Introduction of Secondary low vacuum detector in the Scanning Electron Microscope

The difficulties and limitations of imaging with scanning electron microscopy in high vacuum with some samples lead to manufacturing Environmental Scanning Electron Microscope (ESEM) or special detectors with the ability to work in low vacuum conditions. The vacuum rate inside the chamber in high vacuum SEMs, is approximately [10-3] Pa. The imaging in this condition could be done with appropriate quality. But despite of sputtering thick layer of golden coat, in some nonconductive specimens like Hydroxyapatite and porous Nano Silica, charging effect commonly occurs because of the porosity of the material. Some samples like organic wastes, pastes, binders (like oils), lubricants and other additives may be evaporated in high vacuum and imaging process will get into trouble. Also low vacuum usually is applied for biological samples and scaffolds due to their deformation in high vacuum.