  A simple user-friendly software named PRISA has been developed to determine
optical constants (refractive index and extinction co-efficient), dispersion
parameters (oscillator energy and dispersion energy), absorption co-efficient,
band gap and thickness of semiconductor and dielectric thin films from their
measured transmission spectrum, only. The thickness, refractive index, and
extinction co-efficient of the films have been derived using Envelope method
proposed by Swanepoel. The absorption co-efficient in the strong absorption
region is calculated using the method proposed by Connel and Lewis.
Subsequently, both direct and indirect bandgap of the films is estimated from
the absorption co-efficient spectrum using Tauc plot. The codes for the
software are written in Python and the graphical user interface is programmed
with tkinter package of Python. It provides convenient input and output of the
measured and derived data. The software has a feature to retrieve transmission
spectrum using the derived parameters in order to check their reliability. The
performance of the software is verified by analyzing numerically generated
transmission spectra of a-Si:H amorphous semiconductor thin films, and
experimentally measured transmission spectra of electron beam evaporated HfO2
dielectric thin films as examples. PRISA is found to be much simpler and
accurate as compared to the other freely available softwares. To help other
researchers working on thin films, the software is made freely available at
https://www.shuvendujena.tk/download.
