Light Crown glass
Light Crown glass is referred to as QK glass. It belongs to refractive index and density are small, which basically belong to the K2O-Al2O3-B2O3-SiO2 system. The introduction of fluoride such as KHF2 or AlF3 into the composition can obtain a grade with lower refractive index and dispersion. In addition, some optical glasses with a lower thermal expansion coefficient than general glass, such as QK2, are also included in this category because their optical constants are similar to QK glass. Mainly used as a material for optical parts in optical instruments.
By modifying the glass formula, the optical glass without lead, arsenic and cadmium and other radioactive elements is expressed by a prefix "H-" indicating its envioronment-friendly characteristics, for example: H-QK3L.
