cm4 microscopy

microscopy

One of the most widely used tools in biological sciences

An instrument that produces an enlarged image of an object

Magnification – the increase in an object’s apparent size

Resolution – the power of a microscope to clearly show detail

Principle:

The microscope objective first forms in

the tube a magnified aerial image of the

specimen illuminated below the lamp

and the condenser. The image is then

viewed magnified through the eyepiece.

microscope

What is the standard length of the draw tube?

160 mmWhich is the most important component of the microscope?

Objective lenses If the image remains visible after the exchange of objectives, the lenses are

said to be_____parfocal

I. Light microscopes

1. Simple

2. Compound

a. Brightfield

b. Darkfield

c. Phase contrast

d. Ultraviolet

e. Fluorescence

f. Stereoscopic

II. Electron microscopes

1. transmission

2. scanning

Type of

microscopy

appearancemagnification

use

Brightfield Microbe

stained

1000x Overall

appearance of

most microbes

Dark field Light

microbe not

stained

1000x Overall

appearance of

most microbes

Phase

contrast

Cellular

component

s resolved

1000x Resolution of

many cellular

components

Type of

microscopy

appearancemagnification

use

Ultraviolet UV

absorbing

portion of

cell emitting

light

1000x to

3000x

Cellular

components

that absorb

light

Fluorescent Microbe

fluorescing

1000x to

3000x

m-o’s coated

w/ dye

fluoresce

when struck

by UV

Type of

microscopy

Appearancemagnification

use

TEM Ultrathin

section

showing

cellular

component

s (2-D)

Up to

200,000x

Study of

viruses and

detailed

structure of

larger m-o’s

SEM Surface of

microbe

(3-D)

Up to

50,000x

Study of

surface

structure of

m-o’s

Brightfield Microscope

Dark image

against a

bright or

white

background

Thin, flat components of low

refractile elements and living

cells

polarized light

for birefringent substances

Brightly illuminated specimen

against a dark background

Fluorescent substances

Filters: excitation & barrier

Electron beams &

magnetic lenses