Image A: ET Detection

Image 'A' was obtained by scanning a chromate plated surface using the Everhart and Thornley (ET) detector. ET detection is the most common mode used in conventional SEM. The ET detector generates a signal that has a significant secondary electron component (electrons w/ energy < 50eV) and gives topographical information of the material very close to the surface. Edges are often so bright that information at the edges can be lost. Image 'B' was obtained using the ET detector biased to accept only backscattered electrons (high energy electrons). This mode is referred to as the ET-BSE mode and is analogous to images with only directional lighting, such as lunar images. Image 'B' was obtained from the exact area as Image 'A'. These two images are quite different and can be difficult to reconcile. Image 'A' clearly shows the "mud cracking" at the surface; whereas Image 'B' reveals the subtle micro-roughness at the surface.

Image B: ET-BSE Detection

Image C: ET Detection

Image 'C' was obtained by scanning a tin/lead plated surface using the Everhart and Thornley (ET) detector. This image show the topography of the "as plated" grain structure. Image 'D' was obtained from the exact area as Image 'C' using a solid state backscattered electron detector (SS-BSE). Images generated with a SS-BSE detector give atomic number contrast of materials within approximately one micron of the surface. Image 'D' reveals the location of the tin rich regions vs. the lead rich regions.

Image D: SS-BSE