Flat Object Profile Measurement via Interferometry and Ellipsometry
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Solution Overview
Problem
Existing methods for measuring the surface profile of flat objects with unknown materials are inaccurate due to the influence of underlying material combinations and transparent layers, and often require destructive processes like metal coating.
Innovation Solution
A device combining optical interferometry and ellipsometry systems, with a beam splitter and analysis unit, allows for simultaneous measurement of surface profiles without destructive processes, using a single ellipsometry measurement to correct interferometry data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional optical measurement methods (deflectometry, white light interferometer, triangulation) are used to measure surface profiles, then measurement speed and area coverage are improved, but measurement precision deteriorates due to influence from underlying material combinations and transparent layers
Solution Approach 1:
The patent introduces an intermediary correction process using ellipsometry measurements to determine material properties (refractive index, layer thickness) that mediate between the optical measurement signal and the actual surface profile. This intermediary step allows correction of the raw interferometry data to eliminate distortions caused by transparent layers and material combinations, thereby resolving the contradiction between fast area measurement and accurate profile detection.
Solution Approach 2:
The patent implements a feedback mechanism where ellipsometry measurements provide corrective information that is fed back into the interferometry measurement process. The determined material properties from ellipsometry are used to calculate correction factors that are applied to the raw profile data, creating a closed-loop system that continuously compensates for material-induced measurement errors while maintaining high measurement speed.
2Measurement precision
If destructive metal coating is applied to eliminate material influence, then measurement precision is improved, but manufacturing complexity and process time increase
Solution Approach 1:
The patent replaces the mechanical/chemical process of metal coating with an optical measurement approach. Instead of physically modifying the surface with destructive coating processes, the invention uses optical interferometry combined with ellipsometry to non-destructively measure and correct for material effects, thereby achieving high measurement precision without increasing manufacturing complexity or requiring additional process steps.
Solution Approach 2:
The patent changes the measurement parameters by using multiple optical measurement techniques (interferometry for height, ellipsometry for material properties) instead of relying on a single modified surface approach. By measuring and correcting based on actual material parameters (refractive index, layer thickness) rather than assuming a standardized coated surface, the invention achieves accurate measurements without destructive preprocessing.
3Measurement precision
If ellipsometry measurement is used to correct interferometry data, then measurement precision is improved, but device complexity increases due to additional measurement systems
Solution Approach 1:
The patent merges two optical measurement systems (interferometry and ellipsometry) into a single integrated device that measures both surface height and material properties simultaneously or in sequence. By combining these systems and sharing common components (light source, optical paths, detectors), the invention achieves high measurement precision while minimizing the increase in device complexity through systematic integration rather than separate independent systems.
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 method provides accurate and non-destructive measurement of surface profiles on flat objects with unknown materials, correcting for material and layer effects, and enabling high-speed profiling without the need for explicit modeling of layer systems.
Implementation Method 1
splits a light beam from a light source into an interferometry light beam and an ellipsometry light beam
Implementation Method 2
optical interferometry measuring system... interferometric measurement... light beam... directed to a measurement region on the object surface
Implementation Method 3
ellipsometry measuring system... polarization state of the received sensor beam can be determined... ellipsometry sensor has a polarization filter
Data Source
AI summary
A method and device for measuring the profile of the surface of a flat object of unknown materials, including an interferometry measuring system, ellipsometry measuring system, beam splitter for splitting a light beam of a light source into an interferometry light beam and an ellipsometry light beam, and an analysis unit designed to ascertain the profile height in the measured region on the object surface from an analysis beam analyzed in a detector unit of the interferometry measuring system and a sensor beam received in an ellipsometry sensor. The interferometry measuring system includes a beam divider, reference mirror, and the detector unit, and the ellipsometry measuring system includes a polarizer for polarizing an ellipsometry light beam and transmitting same onto the measuring region on the object surface as well as the ellipsometry sensor, which includes a polarization filter in order to determine the polarization state of a received sensor beam.