A planar laser illumination and imaging (PLIIM) based camera system capable of
producing digital images with reduced levels of speckle-pattern noise. The PLIIM
based camera system comprises a planar laser illumination array (PLIA) including
a plurality of laser diodes for producing and projecting a planar laser illumination
beam (PLIB) so as to illuminate an object as it is moving past said PLIIM based
camera system. An image formation and detection (IFD) module is provided having
a image detection array and imaging forming optics for providing the image detection
array with a field of view (FOV). The PLIB and FOV are arranged in a coplanar relationship
along the working range of the PLIIM based camera system so that the PLIB illuminates
primarily within the FOV of the IFD module. A speckle-pattern noise reduction subsystem
is integrated with the IFD, for reducing the spatial-coherence of said planar laser
illumination beam (PLIB) after the PLIB has illuminated and reflected/scattered
off the target object. The speckle-pattern noise reduction subsystem carries out
a spatial intensity modulation technique after the reflection/scattering of the
PLIB off the target, so that the laser illumination reflected/scattered off the
object consists of spatially coherent-reduced planar laser illumination, causing
numerous substantially different time-varying speckle-noise patterns to be produced
at the image detection array over the photo-integration time period thereof. The
numerous substantially different time-varying speckle-noise patterns are detected
at the image detection array over the photo-integration time period, and the detected
speckle-noise patterns are temporally averaged at said image detection array during
the photo-integration time period thereof. As a result of such temporal averaging,
the RMS power of observable speckle-noise patterns is reduced at the image detection
array. By virtue of the present invention, it is now possible to enjoy the benefits
of laser-based illumination during high-speed imaging operations, without the adverse
effects of speckle-pattern noise.