| 摘要 |
PURPOSE:To obtain a two-dimensional pattern video signal with high precision, by controlling the amplitude gain of a pattern video signal so as to be in inverse proportion to the measured value of a start signal interval, in a two- dimensional pattern inspecting device. CONSTITUTION:That which converts pattern video information accumulated in each interval of an impressed start signal to a pattern video signal successively in accordance with a prescribed clock at the following interval and sends it out is used as a linear image sensor 18 for scanning and inspecting a circuit pattern of a manufacturing mask MSK loaded on an XY table 11. With respect to an A/D converter 21 whose quantization gain is controlled so as to be in inverse proportion to reference voltage Vref, an exposure time T is detected by a start signal interval detector 20 and is provided as reference voltage Vref=J.T (J is a proportional constant), so that an output pattern video signal VO of the sensor 18 is quantized. Accordingly, a photodetecting sensitivity variation is corrected by a real time, and a pattern video signal which is stable and has high accuracy is obtained. |
