The MFP-3D head uses a patent-pending, low noise, position sensitive detector (NPS™) to control the exact position of the cantilever. It corrects for piezo hysteresis and creep that are typical with commercial tube scanners.
The NPS uses a proprietary, low noise, inductive sensor that eliminates the Barkhausen noise that limits traditional inductive LVDT sensors. NPS noise figures are < 0.3 nm Adev in Z in a 10 second measurement, and in a 1kHz bandwidth.
In the most common type of detection (optical lever), a light source, typically a laser beam, is bounced off the back of the cantilever to a photodiode. The noise in this detector determines the smallest forces between the cantilever and sample that can be measured. The MFP-3D uses a low coherence light source that minimizes the optical interference.
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