The standard "GB/T 23886-2009 Method for determination of film thickness of pearl beads" Optical inspection coherence chromatography "describes a method for nondestructive measurement of film thickness of pearl beads using Optical inspection coherence chromatography (OCT) technology. The standard applies to the measurement of bead film thickness of pearls. Optical inspection coherence chromatography obtains images of the internal structure of pearls by coherent processing of backscattered light signals. Analysis of these images by computer technology allows for accurate measurement of the optical path of the beads, thereby calculating the bead Film thickness. The standard also includes relevant terms and definitions, such as optical path, coherent light, and backscatter, to ensure the accuracy and conformity of measurement methods.