optic axis

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Related to Optical axis: focal length, visual axis


 [ak´sis] (pl. ax´es)
1. a line through a center of a body, or about which a structure revolves.
the second cervical vertebra. adj., adj ax´ial.
2. the position of the cylindrical part of a lens, used for correcting astigmatism; the range of values is from 0° to 180°.
celiac axis celiac trunk.
dorsoventral axis one passing from the posterior to the anterior surface of the body.
electrical axis of heart the preponderant direction of current flow through the heart, a consequence of the electromotive forces within the heart. It may be computed on either an instantaneous basis or a mean basis.
frontal axis an imaginary line running from right to left through the center of the eyeball.
axis of heart a line passing through the center of the base of the heart to the apex.
instantaneous electrical axis the electrical axis of the heart determined at a given point in time.
lead axis the imaginary direct line between the two electrodes of the bipolar leads or between the positive electrode and the reference point of the unipolar leads.
mean electrical axis the average direction of the activation or repolarization process during the cardiac cycle; it may be determined for any deflection (P, QRS, ST-T) and in the frontal, transverse, or sagittal plane.
optic axis
1. a line connecting the center of the anterior curvature of the cornea (anterior pole) with that of the posterior curvature of the sclera (posterior pole).
2. the hypothetical straight line passing through the centers of curvature of the front and back surfaces of a simple lens.
phlebostatic axis a point located by drawing an imaginary line from the fourth intercostal space at the sternum and finding its intersection with an imaginary line drawn down the center of the chest below the axillae.
Phlebostatic axis.
sagittal axis an imaginary line extending through the anterior and posterior poles of the eye.
visual axis an imaginary line passing from the midpoint of the visual field to the fovea centralis.
Axes of the eye. From Dorland's , 2000.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

op·tic ax·is

the axis of the eye connecting the anterior and posterior poles; it usually diverges from the visual axis by 5° or more.
Synonym(s): axis opticus [TA]
Farlex Partner Medical Dictionary © Farlex 2012

op·tic ax·is

(op'tik ak'sis) [TA]
The axis of the eye connecting the anterior and posterior poles; it usually diverges from the visual axis by five degrees or more.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
References in periodicals archive ?
For a monochromatic light at a certain wavelength, when the ray is not parallel to the optical axis, the light does not gather at the focal point of the lens but converges to a point on the plane passing through the focus and perpendicular to the axis; this plane is called the focal plane, as shown in Figure 4.
The coordinates of the point [A.sub.i] of the intersection of the optical axis of the camera with the bottom plane are determined by the substitution of the found value of the parameter [t.sub.i] into the equation (2):
In this paper, we consider reflection from a uniform slab with fixed orientation of the optical axis, [angle](n, s) [equivalent to] 0 = const, and reflection from the MM slab in which [phi] varies linearly with the coordinate y.
Therefore, we prefer side-firing fibers that offer smaller numerical apertures; however, reducing the divergence of the radiation cone for a side-firing fiber usually comes with the main lobe of radiation being less orthogonal to the optical axis of the fiber.
The symbols [[theta].sub.x] and [[theta].sub.y], respectively, denote the projection angle of the angle between the light ray and the optical axis.
However, the analysis of the optical axis perturbation properties for a certain UMS has not been reported before.
In the observation plane is guaranteed an even number of Fresnel's zones, in order to obtain a null propagated field [U.sub.0] ([x.sub.1], [y.sub.1], z) = 0 on the optical axis. With this condition, we are able to guarantee that the amplitude of the optical field of the opening and its complement are equal in magnitude with a phase difference of n at the very optical field, as was predicted by Babinet's principle, at the very optical field, as was predicted by Babinet's principle, [U.sub.1]([x.sub.1], [y.sub.1], n) = -[U.sub.2]([x.sub.1],[y.sub.1],n).
The PC NIKKOR series*1 consists of lenses that support a shift function, with which the optical axis is moved parallel to the image plane, and a tilt function, with which the optical axis is tilted in relation to the image plane.
In this study we aimed to evaluate PCO status and treatment required due to PCO obscuring the optical axis in patients 4-12 years of age who underwent pediatric cataract surgery without posterior capsulotomy or anterior vitrectomy.
Because the stage is designed to be supported from the bottom of the microscope near the optical axis and incorporates steel cross roller guides, it is twice as stable and durable as conventional stages.
If the target is not detected directly through the optoelectronic system of the seeker, the optical axis of the head will be automatically set according to the programmed motion and, as a result, the scope of scanned space will be increased.