The display industry is trying to improve yields by refining the automation processes in the manufacturing of Liquid Crystal Display (LCD) Glass. To help achieve better yields, it is necessary to locate with better precision the LCD panels with respect to robotic tools. Two approaches will be discussed to make ranging measurements on LCD Glass: a laser confocal displacement sensor and ultrasonic rangers. The knowledge gained from these measurements will improve the positioning of the robotic tools with respect to the LCD glass during the manufacturing process. © 2003 American Institute of Physics