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TELESCOPES

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ContentsContents

What is telescope?What is telescope?

How it is named?How it is named?

Types of Telescopes?Types of Telescopes?

How different types of telescopes How different types of telescopes work?work?

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TelescopeTelescope

Designed for the Designed for the observation of observation of remote objectsremote objects to magnify distant objectsto magnify distant objects to make faraway objects appear much closerto make faraway objects appear much closer

Name Telescope came from Greek:Name Telescope came from Greek: teletele = 'far' and = 'far' and skopeinskopein = 'to look or see'; = 'to look or see'; teleskoposteleskopos = 'far-seeing‘. = 'far-seeing‘.

Telescopes are mainly of two types:Telescopes are mainly of two types: Reflecting TelescopeReflecting Telescope Refracting MicroscopeRefracting Microscope

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Reflecting TelescopeReflecting Telescope

A telescope in which A telescope in which

light from the object light from the object

is initially focused by is initially focused by

a concave mirrora concave mirror

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Refracting TelescopeRefracting Telescope

A telescope in which a A telescope in which a

lens receives and lens receives and

focuses light that is focuses light that is

then viewed through a then viewed through a

second, magnifying second, magnifying

lens in the eyepiecelens in the eyepiece..

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MICROSCOPES

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ContentsContents

What is Microscope?What is Microscope?

How it is namedHow it is named

Types of Microscopes?Types of Microscopes?

How Different types of How Different types of Microscopes work?Microscopes work?

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MicroscopeMicroscope

Designed forDesigned for viewing objects that are too small to be seen by viewing objects that are too small to be seen by

the naked eyethe naked eye

Microscope name came from Greek:Microscope name came from Greek: ((micronmicron) = small + () = small + (skopeinskopein) = to look at) = to look at

Main types of Microscopes:Main types of Microscopes: Optical MicroscopeOptical Microscope Electron MicropscopeElectron Micropscope

Transmission Electron MicroscopeTransmission Electron Microscope

Scanning Electron MicroscopeScanning Electron Microscope

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Optical microscopesOptical microscopesUse Use visible wavelengthsvisible wavelengths of light of light

The simplest and hence most widely used type in biology and geologyThe simplest and hence most widely used type in biology and geology

Optical microscopes use refractive lenses to focus light into the eye or Optical microscopes use refractive lenses to focus light into the eye or another light detectoranother light detector typically of glass and occasionally of plastictypically of glass and occasionally of plastic

Typical magnification of a light microscope is up to 1500x with a Typical magnification of a light microscope is up to 1500x with a theoretical resolution of around 0.2 micrometres.theoretical resolution of around 0.2 micrometres.

Various wavelengths of light are sometimes used for special purposesVarious wavelengths of light are sometimes used for special purposes UltravioletUltraviolet light is used to illuminate the object being viewed in light is used to illuminate the object being viewed in

order to excite a fluorescent dye which then emits visible light. order to excite a fluorescent dye which then emits visible light. Infrared Infrared light is used to study thick slices of biological tissue light is used to study thick slices of biological tissue

because infrared light's permits viewing deeper into tissue.because infrared light's permits viewing deeper into tissue.

x-ray microscopex-ray microscope Uses electromagnetic wavelengths Uses electromagnetic wavelengths not visiblenot visible to the human eye are to the human eye are

often called optical microscopes. often called optical microscopes.

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Optical MicroscopeOptical Microscope

A device that uses a A device that uses a lens or system of lens or system of lenses to produce a lenses to produce a greatly magnified greatly magnified image of an object. An image of an object. An optical microscope optical microscope uses transmitted or uses transmitted or reflected light to reflected light to obtain the image.obtain the image.

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How do Electron How do Electron Microscopes Work?Microscopes Work?

Electron Microscopes (EMs) function exactly as their optical Electron Microscopes (EMs) function exactly as their optical counterparts counterparts

EMs use a focused beam of electrons instead of light to "image" EMs use a focused beam of electrons instead of light to "image" the specimen and gain information as to its structure and the specimen and gain information as to its structure and composition.composition.

A vacuum is necessary for its proper function as electrons are A vacuum is necessary for its proper function as electrons are minute particles that can be deflected even by air particles.minute particles that can be deflected even by air particles.

The basic steps involved in all EMs: The basic steps involved in all EMs: A stream of electrons is formed by the Electron Source and A stream of electrons is formed by the Electron Source and

accelerated toward the specimen using a positive electrical accelerated toward the specimen using a positive electrical potential potential

This stream is confined and focused using metal apertures This stream is confined and focused using metal apertures and magnetic lenses into a thin, focused, monochromatic and magnetic lenses into a thin, focused, monochromatic beam. beam.

This beam is focused onto the sample using a magnetic lens This beam is focused onto the sample using a magnetic lens Interactions occur inside the irradiated sample, affecting the Interactions occur inside the irradiated sample, affecting the

electron beam electron beam

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Transmission Electron Transmission Electron MicroscopeMicroscope

A high-A high-powered powered microscope that microscope that uses beams of uses beams of electrons focused electrons focused by an electron lens by an electron lens to create a to create a magnified image on magnified image on a fluorescent screen a fluorescent screen or photographic or photographic plateplate..

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Scanning Electron MicroscopeScanning Electron Microscope

It is a microscope that It is a microscope that uses a beam of uses a beam of electrons to scan an electrons to scan an object and produce an object and produce an enlarged image of it enlarged image of it on a cathode-ray.on a cathode-ray.

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OverviewOverview

Telescopes come in two types: Telescopes come in two types: Refractor telescope : uses glass lenses Refractor telescope : uses glass lenses Reflector telescope : uses mirrors instead of Reflector telescope : uses mirrors instead of

the lensesthe lenses

Microscopes can largely be separated into two Microscopes can largely be separated into two classesclasses Optical theory microscopes : electromagnetic Optical theory microscopes : electromagnetic

waves are usedwaves are used Electron microscopes: electron beam is usedElectron microscopes: electron beam is used

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