Development of a Computer Program for the Determination of Optical Constants of Radiation Damaged Optical Elements Using Classical Oscillator Fit to Reflectance and/or Trrnsmittrnce Data

Abstract

A computer program is developed using the classical oscillator model of Hans W. Verleur [1] to study the transmittance and reflectance spectra of pre- and post radiation damaged optical components such as color glass filters, multilayer bandpass filters and band reject filters irradiated by one megarad gamma radiation from a ⁶⁰Co source. In the classical oscillator model, the complex dielectric constant fk(ω) is represented as the sum of classical oscillators with oscillator strength S_i, resonance frequency ω_i, linewidth Γ i and high frequency dielectric constant fk ∞ which are the adjustable parameters to fit the experimental transmittance and reflectance data over a limited range of frequency. The parameters have physical significance in the lattice vibrational region. In the spectral regions corresponding to electronic transitions, the spectra can be fitted accurately with no physical meaning associated with the parameters. The present work has concentrated on the calculations of the optical constants n and k of the radiation damaged optical components to determine the effects of 60Co gamma radiation on the optical constants of both films and substrates in these components.