Eccentrically Rotating Lens for Laser Homogenization
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Solution Overview
Problem
High power laser applications face inefficiencies and high costs due to the use of transmissive diffusers for homogenizing laser light, which also result in undesirable low-angle light that does not effectively bounce inside integrating rods, leading to incomplete homogenization and speckle issues in projectors.
Innovation Solution
An eccentrically rotating lens is positioned between the laser and the integrating rod, focusing light off the optical axis and rotating about a different axis to increase homogenization, with a diffuser on the lens side to further spread the light, reducing low-angle light and enhancing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If transmissive diffusers are used to diffuse laser light, then light homogenization is improved, but efficiency is reduced and cost increases
Solution Approach 1:
The patent extracts the diffusing function from a separate transmissive diffuser component and integrates it into the lens itself through an eccentric rotation mechanism. The lens rotates about an axis offset from its optical axis, causing the focused light spot to sweep across the integrating rod input face, thereby achieving homogenization without requiring a separate diffusing element.
Solution Approach 2:
The patent introduces dynamic motion (eccentric rotation) to achieve homogenization. The lens rotates continuously about an axis offset from its optical axis, creating a time-varying light distribution pattern that sweeps across the integrating rod input face. This dynamic approach replaces static transmissive diffusers, eliminating their associated losses and costs.
2Stability of the object's composition
If transmissive diffusers are used to diffuse laser light, then light homogenization is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges the focusing function of the lens with the homogenization function that would otherwise require a separate transmissive diffuser. By integrating the homogenization mechanism into the lens assembly itself through eccentric rotation, the system reduces component count and overall device complexity while achieving the same homogenization effect.
Solution Approach 2:
The lens assembly is designed to perform multiple functions: focusing the laser light and homogenizing the light distribution across the integrating rod input face. The single lens component with eccentric rotation capability replaces what would traditionally require multiple separate components (lens + diffuser), thereby simplifying the overall device architecture.
3Area of stationary object
If transmissive diffusers are used to diffuse laser light, then light is spread over diffuse area, but low-angle light remains which does not sufficiently bounce inside integrating rod
Solution Approach 1:
The patent employs asymmetric geometry through eccentric rotation, where the rotation axis is offset from the lens's optical axis. This asymmetry causes the focused light spot to trace an asymmetric path across the integrating rod input face, creating a more uniform angular distribution of light rays. The asymmetric motion ensures that light enters the integrating rod at various angles, promoting sufficient internal bouncing and homogenization.
Solution Approach 2:
The patent transitions from static spatial diffusion to dynamic spatio-temporal diffusion. The eccentric rotation adds a temporal dimension to the light distribution, causing the light spot to sweep across different positions and angles over time. This time-varying approach ensures that light enters the integrating rod with a broader angular distribution, eliminating the low-angle light problem associated with static transmissive diffusers.
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 increases light homogenization and reduces low-angle light, improving efficiency and reducing speckle in projector images by ensuring that light is focused at angles greater than 3° from the normal, thereby enhancing the integration and projection quality.
Implementation Method 1
the lens positioned to receive light from the laser, off the optical axis, and focus the light through the input face of the integrating rod
Implementation Method 2
the lens can comprise a diffuser on a side facing the integrating rod, which further homogenizes the light
Data Source
AI summary
A device for homogenizing laser light using a rotating lens is provided. The device comprises: a laser; an integrating rod having an input face; a lens located between the laser and the input face of the integrating rod, the lens having an optical axis, the lens positioned to receive light from the laser, off the optical axis, and focus the light through the input face of the integrating rod; and, an actuator device configured to rotate the lens about an axis of rotation different from the optical axis.