Chapter 2: Light Microscopes

What kind of structures do we use microscopes to study?

Tissues, cells, and subcellular structures

Magnification

Enlargement of size

Resolution

Ability to see details

What kind of working distance does a dissecting microscope have?

Large

What is a dissecting microscope used for?

Dissections and manipulations of larger specimens

What kind of depth of field does dissecting microscope have?

Larger depth of field

What kind of magnification power does dissecting microscope have?

Lower magnification power and resolution

What does the dissecting microscope rely on?

External light source and reflected light to visualize speciman

What kind of image does a dissecting microscope create?

3 dimensional

What is the other name for a dissecting microscope?

Stereoscopic microscope

What does the base do?

Support the microscope

Illumination intensity control

Adjust amount of light emitted from light source

Iris diaphragm

Creates an aperture where light passes to the condenser under the stage; adjusts the amount of light

How is the amount of light passing through the condenser adjusted?

Sliding the lever of iris diaphragm

Condenser

Small lens to focus incoming light onto specimen

Working distance

Distance between the front edge of objective lens and coverslip w/specimen in focus

Focusing

Adjusting the working distance to bring image into view and increase the sharpness of the image

What are the 2 kinds of focus knobs?

Coarse and fine adjustment

Coarse knob

Each turn moves objectives over a larger distance

Fine adjustment

Only this can be used for high magnification objective lenses

What does the body tube do?

Connects objective lenses to eyepieces (ocular lenses)

What does the body tube contain?

The lenses and mirrors to magnify and project images formed by objective lens to our eyes

Total magnification

Magnification power of objective lens x magnification power of eyepiece

What is total magnification the ratio of?

Ratio of image size to object size

What kind of specimens are observed with a compound light microscope?

Thin specimens

What kind of working distance does a compound light microscope use?

Short

What is the con of a short working distance?

It is difficult to manipulate specimen

What kind of image does a compound light microscope make?

2 dimensional image

What kind of depth of field does a compound light microscope have?

Smaller depth of field

Circular field of view

Circular area you see through eye pieces

How does an e look under the microscope?

Upside down and backwards

Which of the following objectives provides the largest working distance under a compound microscope?

4x

What objective lens should we start with when first observing a specimen?

4x

What type of light source is commonly used in light microscopes?

Visible light

What is the function of a focus knob on a microscope

Bring specimen on slide into clear view