Low-speckle laser line generator using beam divider
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Solution Overview
Problem
Existing laser line generation technologies suffer from speckle interference issues, leading to measurement errors in industrial applications due to variations in light intensity, which are not effectively mitigated.
Innovation Solution
A laser line generating assembly that divides a coherent laser beam into incoherent sub-beams using a beam divider and converts them into laser light sheets with uncorrelated speckle patterns through a sub-beam converter, resulting in a low-speckle laser line by intersecting these sheets at a projection plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a coherent laser beam is used as the light source, then the laser line can be generated with high intensity and directionality, but speckle interference patterns appear causing measurement errors
Solution Approach 1:
The patent divides the coherent laser beam into multiple incoherent sub-beams using a beam divider. Each sub-beam has a shorter coherence length, and when these sub-beams are recombined to form the laser line, their speckle patterns are uncorrelated and average out, reducing overall speckle interference while maintaining the required illumination intensity
Solution Approach 2:
The patent changes the coherence length parameter of the light source by using a beam divider to create multiple sub-beams with different optical paths. This parameter change transforms the highly coherent single beam into multiple partially coherent sub-beams, reducing speckle contrast while preserving illumination intensity
2Measurement precision
If multiple incoherent sub-beams are generated to reduce speckle, then speckle interference is mitigated, but the device complexity increases
Solution Approach 1:
The patent introduces a beam divider as an intermediary component that splits the laser beam into multiple sub-beams. This intermediary device enables the transformation from a single coherent beam to multiple incoherent sub-beams, achieving speckle reduction without requiring multiple independent laser sources or complex optical systems
Solution Approach 2:
The beam divider serves multiple functions: it divides the laser beam into multiple sub-beams, creates uncorrelated speckle patterns, and maintains overall beam intensity. This multi-functional component achieves speckle mitigation while keeping the system relatively simple by consolidating multiple roles into a single device
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 solution provides improved uniformity of laser lines and increased apparent source size, reducing speckle interference and enhancing measurement accuracy in industrial applications.
Implementation Method 1
a beam divider configured to divide the laser beam into incoherent multiple sub-beams propagating in a same propagation plane
Implementation Method 2
The speckle effect is a result of the constructive and destructive interference of light waves that take place when coherent light, such as a laser beam, is used as the light source
Implementation Method 3
the laser line elements having respective speckle patterns which are at least partially uncorrelated
Data Source
AI summary
A laser line generating assembly for projecting a low-speckle laser line is provided. The laser line generating includes a laser source, a beam divider and a sub-beam converter. The laser source generating a laser beam having a temporal coherence. The beam divider divides the laser beam into incoherent multiple sub-beams propagating in a same propagation plane. The sub-beam converter generates a plurality of laser light sheets, each laser light sheet being associated with a corresponding one of the sub-beams. Each laser light sheet extends within the propagation plane. The laser light sheets intersect a projection plane to define laser line elements overlapping at least partially to form said low-speckle laser line, the laser line elements having respective speckle patterns which are at least partially uncorrelated.