*4.5. Microscopy Techniques*

Microscopy imaging is extremely useful when examining the size, shape, and detailed morphology of particles, and for understanding morphology-related properties of substances, formulations, and/or dosage forms [121]. The techniques are frequently used in research and development, especially for solid dosage forms while only a limited number of examples are referenced here. In the evaluation of pharmaceutical raw materials such as API and excipients, microscopy images reveal the size, shape, and morphology of particles, which helps in understanding some processing properties and the pharmaceutical performance of these materials [122,123]. The impact of different preparation procedures, such as precipitation or milling methods, on important properties (shape, size, chemical composition) of the resulting API or excipient particles in NCM can be investigated using microscopy [124–127].
