A study of dispersion in chromatic confocal microscopy using digital image processing

A research about digital image processing in chromatic confocal microscopy for the study of dispersion of a homogeneous semitransparent material is presented. The deduction of a mathematical model to determine the refractive index with a chromatic confocal system is made first. Then, a methodology using digital image processing in conjunction with that mathematical model in order to determine the dispersion is proposed. The main parts of this methodology consisted in making an axial scanning of the sample, filling a matrix with the spectral data acquired, obtaining a 256 gray level image (that we called optical thickness matrix or OTM) from this matrix, applying binarization and skeletonization to this image and carrying out a fitting process to obtain a curve. It was found that by means of either horizontal or vertical cuttings in the OTM it is possible to obtain the dispersion of a material. The vertical cuttings are special because they have an interesting analogy with a hypothetical multiple confocal laser system. The OTM can be a very useful tool because it could show a lot of visual information about the sample. Thus, it could give a fast visual estimate of values and characteristics associated with the sample.