Laser Light Assembly Speckle Reduction via Path Length Segmentation
Solution Overview
Problem
Laser projection systems face challenges in reducing speckle, particularly due to the coherent nature of laser light, which results in image deterioration and visual discomfort, and existing methods like splitting orthogonal polarizations are insufficient and costly.
Innovation Solution
A light assembly that splits a laser beam into two portions, with one portion being reflected and the other transmitted, and then directed back through an optical path longer than the coherence length, using reflective and beam-splitting components to reduce speckle without the need for quarter-wave plates, allowing for independent movement of these components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If orthogonal polarizations are split and passed along different length paths to reduce speckle, then speckle patterns become different, but the method is costly and complex requiring quarter-wave plates
Solution Approach 1:
The laser beam is divided into two separate beams by a beam splitter, with each beam traveling along a different optical path. This segmentation allows independent manipulation of each beam's path length without requiring complex polarization control components like quarter-wave plates, thereby reducing device complexity while still achieving speckle reduction through path length differentiation
Solution Approach 2:
The invention changes the path length parameter of the optical paths to be different from each other, specifically making at least one path length exceed the coherence length of the laser. This parameter change creates uncorrelated speckle patterns without requiring polarization manipulation, simplifying the overall optical system while effectively reducing speckle
2Object-affected harmful factors
If multiple laser beams with different speckle patterns are combined, then speckle is reduced through averaging, but the system complexity increases
Solution Approach 1:
Instead of combining multiple independent laser beams, the invention segments a single laser beam into two paths with different lengths. This approach achieves the same speckle reduction effect through path differentiation rather than beam combination, significantly reducing system complexity while maintaining effectiveness
Solution Approach 2:
The beam splitter acts as an intermediary that divides the single laser beam into two separate paths. This intermediary component enables the creation of uncorrelated speckle patterns through path length differentiation without requiring multiple laser sources or complex beam combining mechanisms, thereby simplifying the overall system
3Object-affected harmful factors
If the optical path length is increased to exceed coherence length, then uncorrelated speckle patterns are achieved, but light loss increases
Solution Approach 1:
The invention applies partial path length extension, making at least one optical path exceed the coherence length while keeping the other path relatively shorter. This partial excessive action is sufficient to create uncorrelated speckle patterns without unnecessarily extending both paths, thereby minimizing light loss while achieving the desired speckle reduction effect
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 by creating uncorrelated speckle patterns, improving image quality and reducing light loss, while being cost-effective and efficient.
Implementation Method 1
a means for beam splitting configured to split the laser beam emitted by the laser, by reflecting a first portion of the laser beam and transmitting a second portion of the laser beam
Implementation Method 2
the first and second reflective means and means for beam splitting are arranged to define an optical path for the second portion of the laser beam whose length is equal to, or greater than, a coherence length of the laser beam which is emitted from the at least one laser source
Data Source
AI summary
According to the present invention there is provided a light assembly, comprising, at least one laser source which is operable to emit a laser beam, and a component for reducing speckle, wherein the component for reducing speckle comprises a block, comprising at least first, second and third surface, and a means for beam splitting, and wherein the first and second reflective means and means for beam splitting are arranged to define an optical path for the second portion of the laser beam whose length is equal to, or greater than, a coherence length of the laser beam which is emitted from the at least one laser source.