Optics, a key discipline within physics, centers on the dynamics, control, and detection of electromagnetic radiation, mainly light. The study of light began with three fundamental phenomena: propagation, reflection, and refraction. Ancient Greek thinkers, including Euclid, Hero of Alexandria, and Ptolemaeus, established the foundation for geometric optics, primarily through their conceptualizations of vision based on rays that emanate from the eyes.
In Euclid’s “Optics,” the essential propagation of visual rays is outlined through seven postulates that illustrate how visual rays from the eye create a diverging cone. “Catoptrics,” which is also ascribed to Euclid, explores the reflection from mirrors, detailing various geometric principles for incident and reflected rays. Ptolemaeus’ “Optics” presented the earliest scientific description of refraction and offered insights on several experimental findings, although it did not present a formal mathematical relation between the angles of incidence and refraction.
The Persian scholar Ibn Sahl, in the 10th century, inadvertently set the stage for the sine law of refraction, which was rediscovered much later. This principle defined a mathematical connection between the incidence and refraction angles, marking a significant milestone in optical science.
In the 17th century, prominent mathematicians such as Willebrord Snell and René Descartes independently uncovered the sine law of refraction, with Descartes being the first to publish it in his work “Dioptrique.” Pierre de Fermat also offered a derivation of the law rooted in the principle of least time. Christiaan Huygens subsequently demonstrated its derivation using the wave characteristics of light.
The formulation of the sine law represented a crucial turning point in optics, shaping future advancements such as Isaac Newton’s investigations into the spectrum of light and his writing “Opticks.” These developments remain fundamental to key elements of contemporary physics and technology.