GB/T 33051-2016 "Optical Functional Films—Surface Hardened Films—Test Method for Thickness of Hardened Layer" specifies the test method for determining the thickness of the hardened layer in surface hardened films of optical functional films, and is applicable to quality inspection of related hardened film products. Non-destructive testing methods such as microscopy and interferometry are employed, utilizing specialized measuring instruments to obtain data on the thickness of the hardened layer. Equipment such as metallographic microscopes, interferometers, and thickness measuring instruments are required for testing. During the measurement process, multiple test points should be selected to calculate an average value, providing a technical basis for production quality control and performance evaluation of optical films.