Thomson Scattering Measurement System for EUV Plasma
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Solution Overview
Problem
Current Thomson scattering measurement systems face challenges in performing two-dimensional plasma measurements, leading to increased measurement time and reduced reliability, and struggle with stray light interference, particularly when measuring the ion term in plasma generated by EUV light generation systems.
Innovation Solution
The implementation of a Thomson scattering measurement system that includes a cylindrical lens optical system and a wavelength filter to divide and transfer Thomson scattering light into multiple slit light beams, allowing for simultaneous two-dimensional measurement and reducing stray light interference by filtering out specific wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional Thomson scattering measurement systems are used for two-dimensional plasma measurements, then measurement coverage is improved, but measurement time increases and reliability decreases
Solution Approach 1:
The plasma region is divided into multiple measurement regions along the laser propagation direction, with each region measured by a corresponding probe laser beam. Multiple probe laser beams are arranged parallel to each other, allowing simultaneous measurement of multiple spatial locations. This segmentation enables two-dimensional plasma measurements to be performed in parallel, significantly reducing measurement time while maintaining comprehensive spatial coverage.
2Measurement precision
If conventional measurement systems are used for ion term detection, then measurement capability is provided, but stray light interference reduces accuracy
Solution Approach 1:
A wavelength filter is introduced to extract and block stray light components from the collected scattering light. The filter selectively transmits the ion term signal wavelength while attenuating unwanted wavelengths, thereby separating the desired signal from interfering background light and improving measurement accuracy.
Solution Approach 2:
The wavelength filter acts as an intermediary component between the plasma region and the detector. It mediates the interaction by selectively transmitting specific wavelengths while blocking others, enabling accurate ion term detection in the presence of strong stray light from the plasma and laser system.
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 configuration enables faster and more reliable two-dimensional plasma measurements, improving the accuracy of ion term detection by reducing measurement time and minimizing stray light effects.
Implementation Method 1
Thomson scattering light generated by irradiation of a plasma region with a probe pulse laser beam
Implementation Method 2
a wavelength filter to divide and transfer Thomson scattering light into multiple slit light beams, allowing for simultaneous two-dimensional measurement and reducing stray light interference by filtering out specific wavelengths
Data Source
AI summary
A Thomson scattering measurement system according to the present disclosure includes: a transfer optical system provided on an optical path of a slit light beam group generated by division through a slit array and configured to transfer the slit light beam group to a plurality of transfer image groups separated from each other; and a second slit provided on an optical path of light from the transfer image groups and configured to selectively allow light from a plurality of transfer images positioned on a straight line extending in a direction corresponding to a first direction to pass through the second slit, the transfer images corresponding to slit light beams at positions different from each other in a second direction in the slit light beam group among transfer images included in the transfer image groups.