Limit Resolution For Free

Resolving power or limit of resolution is the ability to distinguish two close objects as distinct. It is calculated by the formula 0.61 ?/ numerical aperture, where ? is the wavelength of light and numerical aperture is the light collecting ability of lens.

The factor of 1.22 applies to circular apertures like the pupil of your eye or the apertures in telescopes and cameras. When light passes through an aperture with diameter D, then diffraction limits the resolution to ? = 1.22?/D. If the angular separation of two sources is less than ?, they cannot be resolved.

If using a green light of 514 nm, an oil-immersion objective with an NA of 1.45, condenser with an NA of 0.95, then the (theoretical) limit of resolution will be 261 nm. As already mentioned, the FWHM can be measured directly from the PSF or calculated using: RFWHM = 0.51?/(NA).

Limit of Resolution means the smallest distance that may separate two points of an object and still permit their observation as distinct separate points.

The minimum angular separation of two sources that can be distinguished by telescope depends on wavelength of light and on the diameter of the telescope. The angle between the separation is known as limit of resolution or diffraction limit. The resolution limit is a dimensionless quantity.

For a microscope, the limit of resolution is given by, X=2A? where ? is the wavelength of light used, and A is the numerical aperture. Hence, substituting the values, X=2×0.

This occurs for two point objects separated by the angle ? = 1.22 ? / D, where ? 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.