MICROSCOPESMICROSCOPES

Some Important VocabularySome Important Vocabulary

MAGNIFICATION- MAGNIFICATION- increase of an object’s increase of an object’s apparent sizeapparent size

RESOLUTION- RESOLUTION- the power to show details the power to show details clearlyclearly

* Microscopes vary in powers of magnification * Microscopes vary in powers of magnification and resolutionand resolution

LIGHT MICROSCOPESLIGHT MICROSCOPES

These are the types of microscopes that we will These are the types of microscopes that we will use in class, along with dissecting scopesuse in class, along with dissecting scopes

- - a specimen a specimen must be mounted on a slide must be mounted on a slide in in order to be viewed with a compound order to be viewed with a compound microscopemicroscope

- specimens must be sliced thin enough to be - specimens must be sliced thin enough to be transparent, or they must be very smalltransparent, or they must be very small

- light microscopes have a total magnification of - light microscopes have a total magnification of 400X400X

- images produced are always backwards and - images produced are always backwards and upside down from the way that the slide looksupside down from the way that the slide looks

* if you move the slide away from you, it * if you move the slide away from you, it appears to be moving toward youappears to be moving toward you

* * if you move the slide to the left, it appears to if you move the slide to the left, it appears to be moving to the rightbe moving to the right

- you should always view a specimen by starting - you should always view a specimen by starting on the on the lowest magnification lowest magnification

As you go from low to high power:As you go from low to high power:

1. 1. Resolution decreasesResolution decreases

2. Field of view (how much of the specimen 2. Field of view (how much of the specimen you can see) decreases- although you can you can see) decreases- although you can see the specimen closer, you cannot see as see the specimen closer, you cannot see as much of itmuch of it

How to prepare a wet mount How to prepare a wet mount slideslide

Many slides used on the light microscope are Many slides used on the light microscope are wet wet mount slidesmount slides

To Make a Wet Mount Slide- To Make a Wet Mount Slide-

1. Obtain a clean slide and cover slip1. Obtain a clean slide and cover slip

2. 2. Place your Place your thin thin specimen on the middle of the specimen on the middle of the slideslide

3. Place a drop of water or stain on the 3. Place a drop of water or stain on the specimenspecimen

4. 4. Cover with the cover slipCover with the cover slip

STEREOSCOPIC/DISSECTING STEREOSCOPIC/DISSECTING MICROSCOPEMICROSCOPE

- enables you to observe objects that are too - enables you to observe objects that are too thick or too large to see with other thick or too large to see with other microscopesmicroscopes

- provides an opportunity for three dimensional - provides an opportunity for three dimensional viewing and viewing of live specimensviewing and viewing of live specimens

- - direction of movement of the object is the direction of movement of the object is the same as the way you move it; images are not same as the way you move it; images are not backwardsbackwards

ELECTRON MICROSCOPESELECTRON MICROSCOPES

Resolution of light microscopes is limited by Resolution of light microscopes is limited by the physical characteristics of lightthe physical characteristics of light

- at powers beyond about 2,000X the image of - at powers beyond about 2,000X the image of the specimen becomes blurrythe specimen becomes blurry

In electron microscopes, a beam of electrons In electron microscopes, a beam of electrons instead of a beam of light produces an instead of a beam of light produces an enlarged image of the specimenenlarged image of the specimen

- some electron microscopes can even show - some electron microscopes can even show individual atoms in a specimenindividual atoms in a specimen

There are 2 types of electron microscopes:There are 2 types of electron microscopes:

1. 1. Transmission electron microscopes Transmission electron microscopes (TEM)(TEM)

2. 2. Scanning electron microscopes (SEM)Scanning electron microscopes (SEM)

TEMTEM

- transmits a beam of electrons through a very - transmits a beam of electrons through a very thinly sliced specimenthinly sliced specimen

- magnetic lenses enlarge the image and - magnetic lenses enlarge the image and focus it on a screenfocus it on a screen

- these microscopes can magnify objects up to - these microscopes can magnify objects up to 200,000 times, 200,000 times, but but cannot be used to view cannot be used to view living specimensliving specimens

Transmission Electron MicroscopeTransmission Electron Microscope

TEM ImageTEM Image

- images- images

SEMSEM

- provides three-dimensional images- provides three-dimensional images

- - specimens are not sliced for viewingspecimens are not sliced for viewing

- the surface of the specimen is sprayed with - the surface of the specimen is sprayed with a fine metal coating, and a beam of a fine metal coating, and a beam of electrons is passed over the specimen’s electrons is passed over the specimen’s surfacesurface

- - this causes the metal coating to emit a this causes the metal coating to emit a shower of electronsshower of electrons

- the electrons are focused onto a screen, - the electrons are focused onto a screen, producing an image of the producing an image of the surface surface of an of an objectobject

- can magnify up to 100,000 times, but also - can magnify up to 100,000 times, but also cannot be used to view living specimenscannot be used to view living specimens

Scanning Electron MicroscopeScanning Electron Microscope SEM - Scanning Electron Microscopy ImageSEM - Scanning Electron Microscopy Image

Gallery Gallery http://www.mos.org/sln/sem/sem.htmlhttp://www.mos.org/sln/sem/sem.html

DIGITAL MICROSCOPESDIGITAL MICROSCOPESDigital microscopes have many of the features Digital microscopes have many of the features

of light microscopes and stereoscopic of light microscopes and stereoscopic microscopes, along with some additions:microscopes, along with some additions:

- Digital microscopes enable us to take Digital microscopes enable us to take pictures of specimens pictures of specimens

- Digital microscopes enable us to view Digital microscopes enable us to view specimens on a TV screen or a projectorspecimens on a TV screen or a projector

- Digital microscopes enable us to easily Digital microscopes enable us to easily share an interesting specimen with the rest share an interesting specimen with the rest of the classof the class