C Light & Optical Systems Presentation PDF

UNIT C LIGHT & OPTICAL SYSTEMS 1.1 The Challenge of Light Since the earliest times, light has been studied. The Greek Scientist Archimedes developed a plan to reflect light to burn enemy ships. However, this has neither been proven or disproved. Recent experiments have shown that if it is true, t...

UNIT C LIGHT & OPTICAL SYSTEMS 1.1 The Challenge of Light Since the earliest times, light has been studied. The Greek Scientist Archimedes developed a plan to reflect light to burn enemy ships. However, this has neither been proven or disproved. Recent experiments have shown that if it is true, the worst an enemy ship would receive is a small burn PYTHAGORAS Pythagoras tried to explain how we see light. He believed beams came from a person’s eyes in straight lines. When they hit the object, that object was seen. Problem: that would make the assumption you would be able to see objects in the dark. EUCLID Euclid was a Greek mathematician. He was fascinated by shape and created a new type of mathematics called geometry that described shapes and angles. Euclid wrote a book called Optiks about the geometry of light and seeing. Euclid used his observations of light in the world around him to make some predictions about light rays: - Light rays are straight lines. - You see an object in a particular direction because light rays come from that direction. PTOLEMY ❏ Ptolemy - astronomer who described that light beams bend when they go from air to glass. ❏ Today we refer to this as refraction. The Law of Refraction al-HAYTHEM ❏ al-Haytham was the first to accurately describe how vision worked and that light bounces off objects then travels to the eye - thus Pythagoras’ theory was dismissed. ❏ ❏ He was a pioneer who made many contributions to understanding vision, optics and light. He used experiments following the scientific method to draw conclusions. SIR ISAAC NEWTON ❏ Sir Isaac Newton was interested in the colors of the rainbow. He discovered that when light passes through a prism, light is split up into different colors. OLE ROEMER ❏ Galileo attempted to measure the speed of light by having two individuals stand on different hilltops. ❏ One would uncover a lantern and the other uncover there’s when they saw the light. The problem was that the speed of light was too fast and distance too short to determine the speed. Ole Roemer was able to determine the speed of light by examining the moon IO as it revolved around Jupiter. He determined it to be 227,000 km/s. Lower than the actual of 300,000 km/s. ALBERT A. MICHELSON Albert Michelson used a three-sided mirror, light source and an observer to calculate the speed of light. By spinning the mirror and using mathematics he was able to determine the speed of light to be 299,798 km/s. He presumably did this between hilltops spread great distances. Light Year A light-year is a unit of distance, not time. A light-year is how astronomer measure distance in space. It is defined by how far a beam of light travels in one year in a vacuum (space) 1 light year = 9.64 trillion miles Think of it as the bigger, badder cousin of the centimeter, meter and kilometer. Light Speed, Fast, but Slow https://interestingengineering.com/video/the-speed-of-light-this-cool-visual-shows-how-fast-but-also-slow-it-is Properties of Light ● Light travels in straight lines ● Light can be reflected ● Light can bend ● Light is a form of energy 1.2 Optical Devices Optical Device Any technology that uses light Simple as a mirror Complex as the James Webb Space telescope Can you think of other technologies that use light? Optical Devices ❏ Fibre optic cable ❏ Computers in pin and chip machines when you use a debit/credit card carries info through light impulses ❏ Light bulbs ❏ Solar powered devices ❏ Medicine - lasers for incisions, cameras, brain imaging ❏ 3D printing ALESSANDRO DELLA SPINA First Optical Devices ❏ ❏ 1300 A.D. and Italian Monk created the world’s first eyeglasses to correct vision. His name, Alessandro della Spina. HANS & ZACHARIAS JANSSEN It is believed that the father and son team of Hans and Zacharias Janssen of the Netherlands first built a microscope in about 1505. ANTONIE VAN LEEUWENHOEK Antonie van Leeuwenhoek (Denmark), a Dutch scientist, experimented with own microscope in the 17th Century. He looked at things like pond water, blood, and plaque from his own teeth. What he saw amazed him and called these “little animalcules”...... which was the first descriptions of bacteria, algae, and red blood cells. Thus began the study of “MICROBIOLOGY” Microscopes Uses lenses to create an enlarged image of a tiny object. Telescopes Both magnify and collect light. Magnifying power of telescopes allowed Galileo to see Venus and faint objects around Jupiter. He also saw mountains and craters on the moon. Types of Telescopes Reflecting Telescopes Refracting Telescopes (use mirrors, smaller) (use lenses and mirros, easier to use) Reflecting Telescope Refracting Telescope Binoculars Binoculars are two refracting telescopes fixed together. Binoculars are not as powerful, but more convenient to use. Since they are refracting, they use refracti ng lenses. Binoculars Binoculars work by using a pair of identical telescopes side by side, which allows for a wider field of view and a three-dimensional image. The lenses in each telescope gather and focus light, which is then magnified by the eyepieces. The eyepieces allow the viewer to adjust the focus and distance between the lenses to match the distance between their eyes, creating a single, clear image.