VCSEL Array Speckle Noise Reduction via Aperture Diversification
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Solution Overview
Problem
Structured light illumination techniques face limitations due to sampling errors and noise from laser speckle, which complicates accurate profile information acquisition and increases computational load for post-processing.
Innovation Solution
A structured light projector system employing an array of VCSELs with different aperture widths to produce diverse speckle patterns, reducing noise by averaging them, and incorporating subwavelength structures to steer light output and manipulate optical wavefronts, thereby minimizing the need for digital post-processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard range-finding or triangulation methods are used to process images, then 3D data representation can be created, but computational load increases due to speckle noise and sampling errors
Solution Approach 1:
The patent applies preliminary action by reducing speckle noise at the image capture stage through optical diversification rather than relying on post-processing computational methods. Multiple VCSELs with different aperture widths and subwavelength structures pre-diversify the speckle patterns before they reach the object, eliminating the need for computationally intensive noise reduction algorithms during 3D reconstruction.
Solution Approach 2:
The patent changes physical parameters of the light source by using VCSELs with different aperture widths and incorporating subwavelength structures, which fundamentally alters the speckle pattern characteristics. This parameter diversification approach transforms the nature of the illumination to inherently reduce speckle noise, improving measurement precision without increasing computational complexity.
2Measurement precision
If a single VCSEL is used to project structured light patterns, then the system is simple, but speckle noise reduces measurement accuracy
Solution Approach 1:
The patent applies segmentation by dividing the light source into multiple VCSELs with different aperture widths rather than using a single VCSEL. Each VCSEL segment produces a different speckle pattern, and their combined effect reduces overall speckle noise. This segmentation approach improves measurement precision while maintaining relatively simple device architecture.
Solution Approach 2:
The patent uses a composite light source configuration combining multiple VCSELs with different aperture widths and subwavelength structures. This composite approach creates diverse speckle patterns that, when averaged, reduce noise and improve measurement accuracy without requiring complex individual components.
3Measurement precision
If computationally intensive post-processing is applied to reduce speckle noise, then measurement accuracy improves, but processing time increases
Solution Approach 1:
The patent performs noise reduction action preliminarily at the optical stage rather than computationally after image capture. By using multiple VCSELs with different aperture widths and subwavelength structures to create diverse speckle patterns during illumination, the system reduces speckle noise before it affects the measurement, eliminating the need for time-consuming post-processing algorithms.
4Object-generated harmful factors
If VCSELs with different aperture widths are used to reduce speckle noise, then noise reduction effectiveness increases, but device complexity increases
Solution Approach 1:
The patent applies local quality by giving each VCSEL a specific aperture width tailored to produce particular speckle pattern characteristics. Rather than making all VCSELs identical, each element has a locally optimized aperture width that contributes to overall noise reduction when combined with others. This local differentiation achieves effective noise reduction with a relatively simple VCSEL array configuration.
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
This approach effectively reduces speckle noise at the image capture stage, eliminating the need for computationally intensive post-processing and enhancing the accuracy and efficiency of 3D image creation without increasing computational load.
Implementation Method 1
A laser source for use in a structured light projector includes a substrate, one or more first VCSELs on the substrate, and one or more second VCSELs on the substrate. The one or more first VCSELs each have a first aperture width and each separately extend above a surface of the substrate. The one or more second VCSELs each have a second aperture width different from the first aperture width
Implementation Method 2
Using an array of VCSELs with different aperture widths provides emitted radiation having different wavelengths, thus providing different speckle patterns. When the different speckle patterns are averaged upon being received at the detector, speckle noise is reduced
Implementation Method 3
The VCSEL can also include a plurality of subwavelength structures to steer the light output. Such subwavelength structures can also be used on the surface of other VCSELs, including standard VCSELs
Data Source
AI summary
A laser source for use in a structured light projector includes a substrate, one or more first VCSELs on the substrate, and one or more second VCSELs on the substrate. The one or more first VCSELs each have a first aperture width and each separately extend above a surface of the substrate. The one or more second VCSELs each have a second aperture width different from the first aperture width, and each separately extend above a surface of the substrate. Using an array of VCSELs with different aperture widths provides emitted radiation having different wavelengths, thus providing different speckle patterns. When the different speckle patterns are averaged upon being received at the detector, speckle noise is reduced. The VCSEL can also include a plurality of subwavelength structures to steer the light output. Such subwavelength structures can also be used on the surface of other VCSELs, including standard VCSELs.