Scanning Probe Deflection Subrange for Surface Finish Measurement
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Solution Overview
Problem
Existing scanning probes are not optimized for surface finish measurements, as stylus tip deflections during these scans are typically small, utilizing only a fraction of the transducer's range, leading to noise in the deflection signal and compromised measurement quality.
Innovation Solution
A scanning probe configured to generate digitized probe data over a selectable subrange of its transducible deflection range, allowing increased measurement resolution by focusing on the range relevant to the specific measurement task, with adjustable boundaries and transducer gain settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a scanning probe uses a transducer with a large transducable deflection range to measure form, then it can measure large deflections, but when measuring surface finish with small deflections, only a small part of the transducer range is utilized leading to noise in the deflection signal
Solution Approach 1:
The scanning probe system dynamically adjusts the transducer measurement range based on the measurement task. For surface finish measurements, the transducer range is reduced to match the smaller deflection magnitudes, thereby improving signal quality and reducing noise while maintaining the ability to perform form measurements when the full range is needed.
Solution Approach 2:
The system changes the operational parameters of the transducer by adjusting the measurement range according to the stylus type and measurement task. This parameter adjustment allows the same transducer to optimize its performance for both surface finish measurements (small deflections) and form measurements (large deflections) without sacrificing signal quality in either mode.
2Measurement precision
If a scanning probe is configured for surface finish measurements with small deflection ranges, then measurement resolution improves, but the ability to perform form measurements with larger deflections is compromised
Solution Approach 1:
The scanning probe is designed with multi-functionality to perform both surface finish measurements and form measurements. The system achieves this by configuring the transducer measurement range based on the attached stylus type and measurement task, allowing a single probe to optimize its performance for different measurement types without sacrificing adaptability.
Solution Approach 2:
The probe system dynamically reconfigures its measurement range based on the operational requirements. When performing surface finish measurements, it adopts a smaller measurement range for higher resolution, and when performing form measurements, it expands the measurement range to accommodate larger deflections, thereby maintaining versatility across different measurement types.
3Reliability
If the transducer measurement range is reduced to match small stylus tip deflections in surface finish scans, then signal noise is reduced, but the probe cannot accommodate larger deflections needed for form measurements
Solution Approach 1:
The system changes the transducer measurement range parameter based on the measurement task and stylus configuration. For surface finish measurements with small deflections, the measurement range is reduced to improve signal quality and reduce noise. For form measurements requiring larger deflections, the measurement range is expanded accordingly, maintaining both signal quality and measurement flexibility.
Solution Approach 2:
The transducer measurement range is dynamically adjusted to match the expected deflection magnitude for the current measurement task. This dynamic reconfiguration ensures optimal signal quality for surface finish measurements while preserving the capability to handle larger deflections during form measurements, thereby maintaining both reliability and adaptability.
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
Enhances measurement resolution and reduces noise by concentrating digitized data within a specific deflection range, optimizing the probe for both surface finish and form measurements without sacrificing the ability to perform broader range scans.
Implementation Method 1
one or more transducers for producing one or more transducer signals indicative of stylus holder deflection, the one or more transducers allowing measurement of stylus holder deflection relative to the probe body over a transducable deflection range
Data Source
Figure 1~2
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Figure 5~6
AI summary
A scanning probe (4; 302) for a coordinate positioning apparatus (1) is described. The scanning probe (4;320 ) comprises a probe body (10) and a stylus holder (11) for holding a stylus (12; 304), the stylus holder (11) being deflectable relative to the probe body (10). One or more transducers (600) are also provided for producing one or more transducer signals indicative of stylus holder deflection, the one or more transducers (600) allowing measurement of stylus holder deflection relative to the probe body over a transducable deflection range. One or more digitisers (606) are also provided to digitise the one or more transducer signals and generate therefrom digitised probe data that describes stylus holder deflection. The scanning probe (4;302) is configurable to generate the digitised probe data for a subrange of the transducable deflection range. A method of setting a subrange of a transducable deflection range is also outlined. In this manner, the scanning probe (4;302) may be used for form and surface finish measurements.