Scanning Probe Microscope Feedback Deviation Data Selection
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Solution Overview
Problem
Scanning probe microscopes face challenges in obtaining accurate sample surface images due to tracking delays and disturbances during feedback control, especially when steep changes in surface elevation occur, leading to inaccurate image data selection in existing data processing techniques.
Innovation Solution
A scanning probe microscope that includes a data obtaining unit for forward and reverse scanning, a reference information obtaining unit for deviation and physical property signal values, and an image data selection processing unit to compare and select the more accurate image data based on reference information, minimizing the influence of tracking delays and disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reciprocal scanning is performed to collect image data in both forward and reverse directions, then the reliability of image data is improved by having multiple data sources, but the complexity of data processing increases due to the need to select between trace and retrace image data
Solution Approach 1:
The patent applies feedback control by using the deviation signal from the feedback control system as a criterion for selecting between trace and retrace image data. The selection is based on which scan direction maintains better feedback control (smaller deviation), thereby automatically selecting the more reliable image data while simplifying the processing logic.
Solution Approach 2:
The patent replaces complex mechanical judgment methods with a signal-based selection mechanism. Instead of using complex algorithms or manual intervention to determine which image data is more accurate, the system uses the deviation signal from the feedback control system to automatically select the appropriate image data, simplifying the processing complexity.
2Measurement precision
If feedback control is used to maintain constant interaction between probe and sample, then measurement precision is improved, but tracking delay occurs when steep changes in surface elevation are present
Solution Approach 1:
The patent performs preliminary scanning in both forward and reverse directions to collect image data before selecting the final image. This allows the system to have backup data from the opposite scan direction that may not be affected by tracking delays, ensuring accurate surface shape measurement even when one scan experiences delays.
Solution Approach 2:
The patent changes the selection criterion from simply averaging trace and retrace data to selecting based on the deviation parameter from feedback control. By monitoring the deviation parameter, the system can identify which scan direction experienced less tracking delay and select that data, thereby maintaining measurement precision.
3Ease of manufacture
If simple averaging of trace and retrace image data is used, then data processing is simplified, but the accuracy decreases when tracking delay occurs in one direction
Solution Approach 1:
The patent uses feedback control deviation as a selection criterion to determine which image data (trace or retrace) is more accurate. This maintains processing simplicity by using a clear decision rule based on feedback signals, while improving accuracy by selecting the data from the scan direction that experienced less tracking delay.
Solution Approach 2:
The patent performs excessive scanning by collecting both trace and retrace image data, then selectively uses only the more accurate portion based on feedback deviation. This partial use of collected data ensures high accuracy while maintaining processing efficiency by discarding the less accurate scan direction.
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 the creation of highly precise sample surface shape images by selecting the most reliable image data, reducing the impact of tracking delays and disturbances, and providing a more accurate representation of the sample surface shape.
Implementation Method 1
an interatomic force is measured as the interaction that acts between the probe and the sample surface
Implementation Method 2
the scanner is subjected to feedback control so as to finely move the sample in the Z-axis direction so that the spacing may be kept constant
Implementation Method 3
the cantilever brought close to the sample surface is vibrated at a frequency around its resonance point
Data Source
AI summary
When trace image data is obtained while a probe is used to scan a region on a sample in a forward direction and retrace image data is obtained while the same region is scanned in the reverse direction, a deviation information storage unit stores deviation detected by a deviation detection unit. This deviation is an indication of the difference between the distance between the probe and the sample and a target value for the distance at a given point in time. An image data selection unit compares the deviation during forward scanning and the deviation during reverse scanning for each measurement point, selects the image data obtained during scanning that has the smaller deviation, and stores the same to a storage region of an image data storage unit as selected image data.