An image scanning device is provided which includes a system for determining
the
distance to a target to be scanned. The image scanning device includes an optical
system and an image sensor array for focusing a light beam and imaging the target.
The device preferably includes an automatic focusing system for adjusting the position
of the optical system in order to adjust the focal point, and thereby focus the
image of the target onto the image sensor array. In one embodiment of the image
scanning device, the distance is determined by analyzing a collimated aiming pattern
formed by collimating the light beam. In another embodiment, the distance is determined
by analyzing a speckle pattern caused by the speckle effect upon the light beam
hitting the target.
