The Compound Light Microscope
Section 1-4
What is a compound light microscope?
• Mechanism for enlarging an image
How Does a Microscope Work?
the specimen the image
the eye Each lens magnifies the image, increasing its overall size
A lens is a bi-convex disk that bends light
The bent rays produces an image The farther the light rays are bent, the larger the image appears
Evolution of the microscope
2 set lenses
Choice of lens magnification
How Does a Microscope Work?
the specimen the image
the eye As the light rays are spread farther apart, the clarity or resolution of the image decreases Resolving power: A measure of the ability of a lens or optical system to form separate and distinct images of two objects with small angular separation. Light microscopes are limited in their magnification by their resolving power!
Resolution vs. Magnification
How Does a Microscope Work?
the specimen the image
the eye The image is always seen upside down and backwards from its actual position
Magnification
• The two lenses are called:
– Eyepiece – Objective
• • • •
The eyepiece has a magnification of “10x” The magnification of the objective lenses vary and are marked on the lens Total magnification =
(Eyepiece) X (Objective)
Example: 10 X 40 = 400
The Parts of the Microscope and Their Function
Maintains proper distance between lenses Hold objectivesrotates to change magnification Magnification Magnification
Support body tube
Supports slide Holds slide In place Regulates amount of light Sharpens the image
Focuses image
Reflects light towards eyepiece
Supports microscope
Proper Procedures
1. Carry the microscope with one hand under the base while grasping the arm with the other hand 2. Place microscope ~5 inches from the edge of the table Be careful of the cord when moving around the lab tables!!
Proper Procedures
3. Rotate the nosepiece to obtain the proper objective lens Make sure the lens clicks into place!! 4. Look through the eyepiece and switch on the lamp This is your field of view!
Proper Procedures
5. Place slide on stage, center specimen over stage 6. Locate specimen on low power using coarse adjustment 7. Carefully switch to medium or high power 8. Focus image with fine adjustment Avoid damaging slide!
Do not use course adjustment with high power!
Storing the Microscope
Four steps prepare the microscope for storage:
1. the 10X objective is in place 2. the stage is all the way down 3. the power is off 4. the cord is wrapped around the base
Let’s Review!
9. 1.
Eyepiece
Body tube
2. 3.
Nosepiece
10.
Arm
Low power
4. Medium power 5. 6. 7. 8.
High power Stage clips Diaphragm Light source
11.
Stage
12. Course adjustment 13. Fine adjustment
14.
Base
Microscope Self Quiz