in accordance with embodiments , viewable images can be created in glass . viewable images may be created in glass by using a projector which projects ultraviolet light to excite light emitting material . clear images may be created in glass because the size the light emitting particles in the glass is less than 400 nanometers . in embodiments , the visible illumination of a transparent substrate to display an image is possible , while the transparent substrate remains transparent . accordingly , for example , drivers of automobiles may view images on their windshield while they are driving . as another example , window shoppers may view enhanced advertisements in the windows of stores that they are approaching .