Wavelength Tunable Laser Precision Positioning System
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current industrial distance measurement systems using swept source interferometry face limitations in precision due to environmental noise, electronic noise, and processing techniques, which hinder the full potential of tunable lasers in achieving ultra-high precision distance measurements.
Innovation Solution
The system employs a method where a swept wavelength laser illuminates both reference and test cavities, with interference signals fitted to a physical model to determine optical frequencies, allowing for precise characterization of test cavity characteristics by minimizing optical frequency uncertainty through regression analysis and phase analysis across overlapping segments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard swept source interferometry is used, then distance measurement capability is achieved, but measurement precision is limited by environmental noise and electronic noise
Solution Approach 1:
The patent introduces reference cavities with known characteristics as intermediary elements between the swept source and test cavities. These reference cavities serve as mediators to establish accurate wavelength references, enabling the system to compensate for noise and drift effects. The reference cavities act as stable benchmarks that facilitate precise measurement by providing a known reference frame against which test cavity measurements can be compared.
Solution Approach 2:
The system implements feedback through regression analysis that continuously refines wavelength determination. By fitting interference signals to physical models and using the results to correct and improve subsequent measurements, the system creates a closed-loop feedback mechanism. This feedback process reduces the impact of environmental and electronic noise by constantly adjusting wavelength values based on observed interference patterns from reference cavities.
2Measurement precision
If wavelength tuning is performed to improve distance measurement accuracy, then optical frequency uncertainty increases due to laser drift and non-linear tuning
Solution Approach 1:
The patent applies preliminary action by measuring and characterizing reference cavities with known characteristics before using them to measure test cavities. This preliminary measurement step establishes accurate wavelength references that account for laser drift and non-linear tuning effects. By performing this calibration action first, the system compensates for frequency uncertainty before the actual measurement process begins.
Solution Approach 2:
The system changes parameters by transitioning from direct wavelength assumptions to model-based wavelength determination. Instead of relying on nominal laser wavelength values, the patent fits interference signals to physical models and extracts actual wavelength values through regression analysis. This parameter change from nominal to measured wavelengths significantly reduces optical frequency uncertainty.
3Measurement precision
If spectral domain techniques are used to collect signals from all sample depths, then sensitivity is improved, but system complexity increases
Solution Approach 1:
The patent applies universality by using the same swept source interferometry platform for multiple functions: wavelength referencing through reference cavities, distance measurement through test cavities, and sensitivity enhancement through spectral domain processing. The reference cavities serve multiple purposes including wavelength calibration, drift compensation, and providing reference interference signals for comparison. This multi-functionality reduces the need for separate specialized components.
Solution Approach 2:
The system segments the measurement process into distinct functional components: reference cavity measurements for wavelength determination, test cavity measurements for distance measurement, and separate processing stages for spectral analysis. This segmentation allows each component to be optimized independently while maintaining overall system sensitivity. The separation of reference and test measurements enables parallel processing that enhances sensitivity without proportionally increasing complexity.
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 enhances the accuracy of distance measurements, reducing uncertainty and improving precision beyond standard methods, making it suitable for high-performance applications like next-generation lithography systems.
Implementation Method 1
measuring interference signals from the test cavity and a reference cavity having a known characteristic
Data Source
Figure 1A
Figure 1B
Figure 2A~2B
AI summary
A method for determining characteristics of a test cavity, the method includes for each of a plurality of optical frequencies within a bandwidth of a tunable laser, measuring interference signals from the test cavity and a reference cavity having a known characteristic. The method includes determining values for the plurality of optical frequencies from the measured interference signals from the reference cavity and the known characteristic of the reference cavity, and determining the characteristic of the test cavity using the determined values of the plurality of optical frequencies.