9. Glossary

Impulse Response (IR)

Function describing the image of a point by an optical instrument. Also called Point Spread Function (PSF).

Optical Transfer Function (OTF)

Function describing the image of a point by an optical instrument in Fourier space. The optical transfer function is the Fourier transform of the FEP.

diffraction limit

Highest spatial frequency that can be transmitted by an imaging optical system. In other words, the parameter corresponding to the upper limit of spatial frequencies for which the FTO modulus is non-zero.

atmospheric turbulence

Complex vortex movements in the atmosphere. In this article, by extension, we refer to atmospheric turbulence as the spatial and temporal inhomogeneities of the refractive...