Wavelength-Selective Polarization Conversion Element
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Solution Overview
Problem
Conventional image projection apparatuses with wavelength-selective polarization conversion elements require multiple optical components and a complex structure, including a wavelength-selective phase plate, which increases the number of components and complicates the system.
Innovation Solution
A wavelength-selective polarization conversion element that incorporates a polarization beam splitting film and a phase plate, where the transmittance for P-polarized and S-polarized light is selectively changed between 50% and below 50% depending on wavelength regions, allowing for the conversion of non-polarized light into polarized light with specific polarization directions for different wavelength regions without the need for additional phase plates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional wavelength-selective polarization conversion element is used, then polarization conversion for different wavelength regions is achieved, but the number of optical components increases and the structure becomes complex
Solution Approach 1:
The patent combines the wavelength-selective phase plate and polarization conversion element into a single integrated element. The polarization conversion element includes a first polarization beam splitting film, a second polarization beam splitting film, and a phase plate, where the phase plate is positioned between the two polarization beam splitting films. This integration merges multiple optical functions (wavelength selection and polarization conversion) into one component, reducing the total number of optical components while maintaining the capability to convert polarization directions for different wavelength regions.
2Manufacturing precision
If a wavelength-selective phase plate is added, then polarization direction control for different wavelengths is improved, but the number of supporting and cooling members increases
Solution Approach 1:
The phase plate is integrated within the polarization conversion element rather than being a separate component. Specifically, the phase plate is positioned between the first and second polarization beam splitting films, forming a unified structure. This integration eliminates the need for separate supporting members that would be required for a standalone phase plate, thereby reducing structural complexity while maintaining precise polarization direction control for different wavelengths.
3Adaptability or versatility
If multiple optical components are used, then optical function is improved, but alignment and positioning difficulty increases
Solution Approach 1:
The patent integrates multiple optical components (first polarization beam splitting film, second polarization beam splitting film, and phase plate) into a single polarization conversion element. This merging reduces the number of separate components that require alignment, thereby simplifying the alignment and positioning process while maintaining the complex optical functions of wavelength-selective polarization conversion.
Solution Approach 2:
The polarization conversion element is designed with distinct functional layers (first polarization beam splitting film, phase plate, second polarization beam splitting film) that are segmented and positioned in a specific sequence. This segmentation allows each layer to perform its specific function while being integrated into a single element, making the overall alignment process more manageable compared to aligning multiple separate components.
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 solution reduces the number of optical components and simplifies the structure by enabling polarization conversion within a single element, allowing light in two wavelength regions to have different polarization directions, thus eliminating the need for a conventional wavelength-selective phase plate and its supporting and cooling members.
Implementation Method 1
a polarization beam splitting film which has a function of splitting light through transmission and reflection and has a characteristic in which each of the transmittance for light with a first polarization direction and the transmittance for light with a second polarization direction orthogonal to the first polarization direction is changed between a value higher than 50% and a value lower than 50% depending on the wavelength region
Implementation Method 2
a phase plate which changes the polarization direction of light transmitted or reflected by the polarization beam splitting film between the first polarization direction and the second polarization direction
Data Source
AI summary
A wavelength-selective polarization conversion element is disclosed which has a polarization conversion function that has been obtained by a polarization conversion element and a wavelength-selective phase plate in the past. The element includes a polarization beam splitting film and a phase plate. The film splits light and has a characteristic in which the transmittance for light with a first polarization direction and the transmittance for light with a second polarization direction are changed between a value higher than 50% and a value lower than 50% depending on wavelength region. The phase plate changes the polarization direction of light transmitted or reflected by the film between the first and second polarization directions. The element converts light in two of the first to third wavelength regions into polarized light with one polarization direction and converts light in the other wavelength region into polarized light with another polarization direction.