Scanning Depth of Field (DOF) of a Barcode Scanning Module

The scanning depth of field (DOF) of a barcode scanning module refers to the effective distance range within which it

can clearly and accurately recognize barcodes or QR codes. Beyond this range, image blurring may cause recognition failure.

The DOF is influenced by optical design, sensor performance, and light source matching, making it a critical indicator of

the module's environmental adaptability.

Technical Principles

The DOF is directly related to lens focal length and aperture size. A short focal length lens with a large DOF design enables

clear imaging across both near and far distances, making it suitable for scenarios like supermarket checkout or warehouse

scanning, where rapid adaptation to varying distances is required. Conversely, a long focal length lens has a shallow DOF,

offering higher recognition precision but requiring stricter distance control—commonly used in fixed-distance industrial scanning

applications.Additionally, the intensity and divergence angle of the light source affect DOF. Uniform and appropriately bright

illumination reduces glare interference and extends the effective recognition distance, particularly when scanning dark

barcodes or low-contrast labels. Proper light source configuration can significantly improve the lower DOF limit.

Practical Applications

DOF requirements vary by scenario:

In logistics sorting, where packages move quickly and scanning distances vary, modules require a large DOF (e.g., 10–100 cm)

to ensure barcode capture at different positions.

For mobile payment scanning, users typically hold codes close to the camera, making the lower DOF limit (e.g., 5–30 cm)

more critical.

Ambient lighting also impacts DOF performance:

Strong light may cause sensor overexposure.

Low light increases image noise.
Both conditions reduce the effective DOF range. Therefore, professional scanning modules often feature Automatic Gain

Control (AGC), adjusting light sensitivity to enhance DOF adaptability under varying lighting conditions.