Origins of Optometric Science PDF

Origins of Optometric Science Prepared By: Cirila De Leon –Salcedo, O.D. Optometric Science The Greek philosophers were the first who sought to explain the nature of light and their argumentation was intimately related to the problem of explaining vision. With different held beliefs, they consider...

Origins of Optometric Science Prepared By: Cirila De Leon –Salcedo, O.D. Optometric Science The Greek philosophers were the first who sought to explain the nature of light and their argumentation was intimately related to the problem of explaining vision. With different held beliefs, they considered the process of seeing as being due to various relations between the eyes of the observer and the object seen.  Optometric Science Euclid The first to state a number of important properties about light that are still commonly used. o These include the rectilinear propagation of light rays and the law of reflection. o When combined with Hero’s principle (~100 A.D.), that light follows the shortest path, and the law of refraction, whose origin dates back to Ptolemy (~170 A.D.), one has the essential basis of so-called geometrical optics. o Father of Geometry  Optometric Science Alhazen An Arab scientist (~1000 A.D.) o Referred as Father of Modern Optics o He made significant contributions to the principles of Optics and Visual Perception in particular. o He was the first to correctly explain the theory of vision, and to argue that vision occurs in the brain, pointing to observations that it is subjective and affected by personal experience.  Optometric Science Alhazen An Arab scientist (~1000 A.D.) o He also stated the principle of least time for refraction which would later become the Fermat’s principle. o He made major contributions to catoptrics and dioptrics by studying reflection, refraction and nature of images formed by light rays  Optometric Science Alhazen An Arab scientist (~1000 A.D.) o He described the anatomy of the eye on the basis of dissections although he erroneously concluded that vision was produced at the surface of the crystalline lens. o He considered every object point to be a source for straight light rays holding a one-to-one correspondence with the image seen.  Optometric Science 13th Century o Italian glassworkers made lenses that were used for spectacles and thus to correct for poor sight caused by presbyopia. o This was a major invention since lenses had previously only been used as burning and magnifying glasses and possibly for decorative purposes. o Did not spur any scientific interest towards explaining how they function so as to improve sight, and such lenses were merely considered magical curiosities of no use for serious studies.  Optometric Science Kepler, 1604 o Johannes Keppler took up the challenge and studied the transmission of rays through lenses with geometrical optics, and he applied his studies to the eye. o He described how spectacle lenses could correct for poor sight and he realised that the external world was seen, not on the crystalline lens as previously thought, but via the inverted image that was formed on the retina.  Optometric Science Da Vinci o Keppler’s demonstration was deemed less precise. o Leonardo Da Vinci compared the eye to his camera obscura— ▪ a simple instrument consisting of a tiny hole through which light rays pass to draw a picture of the outside world on a distant screen.  Optometric Science Galileo o Dutch spectacle-makers had combined two lenses to facilitate magnified viewing of distant objects, and consequently the telescope had been invented. o Galileo Galilei (1609) was the first to see the scientific importance of this tool, and he began to produce his own telescopes that had magnifications up.  Optometric Science Democritus o He had the idea that light consist of material particles and was supported by Isaac Newton (~1704) and Rene Descartes (~1637).  Optometric Science Descartes o Rene Descartes had used a mechanical analogy of light by assuming that it consist of tiny particles. o From this hypothesis he had derived the correct expression of the refraction formula. o Descartes also mentioned that color could be a manifest of different angular velocities of rotation of the light particles and that color is a property inherent to the light itself.  Optometric Science Newton o He made a series of wonderful experiments in order to reveal the nature of light. o The best-known one is where he found that spectral colors can be extracted from white light by making use of the refraction of light when transmitted through a PRISM.  Optometric Science Newton o He believed that light was of a material origin consisting of minute particles and that an attraction of these towards the larger body (prism) was the cause of the refraction phenomenon. o He also demonstrated that light could be in fit of easy transmission or reflection that made it prone to be either transmitted or reflected. o Referred as Corpuscular Theory of Light.  Optometric Science Grimaldi o Fr. Franceso Grimaldi. In 1665, he examined transmission of light by a small hole and its passing of tiny obstacles, and he had observed that a small amount of light appeared in regions of expected shadow had it followed straight lines in accord with classical belief. o He called this phenomenon diffraction. He speculated whether light propagate in a wave-like fashion but eventually denied the possibility.  Optometric Science Grimaldi o An attempted analogy with sound, known to be waves, had previously been used to reject the hypothesis of light waves since it was found not to pass around corners in the same manner as sound. o Euler (1746) contributed to the theory of light waves and, in analogy with sound. Nevertheless, the diffraction experiments of Grimaldi had already shown that light propagation was not necessarily truly rectilinear.  Optometric Science Huygens Christiaan Huygens. In 1690, he believed in the wave-like nature of light and considered it to propagate as small spherical waves that add up to form a wavefront that afterwards acts as a source for new secondary waves..  Optometric Science Young, 1803 o Thomas Young explained that either cancellation or addition of wave amplitudes of light reflected from the two interfaces or interference phenomena. o He performed the Double-Slit experiment that proved that light act as a wave. o He also studied vision and found that accommodation was caused by changes in the shape of the eye lens.  Optometric Science Young, 1803 o Thomas Young suggested that the eye has a discrete number of light- sensitive elements with only three kinds of colour responses (red, green and blue–violet) so that other colours are seen via a proper combination of those. o A solid basis for the wave theory of light was formulated later by Fresnel (1819) who also did experiments on diffraction of light similar to those by Grimaldi and Newton.  Optometric Science Maxwell, 1873 o James Maxwell believed that light is a propagating wave of electric and magnetic fields. o The formulation of the theory of electromagnetism and in making the connection between light and electromagnetic waves. o Light is often identified with a broader spectrum beyond what is visible to the human eye -- to include infrared and ultraviolet radiation discovered as extensions to the visible spectrum.  Optometric Science Einstein, 1905 o Albert Einstein postulated that although light sometimes behaves like a wave, it also consists of discrete packets of energy that he called quanta. o He mentioned that light interacts with materials as if it consist of particles each carrying a tiny lump of energy. o These light quanta were later named photons by Lewis (1926) in analogy with elementary particles. Thanks!