Two-Stage Light Homogenization for Speckle-Reduced Projection
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Solution Overview
Problem
Laser projectors using coherent laser diodes face issues with speckle and color block formation due to uneven surfaces causing optical path differences, leading to reduced image quality and difficulty in homogenizing high-intensity laser beams.
Innovation Solution
A light source system comprising a laser light source module, excitation light source module, light-combining element, first and second light homogenizing elements, and wavelength conversion element, where the first light homogenizing element has a deflection angle to align the light spot shape with the second light homogenizing element, enhancing uniformity and reducing speckle and color block.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If laser diode is used as light source, then high light intensity and high collimation are achieved, but speckle and color block are formed due to interference on uneven surfaces
Solution Approach 1:
The patent segments the laser beam into multiple sub-beams using a microlens array, where each microlens converts one laser beam into multiple sub-beams. These sub-beams are then superimposed to form a composite beam with reduced speckle patterns, as the interference effects from individual sub-beams do not perfectly align.
Solution Approach 2:
The patent introduces a temporal dimension by rapidly switching between multiple laser diodes with different wavelengths or coherence properties. This time-multiplexed approach ensures that speckle patterns from different laser sources do not overlap, effectively reducing the overall speckle visibility in the projected image.
2Speed
If laser beam with high collimation is used, then light can be converged effectively, but it is difficult to homogenize the light beam
Solution Approach 1:
The microlens array divides the highly collimated laser beam into multiple sub-beams, each maintaining good collimation. When these sub-beams are superimposed, they collectively provide both rapid convergence capability and improved homogeneity, as the individual sub-beams fill in the intensity variations of each other.
Solution Approach 2:
The patent merges multiple sub-beams from different microlenses into a single composite beam. This combination maintains the convergence speed advantage of laser while achieving homogeneity through the superposition of multiple slightly different beam profiles, effectively resolving the contradiction between convergence speed and homogeneity.
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 system improves illumination light beam uniformity, reducing speckle and color block in projection devices, thereby enhancing image quality and efficiency.
Implementation Method 1
the first light homogenizing element is disposed between the excitation light source module and the light-combining element and configured to receive and homogenize the second light beam from the excitation light source module
Implementation Method 2
The wavelength conversion element is configured to receive the second light beam from the light-combining element and convert the second light beam into a fluorescent light beam
Implementation Method 3
The wavelength conversion element is configured to receive the second light beam from the light-combining element and convert the second light beam into a fluorescent light beam
Implementation Method 4
The light-combining element is disposed between the first light homogenizing element and the wavelength conversion element to guide the fluorescent light beam from the wavelength conversion element and the first light beam from the laser light source module, so that the first light beam and the fluorescent light beam form a combined light beam
Implementation Method 5
The second light homogenizing element is disposed on a transmission path of the combined light beam and configured to receive the combined light beam and generate an illumination light beam
Data Source
AI summary
A light source system includes laser and excitation light source modules providing first and second light beams respectively, a light-combining element, a first light homogenizing element, a wavelength conversion element, and a second light homogenizing element. The first light homogenizing element has a deflection angle on a plane perpendicular to an optical axis of the second light beam. The light-combining element forms a combined light beam from the first light beam and the second light beam. The second light homogenizing element receives the combined light beam and generates an illumination light beam. A light spot formed by the fluorescent light beam on a light incident surface of the second light homogenizing element has a first shape, and the first shape corresponds to the shape of the light incident surface of the second light homogenizing element.