Precision Tool Technologies’ Prism Gage is specifically designed for a fast accurate check of unintentionally induced prism. Prism can occur for many reasons throughout the generating process. For example, it can be due to the 1) block, 2) blocker, 3) fixture in blocker, 4) generator, 5) fixture in generator, 6) fixture holding lap in lap cutter, 7) lap table in cylinder machine, and 8) improper heating or cooling of a blocked lens. Whatever the case, having a fast, accurate gage is essential to ensure optical quality and help pin-point the source of prism. Operationally, a blocked lens is inserted into the bearing supported turn-table. The indicator tip is positioned to the outside edge of the blocked area. Simply rotate the turn-table and read any deviation. Contact Us Now to order or for more information.