Ibn al-Haytham was an 11th century Persian scientist who made significant contributions to the fields of optics and scientific methodology. He is considered the "father of modern optics" and the "world's first true scientist" for being the first to use experiments and mathematics to test hypotheses. In his influential Book of Optics, he described experiments with lenses, mirrors and light that proved light travels in straight lines and disproved existing theories of vision. He is also credited with developing the first camera obscura and helping establish the scientific method.

1. IBN AL-HAYTHAM Known in the West as Alhazen , Alhacen , or Alhazeni , I bn 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. He was also nicknamed Ptolemaeus Secundus (" Ptolem y the Second") . Ibn al-Haytham is regarded as the “ father of modern optics ” for his influential Book of Optics ( Kitâb al-Manâzir ). ( 965 in Basra - c. 1039 in Cairo )

2. Ibn al-Haytham proved that light travels in straight lines using the scientific method by carrying out various experiments with lenses , mirrors , refraction , and reflection in his Book of Optics (1021). Ibn al-Haytham was a pioneer in many areas of science, making significant contributions in varying disciplines. His pioneering work on number theory, analyti c geometry, and the link between algebra and geometry, also had an influence on René Descartes's (1596-1650) geometric analysis and Isaac Newton's (1643-1727) calculus. His optical writings influenced many Western intellectuals such as Roger Bacon (1214-1294) , John Pecham (1230-1292) , Witelo (1230-?) , Johanne s Kepler (1571-1630) .

3. 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 .

4. Ibn al-Haytham also gave the first clear description and correct analysis of the camera obscura and pinhol e camera and built the world's first camera obscura . 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 . 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 .

5. 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.

6. Optics was translated into Latin by an unknown scholar at the end of the 12th century or the beginning of the 13th century . This work enjoyed a great reputation during the Middle Ages. His Book of Optics has been ranked with Isaac Newton's Philosophiae Naturalis Principia Mathematica as one of the most influential books in the history of physics, for starting a revolution in optics and visual perception. He is described as the " world's first true scientist " . He is also considered to be the founder of experimental psychology for his approach to visual perception and optical illusions .

7. Ibn al-Haytham was a pioneer in many areas of science, making significant contributions in varying disciplines. According to medieval biographers, Ibn al-Haytham wrote more than 200 works on a wide range of subjects,of which at least 96 of his scientific works are known. Most of his works are now lost, but more than 50 of them have survived to some extent. Nearly half of his surviving works are on mathematics , 23 of them are on astronomy , and 14 of them are on optics , with a few on other subjects .