CTE Measurement Using Interference Order Verification
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Solution Overview
Problem
Existing CTE measuring devices face challenges in achieving accurate measurements due to incorrect determination of the order of interference, which can lead to errors in calculating the coefficient of thermal expansion, especially when using single-wavelength light sources and requiring multiple light sources for increased accuracy, resulting in higher costs and maintenance needs.
Innovation Solution
A CTE measuring device and method that generate verification data by varying the order of interference within a predetermined range, selecting suitable data sets based on evaluation index values from multiple approximation functions, and determining the applicability of these data sets to ensure accurate CTE calculation, even with a single-wavelength optical interferometer, thereby reducing costs and maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-wavelength light source is used in the optical interferometer, then the device complexity and cost are reduced, but the measurement precision deteriorates due to incorrect determination of the order of interference
Solution Approach 1:
The patent applies preliminary action by performing preliminary measurement to obtain a preliminary value of the dimension before the actual measurement. This preliminary value is used to estimate the order of interference, which is then used in the main measurement process. By preparing the order of interference estimate in advance, the system can use a single-wavelength light source without suffering from incorrect order determination, thus resolving the contradiction between device simplicity and measurement precision.
2Measurement precision
If multiple light sources with different wavelengths are used to expand the acceptable range of preliminary values, then the measurement precision improves, but the device complexity and maintenance requirements increase
Solution Approach 1:
The patent applies parameter changes by varying the order of interference within a predetermined range to generate multiple pieces of verification data, rather than changing the wavelength of light. This approach allows the system to expand the acceptable range of preliminary values and improve measurement precision while maintaining the use of a single-wavelength light source, thereby avoiding the increased device complexity and maintenance requirements that would result from using multiple light sources.
3Ease of operation
If the order of interference is incorrectly determined from the preliminary value, then the measurement process remains simple, but the measurement precision deteriorates due to offset errors in integral multiples of half wavelength
Solution Approach 1:
The patent applies feedback by generating verification data with different orders of interference and comparing the measurement results to select the most appropriate order. The system calculates measurement results for multiple possible orders of interference and uses evaluation criteria to determine which order produces the most consistent and reliable results. This feedback mechanism corrects potential errors in the initially estimated order of interference while maintaining operational simplicity.
4Measurement precision
If verification data is generated by varying the order of interference and multiple data sets are created, then the measurement precision improves through selective validation, but the processing complexity increases
Solution Approach 1:
The patent applies partial action by generating multiple pieces of verification data with different orders of interference, but not exhaustively testing all possible orders. Instead, the system varies the order within a predetermined reasonable range and selects the most appropriate data set based on evaluation criteria. This approach achieves sufficient measurement precision without the excessive processing complexity that would result from exhaustively analyzing all possible orders of interference.
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 enhances the accuracy and reliability of CTE measurements by selecting the most suitable data sets, correcting errors in interference order determination, and reducing the need for multiple light sources, resulting in cost-effective and stable CTE measurement without the necessity of complex measurement conditions or additional device components.
Implementation Method 1
an optical interferometer configured to measure a length of the object using single-wavelength light
Implementation Method 2
the thermal expansion ΔL can be measured... using an optical interferometer... the length of the object is calculated by the following formula (2)... N represents an order of interference
Data Source
AI summary
A coefficient-of-thermal-expansion measuring device includes temperature control device, optical interferometer, and control device including: an actual data acquiring unit sequentially changing an object's temperature and acquiring actual data measured by the optical interferometer at each temperature; a data set generating unit generating pieces of verification data by setting an order of interference of the actual data within a predetermined range, selecting one piece of verification data at each temperature, and generating data sets each containing the selected piece of verification data at each temperature; and a judging unit deriving approximation functions with different orders from each data set, determining an evaluation index value based on differences of verification data from each approximation function, selecting a candidate data set with the smallest evaluation index value for each approximation function, and determining whether the candidate data set is the same for each approximation function to judge applicability of the candidate data set.