Abstract: A method an apparatus are provided for inspecting the surface of objects such as panels for automobile vehicles wherein the surface of the object is sprayed with an oil mist or the like to increase the reflectivity thereof. The surface is then illuminated with light so that the light image reflected therefrom is formed on a light detector such as a photodiode array. The output of the light detector is analyzed to determine surface features of the object such as "dings" and dents therein.

Abstract: This invention relates to new and useful electro-optical methods and apparatus using photodetector arrays for measurement of parts and other objects in industrial environments. Several particularly useful optical embodiments are illustrated together with desirable electronic circuitry for improving the accuracy of practical systems of this type.

Abstract: 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.