| 摘要 |
<p>RCA 72527/73699 The inspection system detects defects in regular patterns wherein the elements of the patterns may have variations in spatial period. The system includes means for scanning and detecting the elements of a pattern to produce an output signal indicative of the pattern and means for autocorrelating the output signal. In an analog version of the system, means delay the output signal from the scanning and detecting means to produce a delayed output signal. Next, any deviation in period between the undelayed output signal and the delayed output signal is detected by suitable means. Means then match the periods of the undelayed and delayed output signals, and other means correlate the matched original and delayed output signals. A digital version of the system includes means for quantizing the output signal from the scanning and detecting means into binary digital signals, main storage means for storing the quantized signal of a portion of a scan, means for determining element period from the quantized signal and for controlling the output of the main storage means at times related to element period, means for correlating the output from the main storing means with a real time quantized signal of the same scan, and means for indicating the presence of an error related to a pattern defect in response to a miscorrelation signal from the correlating means.</p> |
