Evaluating a Short Distance OCR Setup Using High Resolution Optics and Deep Learning

The vision system included Theia’s ML610M and The Imaging Source’s DFK 33UX178, creating a high-resolution 200lp/mm vision system.

© Theia

When camera manufacturer The Imaging Source set out to implement a high-precision optical character recognition (OCR) system for industrial imaging, Applications Engineer Tommie Minor turned to a combination of Theia Technologies’ ML610M varifocal lens, The Imaging Source's DFK 33UX178 camera, and Zebra’s Aurora Vision Studio software platform with its Deep Learning OCR tool. The objective was to achieve fast, accurate recognition of small characters at a close working distance of roughly nine inches, even in demanding industrial environments. Reliable OCR is critical for applications such as product serialization, label verification, electronics inspection, and automated traceability, where even minor misreads can disrupt production, compliance, or quality control.

Central to the system’s success was Theia’s ML610M 2/3″ format varifocal lens, designed for a 1.55 μm pixel size to resolve detail up to 300 line pairs per millimeter contrast. This exceptionally high resolving power ensured that the fine strokes of small, densely printed characters remained sharp and distinguishable when projected onto the camera sensor. In OCR tasks, where the difference between a “1” and a lowercase “l” or a “5” and an “S” can determine whether a code is read correctly, maintaining edge contrast at the smallest character scales was critical. The lens’s true 4K, 12-megapixel optical design, combined with aerospace-standard sweep vibration resistance from 20 Hz to 200 Hz to 20 Hz at 10 G for 30 minutes per axis and IR correction from 440 to 940 nm, ensured crisp images across variable lighting and industrial operating conditions.