Intro to microscopy

• Microscope


  One of the most recognizable symbols of science
• Development of the microscope

  1. Use of a simple lens in ancient times

  2. First compound microscope around 1590

  3. Microscopes used in 7th grade life science
• Purpose of a microscope

  To magnify or enlarge the image of tiny objects
• Magnification of microscopes used in 7th grade science

  40 times, 100 times, and 400 times the size of the object
• Type of microscope used in 7th grade science

  Compound light microscope
• Light microscope


  Uses light as a source of energy for viewing objects
• Compound microscope


  Contains two lenses for magnifying a specimen at the same time, the eyepiece (ocular) and one of the objective lenses
• Eyepiece


  • Also known as the ocular
  • Contains the first lens you look through - usually a magnification of 10x
  • Located on the top of the body tube
• Objective Lenses


  • Used in combination with the eyepiece to provide a range of magnification
  • Magnification ranges from 40x to 400x
  • Located on the nosepiece at the bottom of the body tube
• Nosepiece


  • Holds the objective lenses
  • Rotates to enable magnification
  • Located at the bottom of the body tube
• Arm


  • Supports the upper parts of the microscope
  • Used to carry the microscope
  • When carrying a microscope, always have one hand on the arm and one hand on the base
• Base


  • Supports the whole microscope
  • Used to carry the microscope
  • When carrying a microscope, always have one hand on the arm and one hand on the base
• Stage


  • Supports the slide
  • The slide contains the specimen or object that you are viewing with the microscope
• Stage Clip


  • Helps to hold the slide in place
  • Usually one on each side of the hole (stage opening)
  • The stage opening allows light to pass from the light source to the lenses
• Light Source


  • Provides light necessary for viewing the specimen
  • Usually either a mirror or illuminator
  • Sends light through the stage opening to the diaphragm
• Diaphragm


  • Wheel or lever located below the stage opening
  • Regulates the amount of light that can enter the lenses
  • May need to be adjusted based on the thickness of the specimen being studied
• Coarse Adjustment Knob


  • Raises and lowers the stage or objective lenses
  • Used only when focusing the low power (4x) objective lens
• Fine Adjustment Knob


  • Raises and lowers the stage or objective lenses a small distance for exact focusing
  • Used when focusing the medium power (10x) and high power (40x) objective lenses
• Microscopy is the main technique to visualize and study the structure and function of cells
• The impact of optical and electron microscopy techniques is enormous in all fields of biomedical research
• Different research areas rely on microscopy in diverse ways
• Microscopes


  Allowed scientists to investigate cell structure, observe the tiniest details of plants, animals, and fungi, and learn about the presence of microbes
• Development of microscopes


  1. Use of a simple lens in ancient times

  2. First compound microscope around 1590

  3. Microscopes used in 7th grade life science
• Microscope


  One of the most recognizable symbols of science
• • scope


  To look at
• Micrographs


  Photographs of cells taken using a microscope
• Microscope


  Theoretically an array of two lenses
• Parts of a classic compound microscope


  • Objective lens
  • Tube lens
  • Eyepiece lens
  • Focal plane
  • Image plane
• Magnification


  A measure of how much larger a microscope (or set of lenses within a microscope) causes an object to appear
• Magnification is defined by the magnification by the objective x the magnification by eyepiece
• Maximum magnification does not mean maximum resolution
• Resolution


  Describes the minimal distance of two points that can be distinguished
• Resolving power


  The smaller the resolution value, the higher the resolving power of the microscope and the better the clarity and detail of the image
• Numerical aperture (NA)


  An estimate of how much light from the sample is collected by the objective
• Numerical aperture, NOT magnification determines resolution
• A lens with a larger NA will be able to visualize finer details and will also collect more light and give a brighter image than a lens with lower NA
• Light


  Electromagnetic radiation, the visible spectrum has wavelengths between 400nm and 700nm
• Photon


  The elementary particle that defines light
• Basic dimensions of light


  • Intensity (amplitude) which is related to the perception of brightness
  • Frequency (wavelength), perceived as colour
  • Polarization (angle of vibration) which is not or weakly perceptible to humans
• Light (Optical) Microscopy


  Visible light is used, glass lenses are used, advantage is it can often be performed on living cells