ABSTRACT

Photochromic glass is likely the most familiar of all the topics in the entire book since it was and still is a commercial product of Corning Incorporated.1,2 The trade names for the sunglass product have varied over the years with the latest being Photogray ExtraTM. For those who do not have or never had a pair of these sunglasses, they darken in the sunlight and fade when in the dark. A typical performance is shown in Figure 5.1.