Electron Microscopes 
                                                  A whole new world to be seen 
                                                                                       
                                                                                       
                                                
                SEM of a plant preparation in cryo conditions, -180                            SEM image of a snowflake, color has been added. 
                degrees Celsius. 
                     What is an electron microscope? 
         Most microscopes you may have seen are light microscopes, 
         they use a lightbulb to illuminate the specimen. A light  
         microscope is limited to a resolution up to 3 micrometers 
         (magnification up to 1500X). After that, two objects close  
         together do not look separate. 
          
          
          In electron microscopy, high resolution images are the  
         result of using electrons as the source of illumination.  
         The resolution is about 0.01 nanometers (magnification  
         up to 300,000X). 
          
         There are two main types of electron microscopes (EM),  
         the scanning EM (SEM), and the transmission EM (TEM).  
                                                
      Scanning Electron Microscope(SEM) 
   The main parts to an SEM are: source 
   of electrons, a column for them to 
   travel with electromagnetic lenses, 
   an electron detector, sample chamber, 
   and a computer and display to view 
   the images. 
    
   A high energy beam of electrons is aimed at the sample. As they 
   interact with the sample, secondary electrons and X-rays are 
   produced. Those signals are collected by the detectors and an 
   image is formed on the computer screen. 
                 
                                                    The image to the below is an SEM of a 
                                                    tardigrade (color has been added). They are 
                                                    a water-dwelling, eight-legged micro-
                                                    animal. The “water bears” have been 
                                                    found everywhere, from mountains to 
                                                    mud volcanos. They are the most resilient 
                                                    known animals, they have even survived 
                                                    exposure to outer space. To the left is a 
                                                    light microscope image for comparison of 
                                                    the resolution. 
    The image above is an SEM of a hydrothermal worm. 
    This worm does not have a digestive tract, it can 
    absorb carbon compounds directly. 
       SEM of 3D Graphene on Nickel Foam