| 摘要 |
A system for reading a two-dimensional image, and for comparing the two-dimensional image to stored data representative of a known image. The optical scanning device comprises a sensor for capturing the two-dimensional image, which sensor includes a light source for projecting an emitted light towards the two-dimensional image and an optical assembly for focussing light, which may be ambient and or emitted light from the light source, reflected from the framed two-dimensional image onto a CMOS or CCD detector for detecting the focussed light, the detector including a photodiode array for sensing the focussed light and generating a signal therefrom. Aiming of the sensor to read the two-dimensional image is facilitated by a frame locator consisting of a laser diode which emits a beam that is modified by optics, including diffractive optics, to divide the beam into beamlets which having a spacing therebetween that expands to match the dimensions of the field of view of the sensor, forming points of light at the target to define the edges of the field of view.
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