| dc.description.abstract | In this thesis, there were two major parts, software and the hardware parts, for measuring the optical constants and thickness of the thin film. For the software, we used novel Genetic Algorithm to design our program. For the hardware, we proposed a polarization phase shifting interferometer based on Twyman-Green interferometer structure. In our arrangement, the low coherence light source is composed of a mercury lamp, which is a polychromatic light source and covering the visible spectral range, and a narrow band pass filter to create a Gaussian power spectral density source.
We chose five color filters (532nm, 580nm, 632nm, 690nm, 730nm) for selecting wavelengths. In the polarization interferometer, a novel pixelated mask with a micro-polarizer phase shifting array was placed just in front of the CCD, so that we can use single shot to extract phase information and it is effective to reduce environmental vibration.
Then we can get the spectrums from U4100 spectrometer made by HITACHI, and use genetic algorithm to write a fitting program to get the refractive index and thickness of single-layer thin film.
We used two parts, transmittances only and transmittances plusing with phases, to process our problems. All the researches need only five phases and spectrums can derive multi-wavelength refractive index and thickness. The measurement results were compared with the results obtained by SOPRA ellipsometer. The results meet reasonable values in both refractive index and thickness.
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