an optical clock

Optics Timeline

Optics is the physical science that studies the origin and propagation of light, how it changes, what effects it produces, and other phenomena associated with it. This "Optics Timeline" highlights important events and developments in the science of optics from prehistory to the beginning of the 21st century. It also includes related developments in other fields and related milestones in the human worldview.


1912 — Development of the science of crystal analysis via X-ray diffraction

William Henry Bragg & William Lawrence Bragg

1913 — Demonstrated the presence of ozone in the upper atmosphere using spectroscopy

Charles Fabry

1913 — Developed Bragg's Law of X-ray diffraction used to determine the structure of crystals.

William Henry Bragg & William Lawrence Bragg

1913 — First to use X-rays to study breast cancer, leading to mammography.

Albert Solomon

1913 — Invention of the hot cathode x-ray tube

William David Coolidge

The hot cathode x-ray tube uses a thermionic tube (a heated cathode electron emitter) to replace the cold, or gas, tube.

1913 — Completion of the theory of atomic structure

Niehls Bohr

Completes theory of atomic structure - electrons reside in particular orbitals around the nucleus, a change in orbital causes the absorption or emission of a discrete amount (quanta) of electromagnetic energy, equal the difference in energy of the orbitals.

1914 — Found the atomic spectral series of hydrogen predicted by Ritz from Balmer's visible series.

Theodore Lyman

1915 — Extended Niels Bohr's atomic theory to include elliptical paths for electrons.

Arnold Sommerfeld

1915 — Awarded the Nobel prize for their work analyzing crystal structures using X-rays.

William Henry Bragg & William Lawrence Bragg

1915 — Built a grating ruling engine that makes equally spaced grooves in a surface.

A. A. Michelson

1916 — Einsteins photoelectric equation confirmed

R. A. Millikan

Confirmed Einstein's phtoelectric equation and obtained an accurate value for Planck's constant, h, which relates the energy carried by a single packet of electromagnetic radiation with its frequency (energy=Planck's constant*frequency).

1916 — Formula for the structure of spectral lines devised

Arnold Sommerfeld

Devised a formula for the structure of spectral lines (light emitted or absorbed by an atom when an electron transitions to a different allowed energy levels), and a general quantum theory of spectral lines.

1917 — Fundamental studies on how light interacts with matter performed

Albert Einstein

Performs fundamental studies on how light interacts with matter, discovering the principles of spontaneous and stimulated emission.

1919 — Eclipse of the sun observed

Sir Arthur Eddington

Observed an eclipse of the Sun to determe the apparent position of stars that appeared close to the Sun's disk, and concluded that the path of light is bent by the Sun's gravitational field in accordance with predictions of Einstein's theory of General Relativity.