A method of accessing content at a speech-enabled automated system is disclosed and comprises receiving a verbal input at an interactive voice response system. A comparator processor independently generates, from the same sensor data, a selected subset or \u201cpoints of light\u201d of the display screen image and compares the points of light data to the data generated by the rendering computer for the same display screen pixel locations. It is preferable that the contents of Sb and Zn in the starting material composition are respectively 0. The optical construction also includes a substantially specular reflector that reflects light that is not scattered by the asymmetric optical diffuser.