Saran's Learn Microbiology

 

 

  TRANSMISSION ELECTRON MICROSCOPE ·        The Transmission Electron Microscope (TEM) was the first type of Electron Microscope to be developed and is patterned exactly on the Light Transmission Microscope except that a focused beam of electrons is used instead of light to "see through" the specimen. ·        TEM was developed by Max Knoll and Ernst Ruska in Germany in 1931. Working Principle ·        Transmission Electron Microscope (TEM) requires vacuum system, consisting of pumps and their associated gauges and valves, and power supplies are required. ·        The Specimen (Sample) to be examined is made extremely thinner than those used in the Optical light microscope and Scanning Electron Microscope. Ultra-thin sections of 20 - 100 nm are cut which is already placed on the specimen holder. ·        In Transmission Electron Microscope (TEM), a finely focused beam of Electrons from an Electron gun passes to a specially prepared, Ultrathin section of the Specim

  SCANNING ELECTRON MICROSCOPE ·        The first Scanning Electron Microscope (SEM) debuted in 1942 with the first commercial instruments around 1965. Its late development was due to the electronics involved in "scanning" the beam of electrons across the sample. Working Principle ·        In Scanning Electron Microscopy (SEM), the Specimen (Sample) is coated with a thin film of a Heavy metal, typically Gold. ·        The Specimen (Sample) to be examined is made extremely thin, at least 200 times thinner than those used in the Optical light microscope. ·        In Scanning Electron Microscopy (SEM), an Electron gun produces a finely focused beam of Electrons called the Primary electron beam. ·        The Primary electron beam passes through the two Electromagnetic Condenser lenses (First Condenser Lens and Second Condenser Lens). ·        The First Electromagnetic Condenser lens largely determines the "spot

  ELECTRON MICROSCOPE ·        The Electron microscope was developed by Ernst Ruska and Max Knoll in 1931 and was in use in many laboratories by the early 1940s. ·        Objects smaller than about 0.2 µm, such as viruses or the internal structures of cells, must be examined with an Electron microscope. ·        Generally, Electron microscopes magnify objects 10,000× to 100,000×, though millions of times magnification with good resolution is possible.   ·        In Electron microscopy, a beam of electrons is used instead of light. Like light, free electrons travel in waves. ·        The Resolving power of the electron microscope is far greater than that of the other microscopes.   ·        Instead of using Glass lenses, an Electron microscope uses Electromagnetic lenses to focus a beam of electrons onto a Specimen. ·        Electron microscopes provide detailed views of the smallest bacteria, viruses, internal cellular structures, biopsy samples, metals, crystals, large m