Reflective Diffraction Grating for EUV Beam Separation and Cooling
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Solution Overview
Problem
Existing EUV excitation light sources face challenges in efficiently separating and superimposing laser pulses due to the use of transmissive optical elements, which limit cooling efficiency, increase fabrication costs, and are prone to damage at high laser powers.
Innovation Solution
Employing a reflective diffraction grating to separate and superimpose laser pulses, allowing for effective cooling and reduced fabrication costs, while maintaining high laser power capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If transmissive optical elements are used to separate and superimpose laser pulses, then the device can be compact, but cooling efficiency is limited and the elements are prone to damage at high laser powers
Solution Approach 1:
The patent replaces transmissive optical elements with a reflective optical system comprising a reflective diffraction grating and reflective mirrors. This substitution eliminates the need for transmissive elements that are prone to damage, while the reflective components can be effectively cooled from the rear side, thereby improving reliability and damage resistance at high laser powers.
2Device complexity
If transmissive optical elements are used for beam separation, then the system can be integrated, but fabrication costs increase and cooling efficiency is reduced
Solution Approach 1:
The patent substitutes transmissive optical elements with a reflective diffraction grating system. The reflective grating can be manufactured on standard substrates and cooled from the rear side, significantly reducing fabrication costs compared to transmissive elements that require expensive specialized materials and cooling arrangements.
Solution Approach 2:
Instead of using transmissive elements where light passes through the optical component, the patent inverts the approach by using reflective elements where light bounces off the surface. This allows cooling to be applied from the rear side of the components, dramatically improving cooling efficiency.
3Device complexity
If the same focusing optical unit is used for both laser pulses, then the system is simplified, but the pulses must superimpose at or near the focusing unit which complicates beam path management
Solution Approach 1:
The patent uses a reflective diffraction grating to separate the two laser pulses into different spatial paths after they are generated. This allows each pulse to be focused at different locations using the same focusing optical unit without the pulses needing to superimpose at or near the focusing unit, simplifying beam path management while maintaining system simplicity.
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 reflective diffraction grating system enables efficient separation and superimposition of laser pulses, enhancing cooling efficiency, reducing costs, and extending the lifetime of the EUV excitation light source.
Implementation Method 1
The separating optical element includes a first reflective diffraction grating
Implementation Method 2
The separating optical element includes a first reflective diffraction grating
Data Source
AI summary
An EUV excitation light source includes a laser source configured to emit a laser beam. The laser beam includes two partial beams having different wavelengths. The EUV excitation light source further includes a separating optical element for separating the two partial beams of the laser beam into two separated beams, and a superposition unit for superimposing the two separated beams at a predefined superposition location with a predefined superposition angle. The separating optical element includes a first reflective diffraction grating.