Just like all of the preceding sciences that had appeared before Islam, the Greek and other ancient civilizations were interested in Optics. They lay a lot of benchmarks that Muslims used when they practiced Optics. Muslims passed on what the Greek mentioned about light refraction, the burning mirror and more. They
didn't stick to passing on alone, but expanded and made stunning additions of their own. Muslims were able to make an honorable history in the field of Optics.

At the beginning, Greek Optics had two contradicting opinions. First: is Entrance, which is the entrance of what represents the object into the eye. Second: is the regeneration, or the formation of an image (visualizing), when light rays are emitted from the eye and hit an object that is in turn seen. The Greek civilization continued to tackle Optics in that manner, and between those two opinions. Aristotle made a lot of efforts in this field, but they all lack conclusive details. Also Euclid, in spite of his remarkable efforts, his theories were limited to presenting a full explanation of vision and ignored physical, physiological and psychological elements of optical phenomenon. He reached that the eye lens produces rays and that only the objects that the rays hit are seen and the ones that are not hit are not seen. He also explained that things that are viewed through a big angle are seen big and the ones that are viewed from a small angle are seen small.

Research continued in the field of Optics around the same theories and without any advances until the Islamic civilization. The Muslims contributions had a different advanced and unique approach. The reason was that Muslims were proficient in several fields of science related to Optics like Astronomy, Geometry, Mechanics and others, and that these sciences would interfere with their creations.

Ibnul Haitham (Alhacen or Alhazen) – A Leap in Optics

The philosopher Abu Yusuf al-Kanady (185- 256 A.H / 805 – 873 A.C) is considered one of the first Muslim scientists who worked in the field of physics. He discussed light phenomenon in his famous book, "The Science of Views", which was the first book in the field of Optics. Kanady considered in his book the Greek emission theory and added a fine description of the principle of radiation. He then composed a new basis for an ideological system that would replace eventually the emission theory. This book got a lot of resonance at Arab scientific societies, then the European during the Middle Ages.

After that came Abul Hasan Ibnul Haitham (354 – 430 A.H) whose accomplishments were considered a new conquest and a significant leap in the world of Optics and the visual physiology. Many western scientists based their theories on his work. On top of the scientists who relied on his theories (and claimed it to themselves) are Roger Bacon, Witelo and others, especially in their researches related to the microscope, the telescope and the magnifying glass.

Ibnul Haitham started first by discussing the theories of Euclid and Ptolemy in the field of vision and showed corruption of some of their aspects. During that time he presented a fine description of the eye, the eye lenses and eye vision. He described states of light ray refraction as it penetrates the air around the globe in general. Then he specifically described the state of light ray refraction when it penetrates a transparent body like air, water or molecules floating in the air. It bends – or refracts – off its course.

He researched in "reflection" and detection of the resulting angles. Ibnul Haitham explained that celestial objects are seen at the horizon at dawn before they are actually there. On the contrary, during sunset, the celestial objects continue to be seen at the horizon even after they hide below it. He is the first to suggest using the black stone which is considered the basis of photography.

The book that immortalized the name of Ibnul Haitham along the centuries is "The Book of Visions". It clarifies the concept of Optics as a primary theory in vision that is completely different than the assumption of visual rays that was preserved by mathematical imitation since Euclid and all the way to al-Kanady.

Ibnul Haitham also added a new method to this explanation of the vision process. Thus he was able to rephrase concepts that were either meaningless (according to the visual ray emission) or ignored by philosophers who were more concerned with the explanation of an image more than the actual process of vision.

In spite of Ibnul Haitham's significance and his original researches in the field of Optics, he remained unknown by a lot of people until Allah (SWT) sent who would uncover his efforts and bring it to the light. Among those was the Arab scientist Mostafa Nazif who wrote a book about Ibnul Haitham with a pioneer study that was published by Cairo University in two binders. He exerted a lot of effort to read Ibnul Haitham's manuscripts and hundreds of other references until he could clearly tell one evident fact; that Ibnul Haitham put the basics of Optics in its modern form.

Professor Mostafa Nazif says, "Ibnul Haitham inverted the old principles upside down and created a new science that dominated the Science of Visions founded at Greece. He also established modern Optics and his contributions in Optics is no less than Newton's contributions in Mechanics. If Newton is truly considered a pioneer in Mechanics in the 17th century, then Ibnul Haitham is definitely worth to be called the pioneer of Optics in the beginning of the 11th century.

Ibnul Haitham ... the Pioneer of Modern Optics

The discoveries of Ibnul Haitham had a great impact on the human intellectual heritage in general. What concerns us most is his scientific specialization is his book "Visions". It was encountered a revolution in the world of Optics because Ibnul Haitham did not adopt Ptolemy's theories to explain it or even correct it. Instead he rejected a number of his Optics theories after concluding several new theories that were seeds for the modern Optics.

Ptolemy, as we pointed out, claimed that vision happens when rays are emitted from the eyes and hit an object. Then following scientists adopted this theory. Then when Ibnul Haitham came, he blew out this theory in his book "Visions". He showed that vision happens when rays are reflected off the object observed and into the eyes of the observer. This conclusion was reached after carrying out a set of experiments that showed that light rays travel in straight lines within a homogeneous
medium.

He proved that in his book "Visions" when he said, "either it (the light ray) is a body or not. If it is a body, then if we look at the sky and see the planets then an object has been produced by the vision and filled between Earth and the sky, and the vision has not been reduced. This is totally impossible and hideous. If it is not a body, then it does not sense vision because sensation is only possible for living bodies."

After discussing concepts like this he presented his own concept (in chapter six of the first article). He said, "Let's conclude all we have mentioned; that vision senses light and color on the surface of the observed object that are extended from the surface of the observed object and all the way to the eye lens, between vision and the observed object. Vision is nothing but the reflected straight lines that are imagined to extend between the observed and the vision center only. If that was concluded and was confirmed that this meaning is possible, without any abstains, then we now announce our claim.

Ibnul Haitham also proved mathematically and geometrically how looking with both eyes at the same time at object happens without seeing a double vision. He explained that both images of the object are matched on the eye retina. Ibnul Haitham placed with this proof and that explanation, the first foundation for what is known now as the Astroscope.

Ibnul Haitham was the first to study the eye scientifically and identified all its parts and anatomy and illustration. He was the first to give names to parts of the eye that the westerns later took either with the same pronunciation or after translation. Some of these names are al-Qaraneyya (Cornea), al-Shabakeyya (Retina), as-Sa'el az-Zugagy (Vitrous Humour), and as-Sa'el al-Ma'ey (Aqueous Humour).

Some of his most important accomplishments in this field, shown in his book "Visions", the following:

-          That he is the first to carry out experiments using the Hole Machine, or the Dark Room, or the Dark Cabinet. This is how discovered that the image appears upside down inside the cabinet, then paved the way to inventing the Camera. With this concept and these experiments, Ibnul Haitham preceded the Italian scientists "Leonardo Da Vinci" and "Della Porta" with five centuries.

-          Ibnul Haitham placed for the first time the laws of refraction and deviation of Optics. He explained how light refraction happens through mediums like water, glass and air. Thus he preceded the English scientist Newton.

-          He defined light in a similar manner to what we know today, and that it is a delicate body composed of rays with lengths and widths. He discussed its functions and defined refraction and specifically showed that the angle which with the light hits the object is exactly equal to the reflection angle in a mirror.

-          He is the first who said that light has a specific speed that can be measured

-          He specified the direction in which the light refracts when moving from one medium into the other of less or more density. He said that refraction (or deviation in his terms) away from or close to the perpendicular line drawn on the separating line between the two mediums.

-          One of his most notable accomplishments in his book "Visions" was his previous experiment of the black box. It is considered the first step for inventing the camera. As Sarton says, Ibnul Haitham is considered the first inventor of cameras, and what is practically called Camera Obscura.

-          He presented reflected images off different surfaces, a presentation called "Ibnul Haitham's Problem". He used a fourth degree equation to specify the point of reflection for all sorts of surfaces.

-          Dr. Mohamed Yunus al-Hamalawy says, "Ibnul Haitham engraved his place in the human development registry with letterz of light when he studied, assimilated, criticized, and disproved the wrong concepts that were adopted by the Optics' pioneers, like Euclid and Ptolemy and others. He added a lot to Optics when he deduced that light has a speed and specified that this speed is definite but is really high that sometimes it seems infinite. He proved that using machines that he invented. Ibnul Haitham invented and manually constructed several Astronomical and Physical machines for commercial fields. By that, Ibnul Haitham would have preceded both scientists, Descartes and Newton. He also preceded Einstein when he showed that the light speed is definite. In spite of that, our students continue to learn facts by any way and from any source but our original Arabic source. They learn from all scientists but their own nation's scientists!!

Ibnul Haitham preceded Witelo and Kepler in putting the foundation for Optics and in spite of that we still refer in our books to both as the founders of Optics.

That is why we should stop here to take a look at Ibnul Haitham's life and his contributions to science and his significance

http://300035.dotdothktrade.tech/en/artical/31890