Colored Optical Glass Colored optical glass is a type of optical glass that selectively absorbs and transmits visible, ultraviolet, or infrared light of specific wavelengths. Also known as filter glass, it is a type of colored glass used in optical applications. Its preparation principles, production methods, and quality requirements are similar to those of colorless optical glass, though its optical constants and uniformity are generally less stringent. The primary technical requirement for colored optical glass is its specific spectral characteristics, typically represented by spectral transmission curves. To achieve these characteristics, appropriate colorants are often added to the raw materials. The coloring mechanisms can be categorized into ion coloring, metal colloid coloring, and sulfur-selenide compound coloring (see colored glass). Today, colored optical glass can be produced across the entire visible spectrum, as well as for ultraviolet and infrared transmission. Advances in production technology not only improve the spectral properties but also enhance mechanical strength and chemical stability, making it suitable for use in environments such as space, underwater, and radiation-exposed settings. Colored optical glass is classified by spectral characteristics into selective absorption types, cut-off types, and neutral gray glass. Other varieties include heat-absorbing glass, color temperature conversion glass, special colored optical glass, and fluorescent glass. Historically, hundreds of types of colored optical glass have been developed. Their designations use one or two Latin letters to indicate color and properties, followed by a Latin letter for the glass type and an Arabic numeral for serial identification. By the 1980s, China produced 96 types of colored optical glass across 13 categories (see table). Categories of Chinese Colored Optical Glass: ZB (UV-transmitting), QB (violet), LB (blue/cyan), JB (green), CB (yellow/gold), HB (orange), (red), HWB (infrared-transmitting), FB (protective), BB (UV-transmitting colorless), AB (neutral/dark), GRB (heat-insulating), SSB (color temperature raising), SJB (color temperature lowering). Colored optical glass is a crucial filtering material. In color film photography, it is used as a filter to alter the tone, contrast, and atmosphere of scenes. For example, red filters can create dawn or dusk effects, blue filters can simulate night or stormy scenes, and yellow filters can enhance contrast and highlight clouds. High-end color cameras for resource and weather satellites, fluorescence microscopes for studying cellular structures in genetics, laser holography systems, various spectroscopic instruments, and display devices for instrumentation all require specialized colored optical glass.