• Light microscopes were first developed in the 
  1500s. 
  • One of the earliest inventors of 
  microscopes was the Dutch lens grinder 
  Anton van Leeuwenhoek. “Father of 
  Microscopy”
  • His microscopes were mostly single lens 
  magnifiers with a place to attach a specimen. 
  He is credited with producing over 250 
  different microscopes.
  • The first compound light microscope was 
   designed by the Jansens in 1590,  even 
   before van Leeuwenhoek.
  • The compound light microscope design 
   allowed biologists to view specimens 
   through a series of two lenses.  This gives 
   a greater  amount of magnification. The 
   total magnification possible is a product of 
   the two lenses used.
      Electron Microscopes:
     Light microscopes can only produce sharp 
   images of objects when the objects are larger 
   than 0.2 micrometers (2 ten thousandths of a 
   millimeter), or about 1/50th of the diameter of the 
   typical cell.
     Electron microscopes focuses a 
   beam of electrons on specimens, and 
   can form images 1000 times smaller 
   than those visible under the light 
   microscope.
   How can Electron microscopes see 
    much smaller objects than light?
  • Light wave lengths are too large for some very 
   tiny objects and do not reflect from them.
  • Electron beams have much                                  
          smaller wavelengths and can                        
                        reflect back from the smaller           
                        objects. (Images cannot be             
                               viewed directly as with light 
   microscopes.)