Expanding Optical Flows for KrF Laser Extraction
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Solution Overview
Problem
Current glass lasers used for inertial confinement fusion have low efficiency and high costs, limiting their commercial viability, and existing Krypton-Fluoride (KrF) lasers face issues with energy extraction efficiency due to medium absorption and amplified spontaneous emission (ASE), which restricts the optical fluence and increases the number of amplifiers required.
Innovation Solution
An optical configuration with expanding optical flows is implemented, optimizing the optical flux throughout a larger fraction of the pumped medium volume by using electron beam pumping and dividing the cross-section into elements of varying dimensions, allowing for efficient extraction and reducing ASE losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional glass lasers are used for inertial confinement fusion, then laser energy output can be achieved, but electrical efficiency is only 0.1% and cost is $3,000/joule
Solution Approach 1:
The patent transitions from glass laser medium to KrF excimer laser medium, changing the fundamental physical and chemical parameters of the laser system. This parameter change enables electrical efficiency improvement from 0.1% to approximately 10% and reduces cost from $3,000/joule to a commercially viable level
2Productivity
If optical fluence is increased to improve extraction, then energy output increases, but medium absorption and ASE increase causing efficiency to fall off with extraction length
Solution Approach 1:
The patent divides the laser medium into multiple independently pumped segments or cells. Each segment has its own electron beam pumping region, allowing optimized extraction from each segment while preventing ASE buildup from propagating through the entire medium. This segmentation maintains high extraction efficiency even at longer total extraction lengths.
Solution Approach 2:
The patent extracts laser energy from the KrF medium at multiple points along its length rather than from a single location. By implementing distributed extraction points, the system reduces the optical fluence required at any single extraction point, thereby minimizing absorption and ASE losses while maintaining high overall energy extraction.
3Productivity
If extraction length is extended to increase energy output, then more energy can be extracted, but efficiency falls off due to absorption and ASE
Solution Approach 1:
The patent divides the laser medium into multiple independently pumped segments or cells. Each segment has its own electron beam pumping region, allowing optimized extraction from each segment while preventing ASE buildup from propagating through the entire medium. This segmentation maintains high extraction efficiency even at longer total extraction lengths.
Solution Approach 2:
The patent transitions from single-sided extraction to two-sided extraction geometry, where laser energy is extracted from both ends of the KrF medium simultaneously. This dimensional change effectively doubles the extraction efficiency for a given medium length, allowing high productivity to be achieved with shorter effective extraction paths.
4Productivity
If number of amplifiers is increased to compensate for efficiency losses, then total energy output can be maintained, but system cost and complexity increase
Solution Approach 1:
The patent divides the laser medium into multiple independently pumped segments or cells. Each segment has its own electron beam pumping region, allowing optimized extraction from each segment while preventing ASE buildup from propagating through the entire medium. This segmentation maintains high extraction efficiency even at longer total extraction lengths.
Solution Approach 2:
The patent combines multiple extraction beams from different segments of the KrF medium into a single integrated output. By merging the beams at an intermediate stage before final compression, the system achieves high total energy output with reduced complexity compared to using multiple separate amplifier systems.
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 approach significantly increases the overall stage gain, enables efficient extraction from a larger gain-length product, reduces the optical area required, and lowers the cost per unit energy, making the laser system more commercially viable.
Implementation Method 1
KrF lasers for the particular application entail a means of electron beam pumping of a gaseous medium that produces an amplification of an input beam
Implementation Method 2
amplification of an input beam
Implementation Method 3
too high an applied optical flux and the laser energy is absorbed locally by the other species
Data Source
AI summary
A set of optical elements for optical extraction composed of packed expanding optical cross sections to efficiently extract from a large gain region. The elements are rectangular shaped concave small expansion lenses matched to rectangular convex collimating lenses. Absorbing sheets divide an overall large volume up into smaller volumes to minimize losses due to amplified spontaneous emission. This arrangement has various applications, particularly in inertial confinement technology, where it may be used to extract energy from KrF laser media energized by electron beams. For certain applications, this regime of the gain medium may have zones at the absorbing sheets where this is no gain.