METHODS OF DEVELOPING THE VISION Presented by- Sarinda Malavige Malika Nawaratne Malika Nawaratne Rachitha Wickremasinghe Rachitha Wickremasinghe Sources:

METHODS OF METHODS OF DEVELOPING THE DEVELOPING THE

VISIONVISION

Presented by- Sarinda MalavigePresented by- Sarinda Malavige Malika NawaratneMalika Nawaratne Rachitha WickremasingheRachitha Wickremasinghe

Sources: Google

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CONTENTSCONTENTS TOPIC SLIDETOPIC SLIDE

IntroductionIntroduction 3 3 Hand lens 4-5Hand lens 4-5 Microscope 6-7Microscope 6-7 History of microscope 8-9History of microscope 8-9 Types of microscopes 10Types of microscopes 10 Optical microscope 11Optical microscope 11 Electron microscope 12-13Electron microscope 12-13 Scanning probe microscope 14Scanning probe microscope 14 Other microscopes 15Other microscopes 15 Precautions to be taken when Precautions to be taken when handling a microscope 16-17handling a microscope 16-17 TelescopeTelescope What is a telescope 18What is a telescope 18 History of telescopes 19History of telescopes 19 Types of telescope 20Types of telescope 20 Optical telescope 21-23Optical telescope 21-23 Radio telescope 24-25Radio telescope 24-25 X-ray telescope 26-27X-ray telescope 26-27 Gamma-ray telescope Gamma-ray telescope 28-29 28-29 Infrared telescopeInfrared telescope 30-31 30-31 Eye Eye 32-39 32-39 Special thanks Special thanks 40 40

IntroductionIntroduction

Optical instruments used to see objects Optical instruments used to see objects magnified ,far away things closer and to see tiny magnified ,far away things closer and to see tiny objects (ex:-Bacteria).objects (ex:-Bacteria).

Lenses are used for this purpose.Lenses are used for this purpose.

There are two main types 1.Concve lensThere are two main types 1.Concve lens

2.Convex lens 2.Convex lens

In some instruments like cameras use not only In some instruments like cameras use not only lenses but other shapes made out of glass. ex:-lenses but other shapes made out of glass. ex:-Glass prisms and hexagons etc.Glass prisms and hexagons etc.

The hand lensThe hand lens Faulty vision that cannot be Faulty vision that cannot be

corrected by eyeglasses or corrected by eyeglasses or contact lenses is called low contact lenses is called low vision. vision.

A variety of tools are available A variety of tools are available to help a person with low to help a person with low vision read and work. vision read and work.

Some people with low vision Some people with low vision are helped with magnifier are helped with magnifier glasses in the form of hand-glasses in the form of hand-held glasses that enlarge type held glasses that enlarge type in books and newspapers.in books and newspapers.

They are commonly known as They are commonly known as hand lenses.hand lenses.

To make magnifying To make magnifying glasses we use concave glasses we use concave lenses.lenses.

We use them because We use them because the light rays that travel the light rays that travel through these lenses gets through these lenses gets enlarged.enlarged.

So the people can see So the people can see small objects or letters small objects or letters which are hard for them which are hard for them to see.to see.

MicroscopesMicroscopes

Microscope is an Microscope is an instrument used to obinstrument used to obtain a magnified tain a magnified image of minute image of minute objects or minute objects or minute details of objects details of objects which can not be which can not be seen by the naked seen by the naked eye. eye.

What is a microscope?What is a microscope?

History of microscopesHistory of microscopes

One of the first persons One of the first persons who discovered the who discovered the microscope was microscope was ANTONIE VAN ANTONIE VAN LEEUWENHOEK LEEUWENHOEK (1632-1723). He was a (1632-1723). He was a cloth trader. He made cloth trader. He made hundreds of simple hundreds of simple microscopes using just microscopes using just one lens.one lens.

English scientist English scientist ROBERT HOOKE ROBERT HOOKE invented this microscope invented this microscope in the 17th century. He in the 17th century. He discovered the cell discovered the cell structure of plants by structure of plants by observing a thin slice of observing a thin slice of cork under his cork under his microscope. microscope.

The 1The 1stst person who person who produced the electron produced the electron microscope and obtained microscope and obtained the PATENT right was the PATENT right was RINHOLT RUDENBURG.RINHOLT RUDENBURG.

Hooke’s microscope

Types of microscopesTypes of microscopes

OPTICAL MICROSCOPEOPTICAL MICROSCOPE

ELECTRON MICROSCOPEELECTRON MICROSCOPE

SCANNING PROBE MICROSCOPESCANNING PROBE MICROSCOPE

OTHER MICROSCOPESOTHER MICROSCOPES

Optical MicroscopeOptical Microscope The optical microscope is the The optical microscope is the

most widely used type of most widely used type of microscopes.microscopes.

It is mostly used for Biology and It is mostly used for Biology and Geology.Geology.

It uses light to get a magnified It uses light to get a magnified image of an object.image of an object.

The simplest optical microscope The simplest optical microscope is the is the double-convex lens with a double-convex lens with a short focal length.short focal length.

It can magnify an object up to 15 It can magnify an object up to 15 times.times.

Electron MicroscopeElectron Microscope An electron microscope is used An electron microscope is used

to observe enlarged images of to observe enlarged images of miniature particles like Viruses.miniature particles like Viruses.

An electron beam is used here An electron beam is used here instead of light rays.instead of light rays.

The magnified image got by the The magnified image got by the microscope is observed by a microscope is observed by a computer monitor.computer monitor.

There are 2 types of electron There are 2 types of electron microscopes-microscopes-

1) 1) Transmission electron Transmission electron microscopemicroscope:-:-

Passes electrons completely Passes electrons completely through the sample.through the sample.

2) 2) Scanning electron Scanning electron microscopemicroscope:-:-

Scanning electron Scanning electron microscope scan the microscope scan the electron with a fine electron electron with a fine electron beam and measure the beam and measure the reflection.reflection.

The modernised light The modernised light microscope is not more microscope is not more than (x200).than (x200).

Maximum magnification of Maximum magnification of a general light microscope a general light microscope is about 600(x600).is about 600(x600).

Sugar crystals enlarged by an electro microscope

Scanning probe microscopeScanning probe microscope

In scanning probe In scanning probe microscopy a physical microscopy a physical probe is used either in probe is used either in close contact to the close contact to the sample or nearly touching sample or nearly touching it. it.

The exact nature of the The exact nature of the interactions between the interactions between the probe and the sample probe and the sample determines exactly what determines exactly what kind of scanning Probe kind of scanning Probe microscopy is used. microscopy is used.

Other MicroscopesOther Microscopes

1) 1) Scanning acousticScanning acoustic microscopes use sound microscopes use sound waves to measure waves to measure variations in acoustic variations in acoustic impedance. impedance.

2) 2) Compound MicroscopeCompound Microscope is is known as the light known as the light microscope of the optical microscope of the optical microscope. It is made microscope. It is made out of convex lenses out of convex lenses having different having different curvatures.curvatures.

Function of the compound microscope

Precautions to be taken when Precautions to be taken when handling a Microscopehandling a Microscope

1) When the Microscope is not in use, it must be 1) When the Microscope is not in use, it must be kept covered to protect from dust.kept covered to protect from dust.

2) Place the hand under the microscope when it is 2) Place the hand under the microscope when it is taken out of it’s cover.taken out of it’s cover.

3) Microscope must be cleaned regularly. The 3) Microscope must be cleaned regularly. The lenses must be wiped with a swab of cotton or lenses must be wiped with a swab of cotton or soft cloth.soft cloth.

4) The object to be examined must always be 4) The object to be examined must always be covered with a cover slip.covered with a cover slip.

5) When the microscope is not in use, the eye 5) When the microscope is not in use, the eye piece and the objective must be detached and piece and the objective must be detached and be kept in a desiccators. When these lenses are be kept in a desiccators. When these lenses are kept exposed to air fungi developed in the kept exposed to air fungi developed in the lenses due to moisture in the air.lenses due to moisture in the air.

6) When carrying the microscope keep the base in 6) When carrying the microscope keep the base in the palm and hold it’s arm safely by the other the palm and hold it’s arm safely by the other hand. hand.

7) Adjust the objective with the minimum 7) Adjust the objective with the minimum magnification along with optical tube, before magnification along with optical tube, before observing any specimen.observing any specimen.

8) Look through the eye piece, and adjust the 8) Look through the eye piece, and adjust the mirror to get the maximum light.mirror to get the maximum light.

TelescopesTelescopes

What is a telescope?What is a telescope?

Telescope is a Telescope is a device that allows device that allows distant and faint distant and faint objects to be seen as objects to be seen as if they were much if they were much brighter and closer to brighter and closer to the observer. the observer. Telescopes are used Telescopes are used to observe the sky to observe the sky mostly.mostly.Early Telescopes

History of the telescopesHistory of the telescopes

Galileo Galileo Galilei was the first Galilei was the first official inventor of the telescope. official inventor of the telescope. Galileo (1564-1642), Italian Galileo (1564-1642), Italian physicist and astronomer who, physicist and astronomer who, with German astronomer with German astronomer Johannes Kepler, initiated the Johannes Kepler, initiated the scientific revolution that flowered scientific revolution that flowered in the work of English physicist in the work of English physicist Sir Isaac Newton.Sir Isaac Newton.

Galileo’s main contributions Galileo’s main contributions were, in astronomy, the use of were, in astronomy, the use of the telescope in observation and the telescope in observation and the discovery of sunspots, the discovery of sunspots, mountains and valleys on the mountains and valleys on the Moon, the four largest satellites Moon, the four largest satellites of Jupiter, and the phases of of Jupiter, and the phases of Venus. Venus. Johannes

Kepler

Types of telescopeTypes of telescope

Optical telescopesOptical telescopes

Radio telescopesRadio telescopes

X-ray telescopeX-ray telescope

Gamma-ray telescopeGamma-ray telescope

Infrared telescopeInfrared telescope

Optical telescopeOptical telescope An optical telescope gathers An optical telescope gathers

and focuses light mainly from and focuses light mainly from the Electromagnetic the Electromagnetic spectrum. Optical telescopes spectrum. Optical telescopes used mostly in astronomy.used mostly in astronomy.

There are 2 types of optical There are 2 types of optical telescopes.telescopes.

1)1) Refracting telescopesRefracting telescopes:-:- Refracting telescopes, or Refracting telescopes, or

refractors, use a glass lens refractors, use a glass lens to bend, or refract, starlight to bend, or refract, starlight and bring it to a focus. and bring it to a focus.

Keck Telescope . This twin telescope is the world’s largest optical telescope. It is situated in Hawaii

The lens is convex, The lens is convex, meaning that the center of meaning that the center of the lens is its thickest part, the lens is its thickest part, and the lens becomes and the lens becomes thinner toward its edgesthinner toward its edges. .

The distance between the The distance between the lens and the place where lens and the place where the rays converge is called the rays converge is called the focal length of the lens. the focal length of the lens.

A refracting telescope’s A refracting telescope’s light-gathering power is light-gathering power is proportional to the size of proportional to the size of the objective, or main, lens the objective, or main, lens and to the ratio of the focal and to the ratio of the focal lengths of the objective lens lengths of the objective lens and the eyepiece.and the eyepiece.

2)2) Reflecting telescopeReflecting telescope:-:- The first reflecting telescope The first reflecting telescope

was designed by Sir Isaac was designed by Sir Isaac Newton in 1668. A reflecting Newton in 1668. A reflecting telescope uses a curved mirror telescope uses a curved mirror to focus the light.to focus the light.

Light from distant objects such Light from distant objects such as stars and galaxies enters as stars and galaxies enters the telescope tube in parallel the telescope tube in parallel rays. These rays are reflected rays. These rays are reflected from the concave mirror to a from the concave mirror to a diagonal plane mirror.diagonal plane mirror.

The diagonal mirror reflects the The diagonal mirror reflects the light through a hole in the side light through a hole in the side of the telescope tube to a lens of the telescope tube to a lens in the eyepiece. in the eyepiece.

Radio telescopesRadio telescopes Radio astronomy was discovered Radio astronomy was discovered

in 1931 when Bell Telephone in 1931 when Bell Telephone Laboratories engineer Karl Laboratories engineer Karl Jansky, using a makeshift Jansky, using a makeshift antenna, realized that annoying antenna, realized that annoying radio static was actually coming radio static was actually coming from the core of our galaxy. from the core of our galaxy.

This was the first time that This was the first time that scientists realized that radio scientists realized that radio waves could come from non waves could come from non terrestrial sources.terrestrial sources.

In the years since, many major In the years since, many major discoveries in radio astronomy discoveries in radio astronomy have similarly occurred by have similarly occurred by accident or coincidence, accident or coincidence, including the detection of active including the detection of active galaxies, pulsars, and the glow of galaxies, pulsars, and the glow of the big bang itself.the big bang itself.

Radio telescopes are used to Radio telescopes are used to pick up radio waves instead of pick up radio waves instead of light waves. They are like light waves. They are like reflecting telescopes having a reflecting telescopes having a big dish to collect and focus big dish to collect and focus data.data.

At the centre of the dish, an At the centre of the dish, an antenna is fixed to pick radio antenna is fixed to pick radio signals.signals.

As radio waves are much As radio waves are much longer than light waves the longer than light waves the dish of the radio telescope is dish of the radio telescope is very big, about up to 100m very big, about up to 100m across.across.

Instead of one big dish, some Instead of one big dish, some radio telescopes use a radio telescopes use a collection of small, linked collection of small, linked dishes.dishes.

X-ray telescopeX-ray telescope X-ray astronomy was developed X-ray astronomy was developed

in the early 1960s when simple in the early 1960s when simple X-ray detectors were mounted X-ray detectors were mounted on rockets.on rockets.

Astronomers were surprised to Astronomers were surprised to

discover X rays streaming from discover X rays streaming from many energetic astronomical many energetic astronomical objects. Space-based X-ray objects. Space-based X-ray astronomy was pioneered in astronomy was pioneered in 1970 by the U.S.1970 by the U.S.

Explorer 42 satellite, which Explorer 42 satellite, which mapped the sky for X rays. Two mapped the sky for X rays. Two important new X-ray telescopes important new X-ray telescopes were launched in 1999 by were launched in 1999 by NASA: X-ray Observatory and NASA: X-ray Observatory and the European Space Agency’s the European Space Agency’s X-ray Multi mirror mission. X-ray Multi mirror mission.

Some X-ray telescopes are Some X-ray telescopes are built like optical reflecting built like optical reflecting telescopes. The main mirror of telescopes. The main mirror of these telescopes must be these telescopes must be nearly cylindrical. nearly cylindrical.

X rays from a targeted object X rays from a targeted object hit the mirror at such a shallow hit the mirror at such a shallow angle that they just graze it in angle that they just graze it in order to be reflected into the order to be reflected into the detector. detector.

Some X-ray telescopes are Some X-ray telescopes are just X-ray detectors that can just X-ray detectors that can be pointed at sources. be pointed at sources.

To block out X rays not coming To block out X rays not coming from the target, most detectors from the target, most detectors are surrounded by a cylinder of are surrounded by a cylinder of X-ray absorbing lead.X-ray absorbing lead.

X-ray image of the sun taken by a X-ray telescope.

Gamma-ray telescopeGamma-ray telescope

Gamma rays are electromagnetiGamma rays are electromagnetic radiation with wavelengths c radiation with wavelengths even shorter than X rays. Some even shorter than X rays. Some of the worst disasters in the of the worst disasters in the universe, such as neutron star universe, such as neutron star collisions and black holes, blast collisions and black holes, blast high-energy gamma rays across high-energy gamma rays across space.space.

Since gamma rays cannot Since gamma rays cannot penetrate Earth’s atmosphere, penetrate Earth’s atmosphere, they must be observed from they must be observed from space. In the early 1990s the space. In the early 1990s the Compton Gamma Ray Compton Gamma Ray Observatory (GRO) found that Observatory (GRO) found that mysterious gamma-ray bursts mysterious gamma-ray bursts are evenly distributed across the are evenly distributed across the sky. sky.

Gamma-ray telescopeGamma-ray telescope

Because of their even Because of their even distribution, astronomers distribution, astronomers believe that these bursts believe that these bursts are extraordinarily are extraordinarily powerful events that powerful events that occur in normal galaxies.occur in normal galaxies.

Many astronomers Many astronomers believe collisions believe collisions between two neutron between two neutron stars or between a stars or between a neutron star and a black neutron star and a black hole produce these hole produce these bursts. bursts.

Infrared telescopeInfrared telescope Infrared astronomy Infrared astronomy

allows scientists to allows scientists to explore the dark dusty explore the dark dusty region of space both within region of space both within and beyond our galaxy to and beyond our galaxy to uncover clues about the uncover clues about the birth of stars, formation of birth of stars, formation of planetary systems, planetary systems, behavior of comets and behavior of comets and planetary atmospheres, the planetary atmospheres, the core of the Milky Way core of the Milky Way Galaxy, and the birth of Galaxy, and the birth of some of the most distant some of the most distant galaxies in the universe. galaxies in the universe.

Despite the fact that Despite the fact that Earth’s atmospheric Earth’s atmospheric water vapor absorbs water vapor absorbs some infrared light, some infrared light, research can be research can be performed from dry high-performed from dry high-altitude observing sites altitude observing sites and aircraft.and aircraft.

Even better is infrared Even better is infrared astronomy from space-astronomy from space-based telescopes, which based telescopes, which offer a crystal clear view, offer a crystal clear view, free of the background free of the background glow produced by Earth’s glow produced by Earth’s atmosphere.atmosphere.

This is a picture of the Orion Nebula taken by an Infrared telescope.

The eyeThe eye

What is an eye?What is an eye? Eye is a light-sensitive organ of Eye is a light-sensitive organ of

vision in animals. The eyes of vision in animals. The eyes of various species vary from simple various species vary from simple structures that are capable only of structures that are capable only of differentiating between light and differentiating between light and dark to complex organs, such as dark to complex organs, such as those of humans and other those of humans and other mammals, that can distinguish mammals, that can distinguish minute variations of shape, color, minute variations of shape, color, brightness, and distance.brightness, and distance.

The actual process of seeing is The actual process of seeing is performed by the brain rather than performed by the brain rather than by the eye. The function of the eye by the eye. The function of the eye is to translate the electromagnetic is to translate the electromagnetic vibrations of light into patterns of vibrations of light into patterns of nerve impulses that are nerve impulses that are transmitted to the brain.transmitted to the brain.

Compound eyes of a fly

Parts of the eyeParts of the eye

Sclerotic layerSclerotic layer -The Sclerotic layer covers the -The Sclerotic layer covers the eye and protect the internal parts of the eye.eye and protect the internal parts of the eye.

CorneaCornea- - The cornea is a tough, five-layered The cornea is a tough, five-layered membrane through which light is admitted to the membrane through which light is admitted to the interior of the eye.interior of the eye.

PupilPupil--The amount of light entering the eye is The amount of light entering the eye is controlled by the pupil, which dilates and controlled by the pupil, which dilates and contracts accordingly.contracts accordingly.

IrisIris- The pigmented iris hangs behind the cornea - The pigmented iris hangs behind the cornea in front of the lens, and has a circular opening in in front of the lens, and has a circular opening in its center. It controls the light entering the eye its center. It controls the light entering the eye by contracting, radial muscles, changing the by contracting, radial muscles, changing the size of the pupil. size of the pupil.

5)5) Eye lensEye lens-It is a convex lens that focuses the pictures of -It is a convex lens that focuses the pictures of the objects in front of the eye on the Retina. Curvature the objects in front of the eye on the Retina. Curvature of the lens can be changed.of the lens can be changed.

6)6) Aqueous humourAqueous humour--Behind the cornea is a chamber filled Behind the cornea is a chamber filled with clear, watery fluid, the aqueous humor, which with clear, watery fluid, the aqueous humor, which separates the cornea from the crystalline lens. Light separates the cornea from the crystalline lens. Light passes through this liquid.passes through this liquid.

7)7) Ciliary musclesCiliary muscles-The eye lens -The eye lens is connected by is connected by ligaments to a ring like muscle, called the ciliary ligaments to a ring like muscle, called the ciliary muscle, which surrounds it. The ciliary muscle and its muscle, which surrounds it. The ciliary muscle and its surrounding tissues form the ciliary body. This muscle, surrounding tissues form the ciliary body. This muscle, by flattening the lens or making it more nearly by flattening the lens or making it more nearly spherical, changes its focal length.spherical, changes its focal length.

8)8) FoveaFovea--Directly behind the pupil is a small yellow-Directly behind the pupil is a small yellow-pigmented spot, the macula lutea, in the center of pigmented spot, the macula lutea, in the center of which is the fovea centralis, the area of greatest visual which is the fovea centralis, the area of greatest visual acuity of the eye.acuity of the eye.

9)9) RetinaRetina--The retina is the innermost layer of the eye. The retina is the innermost layer of the eye. The pattern formed by veins beneath the surface of the The pattern formed by veins beneath the surface of the retina is unique to each individual. This pattern is a retina is unique to each individual. This pattern is a reliable biometric characteristic. The image is formed reliable biometric characteristic. The image is formed on the retina.on the retina.

10)10) Blind spotBlind spot-- Where the optic nerve enters the eyeball, Where the optic nerve enters the eyeball, below and slightly to the inner side of the fovea, a below and slightly to the inner side of the fovea, a small round area of the retina exists that has no light-small round area of the retina exists that has no light-sensitive cells. This optic disk forms the blind spot of sensitive cells. This optic disk forms the blind spot of the eye.the eye.

11)11) Vitreous humourVitreous humour--Behind the lens the main body of the Behind the lens the main body of the eye is filled with a transparent, jellylike substance, the eye is filled with a transparent, jellylike substance, the vitreous humor, enclosed in a thin sac, the hyaloid vitreous humor, enclosed in a thin sac, the hyaloid membrane. The pressure of the vitreous humor keeps membrane. The pressure of the vitreous humor keeps the eyeball distended.the eyeball distended.

12)12) ChoroidChoroid--The middle layer of the coating of the eye is The middle layer of the coating of the eye is the choroid, a vascular layer lining the posterior three-the choroid, a vascular layer lining the posterior three-fifths of the eyeball. The choroid is continuous with the fifths of the eyeball. The choroid is continuous with the ciliary body and with the iris, which lies at the front of ciliary body and with the iris, which lies at the front of the eye. This supply Oxygen and nutrients to the eye.the eye. This supply Oxygen and nutrients to the eye.

Focus of the eyeFocus of the eye