Types of Optical Microscopes

Types of Optical Microscopes

• Two basic types are simple and compound microscopes.
• Simple microscope uses one lens; compound microscope employs multiple lenses for higher magnification.

Simple Microscope

• A simple microscope magnifies objects using a single convex lens.
• Works on the principle of light refraction to create a virtual, erect, and magnified image of objects within its focal length.
• Forms a virtual and erect image which is easier to view.
• Ideal viewing distance relates to the least distance of distinct vision of the human eye.

Magnifying Power

• Magnifying power (M) is given by the formula (M = 1 + \frac{D}{F}) where
  • (D) represents the least distance of distinct vision.
  • (F) is the focal length of the lens, which should be small to enhance magnifying power.
• Applications include studying microscopic algae, fungi, and aiding jewellers in magnifying watch components.

Compound Microscope Structure

• The eyepiece magnifies the specimen image.
• The body tube connects the eyepiece to the objective lenses.
• Objective lenses are crucial for zooming in on the specimen.
• Stage clips secure the specimen slide during observation.

Light Source and Components

• The illuminator serves as the primary light source in a compound microscope.
• The stage holds the slide in place, while the nosepiece allows rotation between objective lenses.
• The aperture permits light passage, and the condenser gathers and focuses light onto the specimen.
• The diaphragm controls the light intensity reaching the specimen.

Total Magnification

• Total magnification is calculated by multiplying the magnifying powers of the objective and eyepiece.

Applications of Compound Microscope

• Used for identifying microorganisms and dead cells.
• Particularly useful in pathology labs for disease identification.

Dark-field Microscope

• Primarily used to observe living, unstained cells and microorganisms.
• Invented by Joseph Jackson Lister, enhancing contrast in transparent specimens.