Complex Laser Spatial Coherence Control for Speckle Reduction
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Solution Overview
Problem
Conventional lasers with high spatial coherence lead to coherent artifacts such as speckle in imaging applications, which impair image interpretation, while thermal sources with low spatial coherence lack sufficient photon density, necessitating a balance between spatial coherence and photon degeneracy for effective imaging.
Innovation Solution
A method for controlling the spatial coherence of complex lasers, such as chaotic cavity lasers, by adjusting the chaoticity and excitation volume, allowing for the configuration of electromagnetic radiation to achieve a desired degree of spatial coherence suitable for specific imaging applications, thereby mitigating coherent artifacts and improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional lasers with high spatial coherence are used for imaging, then directional emission and brightness are improved, but coherent artifacts such as speckle are generated that corrupt image formation
Solution Approach 1:
The patent applies parameter changes by modifying the spatial coherence parameter of the laser source. It transitions from conventional high spatial coherence lasers to complex lasers with reduced spatial coherence, thereby maintaining high brightness while eliminating coherent artifacts like speckle that corrupt image formation
2Object-generated harmful factors
If thermal sources with low spatial coherence are used for imaging, then coherent artifacts are eliminated, but photon density is insufficient for effective imaging
Solution Approach 1:
The patent applies parameter changes by simultaneously optimizing two parameters: reducing spatial coherence to eliminate coherent artifacts while increasing photon density to maintain effective imaging capability. This is achieved by using complex lasers that operate in a regime where multiple spatial modes are excited, providing both high photon flux and reduced spatial coherence
3Object-generated harmful factors
If the number of independent speckle patterns is increased to reduce speckle contrast, then speckle is mitigated, but the required averaging time or complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-reducing the spatial coherence of the laser source before illumination. This preliminary modification of the light source properties eliminates the need for post-acquisition averaging of multiple speckle patterns, thereby reducing the required averaging time and simplifying the imaging process
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The controlled spatial coherence of complex lasers enables the reduction of speckle and coherent artifacts, enhancing image quality and photon degeneracy, making them suitable for various imaging applications, including incoherent and coherent imaging, while maintaining high photon density.
Implementation Method 1
A method for controlling spatial coherence of electromagnetic radiation generated by a complex laser
Implementation Method 2
high spatial coherence leads to coherent artifacts such as speckle that corrupt image formation
Data Source
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AI summary
Systems and methods are provided for imaging using complex lasers. In general, a complex laser may be used as an electromagnetic source for an imaging application. The use of a lower spatial coherence configured complex laser in imaging applications may advantageously mitigate coherent artifacts in imaging such as cross-talk and speckle and improve overall image quality. Imaging applications where a complex laser may be useful include both incoherent imaging applications, such as digital light projectors and traditional microscopy, and coherent imaging applications, such as optical coherence tomography (OCT) and holography. The systems and methods provided also enable controlling the degree of spatial coherence of a complex laser.