MLSP WEEK 13

MICROSCOPE

MICROSCOPE

An optical instrument that is used to observe tiny objects, often objects that cannot be seen at all with the unaided human eye (the “naked eye”).

SIMPLE MICROSCOPE

Defined as a microscope containing only one magnifying lens.

COMPOUND MICROSCOPE

A microscope that contains more than one magnifying lens.

BRIGHTFIELD MICROSCOPE

Is used to observe morphology of microorganisms such as bacteria, protozoa, fungi, and algae in living (unstained) and non-living (stained) state

BRIGHTFIELD MICROSCOPE

Cannot observe microbes less than 0.2 um in diameter or thickness, such as spirochetes and viruses.

DARKFIELD MICROSCOPE

Unstained organisms are observed against a dark background.

DARKFIELD MICROSCOPE

Useful for examining thin spirochetes.  Slightly more difficult to operate than bright field

PHASE-CONTRAST MICROSCOPE

Can be used to observe unstained living microorganisms.

FLUORESCENCE MICROSCOPE

Fluorescent dye attached to organism (e.g., acridine orange and Auramine O).

FLUORESCENCE MICROSCOPE

Primarily an immunodiagnostic technique (immunofluorescence).

FLUORESCENCE MICROSCOPE

Used to detect presence of microbes in cells, tissues, and clinical specimens.

TRANSMISSION-ELECTRON MICROSCOPE (TEM)

Excellent resolution AND Allows examination of cellular and viral ultrastructure

TRANSMISSION-ELECTRON MICROSCOPE (TEM)

Specimen is non-living  Reveals internal features of thin specimens

SCANNING ELECTRON MICROSCOPE (SEM)

Gives the illusion of depth (three-dimensional).  Useful for examining surface features of cells and viruses

SCANNING ELECTRON MICROSCOPE (SEM)

Specimen is non-living.  Resolution is less than that of TEM

A. Eyepiece Lens

the lens at the top that you look through, usually 10x or 15x power.

B. Arm

Supports the binocular body and the revolving nosepiece.

D. FINE ADJUSTMENT KNOB

— A slow but precise control used to fine focus the image when viewing at the higher magnifications.

E. Light Switch

is an electrical control device. Light switches are used to on and off the illuminator.

F. Revolving Nosepiece or Turret

is the part that holds two or more objective lenses and can be rotated to easily change power.

G. Objective Lens

Used to magnify objects placed on the stage.

H. stage

is a flat platform where a slide with a specimen is placed for viewing. The stage has a central aperture through which the focused light from the condenser strikes the specimen. It contains two-stage clips for holding the slide in a fixed position.

I. Aperture

The hole in the middle of the stage that allows light from the illuminator to reach the specimen

J. condenser

is a lens system that collects and focuses the light rays coming from the illuminator on the specimen being viewed.

Condenser Control Knob

Used to adjust the height of the condenser

K. Collector Lens with field diaphgram

controls the amount of light entering the condenser

Rheostat Control Knob

Controls the amount of light emitted from the light source

Field Diaphgram Lever

Used to adjust the amount of light passing through the collector lens

F. Base

is the lowermost part of the microscope that supports the entire microscope structure. It provides stability for the microscope. Illuminator, light switches, and electrical wiring system are fitted in the base.

Stage adjustment Knob

Used to move the stage and microscope slide

Binocular Body

Holds the ocular lenses in their proper locations

Magnification

The ratio of the apparent size of an object as seen through the microscope & the actual size of the object

Resolution/Resolving Power

The ability of the lens to clearly separate or distinguish two points of two lines individually in the image.

Resolution/Resolving Power

It is determined by the shortest wavelength of visible light & maximum numerical aperture

Numerical Aperture

A measurement of the ability of the condenser and the objective lens to gather light. (magnification α numerical aperture)

Scanner

4x and 0.10

LPO

10x and 0.25

HPO

40x and 0.65

OIO (oil immersion objectives)

100x and 1.25

Focal length

Thickness of the object that maybe seen at one time under focus. (focal length 1/α numerical aperture)

Working distance

Distance between the front lens of the objective lens & the top of the cover glass when the specimen is in focus. (working distance 1/α magnification)

Parfocal

Refers to quality of the objectives & eyepiece where practically no change in focus has to be made when objective is substituted for another

Refractive Index

Bending of light rays away from the objective lens when light passes from the glass of the microscope slide to the air.

CARE OF MICROSCOPE

The microscope should be cleaned with lens paper before and after use.

CARE OF MICROSCOPE

Other materials such as laboratory tissue may scratch the lenses.

CARE OF MICROSCOPE

It is especially important that lenses never be left with oil on them.

TRANSPORTING THE MICROSCOPE

A microscope should be left in a permanent position on a study laboratory table in an area where it will not get jammed.

TRANSPORTING THE MICROSCOPE

If the microscope must be moved, it should be held securely with one hand supporting the base and the other had holding the arm.

TRANSPORTING THE MICROSCOPE

The microscope should be places gently on tabletops, to avoid jarring

PRECAUTIONS

Use the coarse adjustment only with the low power objective

PRECAUTIONS

Use oil immersion oil with the oil immersion objective only

PRECAUTIONS

Clean all oculars and objectives with lens paper after each use

PRECAUTIONS

Move or transport the microscope with one hand under the base and the other hand gripping the arm.

PRECAUTIONS

Avoid jarring or bumping the microscope.

PRECAUTIONS

Store the microscope covered in a protected area