Anisotropic Laser Beam Expansion for Projection Illumination
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Solution Overview
Problem
Laser projectors face challenges with increased input laser power leading to decreased conversion efficiency, thermal issues, and energy loss due to the elliptical cone shape of the laser light spot, which affects light emitting efficiency and uniformity.
Innovation Solution
An illumination system incorporating an anisotropic light expanding element that adjusts the laser beam expansion along the slow axis, reducing energy concentration and preventing optical coupling loss, while an anisotropic wavelength conversion element ensures efficient conversion and improved image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If input laser power is increased to achieve higher output brightness, then brightness requirement is met, but laser conversion efficiency decreases due to over-concentration of laser energy
Solution Approach 1:
The patent segments the laser beam expansion into two distinct directional components: fast axis expansion and slow axis expansion. By using separate optical elements (collimator lens for fast axis, cylindrical lens for slow axis), the system divides the beam control function into specialized segments, allowing independent optimization of each axis to prevent energy over-concentration while maintaining high brightness output.
Solution Approach 2:
The patent applies different optical properties to different regions of the laser beam. The collimator lens addresses the fast axis characteristics while the cylindrical lens addresses the slow axis characteristics. This local quality approach ensures that each region of the beam is treated according to its specific divergence properties, optimizing energy distribution across the phosphor wheel surface.
2Stability of the object's composition
If diffusion film is used to diffuse laser light spot and uniform energy, then energy uniformity is improved, but energy loss increases due to absorption and scattering in the diffusion film
Solution Approach 1:
The patent extracts the diffusion function from a separate diffusion film component and integrates it directly into the cylindrical lens structure. The lens itself is designed with refractive properties that provide the necessary diffusion effect. This eliminates the need for a separate diffusion film, thereby removing the associated energy losses from absorption and scattering while maintaining energy uniformity across the laser light spot.
Solution Approach 2:
The cylindrical lens serves as an intermediary optical element that simultaneously performs collimation in the fast axis direction and diffusion in the slow axis direction. By using the lens as a mediator between the laser source and phosphor wheel, the system achieves energy uniformity through controlled refraction rather than through a diffusion film, reducing energy loss in the process.
3Ease of operation
If isotropic diffusion film is used to diffuse laser beam, then light distribution is simplified, but optical coupling efficiency decreases due to overly long light spot axis affecting coupling with phosphor wheel
Solution Approach 1:
The patent introduces asymmetry in the optical system by using a cylindrical lens with different refractive properties along different axes. The lens provides strong focusing in the fast axis direction while providing controlled diffusion in the slow axis direction. This asymmetric optical design creates an optimized elliptical light spot shape that matches the phosphor wheel geometry, maximizing optical coupling efficiency while maintaining ease of operation.
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 achieves improved light uniformity and energy efficiency by anisotropically adjusting the laser light spot, reducing thermal issues and enhancing image quality and reliability in projection apparatuses.
Implementation Method 1
the at least one anisotropic light expanding element allows the laser beam to expand in a light expanding direction, wherein the light expanding direction is substantially parallel to a slow axis of the laser beam
Implementation Method 2
a pure-color optical source for a projector generated by using a laser source to excite phosphor has been developed
Data Source
AI summary
An illumination system including at least one laser source, at least one anisotropic light expanding element and a wavelength conversion element is provided. The at least one laser source emits a laser beam. The at least one anisotropic light expanding element is disposed on the transmission path of the laser beam and causes the laser beam to expand along a light expanding direction. The light expanding direction is substantially parallel to the slow axis of the laser beam. The wavelength conversion element is disposed on the transmission path of the laser beam. A projection apparatus is also provided.