Overview
This lecture covers the parts and functions of the compound microscope, focusing on its components, magnification principles, and its importance in studying microscopic organisms.
Principles of Microscopy
- Microscopes magnify objects too small to be seen by the naked eye.
- Compound microscopes use two or more lenses for greater magnification.
- Magnification increases an object's apparent size (e.g., 4x or 40x).
- Resolution is the ability to distinguish two separate objects clearly.
Parts of a Compound Microscope
- Microscope parts are grouped as magnifying, mechanical, and illuminating parts.
Magnifying Parts
- The ocular (eyepiece) is where you look through, providing additional magnification (ranges from 5x to 15x).
- Objectives (low power objective, LPO, and high power objective, HPO) are lenses providing different magnifications (LPO: 10x, HPO: 40x/43x).
Mechanical Parts
- Draw tube holds the ocular.
- Body tube connects the eyepiece to the objectives.
- Revolving nosepiece allows switching between objectives.
- Coarse adjustment knob raises/lowers the body tube for initial focus; used with LPO.
- Fine adjustment knob is for precise focusing; used with HPO.
- Arm supports the body tube; used to carry the microscope.
- Base supports the entire microscope.
- Stage is the platform for placing specimens.
- Stage clips secure the specimen slide on the stage.
- Inclination joint allows the microscope to tilt.
- Pillar supports the upper parts above the base.
Illuminating Parts
- Mirror gathers and directs external light to illuminate the specimen (avoid direct sunlight).
- Diaphragm regulates the amount of light reaching the specimen.
Importance of the Microscope in Biology
- Allows enlarged viewing of tiny organisms and structures.
- Enables detailed study of organisms not visible to the naked eye.
Key Terms & Definitions
- Magnification — increasing the apparent size of an object.
- Resolution — the ability to differentiate two close objects as separate entities.
- Ocular/Eyepiece — lens you look through; magnifies the image.
- Objective — lens close to the specimen providing various magnifications.
- Stage — platform where slides are placed.
- Diaphragm — device regulating light intensity on the specimen.
Action Items / Next Steps
- Review the names and functions of each microscope part.
- Practice identifying parts on a real or diagrammatic microscope.
- Ensure you can distinguish between magnification and resolution.