METHOD OF SPECKLE-NOISE PATTERN REDUCTION AND APPARATUS THEREFOR BASED ON REDUCING THE SPATIAL-COHERENCE OF THE PLANAR LASER ILLUMINATION BEAM BEFORE THE BEAM ILLUMINATES THE TARGET OBJECT BY APPLYING SPATIAL PHASE SHIFTING TECHNIQUES DURING THE TRANSMISSION OF THE PLIB THERETOWARDS
US6742707B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 12, 2001 |
| Grant date | Jun 1, 2004 |
| Priority date | — |
| Expiry date | Feb 12, 2021 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01S5/4025
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
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) through a light transmission aperture, 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 said 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 spatial-coherence of said planar laser illumination beam (PLIB) before the PLIB illuminates a target object. The speckle-pattern noise reduction subsystem carries out a spatial phase shifting technique during the transmission of the PLIB towards the target, so that the object i…
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