defocus

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defocus

(de-fo'kus) [L. de, away from, + focus, hearth]
The blurring of a visual image caused by spherical aberration, chromatic aberration, or diffraction. Also called optical defocus. Synonym: optical defocus

optical defocus

Defocus.

defocus

To put or go out of focus.
hyperopic defocus State of the eye in which the retinal image is focused behind the retina. It may occur when placing a negative lens in front of an emmetropic presbyopic eye; in an uncorrected presbyopic hyperope; in a high hyperope unable to overcome the ametropia by accommodating; or as an accommodative lag in an uncorrected or corrected myope, as well as in an emmetrope viewing a near object. See lag of accommodation; over-correction.
myopic defocus State of the eye in which the retinal image is focused in front of the retina. It may occur when placing a positive lens in front of an emmetropic eye; in an uncorrected or undercorrected myopic eye; or if there is a lead of accommodation, as is the case in some individuals viewing a distant object. See lead of accommodation; under-correction.
References in periodicals archive ?
The correction factor at each Ps angle depends on the 2th position and width or size of the receiving slit and collimator because the smaller the collimator size and larger the receiving slit, the smaller is the defocusing error, though larger receiving slits decrease the angular resolution.
1(a)), the defocusing (the broadening) of a beam due to the LQPE (Fig.
For a quadratic phase error, in the smeared image the energy tends to be spread uniformly over the distance of the smear for an unweighted aperture, and the sharpness of target image achieves its maximum value when the moving target is ideally focused [29], which makes it possible to estimate its azimuth velocity component by using symmetric defocusing filters.
The increased qualitative and quantitative awareness offered by the three-dimensional ray tracing assists in explaining certain phenomena not clearly seen or understood by the experiments alone, including focusing and defocusing.
The present investigation is concerned with laser power, welding speed and defocusing distance and their effects on the fusion zone shape and micro- structure of SUS301L stainless steel overlap joints.
In [section]4 a similar study is presented for the focusing and the defocusing NLS equation.
Moreover, the development of ME sense of futurity is to be viewed as the increase in the level of abstractness, hence as the evolution of former conceptual structure via defocusing of the divine conceptual subject.
Cameras are protected because the system instantly recognizes the repositioning, covering, or defocusing of a camera.
Ironically, to eliminate autofocusing systems, they devised a defocusing lens.
Bleeding was controlled by increasing the spot size on the micromanipulator and defocusing the laser beam.
When companies are acquiring other companies there is always a defocusing of strategy and customers inevitably get left in the lurch," he said.