Ibn al-Haytham, a great scholar who emerged during the golden age of the Islamic world, is known in the West as "Alhazen." He made significant contributions to fields such as optics, physics, astronomy, and mathematics. He studied the phenomenon of vision and the behavior of light, making revolutionary discoveries in this area. His accomplishments paralleled the political and economic power of the era.
Ibn al-Haytham is a prominent figure who successfully represented the scientific understanding of Ancient Greece in the medieval Islamic world. Not only did he develop the scientific heritage inherited from Ancient Greece, but he also adopted an original and critical approach to Aristotle's ideas. His in-depth studies in optics earned him a reputation as an innovative and creative scientist, and he also contributed to the fields of astronomy and geometry.
According to Ibn al-Haytham’s understanding of science, science is the expression of the laws governing phenomena through observation and experimentation, in a mathematical form. Achieving the truth and undeniable accuracy of knowledge is only possible by addressing the subject through a specific method. The work that best reflects this understanding is his Book of Optics (Kitāb al-Manāẓir).
Camera Obscura Experiments
One of Ibn al-Haytham's most notable works is his experiments on the principle of the dark room (camera obscura). The dark room is a simple setup that explains the formation of an inverted image projected onto a surface in a light-tight box or room. This principle forms the foundation of how modern cameras work.
The mechanism of image formation in the dark room works as follows: A small hole is made in the surface of a completely enclosed box that prevents light from entering. Light reflected from an object outside the box passes through this hole and forms an inverted image on the surface inside the box, opposite the hole. As the hole's diameter decreases, the image sharpens, but because less light enters, the image may not be very clear. To obtain both a sharp and clear image, a lens is placed in place of the hole. Additionally, a mirror placed at a certain angle opposite the hole can produce a straight image of the object by reflecting the light.
The history of the dark room dates back to the 4th century BCE. The first description of the fundamental principle of this technique was made by the Chinese philosopher Mozi (470-390 BCE). Although Mozi's ideas were later supported by other scholars, they could not demonstrate these ideas through experiments.
The first clear definition and invention of this technique is credited to Ibn al-Haytham. Through experiments with various light sources, he succeeded in forming inverted images of objects in the dark room. Being a keen observer, Ibn al-Haytham once noticed light coming through a hole in the window of a room. When this light struck the opposite wall, it took the shape of a crescent similar to what we see during a solar eclipse. Ibn al-Haytham made the following observation based on this: "The image in a solar eclipse, unless it is a total eclipse, shows that when sunlight passes through a narrow and round hole, it takes the shape of a crescent when it falls on the surface opposite the hole." He then conducted further experiments and discovered that light travels in straight lines, and beams of light emanating from bright objects do not scatter when passing through a small hole; instead, they form an inverted image in a plane parallel to the hole. Ibn al-Haytham found that the smaller the hole, the sharper the image, thus inventing the first camera in history, known as the dark room. Ibn al-Haytham used the term beyt muzlim (Beyt al-Muzlim) for this setup, which was later translated into Latin as camera obscura.
Illustration of the dark room (Photo: todoliteratura.com)
In his Book of Optics, Ibn al-Haytham described the dark room as follows: "The room should have a door with two wings. The observer must obtain several candlesticks and place them separately in front of the door. Then the observer enters the room and closes the door again; however, the wings of the door should be slightly ajar, leaving a gap. The observer then observes the wall opposite the door. On this wall, the observer will find light images separated by the number of candlesticks; this happens as the light images enter through the gap. If the observer now darkens the gap and leaves only a small hole, and if this hole is opposite the candlesticks, the observer will again observe as many light images on the wall as the number of candlesticks, and each image will vary depending on the size of the hole.”
The three candle experiment described in Ibn al-Haytham's book (Photo: powertusu.com)
In the 16th century, Leonardo da Vinci observed the similarities between the dark room and the function of the human eye, and utilized this principle. Da Vinci, who conducted several experiments using holes of various diameters in the dark room, used the camera obscura to correctly reflect the perspective in images. Many prominent artists of the time frequently used this technique in their works to achieve accurate perspective and depth.
Effects on Modern Science
Ibn al-Haytham's dark room experiments are critically important both in the history of science and in the development of technology. Renaissance scientists and artists such as Leonardo da Vinci were influenced by Ibn al-Haytham's work and applied this principle in their own works. Furthermore, the development of devices such as cameras and projectors has also been significantly influenced by these principles.
Through his dark room experiments and contributions to optical science, Ibn al-Haytham was a pioneer in scientific developments, both during his time and in the centuries that followed. His emphasis on scientific methods and experiments stands as one of the foundations of modern science.
