Do we need a planefit before doing analysis?

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John Thornton replied on Thu, Feb 2 2012 6:03 AM

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Hi Fenny

Determining whether to apply a planefit really depends on your sample and what you are trying to measure.  You mention both roughness and modulus values in your question.  When you refer to Modulus, if you are referring to the DMT Modulus channel in PeakForce QNM, then you would not want to apply a planefit.  The "Z" value of the DMT Modulus channel is your modulus value, and a planefilt will remove a Z offset from the entire image and change your values.  Also, be aware that the Offline Planefit parameter in the Realtime menu needs to be set to None.  If it is set to Offset or Full, the system will perform a 0th or 1st order planefit to the image, respectively, before it saves the image. 

For roughness studies, you may want to apply either a Flatten, which works on a line-by-line basis, or a planefit, which works on the image as a whole.  I will generally try to use the 0th or 1st order corrections unless I either have bow due to a large scan (as you mentioned), or I want to remove sample curvature to measure the "micro-roughness".  In those cases I will use a 2nd or 3rd order correction.  For roughness studies, you generally will want to be consistent with any modification routines if comparing between samples. 

Also, for planefit, you can apply the fit using part of the image for reference by drawing a box or boxes on the image.  This can be useful if you are trying to remove tilt on a step or on substrate (mica, glass slide, ...). 

I hope this helps.

John

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Fenny replied on Thu, Feb 2 2012 8:12 AM

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Got it. Thanks, John