Scanning Probe Microscope Cantilever Force Curve Control
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Solution Overview
Problem
In conventional scanning probe microscopes, there is a noticeable difference between the target value and actual pressing amount of the cantilever when measuring a force curve, due to timing discrepancies in control movements.
Innovation Solution
A scanning probe microscope with a control device that adjusts the set value for the pressing amount based on differential data from previous measurements, ensuring the actual pressing amount aligns with the target value during force curve measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the control device starts moving the probe and sample apart when the detection value of pressing amount reaches a set value, then the force curve measurement can be performed, but there is a time difference between detection and actual movement start causing noticeable difference between target and actual pressing amount
Solution Approach 1:
The control device performs preliminary action by starting to move the probe and sample apart before the detection value of pressing amount actually reaches the set value. This anticipatory action compensates for the time difference between detection and actual movement, ensuring that the pressing amount reaches the target value accurately despite the finite response time of the system.
Solution Approach 2:
The control device uses feedback from the detection value of pressing amount to adjust the timing of movement. By continuously monitoring the detection value and comparing it with the set value, the control device dynamically adjusts when to start moving the probe and sample apart, thereby maintaining accurate pressing amount control throughout the force curve measurement process.
2Productivity
If the speed at which sample and cantilever are brought closer together is higher than reference speed, then measurement efficiency is improved, but time difference in control causes noticeable difference between target and actual pressing amount
Solution Approach 1:
The control device performs preliminary action by initiating the movement to move the probe and sample apart before the detection value reaches the set value. This is particularly important when the approach speed is high, as it compensates for the reduced time available for control response, thereby maintaining pressing amount accuracy even under high-speed measurement conditions.
Solution Approach 2:
The control device dynamically adjusts the timing and speed of movement based on real-time detection values. When the approach speed is high, the control device accelerates the retracting movement or adjusts the timing accordingly, making the system adaptive to varying measurement speeds while maintaining consistent pressing amount control precision.
Data Source
AI summary
The control device (100) controls the deflection amount (D2), which is the pressing amount, to a deflection amount (D1), which is a target value (DT), based on the set value (DS1, DS2) of the pressing amount when pressing the cantilever (12) against the sample (S) when measuring the force curve, and changing the set value (DS1) to the set value (DS2) based on the deflection amount (D3), which is differential data indicating the difference between the deflection amount (D1), which is the target value (DT), and the deflection amount (D), which is the actual pressing amount, in a previously performed force curve measurement when measuring the force curve.