Week 3: Microscopes Flashcards
Occular Lens
Also known as the eyepiece. This is the part used to look through the microscope. Its found at the top of the microscope. Its standard magnification is 10x
Objective Lens
Magnification lenses. Typically a light microscope has four of these lenses: 4X, 10X, 40X, and 100 x.
4X Lens Name
Scanning Objective
10X Lens Name
Low Power Objective
40X Lens Name
High Power Objective
100X Lens Name
Oil Immersion Lens .. Oil Immersion must always be used with this lens
Specimen Stage & Clips
Platform
Stage Mover
Moves the stage left and right AND front to back
Nosepiece
also known as the revolving turret. It holds the objective lenses. It is movable hence it cal revolve the objective lenses depending on the magnification power of the lens.
Head
Holds the optical parts in the upper part of the microscope
Base
Acts as the microscope’s support
Arm
Connects from the base and to the head. It gives support to the head of the microscope and it is also used when carrying the microscope.
The Adjustment knobs
These are knobs that are used to focus the microscope. There are two types of adjustment knobs i.e fine adjustment knobs and coarse adjustment knobs.
Course Adjustment Knob
Moves the stage up or down for focusing changes
Fine Adjustment Knob
Slightly moves the stage up or down for minor focusing changes that sharpen the image
Diaphragm
It’s also known as the iris. Its found under the stage of the microscope and its primary role is to control the amount of light that reaches the specimen.
Rheostat
Brightness Adjustment
Microscope Illuminator/ Light Source
This is the microscopes light source, located at the base.
Condenser
These are lenses that are used to collect and focus light from the illuminator into the specimen (you can manipulate its direction and angles of reflection). They are found under the stage next to the diaphragm of the microscope.
-They play a major role in ensuring clear sharp images are produced with a high magnification of 400X and above. The higher the magnification of the condenser, the more the image clarity. More sophisticated microscopes come with an Abbe condenser that has a high magnification of about 1000X.
Total Magnification
Product of ocular lens magnification AND objective lens magnification
Low power lens require what light ?
Less light
High power lens require what light ?
More light
Course vs Fine Adjustment Knob usage
Course Adjustment: 4 - 10 X
Fine Adjustment: 40-100 X
Never use course adjustment with 40 or 100 x because you may accidentally push objective into slide
Resolving Power
Measure of the ability to distinguish between two objects that are close together. It is the minimum distance between two points at which those points can still be seen as different objects
The greater the resolving power, the more detail and clarity you can actually see.
Depth of field
how far above and below the sample plane the objective lens and the specimen can be while remaining in perfect focus.
Types of microscopes
- Simple Microscope- can see difference in shapes between RBC
- Compound- - two lenses provide more magnification power
- Stereo (dissecting)- low magnification but used for larger images and can provide 3D view
- Confocal- uses laser light- offer higher degree of magnification.
- Scanning Electron Microscope (SEM)- uses electrons rather than light for image formation. Allows for control over magnification. Also views 3D images
- Transmission Electron Microscope (TEM)- uses electrons in creating a magnified image but with 2D images. Good for viewing objects with some degree of transparency.
Depth of field vs field of view
Depth of field refers to the ability to view details of an object with a certain thickness. Higher magnifications may limit the ability to see details of the specimen in focus due to the thickness
Field of view is a similar concept but it’s the circular area you see when looking through the eyepiece of the microscope.
