Polymerized Liquid Crystal Beam Separator for Laser Speckle Reduction
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Solution Overview
Problem
Laser-based projection systems suffer from image degradation due to speckle, a coherent light artifact caused by reflection off rough surfaces, which existing solutions attempt to address with complex and costly systems that increase power requirements and system size.
Innovation Solution
Employing a beam separator, such as a birefringent wedge or polymerized liquid crystal layer, within the optical path to separate laser beams into orthogonally polarized components, reducing speckle while maintaining image quality and resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional speckle reduction systems (diffusers, image displacing devices, optical fibers) are employed, then speckle is reduced, but system complexity and cost increase substantially
Solution Approach 1:
The patent changes the polarization state parameter of the laser light by introducing a beam separator that creates orthogonally polarized beams. This parameter change allows the speckle pattern to be reduced when beams are recombined, achieving speckle reduction without adding mechanical complexity to the system.
Solution Approach 2:
The patent segments the single coherent laser beam into multiple orthogonally polarized beams using a beam separator. By dividing the original beam into separate polarized components and then recombining them, the system reduces speckle while maintaining a relatively simple optical path without requiring complex mechanical diffusers or image displacing devices.
2Object-affected harmful factors
If conventional speckle reduction systems are employed, then speckle is reduced, but power requirements increase
Solution Approach 1:
The beam separator modifies the polarization parameter of the laser beam passively without requiring additional power input. The orthogonally polarized beams are created through optical property changes rather than active energy consumption, maintaining system efficiency while reducing speckle.
3Object-affected harmful factors
If conventional speckle reduction systems are employed, then speckle is reduced, but system size increases
Solution Approach 1:
The beam separator achieves speckle reduction by manipulating the polarization parameter of light through a compact optical element. This approach eliminates the need for large mechanical diffusers, vibrating components, or long optical fiber lengths, thereby reducing the overall system volume while maintaining effective speckle suppression.
4Object-affected harmful factors
If a beam separator is used to reduce speckle, then speckle is reduced by up to 25%, but image resolution and brightness must be maintained
Solution Approach 1:
The beam separator segments the laser beam into orthogonally polarized components that are later recombined. This segmentation approach reduces speckle through interference cancellation while the precise optical design ensures that image resolution and brightness are preserved during the beam separation and recombination process.
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 by up to 25% without impacting image resolution or brightness, offering a compact, cost-effective, and energy-efficient speckle reduction method suitable for use in laser projection systems.
Implementation Method 1
a beam separator, such as a birefringent wedge or polymerized liquid crystal layer, within the optical path to separate laser beams into orthogonally polarized components
Implementation Method 2
separate laser beams into angularly separated and orthogonally polarized beams from a single laser
Data Source
AI summary
An imaging system (200), such as a scanned laser projection system, includes one or more laser sources (201) configured to produce one or more light beams (204), and a light modulator (203) configured to produce images (206) from the light beams (204). Optional optical alignment devices (220) can be used to orient the light beams (204) into a combined light beam (205). A beam separator (221), which can be any of a birefringent wedge, compensated birefringent wedge, or a polymerized liquid crystal layer, is disposed between at least one of the laser sources (201) and the light modulator (203). The beam separator (221) is configured to receive light from the laser sources (201) and deliver two angularly separated and orthogonally polarized light beams (223) to the light modulator (203) so as to reduce speckle appearing when the images (206) are displayed on a display surface (207).