Shedding Light on Optics

Optics: The Branch of Physics that Studies Light

• Optics is a branch of physics that studies the properties and behavior of light, including its interaction with matter and the construction of instruments that use or detect it.

• Optics describes the behavior of visible, ultraviolet, and infrared light, and other forms of electromagnetic radiation such as X-rays, microwaves, and radio waves.

• Geometric optics is a simplified model that treats light as a collection of rays that travel in straight lines and bend when they pass through or reflect from surfaces.

• Physical optics is a more comprehensive model of light that includes wave effects such as diffraction and interference.

• Quantum optics deals with the application of quantum mechanics to optical systems, and light is modeled as a collection of particles called photons.

• Optics is relevant to and studied in many related disciplines including astronomy, engineering, photography, and medicine.

• The earliest lenses, made from polished crystal, date back to 2000 BC, and lenses from Rhodes date around 700 BC.

• Greek philosophers developed two opposing theories on how vision worked, the intromission theory and the emission theory.

• In the early 17th century, Johannes Kepler expanded on geometric optics in his writings, covering lenses, reflection, and the principles of pinhole cameras.

• In the late 1660s and early 1670s, Isaac Newton expanded Descartes's ideas into a corpuscle theory of light, famously determining that white light was a mix of colors that can be separated into its component parts with a prism.

• Young's double-slit experiment showed that light followed the superposition principle, which is a wave-like property not predicted by Newton's corpuscle theory.

• Classical optics is divided into two main branches: geometrical (or ray) optics and physical (or wave) optics.Overview of Optics

• Geometric optics deals with the propagation of light rays in a straight line and their reflection and refraction from surfaces.

• Spherical mirrors focus light at a common point, while other curved surfaces cause aberrations in the focus.

• Refraction occurs when light passes through an area with a changing index of refraction, which allows for lenses and focusing of light.

• The index of refraction of a medium is related to the speed of light in that medium.

• Lenses produce converging or diverging light rays due to refraction, characterized by their focal length.

• Ray tracing can be used to show how images are formed by a lens.

• Light is considered to propagate as a wave in physical optics, which predicts phenomena such as interference and diffraction.

• Many simplified approximations are available for analyzing and designing optical systems.

• Numerical modeling techniques can be used to model the propagation of light in systems that cannot be solved analytically.

• Superposition and interference of waves can result in constructive or destructive interference, producing bright and dark fringes in regular patterns.

• Interferometry is the science of measuring these patterns, usually to make precise determinations of distances or angular resolutions.

• The appearance of thin films and coatings is directly affected by interference effects.Overview of Physical Optics

• Thin films can create low reflectivity over a broad band or extremely low reflectivity at a single wavelength using constructive interference.

• Diffraction is the process where light interference is most commonly observed, and it was first described in 1665 by Francesco Maria Grimaldi.

• X-ray diffraction uses atoms in a crystal with regular spacing at distances on the order of one angstrom.

• Diffraction effects limit the ability of an optical detector to optically resolve separate light sources.

• Dispersion occurs when different frequencies of light have different phase velocities, due either to material properties or to the geometry of an optical waveguide.

• The separation of colors by a prism is an example of normal dispersion.

• Polarization is a general property of waves that describes the orientation of their oscillations.

• Circularly polarized waves can rotate rightward or leftward in the direction of travel, and which of those two rotations is present in a wave is called the wave's chirality.

• Media that have different indexes of refraction for different polarization modes are called birefringent.

• Media that reduce the amplitude of certain polarization modes are called dichroic.

• Non-birefringent methods to rotate the linear polarization of light beams include the use of prismatic polarization rotators.

• The atmosphere prevents optimal resolution from being achieved in the visible spectrum due to the atmospheric scattering and dispersion which cause stars to twinkle.Overview of Optics

• Optics is the branch of physics that studies the properties and behavior of light.

• Polarization effects occur when light interacts with materials that affect the orientation of the electric fields of the light waves.

• Modern optics deals with the electromagnetic or quantum properties of light and includes subfields such as quantum optics, crystal optics, and non-linear optics.

• Lasers emit light through a process called stimulated emission and have found utility in a variety of applications, including fiber-optic communication, laser printers, and laser hair removal.

• The Kapitsa-Dirac effect causes beams of particles to diffract as a result of meeting a standing wave of light.

• Optics is part of everyday life, with applications in eyeglasses, cameras, and optical communication, among others.

• The human eye functions by focusing light onto the retina, which contains photoreceptor cells called rods and cones that are sensitive to different aspects of light.

• Defects in vision can be corrected using corrective lenses, which are measured in diopters and can correct for presbyopia, hyperopia, myopia, and astigmatism.

• Optical illusions are characterized by visually perceived images that differ from objective reality and can be caused by physical effects, physiological effects, or cognitive illusions.

• Compound optical instruments, such as microscopes and telescopes, combine mirrors, prisms, and lenses for practical uses.

• Optics has practical applications in illumination engineering, photonics, and optoelectronics, among others.

• Nonlinear optics is an area of research that has developed in the last several decades due to advances in laser technology.