Systems and method for optically imaging objects and in particular optical
patterns or codes onto a detection device by a pinhole aperture are
described. According to an embodiment of the invention these systems have
optical attenuation elements between the illumination devices and the
object which substantially compensate the system-inherent imaging detects
caused by the pinhole aperture and in particular the system-inherent
peripheral decrease in brightness of an image of the object formed by a
pinhole aperture on the detection device. According to an embodiment of
the invention, the optical attenuation elements change the illumination
intensity of the object in such a manner that the central areas of the
object are illuminated at a lower light intensity than its peripheral
areas. As a result of the subsequent imaging of the object by a pinhole
aperture, the central areas of the object are imaged onto the detection
device at a higher light intensity than the peripheral areas of the
object. The superimposition of the two effects enables the imaging system
according to the invention to achieve a substantially uniform
system-inherent brightness distribution on the detection device.