Ibn Al-Haytham : The Father of Modern Optics

Ibn Al-Haytham, a 10th century scholar from Basra (Iraq), is considered to be the father of modern optics and of the present-day scientific experimental method. The Year 2015 coincides with the 1,000th anniversary of his seminal work, Kitab al-Manazir (Book of Optics). UNESCO in partnership with the science and cultural heritage organization "1001 Inventions" has launched The “1001 Inventions and the World of Ibn Al-Haytham” campaign to honour his works.His life and works were a subject of several major initiatives during 2015, beginning at the Opening Ceremony at UNESCO HQ in Paris.
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IBN AL-HAYTHAM(b. 965 - d. 1040 AD )
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Born around a thousand years ago in present day Iraq, Al-Hasan Ibn al-Haytham (known in the West by the Latinised form of his first name, initially “Alhacen” and later “Alhazen”) was a pioneering scientific thinker who made important contributions to the understanding of vision, optics and light. His methodology of investigation, in particular using experiment to verify theory, shows certain similarities to what later became known as the modern scientific method. Through hisBook of Optics (Kitab al-Manazir) and its Latin translation (De Aspectibus), his ideas influenced European scholars including those of the European Renaissance. Today, many consider him a pivotal figure in the history of optics and the “Father of modern Optics”.

Ibn al-Haytham was born during a creative period known as the Golden age of Muslim civilisation that saw many fascinating advances in science, technology and medicine. In an area that spread from Spain to China, inspirational men and women, of different faiths and cultures, built upon knowledge of ancient civilizations, making discoveries that had a huge and often underappreciated impact on our world.

Ibn al-Haytham was born in the year 965 AD in Basra, and died in about 1040 AD in Cairo. He was one of the earliest scientists to study the characteristics of light and the mechanism/process of vision. He sought experimental proof of his theories and ideas. During many years living in Egypt, ten of which were spent under what we may now call protective custody (house arrest), he composed one of his most celebrated works, the Kitab al-Manazir, whose title is commonly translated into English as "Book of Optics" but more properly has the broader meaning "Book of Vision". Ibn al-Haytham made significant advances in optics, mathematics and astronomy. His work on optics was characterized by a strong emphasis on carefully designed experiments to test theories and hypotheses. In that regard he was following a procedure somewhat similar to the one modern scientists adhere to in their investigative research.

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HIs contribution to Optics
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Different views about how the process of vision could be explained had been in circulation for centuries mainly among classical Greek thinkers. Some said rays came out of the eyes, while others thought something entered the eyes to represent an object. But it was the 11th-century scientist Ibn al-Haytham who undertook a systematic critique of these ideas about vision in order to demonstrate by both reason and experiment that light was a crucial, and independent, part of the visual process. He thus concluded that vision would only take place when a light ray issued from a luminous source or was reflected from such a source before it entered the eye.Ibn al-Haytham is credited with explaining the nature of light and vision, through using a dark chamber he called “Albeit Almuzlim”, which has the Latin translation as the “Camera obscura”; the device that forms the basis of photography. [IYL2015 Call to action]

Out of the 96 books he is recorded to have written; only 55 are known to have survived. Those related to the subject of light included: The Light of the Moon, The Light of the Stars, The Rainbow and the Halo, Spherical Burning Mirrors, Parabolic Burning Mirrors, The Burning Sphere, The Shape of the Eclipse, The Formation of Shadows, Discourse on Light, as well as his masterpiece, Book of Optics. Latin translations of some of his works are known to have influenced important Medieval and European Renaissance thinkers like Roger Bacon, René Descartes and Christian Huygens, who knew him as “Alhazen”. [IYL2015 Call to action] The crater Alhazen on the Moon is named in his honour, as is the asteroid 59239 Alhazen.

He Invited to Egypt to help build a dam on the Nile. After a field visit, he declined to proceed with the project causing him to end up in what we now call -protective custody for 10 years.
From his observations of light entering a dark room, he made major breakthroughs in understanding light and vision.
His discoveries led him to make significant revision to ancient views about how our eyes see.
Through his studies of earlier work by Galen and others, he gave names to several parts of the eye, such as the lens, the retina and the cornea.
He set new standards in experimental science and completed his great Book of Optics sometime around 1027.
His Book of Optics was translated into Latin and had a significant influence on many scientists of the Middle Ages, Renaissance and Enlightenment. For example, the optics book Perspectiva was authored around 1275 by Erazmus Witelo, who later was called “Alhazen’s Ape” when people realised he had largely copied al-Haytham’s Book of Optics.

The Invention of Camera
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The ancient Greeks thought our eyes emitted rays, like a laser, which enabled us to see. The first person to realise that light enters the eye, rather than leaving it, was the 10th-century Muslim mathematician, astronomer and physicist Ibn al-Haitham. He invented the first pin-hole camera after noticing the way light came through a hole in window shutters. The smaller the hole, the better the picture, he worked out, and set up the first Camera Obscura (from the Arab word qamara for a dark or private room). This idea laid the foundation of the present day Camera.His experimental conclusions were that when the sunlight reached and penetrated the hole, it made a conic shape at the meeting point with the pinhole, and later formed another conic shape in reverse to the first one on the opposite wall in the dark room.‘Light issues in all directions opposite any body that is illuminated with any light [and of course, also opposite any self-luminous body]. Therefore when the eye is opposite a visible object and the object is illuminated with light of any sort, light comes to the surface of the eye from the light of the visible object.’ (10th-century Ibn al-Haytham from his ‘Book of Optics)

Ibn al-Haytham (Alhazen) wrote about naturally-occurring rudimentary pinhole cameras.For example, light may travel through the slits of wicker baskets or the crossing of tree leaves. (The circular dapples on a forest floor, actually pinhole images of the sun, can be seen to have a bite taken out of them during partial solar eclipses opposite to the position of the moon's actual occultation of the sun because of the inverting effect of pinhole lenses.) Alhaitham published this idea in the "Book of Optics" in 1021 AD. He improved on the camera after realizing that the smaller the pinhole, the sharper the image (though the less light).
He provides the first clear description for construction of a camera obscura (Lat. dark chamber).A pinhole camera is a camera without a lens and with a single small aperture – effectively a light-proof box with a small hole in one side. Light from a scene passes through this single point and projects an inverted image on the opposite side of the box.The human eye in bright light acts similarly, as do cameras using small apertures. Up to a certain point, the smaller the hole, the sharper the image, but the dimmer the projected image. Optimally, the size of the aperture should be 1/100 or less of the distance between it and the projected image.

In Later stages, these discoveries led to the invention of the camera obscura, and Ibn Al-Haytham built the first camera, a camera obscura or pinhole camera, in history. He went on to explain that we see objects upright and not upside-down, as the camera does, because of the connection of the optic nerve with the brain, which analyses and defines the image.During his practical experiments, Ibn Al-Haytham often used the term al-Bayt al-Muthim, which was translated into Latin as camera obscura, or dark, private or closed room or enclosed space. Camera is still used today, as is qamara in Arabic which still means a private or dark room.Many of Ibn Al-Haytham’s works, especially his huge Book of Optics, were translated into Latin by the medieval scholar Gerard of Cremona. This has a profound impact on the 13th-century big thinkers like Roger Bacon and Witelo, and even on the 15th-century works of Leonardo da Vinci. Today, the camera has gone from the humble beginnings of Ibn-Al-Haytham’s dark front room, the qamara, to become a sophisticated digital process, while the study of optics has blossomed into a whole science covering lasers, optical sectioning of the human retina and researching red bioluminescence in jelly fish.