Welcome to the Glass Age

38 (Chapter 4). Optical fibers are the subject of Chapter 5. Glasses and light Long ago tailors realized that a glass globe filled with water could focus the light of a candle to aid stitching after the sun had set. More recently glass light bulbs provided an impervious envelope for incandescent lamps, preventing filament oxidation, and a vacuum for electrons to flow in fluorescent lamps; these developments have encouraged reading as well as extending the working day and earning potential of poorer families. For 200 years, glass Fresnel Lenses in coastal lighthouses have beamed the light from huge lamps to distant vessels, warning of danger using a lightweight structure. Monks realized that eyeglasses eased the strain of creating illuminated manuscripts and 2022 is the 670 th anniversary of the first depiction of eyeglasses in a painting. Many famous scientists such as Faraday studied glass lenses and their focusing power and Galileo’s telescope opened our eyes to the wonders of the cosmos; the latest developments in telescopes with glass lenses in space are allowing scientists to see back to the very beginnings of the universe. Microscopes have let us study cells and microbes and so understand diseases. Behind such developments since the 19 th century have been major research studies on the relationship between glass properties and composition and these have led to the capacity to design compositions to fit a particular property profile. Important players in glass optical property development have been the Germans and it is appropriate that 2022 celebrates the centenary of the German Glass Society. Glasses and measurement Glass being transparent, hard and inert has allowed the creation of many different instruments. Important Figure 2.7. 3D printed optical glass artefact. Source: iStock catalogue.