Toy Box Optics: Hiding Messages in Plain Sight

Different properties of light such as polarization and its diverse wavelength spectrum, are commonly utilized throughout our daily lives. Using easy to obtain household items, we can perform activities illustrating the concept of light properties and principle of how these concepts are used in various applications. In this paper, we design and demonstrate two easy-to-follow activities to introduce how messages can be displayed or hidden using light’s properties. First, light from liquid crystal display (LCD) is used, which oscillates at a certain orientation or polarization. Messages from an LCD can be blocked from view if an observer is wearing polarized sunglasses with a polarization that is perpendicular to that of the LCD. Using an acrylic sheet, the LCD light’s polarization can be rotated, allowing the observer to see the LCD content. In our second experiment, messages written in different colors can be hidden in plain sight using a translucent putty of the same color. Putty reflects and scatters light that is of the same color. When the message and putty color matches, there is no light of the same color reflected off of the message. Making the message invisible to the viewer. Video demonstrations of both experiments can be found on the YouTube channel Play with Light. By using familiar objects, these demonstrations allow students to learn through play. Students can gain better insight into the nature of how light interacts with our surroundings to hide or reveal content. Providing greater insight into how modern technology utilizes these properties.