Laser Beam Amplifier Optical Axis Stability
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Solution Overview
Problem
Conventional multipass amplification type laser beam amplifiers face challenges with optical axis stability, leading to inefficient energy utilization and unstable amplification due to slight shifts in the optical axis, which affects the position accuracy and focusing ability of the laser beam, particularly in EUV light source applications.
Innovation Solution
A laser beam amplifier design with a conjugate optical system where the amplification region is located between a first point and a second point, ensuring the laser beam passes through at least twice, maintaining optical axis stability and allowing for easy alignment by referencing these points, thereby suppressing errors and maintaining energy utilization efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a multipass amplification system is used to increase amplification efficiency, then the optical path length becomes very long (up to ten meters), but the optical axis stability deteriorates and amplification becomes unstable due to slight shifts in the optical axis
Solution Approach 1:
The optical path is segmented into multiple discrete reflection points between the amplification region endpoints. By defining specific first and second points and using mirrors to create a multipass configuration, the system achieves long optical path length while maintaining stability through controlled segmentation of the beam trajectory.
Solution Approach 2:
The optical system is pre-configured with mirrors positioned to reflect the laser beam between the first and second points, establishing a stable multipass path before amplification begins. This preliminary arrangement ensures that the optical axis remains stable throughout the amplification process.
2Productivity
If the optical path length is increased to improve amplification, then more passes through the amplification region are achieved, but the position accuracy and focusing ability deteriorate due to optical axis shifts
Solution Approach 1:
The optical path is divided into discrete segments with defined reflection points. By segmenting the beam path into controlled passes between the first and second points, the system maintains position accuracy at each reflection point while accumulating amplification over multiple segments.
Solution Approach 2:
The laser beam is reflected multiple times between mirrors to create multiple copies of the same optical path. Each reflection creates a copied trajectory that follows the same stable geometric path, ensuring consistent position accuracy across all passes through the amplification region.
3Productivity
If mirrors are used to create a multipass optical path, then amplification efficiency improves, but the device complexity increases and alignment becomes more difficult
Solution Approach 1:
The mirrors serve multiple functions: they redirect the laser beam to create the multipass path, define the optical axis, and establish the reflection points between the first and second points. This multi-functionality reduces the need for additional alignment components and simplifies the overall optical system.
Solution Approach 2:
The optical system is designed with mirrors positioned to create an equipotential optical path where each reflection point maintains equivalent optical conditions. This symmetry in the optical configuration simplifies alignment procedures and reduces the complexity of maintaining stable optical axes throughout the multipass amplification process.
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 provides stable optical axis alignment, improved amplification efficiency, and enhanced EUV light generation with high energy stability by ensuring the optical path remains consistent, even with slight shifts in the optical axis, facilitating accurate focusing and efficient energy transfer.
Implementation Method 1
an optical system for forming an optical path between a first point, upon which the laser beam is incident, and a second point, from which the laser beam is outputted, such that an amplification region for amplifying the laser beam is located in the optical path between the first point and the second point
Implementation Method 2
a discharging unit for exciting a CO2 laser gas containing carbon dioxide (CO2), nitrogen (N2), helium (He), and additionally, according to need, hydrogen (H2), carbon monoxide (CO), xenon (Xe), and so on by discharge
Implementation Method 3
The laser beam amplifier has a discharging unit for exciting a CO2 laser gas... The seed laser beam generated by the laser oscillator is amplified into a laser beam having desired energy
Implementation Method 4
The amplified laser beam is focused by a laser beam focusing optics and applied to a target material such as tin (Sn), xenon (Xe), or the like
Implementation Method 5
a laser beam amplifier for amplifying a seed laser beam... especially, the present invention relates to a driver laser apparatus for irradiating a target material with a laser beam to turn the target material into plasma
Implementation Method 6
irradiating a target material with a laser beam to turn the target material into plasma
Data Source
AI summary
A laser beam amplifier with high optical axis stability is provided. The laser beam amplifier includes: a container for accommodating a laser medium; a pair of electrodes for performing discharge in the laser medium to form an amplification region for a laser beam in the laser medium; and an optical system for forming an optical path between a first point, upon which the laser beam is incident, and a second point, from which the laser beam is outputted, such that the amplification region is located in the optical path between the first point and the second point, wherein the first point and the second point are conjugate to each other, and the laser beam incident upon the first point is amplified while passing through the amplification region at least twice and then transferred to the second point.