Arrangement for and method of imaging targets with improved light collecting efficiency over extended range of working distances

摘要

An imaging lens assembly for an imaging reader includes a base lens having an optical power, a target side facing a target, and an imager side facing an imager. An aperture stop directly contacts the imager side and has an aperture through which return light from the target passes. The aperture is magnified in apparent size by the optical power of the base lens to form a magnified entrance pupil as seen through the target side. A variable focus liquid lens focuses the return light captured by the magnified entrance pupil over an extended range of working distances onto the imager. The magnified entrance pupil captures more of the return light from the target to pass through the base lens and the liquid lens to the imager, and also allows the target to be illuminated with a lower brightness to conserve electrical power.

主权项

1. An imaging lens assembly for capturing return light from a target over a field of view of an array of image sensors of a solid-state imager, and for projecting the captured return light onto the array during electro-optical reading of the target, the assembly comprising:
a base lens through which the captured return light passes along an optical axis, the base lens having an optical power, a target side facing the target, and an imager side facing the imager; an aperture stop in direct surface area contact with the imager side of the base lens and having an aperture through which the optical axis extends and the captured return light passes, the aperture being magnified in apparent size by the optical power of the base lens to form a magnified entrance pupil as seen through the target side; and a variable focus liquid lens arranged along the optical axis between the aperture stop and the imager for focusing a substantial amount of the return light captured by the magnified entrance pupil over an extended range of working distances onto the imager.