Yes you can in principle but the problem is that you need to assume the very localised SEM measurement over no more than a um squared is reflective of the roughness everywhere else...- its not often the case because many features giving rise to surface roughness are themselves on the micron scale so you need to define what you want. There is an inherent challenge for nanoscience in developing nanoscale resolution over far field dimensions...

Beyond the requirement mentioned by J Canning, I imagine that one has to be exceptionally careful to fulfill other key requirements in instrument configuration, data capture, and data analysis in order to convert a two-dimensional SEM grayscale image to a pseudo-three-dimensional representation of surface heights, from which roughness would be calculated. I would wonder for example how one should "calibrate" the grayscale to a height metric from sample to sample.

Yes one has to always be exceptionally careful and calibrate against a known material sample for fixed energies and so on and reference against other methods. But then again given that I have rarely seen surface roughness estimates from many other techniques coincide from raw data alone particularly between short range methods such as AFM and SEM and long range etalon fringe methods, then the definition of surface roughness as a statistical function of length scale and acceptable resolution (even in the presence of possible localisation effects that can mislead figures) might on occasion be the bigger problem. 

There is a very practical method to make surface roughness measurement in SEM and that is to make stereographic imaging. It consist of taking 2 Images with different tilt angle which are then used to calculate a 3D image of the surface. This 3D image can then be used for any kind of surface analysis. An example of such 3D SEM imaging is the MeX-3D software from Aliconia. We tested it in comparison with a confocal laser microscope and found reasonable results.

As others have mentioned, yes, it is possible with SEM, but the easiest and more direct method would be to use AFM.

Don't agree. With SEM one can only obtain get gray scale image of some times crystalline structure - what depends not on the shape of surface directly, but of chemical composition what impact on less or more electron scattering/absorption. That is why the gray scale image does not represent roughness/height. White odes not mean always that something is high; darker does mean that we see kind of hole. For time to time I see some mathematical model (some kind of reconstruction) design to obtain 3d structure from data of same rotated and tilted sample. According to this all, better is AFM and light profilometry.

To get surface roughness, easiest way is perhaps use AFM or an optical profiler (see e.g. Bei et al. (2013) Optical Materials Express 3(9): 1285-1301 ). 

(white light or laser)- confocal scanning microscopy, including (optical interference) (e.g. leica, zeiss, olympus) and focus variation (e.g. alicona) are propobly easier and faster methodes.

Kirsten Ingolf Schiffmann Have you ever tried this Aliconia Mex to measure roughness at nano scale also?

Dear Hernando Siy Salapare III,

There is a very practical method to make surface roughness measurement in SEMand that is to make stereographic imaging. It consists of taking 2 Images with different tilt angle which are then used to calculate a 3D image of the surface. An example of such 3D SEM imaging is the MeX-3D software from Aliconia.

Surface roughness can be measured by three apparatus namely chromatic confocal microscopy (CCM) with scanning electron microscopy, atomic force microscopy (AFM) and focus-variation microscopy (FVM) to characterize surfaces of variable roughness after FSL cutting.

Compared to FVM and AFM, CCM is a relatively new technology for roughness characterization, and to our knowledge has not yet been used on corneal tissue. It appears a reliable alternative combining sufficient resolution, large field of observation, and acceptable acquisition time. Chromatic confocal microscopy may thus be recommended for the objective comparison of corneal cutting methods.

From the article reference given below-

The aspect of the stromal surface can be found to be similar with both SEM techniques, showing that the dehydration and metallization required for sSEM did not affect surface appearance. On the contrary, sSEM provided better contrast and thus better qualitative assessment. For this application, eSEM can thus not be recommended. We also showed with CCM that sample preparation did not cause roughness value bias. We strongly recommend dehydrated, metallized corneal samples, given their advantages over fresh specimens (storage, possibility of reexamination).

For detail, please look at this reference article given below.

https://www.osapublishing.org/DirectPDFAccess/EB72A43D-E57E-A9E0-3263A5DB881046E2_375182/boe-8-11-4974.pdf?da=1&id=375182&seq=0&mobile=no

In this above article, please go through Fig. 5 and 6 graph to understand the roughness is measured by CCM and comparison to FVM and AFM.

Hope it help you out.

Ashish

Not as carefully as done with AFM.

You can measure pore size and porosity using SEM spectrum. 3D topography image using AFM technique can be used for investigating nano-scale surface roughness. Generally, Profilometer is used to estimate the surface roughness in micro-scale though this method can not detect the nanopores and measure nano-scale surface roughness.

Nice discussion,

Dear Hernando Siy Salapare III

I second the thoughts shared by Gujie Qian , Ashish Thakur , Md Al-Amin

You may look in the below attached which uses SEM and AFM:

Article Silver-Soret Nanoparticles for Femtomolar Sensing of Glutath...

Article Metal-Free, Graphene Oxide-Based Tunable Soliton and Plasmon...