Meaning
Diffraction criterion defining the minimum resolvable distance between two distinct points in an imaging system. The rayleigh limit occurs when the central maximum of the diffraction pattern from one point coincides with the first minimum of the second point. This value represents the fundamental physical boundary of an optical instrument’s resolution.
No amount of magnification can show more detail once this limit is reached.
Resolution Threshold
Aperture size and light wavelength are the only variables that change this boundary. A larger lens or a shorter wavelength allows for the separation of points that are closer together in the rayleigh limit.
Optical Performance
Manufacturers of microscopes and telescopes design their instruments to reach this level of clarity. When the rayleigh limit is achieved, the system is said to be diffraction limited.
Wavefront Quality
Imperfections in the glass or misalignments in the assembly will prevent a system from meeting its potential. Precision testing uses interferometry to measure how much the actual performance deviates from the theoretical ideal. Achieving the rayleigh limit in a production environment requires cleanroom assembly and high precision polishing.
Any dust or thermal distortion will scatter the light and blur the image, effectively reducing the resolution below the physical maximum.
