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are then created at that centroid and the PSF energy within each circle is calculated and divided by the total energy. As the circle increases in radius, more of the PSF energy is enclosed, until the circle is sufficiently large to completely contain all the PSF energy. The encircled energy curve
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of the optical system projecting the beam. As in star image PSF's, the linear spreading of the beam expressed as encircled energy is divided by the projection distance to give the angular spreading.
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Encircled energy is also used to quantify the spreading of a laser beam at a given distance. All laser beams spread due to the necessarily limited
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An alternative to encircled energy is ensquared energy, typically used when quantifying image sharpness for digital imaging cameras using
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A typical criterion for encircled energy (EE) is the radius of the PSF at which either 50% or 80% of the energy is encircled. This is a
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Encircled energy is calculated by first determining the total energy of the PSF over the full image plane, then determining the
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or PSF), calculation of the encircled energy of the resulting image gives the distribution of energy in that PSF.
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at a given range. For example, if a single star is brought to its sharpest
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giving the smallest image possible with that given lens (called a
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126:, pp. 383–385. New York: McGraw-Hill, Inc., 2000.
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55:of the PSF. Circles of increasing
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24:is a measure of concentration of
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79:optical system performance.
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122:Modern Optical Engineering
67:dimension, typically in
103:Point spread function
46:point spread function
157:Engineering concepts
162:Optical quantities
147:Geometrical optics
119:Smith, Warren J.,
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75:when specifying
22:encircled energy
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152:Physical optics
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77:astronomical
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73:arc-seconds
69:micrometers
141:Categories
114:References
124:, 3rd ed.
108:Airy disc
97:See also
84:aperture
53:centroid
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91:pixels
65:linear
57:radius
28:in an
26:energy
18:optics
40:by a
38:focus
34:laser
30:image
128:ISBN
42:lens
16:In
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