PRAC

• Zacharias Janssen developed the first compound microscope in Middleburg, Holland in the 1590s
• Zacharias Janssen's microscope enlarged the image of a specimen three to nine times the specimen's actual size
• Microscope


  A precision instrument that produces enlarged images of small objects, allowing the observer an exceedingly close view of minute structures at a scale convenient for examination and analysis
• Types of Microscopes

  • Simple Microscopes
  • Compound Microscopes
• Simple Microscopes


  • Single magnifying lens magnifying glass; magnifies images of an object from 3 to 20 times the actual object size
• Compound Microscopes

  • 2 magnifying lens systems and a visible light source that passes through the specimen and the lenses to the observer's eye
• Proper use & handling of the microscope

  Transporting, cleaning, focusing, using coverslips, and storing the microscope properly
• Aperture Iris Diaphragm Knob


  • Controls the amount of light passing through the condenser, improving contrast
• Base Microscope Frame

  • Connects the head and base, houses the focusing mechanism, nosepiece, stage, and condenser
• Coarse Adjustment Knob

  • Allows for large adjustments to the height of the stage to initially focus the specimen
• Condenser


  • Small non-magnifying lens located beneath the stage that concentrates light on the specimen
• Condenser Centering Screw


  • Raises and lowers the condenser to vary the light delivery, best position is close to the inferior surface of the stage
• Diopter Adjustment Ring


  • Changes the focus of the eyepiece, used for adjustments when the user has better vision in one eye
• Fine Adjustment Knob


  • Used for precise focusing once the initial coarse focusing has been completed
• Eyepiece/Ocular


  • Most ocular lenses have a magnification power of 10x, some may have a pointer and/or reticle
• High Power Objective


  • Also known as High Dry Objective, magnifies the image 40 times its normal size
• Low Power Objective


  • Magnifies the image 10 times its normal size
• Oil Immersion Objective


  • Magnifies the image 100 times its normal size, uses oil
• Scanner


  • The lowest power objective lens that magnifies the specimen four times its normal size
• Interpupillary Distance Scale


  • Scale used to measure the interpupillary distance
• Objective lens

  • Magnifies the image 10 times its normal size
• Oil Immersion Objective


  • Magnifies the image 100 times its normal size usually at 1000x total power
  • Uses oil
• Scanner


  • Magnifies the specimen four times its normal size
• Interpupillary Distance Scale


  Used to measure the distance between the pupils of the eyes
• Light Intensity Control Knob

  • Alters the voltage going to the substage lamp to regulate the brightness of the light
• Light source/Filter holder


  • Located in the base
  • Allows light to pass through the specimen on the stage, through the lenses of the microscope, and ultimately to the eye
  • Microscope filters are used to adjust the color for observation or photo microscopy
• Mechanical Stage

  • Holds the specimen, contains clips to hold a slide in place, and knobs for positioning the slide
• Main Switch

  • Located on the base of the microscope; used to turn the power on or off
• Revolving nosepiece


  • Connects the objective lenses to the head of the microscope to change objective lenses
• Specimen Holder

  • Also known as Slide Clip
  • Holds microscope slide in position for precise movement
• Simplified Prefocusing Dial


  • Ensures the objective does not damage the specimen
• Transport Lock Pin/Stage lock control

  • Allows fixing the stage into position with respect to its rotation around the condenser axis
• Translation Mechanism/ Mechanical stage controls

  • Enables the head of the microscope to rotate
• X Translation Mechanism


  • Moves a slide in the X axis (horizontally) on the mechanical stage
• Y Translation Mechanism


  • Moves a slide in the Y axis (vertically) on the mechanical stage
• Types of Microscopes in Light Microscopy

  • Bright Field Microscopy
  • Dark Field Microscopy
  • Fluorescence Microscopy
  • Phase-Contrast Microscopy
  • Confocal Microscopy
• Magnifying power


  Allows making the object appear bigger
• Resolving power


  Ability to separate two closely spaced objects to see two distinct images
• Parfocal


  Objectives that can be changed with minimal or no refocusing
• Most microscopes are parfocal