43 lines
2.6 KiB
Markdown
43 lines
2.6 KiB
Markdown
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title = "An instrument for 3d x-ray nano-imaging"
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author = ["Thomas Dehaeze"]
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Tags
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: [Nano Active Stabilization System]({{< relref "nano_active_stabilization_system" >}}), [Positioning Stations]({{< relref "positioning_stations" >}})
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Reference
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: <sup id="66ab0e7602a1dedda963d7da60533b0d"><a href="#holler12_instr_x_ray_nano_imagin" title="Holler, Raabe, Diaz, Guizar-Sicairos, , Quitmann, Menzel \& Bunk, An Instrument for 3d X-Ray Nano-Imaging, {Review of Scientific Instruments}, v(7), 073703 (2012).">(Holler {\it et al.}, 2012)</a></sup>
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Author(s)
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: Holler, M., Raabe, J., Diaz, A., Guizar-Sicairos, M., Quitmann, C., Menzel, A., & Bunk, O.
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Year
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: 2012
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Instrument similar to the NASS.
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Obtain position stability of 10nm (standard deviation).
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<a id="orgba4a339"></a>
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{{< figure src="/ox-hugo/holler12_station.png" caption="Figure 1: Schematic of the tomography setup" >}}
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- **Limited resolution due to instrumentation**:
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The resolution of ptychographic tomography remains above 100nm due to instabilities and drifts of the scanning systems.
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- **Need of a Metrology System**:
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> To achieve positioning accuracy and stability in the nanometer range, one cannot rely on the position encoders built into individual positioning stages.
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> A precise exteroceptive measurement of the relative position of the optical elements with respect to the sample is mandatory.
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> Thus, thermal drifts and parasitic motions can be measured and compensated for.
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- **Interferometer System Concept**:
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The sample is aligned with the X-ray with the XYZ piezo stage.
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As a result, the metrology sphere will be usually off center with respect to the rotation axis of the spindle.
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That implies that the laser will not propagate back to the interferometer at all rotation angles.
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A position sensitive detector (PSD) is used, it provides a measurement of the position of the sphere in the plane perpendicular to the laser.
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The interferometer is positionned on top of a translation stage. The PSD information is used to close the loop so that the interferometer follows the displacement of the metrology sphere.
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- **Feedback Loop**: Using the signals from the 2 interferometers, the loop is closed to compensate low frequency vibrations and thermal drifts.
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# Bibliography
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<a id="holler12_instr_x_ray_nano_imagin"></a>Holler, M., Raabe, J., Diaz, A., Guizar-Sicairos, M., Quitmann, C., Menzel, A., & Bunk, O., *An instrument for 3d x-ray nano-imaging*, Review of Scientific Instruments, *83(7)*, 073703 (2012). http://dx.doi.org/10.1063/1.4737624 [↩](#66ab0e7602a1dedda963d7da60533b0d)
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