Step and Repeat type Electro-Optic sensing system for In Process TFT arrays have been evaluated by several Japanese LCD manufacturers which have proven the unique technology. In this paper, the concept of testing flat panel displays using "Non-contact Voltage Imaging" is described. One of the major problems in the AMLCD industry was the difficulty to do adequate non-contact tesing of the active substrate prior to final assembly. This paper describes the technology of AMLCD pixel and line defects detection that permits full functional testing on the panel during the manufacturing process.