Projection Illumination System Using Polarization Beam Splitting
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Solution Overview
Problem
Current projection apparatuses face challenges with laser speckle phenomenon and low optical utilization efficiency due to the need for multiple lens assemblies and dichroic mirrors, which also restrict the number of applicable laser beams and reduce efficiency.
Innovation Solution
The use of multiple light sources with different polarization states for red, green, and blue beams, combined using a light-splitting device and homogenized, eliminates the need for a diffusion sheet and enhances light source utilization efficiency by doubling the number of light sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a diffusion sheet is applied to mitigate laser speckle phenomenon, then the laser speckle phenomenon is reduced, but the optical utilization efficiency is greatly reduced
Solution Approach 1:
The invention segments the single laser beam into multiple separate laser beams using beam splitting optics. By dividing the original laser beam into several parallel beams with different spatial paths, the speckle patterns generated by each beam are statistically independent, and their superposition reduces the overall speckle contrast in the projection image, thereby mitigating the laser speckle phenomenon without requiring a diffusion sheet
Solution Approach 2:
The invention introduces spatial dimensionality by arranging multiple laser beams in different spatial positions and directions. Instead of treating the laser beam as a single entity, the system creates a multi-dimensional beam structure where beams are distributed across different spatial coordinates, allowing the speckle patterns to diverge and reduce interference while maintaining optical efficiency
2Adaptability or versatility
If multiple lens assemblies and dichroic mirrors are used to combine laser beams of different wavelengths, then light combination is achieved, but the device complexity and occupied area increase significantly
Solution Approach 1:
The invention merges the functions of multiple wavelength-specific optical components into a single integrated light-combining module. By using a carefully designed arrangement of beam splitting and combining optics, the system combines red, green, and blue laser beams of different wavelengths into a single composite beam path, eliminating the need for separate lens assemblies and dichroic mirrors for each wavelength
Solution Approach 2:
The light-combining module is designed as a universal optical component that can handle multiple wavelengths simultaneously. The optical design allows the same module to combine red, green, and blue laser beams through a unified optical path, making the system more compact and reducing the total number of specialized components required
3Object-affected harmful factors
If a large diffusion sheet is used to resolve laser speckle, then the speckle phenomenon is reduced, but the optical utilization efficiency is greatly reduced
Solution Approach 1:
The invention segments the single laser beam into multiple separate laser beams using beam splitting optics. By dividing the original laser beam into several parallel beams with different spatial paths, the speckle patterns generated by each beam are statistically independent, and their superposition reduces the overall speckle contrast in the projection image, thereby mitigating the laser speckle phenomenon without requiring a diffusion sheet
Solution Approach 2:
The invention replaces the mechanical diffusion sheet approach with an optical beam segmentation approach. Instead of using a physical diffusion material that scatters light mechanically, the system uses precision optical elements to divide and redirect laser beams along different paths, achieving speckle reduction through optical path diversification rather than physical diffusion
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
This configuration alleviates the laser speckle phenomenon and improves light-combining efficiency without the need for a high haze diffusion sheet, enhancing the overall performance of the illumination system and projection apparatus.
Implementation Method 1
The first light-splitting device allows the first red light beam and the second red light beam to pass but reflects the first blue light beam and the second blue light beam or allows the first blue light beam and the second blue light beam to pass but reflects the first red light beam and the second red light beam
Implementation Method 2
the mixed light then enters a light-homogenizing apparatus, so as to be shaped and homogenized
Implementation Method 3
convert an illumination beam generated by an illumination system to an image beam through a light valve
Data Source
AI summary
An illumination system includes first and second red light sources, first and second green light sources, first and second blue light sources, and a first light-splitting device. The first red light source, the first green light source, and the first blue light source respectively provide a first red light beam, a first green light beam, and a first blue light beam with a first polarization state. The second red light source, the second green light source, and the second blue light source respectively provide a second red light beam, a second green light beam, and a second blue light beam with a second polarization state. The first light-splitting device is disposed on transmission paths of the first and second red light beams, the first and second green light beams, and the first and second blue light beams to form an illumination beam.