Integrated Interference Scanning Using Correction Factors
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Solution Overview
Problem
Conventional interference scanning methods require multiple light sources and complex switching mechanisms, leading to increased costs and reduced measurement efficiency due to limitations in precision and range, particularly when trying to merge data from Vertical Scanning Interferometry (VSI) and Phase Shifting Interferometry (PSI) measurements.
Innovation Solution
An integrated interference scanning method that utilizes a single wideband light source, employing slope and displacement correction factors to integrate VSI and PSI height data arrays, eliminating the need for a narrow-band light source and reducing system complexity and error.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single wideband light source is used for both VSI and PSI measurements, then system complexity and cost are reduced, but wavelength deviation and measurement precision deteriorate
Solution Approach 1:
The patent applies parameter changes by introducing correction factors (slope correction factor and displacement correction factor) that adjust the measured parameters based on the actual wavelength deviation. The slope correction factor corrects the inclination affected by slope-NA value, while the displacement correction factor corrects the height difference and intersection distance. This allows the system to use a single wideband light source while maintaining measurement precision through mathematical correction of the wavelength deviation effects.
2Productivity
If VSI and PSI measurements are merged without correction factors, then measurement efficiency is improved, but measurement accuracy deteriorates due to height inconsistency and inclination deviation
Solution Approach 1:
The patent implements feedback by using the measured data from VSI and PSI to calculate correction factors that are then applied back to the measurement process. The slope correction factor is derived from the inclination information, and the displacement correction factor is derived from the height difference information. These correction factors feed back into the data merging process, continuously improving the accuracy of the integrated measurement results while maintaining high measurement efficiency.
3Measurement precision
If conventional two-stage scanning is performed with both wideband and narrow-band light sources, then measurement precision is improved, but measurement time and system cost increase
Solution Approach 1:
The patent merges the VSI and PSI measurement processes into a single integrated scanning operation using one wideband light source. Instead of performing separate two-stage scanning with different light sources, the system collects interference signals during a single scan and processes them to extract both VSI height information and PSI phase information. This combining of operations reduces measurement time while maintaining precision through the application of correction factors.
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 enables more accurate and efficient measurements by correcting wavelength deviations and merging data from both methods using a single light source, achieving high precision and limitless measurement range while reducing system complexity and cost.
Implementation Method 1
the interferometry is utilized to obtain the surface profile of the object to be measured through the interference fringes by making use of the light path difference and interference principle
Data Source
AI summary
An integrated interference scanning method, mainly used to integrate the respective advantages of VSI and PSI measurements, hereby achieving the characteristic of high precision and limitless measurement range. In particular, the slope correction factor and the displacement correction factor between the VSI measurement and PSI measurement may be utilized to execute the integration calculation of the height data arrays of the VSI and PSI, so that the scanning procedure may be achieved through merely using the wideband light source of the interference scanning system, as such reducing the errors and complexity of the interference scanning system.