Dual Beam Interferometer Surface Profile Measurement
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Solution Overview
Problem
Existing surface profile measurement techniques using white light interference struggle with non-uniform interference effects due to tilt angles, limiting accurate measurement beyond a certain inclination angle, and fail to measure surface profiles with varying geometries or tilt angle distributions.
Innovation Solution
A dual beam interferometer configuration that dynamically adjusts the standard plane's orientation relative to the incident optical axis, allowing for the acquisition of interferograms at varying positions to calculate local surface orientations and measure surface profiles accurately across a wide tilt angle range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the standard plane's surface orientation is fixed without being configured to change with respect to the incident optical axis, then the device structure is simple, but the interference effect is attenuated when the surface orientation in the measured region changes, limiting measurement accuracy
Solution Approach 1:
The standard plane is configured with adjustable orientation relative to the incident optical axis, transforming from a static component to a dynamic one that can adapt to different measurement conditions. This allows the standard plane to be tilted at appropriate angles to maintain optimal interference effects when measuring surfaces with varying orientations, thereby resolving the contradiction between measurement precision and device complexity.
2Adaptability or versatility
If the standard plane is adjusted to match local surface orientations, then the interference effect is maximized and measurement range is extended, but the device complexity increases
Solution Approach 1:
The standard plane is designed with adjustable orientation capability, allowing it to dynamically adapt to different tilt angles during measurement. This dynamic configuration enables the system to measure surfaces with varying orientations while maintaining high interference contrast, thereby extending the tilt angle dynamic range without requiring overly complex additional mechanisms.
3Measurement precision
If the interference effect is maximized by adjusting the standard plane orientation, then measurement accuracy is improved, but the measurement process becomes more complex
Solution Approach 1:
The system automatically determines the appropriate tilt angle for the standard plane based on the measured surface characteristics, eliminating the need for manual adjustment by the operator. This self-service approach maintains high measurement precision while simplifying the operation process, as the system autonomously optimizes the interference effect without requiring user intervention in the complex adjustment procedures.
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
Enables nondestructive, noncontact surface profile measurement with high accuracy and wide tilt angle dynamic range, effectively addressing limitations in existing methods by maximizing interference contrast and aligning optical paths for precise surface profiling.
Implementation Method 1
detecting, with a two-dimensional image sensor, an interference figure (an interferogram) obtained by causing reflected light from a micro region on a sample surface and reflected light from a standard plane incorporated in the dual beam interferometer to interfere with each other
Data Source
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AI summary
To provide a technique that can measure a surface profile of any test object in a nondestructive manner and noncontact manner, highly accurately, and in a wide tilt angle dynamic range. In white light interference method using a dual beam interferometer, the technique is configured to be capable of changing a surface orientation of a standard plane with respect to an incident optical axis on the standard plane, acquires, while relatively changing the surface orientation of the standard plane with respect to a local surface orientation in any position on a test surface, a plurality of interferograms generated by interference of reflected light from the test surface and reflected light from the standard plane, and calculates the local surface orientation on the test surface from the interferograms to thereby measure a surface profile of the test surface.