For the selection of visible-light-absorbing substances, this project designed two kinds of samples, a single-colour sample and a complex-colour sample. The single-colour sample was made of blue ink, which is Bleu Pervenche fountain pen ink. However, in scientific research or daily life, the samples to be tested are usually composed of multi-component or multi-coloured particles, so this project designed the complex-colour sample, which is composed of blue ink droplets and Rose Bengal droplets. For the selection of fluorescent substances, initially a randomly selection one of fluorescent dyes was used for sample preparation. However, initial experiments suggested that it was found that the fluorescent dye can only be excited by UV light in the dilute solution state, due to fluorescence quenching in the absence of solvent. This phenomenon occurs because in the solid state, strong π-π stacking of aromatic rings adjacent to the fluorophore results in ordered or disordered aggregates that do not emit radiation when they decay from excited states, which means they do not produce fluorescence, also known as aggregation-caused quenching (ACQ) . However, Jingdong Luo et al. found that some fluorescent dyes can still emit strong fluorescence in the solid state, which is called the Aggregation-induced emission (AIE) effect. Therefore, this project selected two dyes that have AIE effect, 6,7-Dihydroxycoumarin-3carboxylic acid and 7-(Diethylamino)-coumarin-3-carboxylic acid.