I am currently conducting research on polymer films and my current objective is to calculate the attenuation coefficient of the polymer film in order to determine its penetration depth. Using an integrating sphere setup, I performed UV-Vis measurements in the range of 300–1000 nm and obtained the following data: transmittance, diffuse reflectance, and specular reflectance.I intended to use these values to calculate the internal transmittance using the formula $\frac{T}{(1–R)^2}$.
However, I'm confused about how to process the reflectance data, since the measured reflectance values include multiple reflections rather than just the front surface reflection. In particular, I'm not sure how to properly incorporate the diffuse reflectance component into the calculation.
As a rough estimate, the measured values are: transmittance 83%, specular reflectance 8%, and diffuse reflectance 4%.Given this situation, I would appreciate any guidance on which model would be appropriate for calculating the penetration depth and the reason behind the choice of the specific model.
