Incoherent spectrophotometry of soda-lime glass (SLG) substrates

Staskov N., Gremeneok V., Pyatlitski A., Akçay N., Özçelik S.

2nd International Conference on Ligh t and Light Light-Based Technologies (2nd ICLLT 2021), Ankara, Turkey, 26 - 28 May 2021, pp.64

  • Publication Type: Conference Paper / Summary Text
  • City: Ankara
  • Country: Turkey
  • Page Numbers: pp.64


Millimeter-thick planar soda-lime glasses (SLG) are widely used as substrates for film deposition. In the literature, the optical constants of 𝑛(𝜆) and 𝑘(𝜆) for technical glass substrates are known calculated from the measured transmittance 𝑇(𝜆) and reflectance 𝑅(𝜆) at the normal (𝜃 = 00) incidence of light in the spectral range from =310 nm to =3700 nm. This method does not allow us to determine the values of 𝑛(𝜆) and 𝑘(𝜆) in the spectral region of  < 310 nm due to the large 𝑘(𝜆), because 𝑇(𝜆) → 0. To determine the optical characteristics of a homogeneous plane-parallel plate SLG (d=1.2 mm), we measured eight spectra of 𝑇𝑠,𝑝(𝜆) and 𝑅𝑠,𝑝(𝜆) (s and p: light polarized perpendicular and parallel, respectively) at 𝜃1 = 100 and 𝜃2 = 550 (Photon RT spectrophotometer, Belarus, Minsk). The calculation was performed analytically [1] using the measured spectra of 𝑇𝑠(𝜆, 𝜃𝑗 ) and 𝑅𝑠(𝜆, 𝜃𝑗 ) (j=1, 2) in the spectral range from  = 250 nm to  = 800 nm: i) 𝑅𝑝(𝜆, 𝜃𝑗 ) × [𝑅𝑠(𝜆, 𝜃𝑗 )]−1and 𝑅𝑠(𝜆, 𝜃𝑗 ) in the spectral range from =250 nm to =310 nm, ii) 𝑅𝑠(𝜆, 𝜃1) and 𝑅𝑠(𝜆, 𝜃2) in the spectral range from =250 nm to =310 nm. The correctness of the obtained values is verified by comparing the measured and calculated spectra of ellipsometric angles (𝜃 = 560) and 𝑇(𝜆), 𝑅(𝜆) (𝜃 = 00). The spectrum of is interpolated by the classical dispersion model for the dielectric constant 𝜀(𝜆) = (𝑛(𝜆) − 𝑖𝑘(𝜆))2.