The MFP-3D scanner uses a sensored, two-dimensional flexure to scan the sample in the X and Y axes (and a separate flexure to move the cantilever in the Z axis in the MFP-3D head). The use of separate position sensors allow real time correction of piezo behavior (usually referred to as closed loop operation), or used to simply measure the piezo motion with the sensor and make corrections after the measurement is completed.
This design has definite advantages over tube scanners. One problem with tube scanners is cross coupling where motion along one direction causes unwanted motion in other directions. Because the tube scanner relies on bending motion of the tube, as the sample moves along the X direction, it also moves along the Z axis. This parasitic motion can cause a distortion of the apparent sample shape. For lateral motion, (for example, unwanted motion in Y while scanning in X), cross coupling can distort the shape and dimensions of features on the sample surface. Flexure-based devices provide a means of reducing or even eliminating unwanted parasitic motion. They can also be designed with a high degree of orthogonality, allowing undistorted, orthogonal imaging of features.
In addition, our patent-pending NPS LVDT sensor is the most quiet in the industry. 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, <0.6 nm Adev in X and Y, in a 10 second measurement, and in a 1kHz bandwidth.
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