An Etymological Dictionary of Astronomy and Astrophysics

A plane curve whose Cartesian coordinates are given in parametric form by the → Fresnel integrals. Cornu’s spiral is an auxiliary tool for calculating the Fresnel integrals. It is
particularly used for the calculation of the diffraction of light at the straight edge of a flat screen or at a straight slit. It is characterized by the fact that the angle it makes with the abscissa axis is proportional to the square of the distance along the curve from the origin of coordinates. Cornu’s spiral comprises two branches, symmetrical with respect to the origin and winding asymptotically on the points (0.5,0.5) and (-0.5,-0.5) respectively. Also known as the → clothoid or Euler’s spiral.

See also: Named after the French physicist Alfred Cornu (1841-1902); → spiral.