Laser Light Source Device Speckle Reduction via Dual Diffusion Angle Mixing
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Solution Overview
Problem
Existing projector systems using laser light sources face a trade-off between speckle reduction and light utilization efficiency, as increasing the diffusion angle to reduce speckle leads to increased radiation-side etendue and decreased efficiency, while decreasing the diffusion angle compromises speckle reduction effectiveness, and the need for a rotating diffusion plate adds cost and size to the device.
Innovation Solution
A light source device with a plurality of laser light sources divided into two groups, where the first group's light is diffused by a first diffusion plate and the second group's light by a second diffusion plate with a larger diffusion angle, and the optical paths are merged using an optical path merging member to create a third diffused light with reduced coherence and maintained efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the diffusion angle of laser light is increased to reduce speckle, then the speckle reduction effect is improved, but the radiation-side etendue increases and the light utilization efficiency decreases
Solution Approach 1:
The patent divides the laser light source into multiple independent groups (first laser light source group, second laser light source group, etc.) and applies different diffusion plates to each group. Each diffusion plate has a different diffusion angle, allowing the system to combine light with varying degrees of diffusion. This segmentation enables the system to achieve speckle reduction through multiple diffusion paths while maintaining better light utilization efficiency compared to using a single high-diffusion-angle plate.
2Object-affected harmful factors
If a rotating diffusion plate is used to reduce speckle, then the speckle reduction effect is improved, but the device complexity and cost increase due to the need for a drive device
Solution Approach 1:
The patent replaces the rotating diffusion plate mechanism with multiple stationary diffusion plates arranged in different optical paths. Instead of dynamically rotating a single plate, the system uses multiple static plates with different diffusion characteristics. This dynamic-to-static transformation eliminates the need for motors, sensors, and control systems while achieving similar or better speckle reduction through the combination of multiple diffusion paths.
3Loss of energy
If the diffusion angle of laser light is decreased to maintain light utilization efficiency, then the light utilization efficiency is improved, but the speckle reduction effect becomes insufficient
Solution Approach 1:
The patent merges the optical paths of light from multiple laser light source groups that have passed through different diffusion plates. By combining light beams with different diffusion angles and coherence characteristics, the system achieves both adequate speckle reduction and maintained light utilization efficiency. The merged light contains diverse spatial and angular characteristics that reduce speckle while preserving overall light intensity.
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 while limiting the decrease in light utilization efficiency and eliminates the need for a drive device to rotate the diffusion plate, thereby reducing costs and size.
Implementation Method 1
a first diffusion plate that diffuses light emitted from the first laser light source group
Implementation Method 2
a second diffusion plate that diffuses light emitted from the second laser light source group and that emits a second diffused light having a larger diffusion angle than the first diffused light
Implementation Method 3
an optical path merging member that bends an optical path of the first diffused light to merge with an optical path of the second diffused light and that supplies a third diffused light in which the first and second diffused light are mixed
Data Source
AI summary
A light source device includes: a light source unit provided with a plurality of laser light sources provided in an array, the laser light sources being divided into first and second laser light source groups; a first diffusion plate that diffuses light emitted by the first laser light source group and emits first diffused light; a second diffusion plate that diffuses light emitted by the second laser light source group and emits second diffused light having a diffusion angle greater than that of the first diffused light; and optical path merging members that bend the optical path of the first diffused light to merge the optical path of the first diffused light with the optical path of the second diffused light and supply third diffused light in which the first and second diffused light are mixed.