Diffractionlimite

Diffractionlimite refers to the theoretical limit of resolution achievable by an optical instrument, determined by the wave nature of light. This limit is not due to imperfections in the optics, such as aberrations or manufacturing flaws, but rather an inherent consequence of diffraction. When light passes through an aperture or reflects off a surface, it spreads out, a phenomenon known as diffraction. This spreading causes point sources of light, even if perfectly focused, to appear as a small, blurred disc surrounded by faint rings.

The ability of an optical system to distinguish between two closely spaced objects is therefore fundamentally limited by the size of these diffraction patterns. This diffraction-limited resolution is typically expressed in terms of angular resolution or spatial resolution. For a circular aperture, the angular resolution is often described by the Rayleigh criterion, which states that two point sources are just resolvable when the center of the diffraction pattern of one source is directly over the first minimum of the diffraction pattern of the other.

Factors influencing the diffraction limit include the wavelength of light used and the diameter of the aperture or objective lens. Shorter wavelengths of light and larger apertures lead to a smaller diffraction pattern and thus better resolution, meaning finer details can be distinguished. In practice, achieving diffraction-limited performance requires that the optical system's aberrations are negligible compared to the effects of diffraction. Many high-quality telescopes and microscopes are designed to operate at or near their diffraction limit.