Laser Crystal Degradation Compensation via Site Shifting
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Solution Overview
Problem
Existing inspection systems for semiconductor materials face inefficiencies due to the time-consuming process of re-calibration and re-alignment required when shifting from a degraded laser source site to a fresh site, as the beam parameters significantly change, leading to system optimization and re-alignment challenges.
Innovation Solution
The method involves defining multiple sites on a frequency converting crystal, determining their degradation rates, and iteratively shifting among these sites for short intervals, with each site used continuously for a duration t, which is a fraction of the total time T before system optimization is needed, thereby reducing the need for frequent system optimizations and re-calibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the laser source is shifted to a fresh crystal site when degradation reaches end of life, then the laser source can continue operation, but system re-calibration and re-alignment become time-consuming
Solution Approach 1:
The crystal is divided into multiple discrete sites (first site, second site, third site, etc.) that can be independently utilized. By segmenting the crystal into multiple usable areas, the system can switch between sites without requiring complete re-calibration, as each site maintains similar optical characteristics. This segmentation allows the laser source to extend its operational lifetime by rotating through multiple sites while minimizing downtime for re-alignment.
2Duration of action of stationary object
If the laser source is shifted to a fresh crystal site, then continued operation is possible, but beam parameters change significantly requiring system optimization
Solution Approach 1:
Different regions (sites) of the crystal are characterized and selected based on their local optical properties. Sites are chosen that maintain consistent beam parameters (waist location, waist diameter, astigmatism, M-squared) to ensure uniform system performance. This local quality approach ensures that when switching between sites, the beam characteristics remain sufficiently similar to avoid complex re-optimization.
3Ease of operation
If a single crystal site is used continuously until end of life, then system operation is simple, but the laser source degrades to undesirable levels
Solution Approach 1:
The system implements periodic switching between crystal sites based on predetermined usage time intervals or degradation thresholds. Instead of using a single site continuously until failure, the system periodically rotates to the next site before significant degradation occurs. This periodic action maintains beam parameters within tolerable variations while extending overall system lifetime, balancing operational simplicity with reliability.
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 extends the lifetime of the laser source by minimizing system optimizations and re-calibrations, maintaining uniform system performance and maximizing utilization by reducing abrupt changes in beam parameters, thus avoiding major re-alignment requirements.
Implementation Method 1
a frequency converting crystal, configured for receiving a laser from the laser source and providing a frequency converted beam as output
Data Source
AI summary
Method and system for laser crystal degradation compensation are disclosed. The method includes: defining a plurality of sites on a frequency converting crystal; determining a degradation rate associated with each of the plurality of sites; determining an amount of time T wherein a site is continuously operable within a tolerated variation of at least one beam parameter, the amount of time T being determined based on the tolerated variation of the at least one beam parameter and the degradation rate; determining an amount of time t wherein t is a fraction of T; and iteratively shifting among the plurality of sites, wherein each of the plurality of sites is utilized continuously for a duration of time t for each iteration.