Optical Measuring Head for Surface Topography
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Solution Overview
Problem
Existing optical measurement systems for surface topography are limited by the need for considerable space due to separately arranged optical components and fail to account for systematic measurement errors and long-term changes, leading to unreliable data, especially in the nanometer range.
Innovation Solution
An optical measuring process using a measuring device with a measuring head that employs chromatic confocal or spectral interferometric OCT techniques, where spectrally broadband light is used to form measurement spots on the object, and reflection spectra are digitized to correct for time variations and deviations, allowing for precise determination of surface topography in the nanometer range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical components are arranged separately to perform surface topography measurement, then measurement capability is achieved, but the device occupies considerable space
Solution Approach 1:
The patent combines multiple optical components (light source, beam splitter, reference face, detector) into an integrated optical measuring system where components are closely arranged rather than separately positioned. The beam path is optimized to allow compact configuration while maintaining measurement functionality, thereby reducing the overall device footprint.
2Productivity
If conventional optical measurement systems are used, then basic measurement is possible, but systematic measurement errors and long-term changes are not accounted for, leading to unreliable data
Solution Approach 1:
The patent implements a feedback mechanism where the measured surface topography data is used to calculate and apply correction values that compensate for systematic measurement errors and long-term drift. The system continuously monitors measurement deviations and adjusts subsequent measurements based on previously identified error patterns, thereby maintaining high reliability over time.
Solution Approach 2:
The patent performs preliminary calibration measurements to establish baseline error characteristics before actual surface topography measurements are taken. Correction factors are pre-calculated based on these initial measurements, allowing the system to compensate for systematic errors proactively rather than reactively.
3Device complexity
If measurement systems do not correct for time variations and systematic errors, then measurement process is simpler, but measurement accuracy in the nanometer range deteriorates
Solution Approach 1:
The patent changes the temporal parameter of measurement by performing multiple measurements at different time points and using these variations to separate real surface topography from systematic errors. By analyzing measurements taken under varying conditions, the system can identify and eliminate time-dependent error components while preserving genuine surface features.
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 accurate separation of real surface topography from measurement errors, providing reliable data with enhanced precision and resolution in the nanometer range by correcting for systematic errors and deviations, thus improving measurement accuracy.
Implementation Method 1
a measuring head (4) in a measuring head guide arrangement (5) for chromatic confocal measurement of the surface topography (1) or for spectral interferometric OCT measurement of a distance between the measuring head optic (10) and the measurement object surface (16)
Implementation Method 2
a measuring head (4) in a measuring head guide arrangement (5) for chromatic confocal measurement of the surface topography (1) or for spectral interferometric OCT measurement of a distance between the measuring head optic (10) and the measurement object surface (16)
Implementation Method 3
broadband light from a light source is directed onto a measurement object (2) via a common measuring head optic (10) with formation of a spot array (11) of measurement spots (12-15)
Implementation Method 4
the reflected light or the three partial beams of the light reflected by the surface are directed together with a second part of the measuring light towards a spatially resolving detector
Data Source
AI summary
The invention relates to an optical measuring process for acquiring a surface topography of a measurement object. To this end, a measuring device with a measuring head in a measuring head guide device is provided for chromatic confocal acquisition of the surface topography or for spectral interferometric OCT acquisition of the distance to the surface topography. Firstly, spectrally broadband light of a light source from a fibre array with i fibres of i measurement spots is directed onto the measurement object via a common measuring head optic, with formation of a spot array of i measurement spots. i reflection spectra of the i measurement channels are then acquired and digitized. Finally, the digitized reflection spectra are evaluated with removal of time variations of systematic measurement errors and time-related deviation movements of the measuring head guide device.