Two mutually perpendicular light beam patterns are directed across a continuously moving conveyor toward an array of light sensitive devices arranged in pairs for inspecting the silhouette of articles on the conveyor. The leaner inspection circuitry includes a pulse generating and counting means capable of providing two signals indicative of the degree of lean of an article in two mutually perpendicular directions. These signals, or series of pulses, are squared, respectively, and then summed to be compared to some predetermined acceptable range.