighting the changes in the structure or in the interactions between the constituent components of the samples. Several Schott BK-7 glass samples were irradiated using the IFIN-HH - gamma irradiation facility, at a dose rate of about 0.163KGy/h ±7% produced by gamma energies of 1.332MeV and 1.173MeV. Energetic and spatial beam characterizations (according to ISO 11554 and ISO 11146-1 standards) and linear dichroism highlighting, were performed on a low power He-Ne laser beam (linearly polarized), before and after passing the beam through each irradiated glass sample. According to the changes in the glass transmittance, were evaluated: dichroism induced by gamma radiation (the magnitude of linear dichroism and the mean factor of the sample transmission), the evolution of power energy and the laser beam propagation test. Spatial beam characterization was performed to see whether or not there are changes in the internal structure of glass samples, shown by the varied values of the beam propagation factor M2. In our case, the experimental set-up ha.

Keywords

ISO- Standard, laser beam, He-Ne laser, Schott BK-7 glass, Gamma rays, Linear dichroism.

Submitted at: May 27, 2013
Accepted at: Jan. 22, 2014

Citation

M. R. IOAN, I. GRUIA, G. V. IOAN, L. RUSEN, P. IOAN, Laser beam used to measure and highlight the transparency changes in gamma irradiated borosilicate glass, Journal of Optoelectronics and Advanced Materials Vol. 16, Iss. 1-2, pp. 162-169 (2014)