Excimer Laser Gas Temperature Control for Optical Element Lifespan
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Solution Overview
Problem
The spectral linewidths of KrF and ArF excimer laser apparatuses are wide, leading to chromatic aberration and degraded resolving power, necessitating a line narrowing module to reduce spectral linewidth, which can cause local degradation in optical elements due to refractive index changes from acoustic waves generated during discharge.
Innovation Solution
A gas laser apparatus with a laser chamber, discharge electrodes, and a processor that adjusts laser gas temperature based on the number of pulses or elapsed time to control the target temperature, minimizing refractive index fluctuations and extending the lifespan of optical elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a line narrowing module is added to narrow the spectral linewidth, then the chromatic aberration is reduced, but the optical elements experience local degradation due to refractive index changes from acoustic waves
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the laser gas temperature based on the number of pulses or elapsed time. This temperature control modifies the physical state of the laser gas, stabilizing the refractive index and reducing acoustic wave generation, thereby protecting optical elements while maintaining narrow spectral linewidth
Solution Approach 2:
The patent implements periodic action through dynamic temperature adjustment cycles. The processor periodically changes the target temperature based on pulse count or time intervals, creating a controlled thermal cycle that prevents cumulative damage to optical elements while maintaining laser performance
2Productivity
If the laser operates continuously for extended periods, then productivity is improved, but the optical elements degrade faster due to accumulated thermal effects
Solution Approach 1:
The patent applies dynamics by transitioning from static temperature control to dynamic temperature adjustment. The processor continuously modifies the target temperature based on real-time operating conditions (pulse count or elapsed time), enabling the system to adapt to thermal accumulation and extend optical element lifespan while maintaining continuous operation
Solution Approach 2:
The patent implements preliminary action by proactively adjusting the target temperature before significant thermal damage occurs. The processor predicts thermal accumulation based on pulse count or time and preemptively modifies temperature settings to prevent optical element degradation
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 dynamic temperature control stabilizes the beam profile, reducing local degradation in optical elements and enhancing the lifespan of these components.
Implementation Method 1
a discharge electrode that is disposed inside the laser chamber and is configured to cause discharge-excitation of laser gas
Implementation Method 2
a processor configured to change a target temperature of the laser gas based on either a number of pulses of the pulsed laser light or an elapsed time during which the pulsed laser light is output
Data Source
AI summary
A gas laser apparatus that outputs pulsed laser light includes a laser chamber that accommodates laser gas, a discharge electrode that is disposed inside the laser chamber and is configured to cause discharge-excitation of the laser gas, an optical element that is disposed on an optical path of the pulsed laser light, and a processor configured to change a target temperature of the laser gas based on either a number of pulses of the pulsed laser light or an elapsed time during which the pulsed laser light is output.