A planar laser illumination and imaging (PLLIM) 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 PLIA, for reducing the temporal-coherence of said planar
laser illumination beam (PLIB) before the PLIB illuminates a target object. The
speckle-pattern noise reduction subsystem carries out a temporal phase modulation
technique during the transmission of the PLIB towards the target, so that the object
is illuminate with a temporally coherent-reduced planar laser illumination beam
(PLIB) and numerous substantially different time-varying speckle-noise patterns
are 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 using laser-based illumination during high-speed imaging
operations, without the adverse effects associated with speckle-pattern noise.