Multi-Wavelength Laser Device Using Blazed Grating for Speckle Noise Reduction
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Solution Overview
Problem
Conventional multi-wavelength laser devices with solid state laser media have narrow wavelength spectrum widths, leading to high coherency and strong interference, resulting in speckle noise in display devices, and their complex structures make it difficult to superpose lights with different wavelengths on the same axis.
Innovation Solution
A multi-wavelength laser device with a dispersing element, such as a diffraction grating, is used to change the traveling direction of laser lights based on wavelength, allowing them to be superposed on the same axis using a blazed grating and a wavelength conversion element with quasi-phase matching, enabling efficient wavelength conversion and reducing structural complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a solid state laser medium is used to generate fundamental wave laser light, then laser oscillation occurs at a specific fundamental wavelength, but the wavelength spectrum width becomes very narrow
Solution Approach 1:
The invention segments the wavelength spectrum by using multiple solid state laser media, each tuned to oscillate at different fundamental wavelengths. This allows the system to achieve both narrow linewidth (high coherence) at each wavelength and broad overall spectrum coverage by combining multiple segmented wavelength sources.
2Reliability
If fundamental wave laser lights with narrow wavelength spectrum are used, then high coherency is achieved, but strong interference occurs resulting in speckle noise
Solution Approach 1:
The invention segments the coherent laser light into multiple wavelength components, each maintaining high coherence individually. By superposing these segmented wavelength lights, the overall coherence is reduced while maintaining the benefits of coherent light sources, thereby suppressing speckle noise generation.
Solution Approach 2:
The invention changes the wavelength parameter by using multiple fundamental wavelengths and their corresponding second harmonic wavelengths. This parameter diversity allows the system to maintain high coherence at each wavelength while reducing overall coherence through wavelength diversity, suppressing speckle noise.
3Adaptability or versatility
If multiple wavelength conversion elements are used to generate different laser lights, then multiple colors are produced, but the device structure becomes complicated
Solution Approach 1:
The invention merges multiple wavelength conversion processes into a single integrated system. Multiple solid state laser media and their corresponding wavelength conversion elements are combined to generate multiple laser lights simultaneously, reducing structural complexity while maintaining multi-color generation capability.
Solution Approach 2:
The invention creates a universal laser device structure that can generate multiple wavelengths and colors through a standardized configuration of solid state laser media and wavelength conversion elements. This multi-functional design allows the same basic structure to produce various laser lights by simply changing the laser medium or conversion element.
4Adaptability or versatility
If lights with different wavelengths are to be superposed on the same axis, then multi-wavelength output is achieved, but alignment and structural complexity increase
Solution Approach 1:
The invention designs the optical paths and wavelength conversion elements such that all fundamental wave laser lights and their corresponding second harmonic lights are naturally superposed on the same axis. This equipotential design eliminates the need for complex alignment mechanisms, reducing structural complexity while achieving wavelength superposition.
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 device achieves efficient wavelength conversion with reduced light loss and improved coherency, allowing for effective superposition of multiple laser lights on the same axis with a simpler structure, thereby minimizing speckle noise and enhancing display performance.
Implementation Method 1
The semiconductor laser element generates a pumping light for the laser medium
Implementation Method 2
The generated pumping light is absorbed by the laser medium
Implementation Method 3
a gain for amplifying a fundamental wave laser light is generated in the laser medium
Implementation Method 4
a gain for amplifying a fundamental wave laser light is generated in the laser medium
Implementation Method 5
laser oscillation occurs at a fundamental wavelength in the laser medium and a fundamental wave laser light is emitted
Implementation Method 6
The fundamental wave laser light emitted from the laser medium is converted into a light which is a second harmonic wave through the wavelength conversion in the non-linear optical material
Data Source
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AI summary
It is an object of the present invention to provide a multi wavelength laser device that can provide a plurality of lights after wavelength conversion which are superposed on the same axis with a simple structure, and that can ease restrictions imposed on the lights which are superposed. The multi wavelength laser device includes a laser light source 10 that emits a plurality of laser lights 20 whose fundamental wavelengths differ from one another, a dispersing element 30 that changes the traveling direction of each of the plurality of laser lights emitted from the laser light source 10 according to the wavelength and the incidence direction, and that emits the laser lights in a state in which the laser lights are superposed on the same axis, and a wavelength conversion element 40 that has a polarization inverted region and a polarization non-inverted region which are formed periodically, and that performs wavelength conversion on the plurality of fundamental wave laser lights emitted from the dispersing element 30 and placed in the state in which the laser lights are superposed on the same axis, and emits a plurality of laser lights 50 acquired through the wavelength conversion in a state in which the laser lights are superposed on the same axis.