Optical glass ' used in the construction of spectacles is made by

Optical glass used in the construction of spectacles is primarily Crookes glass. This specific type of glass contains cerium oxide, which allows it to effectively absorb harmful ultraviolet (UV) rays from sunlight, making it ideal for protective eyewear. While flint glass and crown glass are also types of optical glass, they are more commonly associated with high-precision optical instruments like telescopes, microscopes, and prisms due to their specific refractive indices and dispersion properties [1]. Flint glass, characterized by its lead oxide content, is often used for concave lenses and prisms [1]. Crown glass is a soda-lime-silica glass frequently used for general eyeglass lenses, but Crookes glass is the specialized optical glass specifically noted for its UV-filtering properties in spectacles. Quartz glass is typically reserved for laboratory equipment and ultraviolet lamps.

Sources

1. [1] https://www.haflonggovtcollege.ac.in/online_portal/attendence/classnotes/files/1711529173.pdf