The document discusses Ibn al-Haytham (965-1039), also known as Alhazen, who is considered the "Father of Optics". It notes that he made seminal contributions to optics and the scientific method through his work, including developing the first correct analysis of the camera obscura and pinhole camera. The document also provides background on Ibn al-Haytham's work in optics, including his book "Book of Optics" where he established the modern theories of vision and light through experimentation. The International Year of Light 2015 focused on celebrating Ibn al-Haytham and promoting awareness of his contributions through partnerships with organizations like 1001 Inventions.

1. Ibn al-Haytham, Father of
Optics: An Optician,
Optometrist and
Ophthalmologist
Dr. Abdul Latif
Department of Ilmul Adiva
Faculty of Unani Medicine, AMU,Aligarh
abdullatifamu@gmail.com

2. The International Year of Light 2015 (IYL2015),
• IBN AL-HAYTHAM TO BE THE FOCUS OF THE INTERNATIONAL YEAR OF LIGHT
2015
• UNESCO and the International Year of Light 2015 partners with 1001
Inventions for 2015 campaign for Ibn Al-Haytham
• The International Year of Light and Light-based Technologies (IYL2015) is
delighted to welcome as Founding Partner the award-winning educational
organization 1001 Inventions. British-based 1001 Inventions has the specific
mission to raise awareness of the contributions to science, technology and
culture from the Golden Age of Muslim Civilization, and will play a key role
during IYL2015 to promote and celebrate the 10th century pioneer
Ibn Al-Haytham. Ibn Al-Haytham’s seminal work on optics Kitab al-Manazir
(The Book of Optics) was written around 1015, and its 1000th anniversary is
listed openly in the United Nations resolution on IYL2015 as a focal point of
celebration.

3. UNESCO announces partnership with
1001 Inventions to celebrate
Ibn Al-Haytham
Director-General Irina Bokova
announces UNESCO's partnership with
1001 Inventions to launch a global
campaign to celebrate the 10th century
scientist Ibn Al-Haytham. The campaign
called "1001 Inventions and the World
of Ibn Al-Haytham" will be part of the
UNESCO led International Year of Light
2015.
Click here

4. Anyone who has ever
used vision glasses or
contact lenses, taken
a picture with a
camera or watched
television has a
reason to be thankful
to the Father of
Optics, Al-Haytham

5. Ibn al Haytham
Abu Ali al-Hasan Ibn-al-Haytham known was born in 965 CE
in Basra (Iraq); also known as Al-Basri. He received his education
in Basra and Baghdad and later traveled to Egypt and Spain and died in
1040 possibly in Cairo, Egypt. He was also one of the most eminent
physicist’s who ever lived. Along with that he is also famous
Mathematician, and astronomer.
Known in the West as Alhazen, Alhacen, or Alhazeni, Ibn al-Haytham
was the first person to test hypotheses with verifiable experiments,
developing the scientific method more than 200 years
before European scholars learned of it—by reading his books.
Ibn al-Haytham is regarded as the “father of modern optics” for his
influential Book of Optics (Kitâb al-Manâzir ) and his extensive
contribution in the field of optics.

6. In his massive study of light and vision,
Kitâb al-Manâzir (Book of Optics ), Ibn
al-Haytham submitted every hypothesis
to a physical test or mathematical proof.
Besides the Book of Optics, Ibn al-
Haytham wrote several other treatises
on optics.
His Risala fi l-Daw’ (Treatise on Light)
is a supplement to his Kitab al-Manazir
(Book of Optics). The text contained
further investigations on the properties of
luminance and its radiant dispersion
through various transparent and
translucent media.
He also carried out further examinations
into anatomy of the eye and illusions in
visual perception.

7. Ibn al-Haytham also gave the first clear description and correct analysis of the
camera obscura and pinhole camera and built the world's first camera
obscura.
While Aristotle, Theon of Alexandria(335-405), Al-Kindi(801-873) and
Chinese philosopher Mozi(470-391 B.C.) had earlier described the effects of
a single light passing through a pinhole, none of them suggested that,what is
being projected onto the screen is an image of everything on the other side of
the aperture.
Ibn al-Haytham was the first to demonstrate this with his lamp experiment
where several different light sources are arranged across a large area. He was
thus the first to successfully project an entire image from outdoors onto a
screen indoors with the camera obscura.

8. Two major theories on vision prevailed in classical antiquity.
The first theory, the emission theory, was supported by such
thinkers as Euclid(323-283 B.C.) and Ptolemy(90-168), who
believed that sight worked by the eye emitting rays of light.
The second theory, the intromission theory supported by
Aristotle(384-322 B.C.) and his followers, had physical forms
entering the eye from an object.
Ibn al-Haytham argued that the process of vision occurs
neither by rays emitted from the eye, nor through physical
forms entering it.
He instead developed a highly successful theory which explained
the process of vision as rays of light proceeding to the eye from
each point on an object, which he proved through the use of
experimentation.

9. Lens (c.984)
Ibn al-Haytham’s treatise established optical science.
The earlier lenses were made of circular pieces
of rock crystal or semiprecious stone, such as beryl
and quartz, which were ground and polished so that
they produced a magnified image when looked
through. The oldest known lens artifact was one made
of rock crystal dating from around 640 B.C.E. and
excavated in Nineveh, near the modern city of Mosul,
Iraq. The most common form was circular and thicker
in the middle than around the edge, and having both
its front and back surfaces the same shape.
The modern convex lens developed from the
ancient Greek burning glass. Here a spherical vase of
water would be used to concentrate the rays of the sun
onto a small area, which heated up. The heat was used
to ignite fires in temples or to cauterized wounds.

10. The Iraqi mathematician and optics engineer Ibn Sahl (c. 940-1000) wrote
the treatise On Burning Mirrors and Lenses (984) in which he set out his
understanding of how curved mirrors and lenses bend and focus light, using
what is now known as Snell’s law to calculate the shape of lenses. But the Iraqi
Ibn al Haytham (965-1039), also known as Alhazen, is regarded as “the father
of optics” for his treatise, the Book of Optics, (1011-1021), in which he proved
that rays of light travel in straight lines, explained hoe the lens in the human
eye forms an image on the retina, and described experiments with a pin hole
camera.
In the thirteen century convex lenses were used in spectacles to correct
farsightedness. The use of concave lenses, which disperse the light as opposed
to concentrating it, to correct for farsightedness, came in the early fifteen
century. DH
GLASS, TELESCOPE, MICROSCOPE, SPECTACLES,
BIFOLCALS, EYE TEST, SPECTROSCOPE, CONTACT LENSES.

11. Refractive Errors
Refractive errors often are the main reason a person seeks
the services of an optician ,optometrist or ophthalmologist.
But what does it really mean when we're told that our
vision is blurry because we have a refractive error?
We see the world around us because of the way our eyes
bend (refract) light. Refractive errors are optical
imperfections that prevent the eye from properly focusing
light, causing blurred vision. The primary refractive errors
are nearsightedness, farsightedness and astigmatism.
Refractive errors usually can be "corrected"
with eyeglasses or contact lenses, or they can be
permanently treated with LASIK and other vision correction
surgery (also called refractive surgery).

12. How Light Travels Through
the Eye
In order to see, we must have light. While we don't fully understand all the
different properties of light, we do have an idea of how light travels.
A light ray can be deflected, reflected, bent or absorbed, depending on the
different substances it encounters.
Watch this video on what causes blurry vision and how we can correct it
When light travels through water or a lens, for example, its path is bent or
refracted. Certain eye structures have refractive properties similar to water
or lenses and can bend light rays into a precise point of focus essential for
sharp vision.
Most refraction in the eye occurs when light rays travel through the curved,
clear front surface of the eye (cornea). The eye's natural (crystalline) lens also
bends light rays. Even the eye's tear film and internal fluids (aqueous humor
and vitreous) have refractive abilities.

13. How the Eye Sees
The process of vision begins when light rays that reflect off
objects and travel through the eye's optical system are refracted
and focused into a point of sharp focus.
For good vision, this focus point must be on the retina. The
retina is the tissue that lines the inside of the back of the eye,
where light-sensitive cells (photoreceptors) capture images in
much the same way that film in a camera does when exposed to
light. These images then are transmitted through the eye's optic
nerve to the brain for interpretation.
Just as a camera's aperture (called the diaphragm) is used to
adjust the amount of light needed to expose film in just the right
way, the eye's pupil widens or constricts to control the amount of
light that reaches the retina.
In dark conditions, the pupil widens. In bright conditions, the
pupil constricts.

14. Causes of Refractive Errors
The eye's ability to refract or focus light sharply on the retina primarily is based on
three eye anatomy features: 1) the overall length of the eye, 2) the curvature of the
cornea and 3) the curvature of the lens inside the eye.
•Eye length. If the eye is too long, light is focused before it reaches the retina,
causing nearsightedness. If the eye is too short, light is not focused by the time it
reaches the retina. This causes farsightedness or hyperopia.
•Curvature of the cornea. If the cornea is not perfectly spherical, then the image is
refracted or focused irregularly to create a condition called astigmatism. A person
can be nearsighted or farsighted with or without astigmatism.
•Curvature of the lens. If the lens is too steeply curved in relation to the length of
the eye and the curvature of the cornea, this causes nearsightedness. If the lens is
too flat, the result is farsightedness.
More obscure vision errors, known as higher-order aberrations, also are related to
flaws in the way light rays are refracted as they travel through the eye's optical
system.
These types of vision errors, which can create problems such as poor contrast
sensitivity, are detected through new technology known as wave front analysis.

15. Detection and Treatment of
Refractive Errors
Your eye doctor determines the type and degree of
refractive error you have by performing a test called a
refraction.
This can be done with a computerized instrument
(automated refraction) or with a mechanical instrument
called a phoropter that allows your eye doctor to show you
one lens at a time (manual refraction).
Often, an automated refraction will be performed by a
member of the doctor's staff, and then the eye care
practitioner will refine and verify the results with a manual
refraction.
Your refraction may reveal that you have more than one
type of refractive error. Contd…

16. For example, your blurred vision may be
due to both nearsighted and astigmatism.
Your eye doctor will use the results of your
refraction to determine your eyeglasses
prescription. A refraction, however, does
not provide sufficient information to write
a contact lens prescription, which requires
a contact lens fitting.
Eyeglass lenses and contact lenses are
fabricated with precise curves to refract
light to the degree necessary to
compensate for refractive errors and bring
light to a sharp focus on the retina.
Vision correction surgeries such as LASIK
aim to correct refractive errors by changing
the shape of the cornea, so that light rays
are bent into a more accurate point of
focus.
An eye care practitioner
performs a manual refraction.
(Image: National Eye Institute)

17. Conclusion
His theory of vision is basis
of all optical requirement
Thanks to Ibn al haytham