Light Source Apparatus for Reducing Speckle in Laser Projection
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Solution Overview
Problem
Projectors using laser light sources for red, green, and blue illumination often experience speckle and color unevenness due to differences in light output and incident angle distributions, leading to flicker and image quality issues.
Innovation Solution
A light source apparatus with a first emitter for red and green laser light sources and a second emitter for blue, combined with a rotational diffusion plate and collimator lenses, where the focal lengths of the lenses satisfy specific ratios to ensure balanced light distribution and reduce speckle, thereby addressing color unevenness without increasing the number of parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single diffusion plate is used for all colors, then the device complexity is reduced, but color unevenness occurs due to different incident angle distributions
Solution Approach 1:
The diffusion plate is designed with spatially varying diffusion characteristics - the diffusion coefficient changes in the vertical direction (y-direction) to match the incident angle distribution of each color. The upper region has higher diffusion coefficients while the lower region has lower diffusion coefficients, creating local variations that compensate for color-specific incident angle differences and achieve uniform color distribution.
Solution Approach 2:
The diffusion coefficient of the diffusion plate is specifically optimized for blue laser light with higher incident angles, while maintaining adequate performance for red and green lasers. By changing the diffusion parameter distribution across the plate surface, the system achieves uniform color mixing without requiring separate diffusion plates for each color.
2Manufacturing precision
If multiple rotational diffusion plates with different diffusion characteristics are used, then color unevenness is reduced, but the device complexity and size increase
Solution Approach 1:
Multiple diffusion functions are merged into a single diffusion plate by implementing spatially varying diffusion coefficients. Instead of using separate diffusion plates for different colors, the invention combines the diffusion characteristics of multiple plates into one plate with position-dependent diffusion properties, achieving the same color uniformity effect with reduced complexity.
Solution Approach 2:
The single diffusion plate performs multiple functions simultaneously - it diffuses blue, green, and red laser lights with different incident angle distributions using different regions of the plate. The plate is designed to handle all three colors with their respective characteristics, making it a universal diffusion element that replaces multiple color-specific plates.
3Quantity of substance
If blue laser light sources are reduced in number due to higher output, then the light source count is reduced, but incident angle distribution differences cause color unevenness
Solution Approach 1:
The diffusion plate creates local quality variations in the diffusion process - regions with different diffusion coefficients are positioned to handle different color inputs. This local differentiation compensates for the reduced number of blue laser sources and their different incident angle distribution, ensuring uniform color output.
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 effectively reduces speckle and color unevenness in projected images by ensuring balanced light distribution and beam diameters for all colors, enhancing image quality without the need for multiple rotational diffusion plates.
Implementation Method 1
making the laser light enter a diffusion plate, rotating the diffusion plate with a motor to acquire diffused light
Implementation Method 2
a first collimator lens configured to collimate the diffused first color light, and a second collimator lens configured to collimate the diffused second color light
Data Source
AI summary
An apparatus includes a first emitter configured to emit first color light, a second emitter configured to emit second color light, a plate configured to diffuse the first color light and the second color light, a first lens configured to collimate the diffused first color light, and a second lens configured to collimate the diffused second color light. A predetermined condition is satisfied.