2023.01.06
【論文】WRH森川淳子教授とSaulius Juodkazis特任教授の共著論文“RGB-Color Image Analysis for Determination of Birefringence of Micro-Films and Columnar Coatings”が掲載されました。
物質理工学院 森川淳子教授とSaulius Juodkazis特任教授の共著論文が、Laser & Photonics Reviews に掲載されました。
“RGB-Color Image Analysis for Determination of Birefringence of Micro-Films and Columnar Coatings”
https://doi.org/10.1002/lpor.202200535
<要旨>
The birefringence analysis of thin $\approx 1\hspace*{3.33333pt}\umu $m SiO2 films deposited via evaporation at a glancing angle of $\hspace*{3.33333pt}{70}^{\circ}$ to the normal on resist pillar arrays on Si and nanopatterned SiO2 substrates is carried out by spectral and color (red–green–blue [RGB]) imaging modes. Retardance and birefringence of the films deposited over flat and structured regions can be distinguished with only ≈1% difference between neighboring regions for the visible spectral range using RGB numerical analysis of images. The Michel-Lévy color map is used for color rendering of birefringence to make quantitative measurements by numerical RGB color filtering. It is shown that by using $\lambda /2$ at 530 nm waveplate inserted at $\pi /4$ angle to the cross polarizer-analyzer setup, the range of changes in chromaticity xy-coordinates expands approximately twice upon angular rotation of a birefringent sample. This facilitates a better signal-to-noise determination of birefringence. The proposed method with $\lambda /2$-plate color shifting can be directly used to determine birefringence from step-like spectral features in reflection and transmission polariscopy. Direct measurement of birefringence (${\Delta}n=0.023$) and retardance of SiO2 chevron film is carried out using Berek compensator as a benchmark.