Microscopes Flashcards
Use a compound microscope correctly
They use light as a source of illumination.
Thick or opaque objects cannot be examined.
Used for viewing small and transparent whole objects or thin slices of larger specimens.
Compound microscope
Ocular lens
The top most magnifying lens through which an object is viewed.
The magnifying power of a lens is usually indicated by markings on the casing.
Objective lenses
These magnifying lenses are closest to the specimen and also magnify the image you see of specimen.
There are several objective lenses and the magnification of the objective lenses is inscribed on the side of each lens.
Stage
A platform that supports the specimen.
Our compound microscopes have an apparatus on top of the stage that holds the slide on the stage and allows very precise movement of the slide.
Coarse focus knob
The coarse focus knob is used to bring the image of the specimen into approximate focus
Fine focus knob
The fine focus knob is used to bring the image into sharp focus after it has been roughly focused.
Condenser
The condenser is the unit located directly under the stage that can move up and down.
Condenser lenses
Focuses the light into the specimen and are found below the stage at the very top of the condenser.
Iris diaphragm
Is found below the condenser lenses.
It opens and closes to regulate the amount of light that reaches the specimen from the lamp below.
Iris diaphragm lever
This lever opens and closes the iris diaphragm.
Condenser adjustment knob
This knob adjusts the height of the condenser. In general, the condenser should be positioned almost as high as possible. If the condenser is at the wrong height, you will see a ground glad texture through the microscope.
Total magnification
Determined by multiplying magnification of the ocular lens by magnification of the objective lens.
Field of view
The area that can be seen as a circle of light when looming through the microscope.
Mm to um is multiply by 1000.
Field of view
The area that can be seen as a circle of light when looming through the microscope.
Mm to um is multiply by 1000.
Dissecting microscope
View larger three dimensional specimens.
View live specimens.
They are not transparent and good for viewing and details of the larger specimens.
It can be used while dissecting specimens.
A light microscope.
Estimation of actual size
Estimate the fraction of the field of view. Then multiply by the diameter of the field of view. 1.8mm x 4 (1/4)
Resolution
Clarity of the image, the minimum distance between two points or lines that can be separated and still be distinguished as separate units.
Depth of field
The vertical distance that remains in focus at one time.
When you increase the magnification the depth of field is decreased.
Contrast
How well the specimen can be seen in comparison to the background.
Enhanced by applying stains to the specimen.
Closing the iris diaphragm.
Decreasing the intensity of the light.
Adjusting the height of the condenser.
Transmission electron microscope
Use beams of electrons instead of lightwaves.
Specimen must be dehydrated, stained, and the sliced into ultra thin sections. They are then stained.
Electrons passing through the specimen will be deflected by the heavy metal stain and are then reflected back.
Shows the internal anatomy.
Scanning electron miscroscope
Specimen must be killed, dehydrated and coated with an atom thick layer of metal.
Use beams of electrons.
Whole specimens are viewed in 3d. Exterior of the organism.
