Wave optics
Introduction
Wave optics, also known as physical optics, is the branch of optics that studies interference, diffraction, polarization, and other phenomena for which the ray approximation of geometric optics is not valid. This usage tends not to include effects such as quantum noise, which is studied in the quantum theory of light.
Wave Theory of Light
The wave theory of light was a way of explaining the interference, diffraction, and polarization of light, as observed around the time of the scientific revolution. Huygens (1629–1695) is the most often credited with the creation of this theory. His work included some reasoned assumptions about the nature of light, including:
- Light travels in straight lines.
- Light is a transverse wave.
- The speed of light is much greater than the speed of sound.
Interference
Interference is the superposition of two or more waves that results in a new wave pattern. As most commonly used, the term usually refers to the interference of waves which are correlated or coherent with each other, either because they come from the same source or because they have the same or nearly the same frequency.
Diffraction
Diffraction refers to various phenomena that occur when a wave encounters an obstacle or a slit. It is defined as the bending of waves around the corners of an obstacle or aperture into the region of geometrical shadow of the obstacle. In classical physics, the diffraction phenomenon is described as the apparent bending of waves around small obstacles and the spreading out of waves past small openings.
Polarization
Polarization is a property of waves that can oscillate with more than one orientation. Electromagnetic waves, such as light, and gravitational waves exhibit polarization. By convention, the polarization of light is described by specifying the direction of the wave's electric field. When light is unpolarized, the direction of the electric field is a random value in the plane perpendicular to the direction of wave propagation.
Applications of Wave Optics
Wave optics is used in many areas of physics and engineering including laser physics, fiber optics, and optical coherence tomography. It is also essential in the interpretation of modern interferometry, holography, and x-ray diffraction experiments.