Update many posts

content/article/holler12_instr_x_ray_nano_imagin.md

@@ -0,0 +1,42 @@
++++
+title = "An instrument for 3d x-ray nano-imaging"
+author = ["Thomas Dehaeze"]
+draft = false
++++
+
+Tags
+: [Nano Active Stabilization System]({{< relref "nano_active_stabilization_system" >}}), [Positioning Stations]({{< relref "positioning_stations" >}})
+
+Reference
+: <sup id="66ab0e7602a1dedda963d7da60533b0d"><a class="reference-link" href="#holler12_instr_x_ray_nano_imagin" title="Holler, Raabe, Diaz, Guizar-Sicairos, , Quitmann, Menzel \&amp; Bunk, An Instrument for 3d X-Ray Nano-Imaging, {Review of Scientific Instruments}, v(7), 073703 (2012).">(Holler {\it et al.}, 2012)</a></sup>
+
+Author(s)
+: Holler, M., Raabe, J., Diaz, A., Guizar-Sicairos, M., Quitmann, C., Menzel, A., & Bunk, O.
+
+Year
+: 2012
+
+Instrument similar to the NASS.
+Obtain position stability of 10nm (standard deviation).
+
+<a id="org16e51fb"></a>
+
+{{< figure src="/ox-hugo/holler12_station.png" caption="Figure 1: Schematic of the tomography setup" >}}
+
+-   **Limited resolution due to instrumentation**:
+    The resolution of ptychographic tomography remains above 100nm due to instabilities and drifts of the scanning systems.
+-   **Need of a Metrology System**:
+
+    > To achieve positioning accuracy and stability in the nanometer range, one cannot rely on the position encoders built into individual positioning stages.
+    > A precise exteroceptive measurement of the relative position of the optical elements with respect to the sample is mandatory.
+    > Thus, thermal drifts and parasitic motions can be measured and compensated for.
+-   **Interferometer System Concept**:
+    The sample is aligned with the X-ray with the XYZ piezo stage.
+    As a result, the metrology sphere will be usually off center with respect to the rotation axis of the spindle.
+    That implies that the laser will not propagate back to the interferometer at all rotation angles.
+    A position sensitive detector (PSD) is used, it provides a measurement of the position of the sphere in the plane perpendicular to the laser.
+    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.
+-   **Feedback Loop**: Using the signals from the 2 interferometers, the loop is closed to compensate low frequency vibrations and thermal drifts.
+
+# Bibliography
+<a class="bibtex-entry" id="holler12_instr_x_ray_nano_imagin">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</a> [↩](#66ab0e7602a1dedda963d7da60533b0d)