Microscope Study Guide - Exercise 3

Human Anatomy & Physiology I • BIOL 2111

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Microscope parts
Focusing the microscope
Meiji Techno Co., Ltd. microscope
National Optical & Scientific Instruments Inc. digital microscope
Motic digital microscopy software suite
Confocal microscopy

Know the information below.
Be able to identify the microscope parts on one of the lab microscopes.
Be able to answer questions about focusing technique as described below.

(cf. Human Anatomy & Physiology Laboratory Manual
Exercise 3 - The Microscope pp. 21-29 in 8^th Ed. pp. 27-34 in 9^th Ed.)

Microscope parts

The microscopes we use in lab are compound light microscopes.
Compound light microscopes have lenses in the oculars and in the objectives.

arm: the column between the base and the stage
It is used for carrying the microscope.
stage: the platform that holds a slide
stage clips: hold a slide in place on the stage
stage control knobs: knobs below the stage that can move it forward and backward or from side to side
coarse focus: the large knob for focusing at 4x and 10x objective
fine focus: the small knob for focusing at 40x and 100x objective
ocular: the lenses of the microscope nearest the eye
The ocular is 10x.
objectives: the lenses of the microscope immediately above the slide
Notice that each of the 4 objectives is labeled with its magnification and that the higher magnifications are longer.
4x magnification: is used to scan the slide and find the specimen
100x magnification: used only for the oil immersion technique where oil is placed on the microscope slide
nosepiece or turret: the revolving device that holds the 4 objectives
light source: an electric bulb in the microscope base
condenser: lenses below the stage that focus light from the light source to improve resolution
iris diaphragm lever: controls the brightness of light from the microscope’s light source below the stage that passes through the slide into the objective
total magnification: the power of the ocular multiplied by the power of the objective
For instance, if the ocular is 10x and the objective is 4x, then the total magnification is 40x.
field of view: the surface area of a microscope slide that can be viewed without moving the slide
The diameter of the field of view decreases as magnification increases.
depth of field: the vertical distance that is in focus at a particular magnification without changing the focus
Depth of field decreases as magnification increases.
At high magnifications only a very thin slice of the specimen can be in focus at one time.
resolution: refers to the degree of detail that can be seen through a microscope
At a higher resolution, two objects can be closer and still be distinguished as separate.
Wavelength affects resolution. Shorter wavelengths have higher resolution.
That's why the microscope light source uses blue light ,
around 475 nm (475 x 10^-9 m).
Electron microscopes have a very high resolution because electrons have a shorter wavelength than visible light.
The wavelength of an electron is around 10 pm (10 x 10^-12 m), one-thounsandth that of visible light.
parfocal: means a microscope will hold focus when you change objectives

Focusing the microscope at 40x objective

Remember: The ocular is 10x.

Move the 10x objective into position.
(10x ocular times 10x objective equals 100x total)
Bring the stage up with the coarse adjustment knob until it stops.
Slowly move the stage down with the coarse adjustment knob until the specimen is in focus.
Leave the stage in its position!
Move the 40x objective into position.
(10x ocular times 40x objective equals 400x total)
Focus on the specimen with the fine adjustment knob.

Meiji Techno Co., Ltd. microscope

Meiji Techno Co., Ltd. makes the lab microscopes.

National Optical & Scientific Instruments Inc. digital microscope

National Optical & Scientific Instruments Inc. makes the DC5-163 digital microsope that is used to take slide pictures for the computer. It’s a very expensive piece of equipment.