Laser Illumination System Speckle Reduction via Movable Diffuser
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Solution Overview
Problem
Laser diode-based projection systems suffer from speckle noise due to coherent light beams interacting with uneven surfaces, leading to uneven luminance and decreased image quality.
Innovation Solution
An illumination system comprising a coherent light source, an optical module with a light-diffusing surface, and a movable light-diffusing device that adjusts the diffusion angle of the light beam, creating uniform luminance by generating two different light diffusion effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a laser diode is used as a light source, then high collimation and high energy are achieved, but speckle noise is generated due to coherent light interaction with uneven surfaces
Solution Approach 1:
The patent introduces a movable light-diffusing device that can change positions along the optical axis, enabling dynamic adjustment of the diffusion angle. This dynamic mechanism allows the system to adapt the degree of light diffusion, thereby controlling speckle noise while preserving laser energy for projection.
Solution Approach 2:
The patent changes the diffusion angle parameter by moving the light-diffusing device to different positions. This parameter adjustment modifies the interaction between coherent light and the diffusing surface, reducing speckle noise while maintaining adequate illumination energy for the projection system.
2Device complexity
If a fixed light-diffusing device is used, then the optical path is simple, but the illumination uniformity cannot be optimized
Solution Approach 1:
The light-diffusing device is designed to be movable rather than fixed, allowing adjustment of its position along the optical axis. This dynamic capability enables optimization of illumination uniformity by selecting appropriate diffusion angles, while the overall optical path remains relatively simple.
3Object-affected harmful factors
If the diffusion angle is increased to reduce speckle, then the light beam spreads too much and reduces projection efficiency
Solution Approach 1:
The movable light-diffusing device enables dynamic control of the diffusion angle, allowing the system to find an optimal balance between speckle reduction and light beam concentration. By adjusting the device position, the system can achieve sufficient speckle mitigation while maintaining adequate projection efficiency.
Solution Approach 2:
The diffusion angle is adjusted as a controllable parameter through position changes of the light-diffusing device. This parameter optimization allows the system to reduce speckle noise to acceptable levels while preventing excessive light beam spread that would harm projection efficiency.
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 produces a uniform illumination light beam, enhancing image quality and user perception by reducing speckle noise and achieving consistent luminance in projection systems.
Implementation Method 1
The optical module has an optical surface and a light-diffusing surface, and the coherent light beam focuses on a first position through the optical surface of the optical module. The first light-diffusing device is located on the transmission path of the coherent light beam and is located at the first position or in vicinity of the first position. The coherent light beam passes through the first light-diffusing device so that a diffusion angle of the coherent light beam is sequentially changed
Implementation Method 2
The optical module has an optical surface and a light-diffusing surface, and the coherent light beam focuses on a first position through the optical surface of the optical module
Data Source
AI summary
An illumination system and a projection apparatus are provided. The illumination system includes a coherent light source, an optical module, and a first light-diffusing device. The coherent light source emits a coherent light beam. The optical module and the first light-diffusing device are located on a transmission path of the coherent light beam. The optical module has an optical surface and a light-diffusing surface, and the coherent light beam focuses on a first position through the optical surface of the optical module. The first light-diffusing device is located at the first position or in vicinity of the first position. The coherent light beam passes through the first light-diffusing device so that a diffusion angle of the coherent light beam is sequentially changed. A display frame exhibiting a uniform luminance is thereby provided by the illumination system and the projection apparatus of the invention.