Lab 2: Microscopes

Microscopes

• A microscope is an instrument used to view objects that are too small to be seen by the unaided eye.
• The name "microscope" comes from the Greek words "mikron", meaning small, and "Scopeos", meaning to look.

Types of Microscopes

• There are two main types of microscopes: Light Microscopes and Electron Microscopes.
• Light Microscopes are used to examine cells at relatively low magnifications (up to 2000x).
• Electron Microscopes are used to examine cells and cell structure at very high magnifications (up to 10,000,000x).

Light Microscopes

• Use lenses to focus light on the specimen, magnifying it and producing an image.
• Types of Light Microscopes include:
  • Bright Field Microscopy (Compound Light Microscope)
  • Dark Field Microscopy
  • Fluorescence Microscopy

Compound Light Microscope

• The most common microscope used in microbiology.
• Consists of two lens systems that combine to magnify the image using visible light photons.
• Basic parts include:
  • Course Focus (raises or lowers the stage to focus)
  • Fine Focus (raises and lowers the stage to bring objects into focus)

Dark Field Microscopy

• A light microscope in which the light reaches the specimen from the sides only.
• The specimen appears light on a dark background.
• Used to observe microbial motility.

Fluorescence Microscopy

• Used to visualize specimens that fluoresce (emit light of one color) following absorption of light.
• Cells fluoresce either:
  • Naturally (e.g. containing chlorophyll)
  • After staining with fluorescent dyes (e.g. DAPI, which is widely used to stain cell DNA)

Electron Microscope

• Uses a beam of electrons as a source of illumination.
• Allows for very high magnifications (up to 10,000,000x).

Microscopes

• A microscope is an instrument used to view objects that are too small to be seen by the unaided eye.
• The name "microscope" comes from the Greek words "mikron", meaning small, and "Scopeos", meaning to look.

Types of Microscopes

• There are two main types of microscopes: Light Microscopes and Electron Microscopes.
• Light Microscopes are used to examine cells at relatively low magnifications (up to 2000x).
• Electron Microscopes are used to examine cells and cell structure at very high magnifications (up to 10,000,000x).

Light Microscopes

• Use lenses to focus light on the specimen, magnifying it and producing an image.
• Types of Light Microscopes include:
  • Bright Field Microscopy (Compound Light Microscope)
  • Dark Field Microscopy
  • Fluorescence Microscopy

Compound Light Microscope

• The most common microscope used in microbiology.
• Consists of two lens systems that combine to magnify the image using visible light photons.
• Basic parts include:
  • Course Focus (raises or lowers the stage to focus)
  • Fine Focus (raises and lowers the stage to bring objects into focus)

Dark Field Microscopy

• A light microscope in which the light reaches the specimen from the sides only.
• The specimen appears light on a dark background.
• Used to observe microbial motility.

Fluorescence Microscopy

• Used to visualize specimens that fluoresce (emit light of one color) following absorption of light.
• Cells fluoresce either:
  • Naturally (e.g. containing chlorophyll)
  • After staining with fluorescent dyes (e.g. DAPI, which is widely used to stain cell DNA)

Electron Microscope

• Uses a beam of electrons as a source of illumination.
• Allows for very high magnifications (up to 10,000,000x).