Description

• Diffraction limits resolution. • For a circular aperture, lens, or mirror, the Rayleigh criterion states that two images are just resolvable when the center of the diffraction pattern of one is directly over the first minimum of the diffraction pattern of the other. • This occurs for two point objects separated by the angle θ = 1.22 λ / D, where λ is the wavelength of light (or other electromagnetic radiation) and D is the diameter of the aperture, lens, mirror, etc. This equation also gives the angular spreading of a source of light having a diameter D. From http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/Raylei.html Average vision is 5 × 10⁻⁴ radians or 103.13 arcseconds or a ratio of 1:2000 [1 unit resolvable at 2000 units]