K9 glass is a glass product made of K9 material. K9 material belongs to optical glass. Because it is crystal clear, the processed product is called crystal glass in the market. The composition of K9 is as follows: SiO2 = 69.13% B2O3 = 10.75% BaO = 3.07% Na20 = 10.40% K20 = 6.29% As2O3 = 0.36%. The brand glass in optical glass belongs to the borosilicate system. Its refractive index and Abbe number are very low, the price is low, the micro-machining performance is good, its optical coefficient is 1.5163, the dispersion is more than 80, almost no bubbles and impurities, the appearance is clear and colorless, and it is made of high-purity material. The technology of making micro- and nano-scale microstructures and micro-devices on K9 glass has been applied to many fields such as optoelectronics, microwave technology, and diffractive optical components.