Instrument: Scanning Electron Microscope
A scanning electron microscope (SEM) scans a focused electron beam over a surface to create an image. The electrons in the beam interact with the sample, producing various signals that can be used to obtain information about the surface topography and composition.
Scanning electron microscopy (SEM) of the filters was done on a Zeiss 1550 VP Field Emission Scanning Electron Microscope at the GPS Division Analytical Facility at Caltech.