MULTI-FOCAL VISION SYSTEM

A machine vision system images bar code labels moving through a horizontal plane at variable object distances within the system's object depth of field Z .sub.obj with a plurality of sequential line images, each with different object lengths which gradate Z .sub.obj into plural focused object planes, and the object plane within which the bar code label lies provides a focused optical image of the bar code to a multilinear photodetector which transduces the focused optical image into a corresponding electrical signal for further processing.