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known as Alhazen

born in 965, Basrah, Iraq

died in 1040 in Cairo

a physician, mathematician and astronomer

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invented the pinhole camera

discovered the laws of refraction

studied a number of natural phenomena such as rainbow and eclipses

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Optics – The Book of Optics that he wrote to discuss the principles and working of light had seven volumes. He researched working of light and wrote about it in the book for ten years. The book was translated into many languages and got huge In his book, he described how our eye sees and disproved many old concepts. Also, he proved that light travel in straight lines. He described every principle in his book on the basis of experimental observations.

Camera Obscura (Pinhole Camera)- Ibn Al-Haytham invented a working model of camera obscura that worked on the principles of light. This camera constructed the projection of objects when light from objects entered in the hole of the camera. The entered light then projected the inverted image of the actual object inside the camera. Ibn Al-Haytham was also successful in projecting the solar eclipse in his camera.

Mathematics – Ibn Al-Haytham was also a famous mathematician who provided a link between geometry and algebra. He also developed a mathematical formula for finding the sum of the first 100 number of Natural Set

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He wrote at least 96 books. His most famous is the Book of Optics or Kitab al-Manazir which was translated into Latin and bcame very influential.
He laid out completely new ideas about light and vision in this book.

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This sketch of the human optical system based on the original drawing from the book of optics shows how eyes are connected to the brain

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This sketch of the human optical system based on the original drawing from the book of optics shows how eyes are connected to the brain

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By observing the behavior of light in the camera obscura, he was able to understand that something similar must happen in our eyes. As light passes through the tiny opening in our eye, the pupil creates an upside-down projection on the back of our eye. This revelation led Ibn al-Haytham to another: he was the first to argue that vision happens in the brain, not the eyes. Our brain reinterprets the upside-down projection of light, so we see things right-side-up. His book included detailed diagrams, including the one you see him drawing here, which labeled the different parts of the eye and showed the pathways of the optical nerves.

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Camera obscura is a Latin phrase meaning “dark chamber.” When the light of the Moon passed through a small hole into Ibn al-Haytham’s dark room, it produced an effect that humans have known about and been experimenting with since at least the fourth century in ancient Greece and China. Ibn al-Haytham wanted to know why the projection produced an upside-down image. This effect helped him understand that light moves in straight lines. When light is reflected off an object, it travels in straight lines away from the object in all directions. So, for example, when that light reflecting from the top of an object hits a tiny opening, like the hole in Ibn al-Haytham’s room, it must travel in a straight line. So, it can only land at the bottom of the room. Likewise, light reflecting off the bottom of the object can only land at the top of the room. That’s why the Moon appeared upside down on his wall.

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He built on the mathematical works of Euclid and Thabit ibn Qurra and worked on "the beginnings of the link between algebra and geometry". He developed a formula for summing the first 100 natural numbers, using a geometric proof to prove the formula.

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“ If learning the truth is the scientist’s goal, then he must make himself the enemy of all that he reads”

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“ If learning the truth is the scientist’s goal, then he must make himself the enemy of all that he reads”