Bandwidth

The frequency range to which the amplitude of the stage’s motion is dropped by 3dB with a small input scanning signal. It reflects how well the stage can follow the driving signal for a particular frequency range.

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Backlash

The motion error produced by direction reversing of the motion. It is presented as a constant hysteresis over the range and is an inherent problem in conventional motion translation mechanisms such as screw/nut, gears, trains and bearings, etc. Normally it is related to machining tolerance, wear, contact stiffness, temperature and loads, etc. nPoint’s flexure motion […]

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Accuracy

Represents how close the actual position of a nanopositioner is to the theoretical position to which it is expected to move. It is affected (or determined) by linearity error, hysteresis, abbe error, scale factor error and positioning noise, etc.

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Abbe error

A positioning or measurement error caused by parasitic rotations when a misalignment exists between the measurement axis and the point of interest. By reducing either parasitic rotations or the offset of misalignment, or both, the abbe error can be minimized. The abbe error can be estimated as: δ = ι * α where δ is […]

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How does the step response specification relate to scanning speed?

A nanopositioner with a high resonant frequency will have a fast step response specification. A nanopositioner with a fast step response specification allows the user to increase the bandwidth of the control loop. A high bandwidth control loop reduces phase delay, which in turn allows the user to scan at an increased rate. Phase delay […]

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What does bandwidth mean?

Bandwidth is the frequency at which the actual oscillation amplitude is attenuated by -3dB from the commanded oscillation amplitude. This is approximately equal to the frequency at which the actual oscillation amplitude attenuates by 30% from the commanded oscillation amplitude. The bandwidth has to be tested with small driving signal, which guarantees that the attenuation […]

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