Patent ID: 8448867

Claim:
An imaging-based bar code system comprising: a scanning arrangement comprising a sensor assembly for capturing an image from a target object, the sensor assembly having a field-of-view focused by an optical arrangement onto a sensor array located within the sensor assembly; an illumination system comprising a first illumination assembly and a second illumination assembly, each of the first and second assemblies including an illumination source directing illumination through a light pipe and a focusing lens to generate an illumination pattern directed towards a target object, wherein the light pipe comprises an input surface and an output surface, the light pipe is configured to change the light intensity distribution at its output surface; wherein the light pipe in the first illumination assembly is configured to change the illumination from the illumination source to generate through the focusing lens in the first illumination assembly a first illumination distribution pattern that is essentially reflectively asymmetrical with respect to a vertical plane located on an optical axis of the focusing lens in the first illumination assembly, wherein the first illumination distribution pattern includes a first gradient illumination distribution pattern with light intensity changing along a horizontal direction; wherein the light pipe in the second illumination assembly is configured to change the illumination from the illumination source to generate through the focusing lens in the second illumination assembly a second illumination distribution pattern that is essentially reflectively asymmetrical with respect to a vertical plane located on an optical axis of the focusing lens in the second illumination assembly, wherein the second illumination distribution pattern includes a second gradient illumination distribution pattern with light intensity changing along the horizontal direction; and wherein the first gradient illumination distribution pattern and the second gradient illumination distribution pattern are combined to form an improved illumination distribution pattern within the field-of-view by compensating an increase of light intensity of the first gradient illumination distribution pattern with a decrease of light intensity of the second gradient illumination distribution pattern.