Low-resolution optical microscopy under parallel white light illumination provides a fast method for large scale and spatially resolved analysis of structure, morphology and quality of colloidal multilayer crystals. This microscopy technique excludes Bragg scattered light from image construction leading to an enhanced color contrast between crystal grains of different crystal symmetry, layer numbers or stacking sequence. Grain boundaries as well as defects appear more markedly thus providing information about morphology and crystal quality.
Structure and morphology of colloidal crystals is of both scientific and technological interest, e. g. for fabricating masks for photo lithographic purposes, diffractive optical elements or photonic crystals. Bright-light microscopy with low aperture is an easy and a fast optical microscopic method for characterizing colloidal multilayer crystals. It is not restricted to the topmost layer as in the case of AFM and electron microscopy, and it provides spatially resolved information instead of spatially averaged information as in the case of scattering methods.
