As critical dimensions in magnetic data storage systems, e.g. hard disk drives, are continuing to shrink to a few tens of nanometers, the development of characterization techniques that may be used in manufacturing or research and development has become increasingly demanding. For example, optical and magneto-optical metrology methods do not provide the spatial resolution required to determine properties of the write-field emanating from the write pole on the nanometer length scale. Magnetic Force Microscopy, on the other hand, has high spatial resolution but does not provide quantitative information about the magnetic field strength. In addition, current magnetic recording heads include other features that are on the nanometer length scale that are desirable to characterize, but that cannot be adequately measured using conventional metrology systems. By way of example, some magnetic recording heads include features such as optical nano-apertures for heat assisted magnetic recording (HAMR), for which characterization of the optical power in the near-field of these nano-apertures is desired. Accordingly, improved metrology methods for characterizing, e.g., magnetic recording heads is desired.