Optical glass suffering little change in refractive index when exposed to ultra-violet light during service

摘要

An optical glass wherein an amount of change in refractive index ( DELTA n: difference in refractive index between a state before radiation and a state after radiation) caused by radiation of laser beam at wavelength of 351nm having average output power of 0.43W, pulse repetition rate of 5kHz andpulse width of 400ns for one hour is 5 ppm or below.. The optical glass comprises a fluorine ingredient and/or a titanium oxide ingredient and/or an arsenic oxide ingredient. The optical glass suffers little change in refractive index by radiation of strong light having wavelengths of 300 nm to 400 nm such as ultraviolet laser.