Non-Destructive Measurement of Optically Scattering Polymer Films Using Image Processing

We establish a sample- and data-processing pipeline that allows for high-throughput measurement optical microscope measurement of porous films, provided that the film is sufficiently optically scattering. Here, self-limiting electrospray deposition (SLED) is used to manufacture scattering films of different morphologies. This technique compensates for the scattering of the films through background subtraction of the reflection image with the transmission image. This process is implemented through a combination ImageJ-MATLAB data pipeline; the Canny edge-detector is used as the image-processing algorithm to identify boundaries of the film. We verify this process against manually measured images; a comparative study between cross-sectional scanning electron microscopy (where scattering effects are diminished) and optical microscopy also verifies that our optical microscopy technique can be used to consistently, non-destructively measure film thickness regardless of film morphology. In addition, this technique can be used in combination with dense film measurements to measure film porosity.