Now let’s take a look at the construction of a typical segmented display. There are several layers that make up the display as shown in the illustration. The first layer is a vertical polarizer that only allows a single axis of light to pass. Following the polarizer is the glass substrate with the Indium Tin Oxide (ITO) segments. The third layer is the actual liquid crystal material used to “twist” the light. The fourth layer is the glass substrate with an ITO film used as the common reference for the ITO segments. After the common there is another polarizer, this time oriented to allow only light waves in the horizontal plane to pass. This is 90 degrees out of phase with the first polarizer. Beyond the polarizer is the light source. This is either a reflective surface to bounce the incoming light through the display or it can be a backlight. All of the layers are transparent and serve a specific function in passing the light through the display.