Light & Optical Systems

• Ancient Times:

  • China and Greece were the first to use mirrors
  • Archimedes planned for the use of mirrors in war
  • Pythagoras believed light was beams of light that came from our eyes
  • Discovered that light was reflective and travels in straight lines
• 1st Century:

  • Ptolemy discovered that light bends from air to glass
• Middle Ages (1000 AD):

  • Al-Haythem wrote a book to explain optics and accurately describe how vision worked
• 1670:

  • Isaac Newton showed that white light is a mixture of different colors of light
  • Isaac Newton created the color sequence ROYGBIV (red, orange, yellow, green, blue, indigo, violet)
• 1676:

  • Ole Romer determined the speed of light
• 1920's:

  • Alberta A. Michelson determined the speed of light more accurately
• Four basic properties of light:

  • Light travels in straight lines
  • Light can be reflected
  • Light can be bent
  • Light is a form of energy
• 1300 AD:

  • Alessandra Della Spina wore the first pair of eyeglasses
• 1595:

  • Zacharias Jansen built the first microscope
• 17th Century (1600):

  • Antonie Van Leeuwenhoek discovered cells using a simple microscope
  • Galileo Galilei invented the refracting telescope
  • Isaac Newton invented the reflecting telescope
• 1854:

  • Ignatio Porro created the prism erecting system (simple binoculars)
• 1985:

  • The first Endoscope was used
• 1990:

  • The Hubble Space Telescope launched, named after Edwin Hubble, who believed in an "expanding" universe forming the basis of the Big Bang theory
• 2021:

  • The James Webb Telescope was launched after 20-30 years of construction
• Luminous means a light source.
• Concave lenses diverge light rays while convex lenses converge them.
• Law of Reflection - The angle of incidence equals the angle of reflection.
• Law of refraction: When light moves from one substance to another, it bends.
• Rays can help explain how shadows are formed when an object blocks the ray of light.
• Ray diagrams can help demonstrate brightness or intensity of light through changes of distance.
• Light Interacts with Materials: Translucent - A frosted glass window. Transparent - A glass window. Opaque - A wooden door.
• Types of reflection: Diffuse reflection occurs if the light hits a rough or uneven surface (Scattered.)
• Types of reflection: Regular reflection occurs when light hits a smooth surface, the light reflects to an opposite angle to the angle hits.
• Light coming from a light source is called the incident ray and the light that bounces off the surface is called a reflected ray.
• A line that is perpendicular (90 degrees with the surface) is the normal line.
• The angle between the incident ray and the normal line is called the angle of incidence.
• The angle between the reflected ray and the normal line is called the angle of reflection.