1: the microscope

Anton van Leeuwenhoek

1st to see single-celled organisms in pond water

simple

Early microscopes were described as ____ since they only had one lens; like a magnifying glass

Hans & Zacharias Janssen

invented the compound microscope

Hans & Zacharias Janssen

introduced a second lens system

LIGHT MICROSCOPE

light transmits the image to the eye

ELECTRON MICROSCOPE

used to observe very small objects: viruses, DNA, parts of cells

ELECTRON MICROSCOPE

usesbeamsofelectrons rather than light • much more powerful

COMPOUND MICROSCOPE

optical instrument with a two-lens system, the objectives and the eyepiece or ocular; controllable illumination system and a geared focusing mechanism

COMPOUND MICROSCOPE

1st type of microscope, most widely used; monocular/binocular

COMPOUND MICROSCOPE

can magnify up to 1500-2000x • requires that the material being examined be sliced thinly enough for light to pass through

DISSECTING MICROSCOPE

viewing of opaque subjects

DISSECTING MICROSCOPE

can magnify an object up to 20-40x its actual size • used for examining big specimens when low magnification is needed

TRANSMISSION ELECTRON MICROSCOPE

uses a very thin section of the

specimen, this electron beam can carry and transmit the information about the internal structure of the sample

TRANSMISSION ELECTRON MICROSCOPE

uses a high-voltage electron beam emitted by a cathode and formed by magnetic lenses

TRANSMISSION ELECTRON MICROSCOPE

can magnify up to 250,000x

SCANNING ELECTRON MICROSCOPE

produces images by detecting secondary electrons which are emittedfromthesurfacedueto excitation by the primary electron beam

SCANNING ELECTRON MICROSCOPE

surface of the specimen is bombarded with electrons to see a - dimensional image of the specimen's surface

SCANNING ELECTRON MICROSCOPE

can magnify up to 3,000-10,000x, makes use of beam transmission

SCANNING TRANSMISSION ELECTRON MICROSCOPE

type of TEM in which the electrons pass through the specimen, but as in SEM, sample is scanned through a beamofelectrons

SCANNING TUNNELING MICROSCOPE

newest machinethat can reveal

individual atoms only 3 Angstrom acros

SCANNING TUNNELING MICROSCOPE

produces 3-dimensional image by scanning the surface sample with a beam ofelectrons

Electron tunneling

the tendency of electrons to jump between the tip of a finemetalneedleandthesurfacetobe studied

scanning Electron Microscope (SEM)

* Used to produce excellent images of the surfaces of cells and small organisms. Excellent for studying surface morphology of the organisms, cells or any suitable material under study

transmission Electron Microscope (TEM)

Used to study the ultra structure of the cell and its components. It can see objects as small as a protein molecule or even at nano level. Provides details about internal composition of cells or any suitable material under study

• Electron beam pass through the sample

Scanning Electron Microscope

* Depth of field: High
* Magnifying power: 100,000X
* Specimen contrast: by electron adsorption
* Produces three-dimensional black and white images
* Preparation technique; easy
* Preparation thickness: variable
* Specimen mounting: Aluminum stubs
* Field of view: Large

Transmission Electron Microscope

Depth of field: Moderate

• Magnifying power: 5,000,000X

• By electron scattering

• Produces two-dimensional black and white images

• Skilled, very thin sample is required • Very thin• Thin f ilms on copper grids• Limited

base

lower part of the microscope that provides support

base

wide and heavy thus providing stability when the microscope is placed on a table/working bench

* top lighting

* shines down on the stage to light up solid s

* bottom lighting

* transmitted up through the stage to highlight translucent objects

arm

* described as the "backbone" of the microscope:
* may either be a hollow, cylindrical rod or a rigid arm with a cuboid shape (elongated cuboid)

arm

* it provides support to the head part of the microscope by connecting it to the microscope base

zoom knob

* located on both sides of the microscope head
* zoom in on to a particular area of interest on the field of view to get a closer look

zoom knob

* resolution may be affected, the user may have to re- adjust the focus knob in order to bring the image into focus.

cord

the ____ for incident illumination may be located, or originate from, the upper-most part of the stand allowing the specimen to be illuminated from above.

Stage Plate

* specimen is placed on the ____ for viewing; mounted on the base of the microscope

\

Stage Clips

lie to either side of the stage, which can be used to hold a glass slide in place

Objective Lens

extends down from the head of the microscope, toward the stage.

Objective Lens

Themicroscope’smagnificationis determined by the eyepiece and ____

stereo head

moveable top portion with two adjustable eyepieces, similar to binoculars

diopter

* no two eyes are exactly alike, slight adjustments can be made to the ocular lens to compensate for the differences

diopter

* allowing both eyes to focus on a single image clearly

Eyepieces

* known as the ocular lenses
* part of the microscope through which the

user looks into to observe the image of the

object/specimen.

Eyepieces

* magnifier that serve to magnify the image

projected from the objective
* help increase the size of the image to

study details of the object under investigation

magnifying Parts

Eyepiece/ocularlenses• Objectives/objectivelenses

Eyepiece

known as the ocular lenses

* contains the first lens you look

through - 10x

eyepiece

* detachable cylinder located at

the upper end of the tube
* may have a line inside that

serves as a pointer and rotates as the ocular is rotated

objectives

* used in combination with the

eyepiece to provide a range of

magnif ication
* magnification ranges from 40x

to 400x

objectives

* located on the nosepiece at the

bottom of the body tube

Scanner objective

* the shortest cylinder with a very large opening,


0. usuallymarkedwith“4x"

Scanner objective

* provided with a large lens for very low magnification and is used to observe a much wider field of the object

Low-power objective

shorter cylinder with a large lens opening

* used to observe the general outline and locate the various parts of the specimen

Low-power objective

focused using the coarse adjustment

• 10x

High-power objective

* longer cylinder with a small lens opening, 40x

High-power objective

* equipped with lenses of higher magnifying power and is used to study the detailed parts of the specimen
* focused by using the fine adjustment knob

Oil immersion objective

* longest cylinder with a very small lens opening; 100x

Oil immersion objective

* equipped with very small lenses for very high magnification and is used to study the details of specific parts of the specimen

Oil immersion objective

* small drop of special oil is needed so that the light passing through it is uniformly distributed or is dispersed.

Base

* usuallyU-orV-shaped
* wherethemicroscopefirmly

rests

base

supports the whole microscope

* usedtocarrythemicroscope

arm

supports the upper parts of the microscope

• connectsthebaseandthebody tube together

arm

* serves as a handle for carrying the microscope

Stage

* platform that holds/supports the slide containing the specimen

Stage

* has an opening at the center that allows light to pass from below into the specimen for study

Pillar

support or post of the base where the arm is attached

Stage Clips

* Helps to hold the slide in place
* Usually one on each side of the

hole (stage opening) 

Substage

found below the stage• holds the condenser above and

the iris diaphragm below

Body tube

thecylinderthatattachesthe draw tube into the microscope and acts as the passageway of light from the objective to the eyepiece

Coarse Adjustment Knob

raises and lowers the objective lenses

• upper,largerknobsusedto bring an object into focus

Coarse Adjustment Knob

used only when focusing the low power (4x) objective lens

Fine Adjustment Knob

lower, smaller knobs for the slow movement of the body tube when focusing under the high-power objective and other high-powered lenses

Nosepiece

* holds the objective lenses
* rotates to enable magnification

Nosepiece

* locatedatthebottomofthe

body tube
* lenses must be “clicked” in place

for the field to be visible

Draw tube

smallcylindricalattachedto the upper part of the body tube that holds the ocular

Light Source

* Provides light necessary for viewing the specimen
* Usually either a mirror or illuminator
* Sends light through the stage opening to the diaphragm

Mirror

* planar on one side and concave on the other
* used to reflect light through the object and lenses of the eyes

concave side

* used for natural light

flat side

* used for artificial light.

Condenser

\
* located on a substage held in place by a rack
* used to condense or concentrate the light reflected from the mirror to the object or specimen being examined

Diaphragm

wheelorleverlocatedbelowthe stage opening

* regulates the amount of light that can enter the lenses

Diaphragm

* may need to be adjusted based on the thicknes