Light Source Apparatus Polarization Maintenance Illumination Efficiency
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Solution Overview
Problem
Existing light source apparatuses for image projection systems face efficiency issues due to the small Etendue of illumination optical systems, which leads to fluorescence saturation and reduced illumination efficiency when using polarization conversion elements to convert nonpolarized fluorescent light into linear polarization light.
Innovation Solution
A light source apparatus that includes a light emitting element, a polarization separation element, a wavelength conversion element, and a combination element to maintain polarization and combine different linear polarization lights, eliminating the need for polarization conversion elements and increasing the Etendue of the illumination optical system, thereby improving illumination efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a polarization conversion element is used to convert fluorescent light into linear polarization light, then the illumination light can be introduced into the light modulation element, but the Etendue becomes small and illumination efficiency lowers due to fluorescence saturation
Solution Approach 1:
Instead of converting nonpolarized fluorescent light into linear polarization light (conventional approach), the invention inverts the approach by using linear polarization light as excitation light from the beginning. The light source unit emits linear polarization light directly, which then excites the fluorescent body to produce fluorescent light that maintains linear polarization characteristics, eliminating the need for polarization conversion elements and their associated Etendue limitations.
Solution Approach 2:
The invention changes the polarization state parameter of the excitation light from nonpolarized or circular polarization to linear polarization. By controlling the light source to emit linear polarization light and adjusting its polarization direction to be parallel to the longitudinal direction of the fluorescent body, the system achieves high illumination efficiency while maintaining large Etendue, as the polarization state of the excitation light directly influences the polarization state of the emitted fluorescent light.
2Area of stationary object
If the spot diameter of the fluorescent body is reduced to match small Etendue, then the illumination optical system can be compact, but fluorescence saturation occurs and illumination efficiency decreases
Solution Approach 1:
The invention inverts the conventional relationship between spot size and efficiency. Instead of reducing spot size to match small Etendue from polarization conversion elements, the system uses linear polarization excitation light that produces fluorescent light with maintained linear polarization and high intensity. This allows the fluorescent body to have a larger spot diameter without causing fluorescence saturation, as the excitation mechanism is fundamentally changed from nonpolarized/circular to linear polarization.
3Productivity
If linear polarization light is used to excite the fluorescent body, then the fluorescent light maintains linear polarization state and high illumination efficiency is achieved, but the system requires precise alignment of polarization directions
Solution Approach 1:
The invention changes the polarization parameter of the excitation light to linear polarization and aligns its polarization direction parallel to the longitudinal direction of the fluorescent body. This parameter change ensures that the fluorescent light maintains linear polarization state with high intensity. The system achieves high illumination efficiency while the alignment requirement is simplified to a single directional parameter (parallel alignment) rather than more complex polarization state control.
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 enables the light source apparatus to emit linear polarization light with high illumination efficiency, reducing fluorescence saturation and maintaining efficiency even when the spot diameter of the excitation light is doubled, thus preventing deterioration in conversion efficiency.
Implementation Method 1
a light emitting element configured to emit light having a first wavelength band
Implementation Method 2
a polarization separation element configured to separate the light having the first wavelength band into a first linear polarization light and a second linear polarization light having polarization directions different from each other
Implementation Method 3
a wavelength conversion element configured to convert the first linear polarization light into a third linear polarization light having a wavelength band different from the first wavelength band
Data Source
AI summary
A light source apparatus includes a light emitting element configured to emit light having a first wavelength band, a polarization separation element configured to separate the light having the first wavelength band into a first linear polarization light and a second linear polarization light having polarization directions different from each other, a wavelength conversion element configured to convert the first linear polarization light into a third linear polarization light having a wavelength band different from the first wavelength band, and a combination element configured to combine the second linear polarization light and the third linear polarization light with each other. Light from the light source apparatus maintains a polarization state and illuminates a light modulation element via an illumination optical system.