Angular
resolution or spatial
resolution describes the ability of any image-forming device such as an optical
or radio telescope, a microscope, a camera, or an eye, to distinguish small
details of an object, thereby making it a major determinant of image resolution.
The imaging system's resolution can be limited either by aberration or by diffraction causing blurring of the image. These two phenomena have different origins and are unrelated. Aberrations can be explained by geometrical optics and can in principle be solved by increasing the optical quality — and consequently the cost — of the system. On the other hand, diffraction comes from the wave nature of light and is determined by the finite aperture of the optical elements. The lens' circular aperture is analogous to a two-dimensional version of the single-slit experiment. Light passing through the lens interferes with itself creating a ring-shape diffraction pattern, known as the Airy pattern, if the wavefront of the transmitted light is taken to be spherical or plane over the exit aperture.
The interplay between diffraction and aberration can be characterised by the point spread function (PSF). The narrower the aperture of a lens the more likely the PSF is dominated by diffraction. In that case, the angular resolution of an optical system can be estimated (from the diameter of the aperture and the wavelength of the light) by the Rayleigh criterion defined by Lord Rayleigh:
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Raleigh
A new approach using lasers and calculus equations allows overlapping images to be separated as has been accomplished through recent research. See this link:
Definition of Terms
Resolving
power is the ability of
an imaging device to separate (i.e., to see as distinct) points of an object
that are located at a small angular distance or it is the power of an optical
instrument to separate far away objects, that are close together, into
individual images. The term resolution or minimum resolvable distance
is the minimum distance between distinguishable objects in an image, although
the term is loosely used by many users of microscopes and telescopes to describe
resolving power. In scientific analysis, in general, the term
"resolution" is used to describe the precision with which any
instrument measures and records (in an image or spectrum) any variable in the
specimen or sample under study.
Explanation
The imaging system's resolution can be limited either by aberration or by diffraction causing blurring of the image. These two phenomena have different origins and are unrelated. Aberrations can be explained by geometrical optics and can in principle be solved by increasing the optical quality — and consequently the cost — of the system. On the other hand, diffraction comes from the wave nature of light and is determined by the finite aperture of the optical elements. The lens' circular aperture is analogous to a two-dimensional version of the single-slit experiment. Light passing through the lens interferes with itself creating a ring-shape diffraction pattern, known as the Airy pattern, if the wavefront of the transmitted light is taken to be spherical or plane over the exit aperture.
The interplay between diffraction and aberration can be characterised by the point spread function (PSF). The narrower the aperture of a lens the more likely the PSF is dominated by diffraction. In that case, the angular resolution of an optical system can be estimated (from the diameter of the aperture and the wavelength of the light) by the Rayleigh criterion defined by Lord Rayleigh:
Two point sources are regarded
as just resolved when the principal diffraction maximum of one image coincides
with the first minimum of the other. If the distance is greater, the two points
are well resolved and if it is smaller, they are regarded as not resolved.
Rayleigh defended this criteria on sources of equal strength.
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A new approach using lasers and calculus equations allows overlapping images to be separated as has been accomplished through recent research. See this link:
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