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Started section regarding tip status
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===Height Accuracy===
===Height Accuracy===
Heigh accuracy estimations in AFM measurements are complex and depends on the scale you are interested in. At sub nanometer scale or a few nanometers the height measurement may be affected by the properties of the cantilever tip, your sample material stiffness and the scanning force. These parameters are less important when measuring in the 100 nm range and above. At all scales calibration of the Z-piezo is important.  
Height accuracy estimations in AFM measurements are complex and depends on the scale you are interested in. At sub nanometer scale or a few nanometers the height measurement may be affected by the properties of the cantilever tip, your sample material stiffness and the scanning force. These parameters are less important when measuring in the 100 nm range and above. At all scales calibration of the Z-piezo is important.  


Here at DTU Nanolab we calibrate the Z-piezo with a certified sample that is approximately 200 nm in height. This sample height is given with an uncertainty that is calculated based on variation on the calibration sample and measurement uncertainties of the instrument used for certification. The uncertainty on the calibration sample is ≤ 1.5 nm. Following our QC procedure we accept an offset from the certified value of 2%. For a 200 nm sample this is 4 nm.  If we use the formula for combined uncertainties then the uncertainty is: 4.3 nm or 2.1%
Here at DTU Nanolab we calibrate the Z-piezo with a certified sample that is approximately 200 nm in height. This sample height is given with an uncertainty that is calculated based on variation on the calibration sample and measurement uncertainties of the instrument used for certification. The uncertainty on the calibration sample is ≤ 1.5 nm. Following our QC procedure we accept an offset from the certified value of 2%. For a 200 nm sample this is 4 nm.  If we use the formula for combined uncertainties then the uncertainty is: 4.3 nm or 2.1%
However when we check the value it is typically less then 1% off given a combined uncertainty of: 0.75%
However when we check the value it is typically less then 1% off given a combined uncertainty of: 0.75%
===Tip status===
''This section is written by Jesper Pan @DTU Nanolab
[[Image:section under construction.jpg|150px]]
When measuring a sample using an AFM, the resulting image is the convolution of the tip shape and sample shape.
As the tip is worn, it will become less sharp, thus the resulting image will look blurry.
This effect is especially visible when imaging samples with sharp/edged features, and drastically change roughness parameters like R<sub>max</sub>, R<sub>q</sub> and R<sub>a</sub>. Therefore it is important to be able to identify a worn tip.
{| class="wikitable"
|+ Caption text
|-
! !! SEM Image !! Worn Probe !! New probe
|-
! Image
| SEM Image of tip checker (WIP)
| [[File:AFMWornTip.jpg|300px|thumb|left|alt=Image taken using a worn probe|AFM image of the tip checker sample taken using a worn AFM probe]]
| [[File:AFMNewTip.jpg|300px|thumb|left|alt=Image taken using a new probe|AFM image of the tip checker sample taken using a worn AFM probe]]
|-
! Scan Parameters and
Roughness information
| Example
|
* Size: 1µm
* Scan Speed: 1Hz
* R<sub>q</sub>: 2.49 nm
* R<sub>a</sub>: 1.97 nm
* R<sub>max</sub>: 18.8 nm
|
* Size: 1µm
* Scan Speed: 1Hz
* R<sub>q</sub>: 10.5 nm
* R<sub>a</sub>: 8.45 nm
* R<sub>max</sub>: 78.3 nm
|-
! Comments
| Example
| Example
| Example
|}
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