04394683 is referenced by 37 patents and cites 4 patents.

A method and apparatus are provided for analyzing the light pattern produced on a photodetector array. The signal produced by the array is filtered with a low pass filter and the output of the filter is differentiated to obtain either the first or second derivative of the filtered signal for one or more points in the pattern. The zero crossing of the differentiated signal is detected and the zero crossing point is timed relative to a further point, e.g., the start of the scan of the array, so as to obtain an output related to the position of the corresponding point or points in the pattern.

Title
New photodetector array based optical measurement systems
Application Number
6/163290
Publication Number
4394683
Application Date
June 26, 1980
Publication Date
July 19, 1983
Inventor
Donald A Clarke
Windsor
CA
Timothy R Pryor
Tecumseh
CA
Roland Renaud
Windsor
CA
Nicholas Liptay Wagner
Windsor
CA
Agent
Larson and Taylor
Assignee
Diffracto
CA
IPC
H04N 7/18
View Original Source