optical axis

In optics, the term optical axis is used to define a direction along which there is some degree of rotational symmetry. It can be used in several contexts:In an optical system, the optical axis is an imaginary line that defines the path along which light propagates through the system. For a system composed of simple lenses and mirrors, the axis passes through the center of curvature of each surface, and coincides with the axis of rotational symmetry. The optical axis is often coincident with the system's mechanical axis, but not always, as in the case of off-axis optical systems.In an uniaxial birefringent material, the optical axis is the axis of optical anisotropy.For an optical fiber, the optical axis is along the center of the fiber core, and is also known as the fiber axis.
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1. Of a refractive or reflective optical element, the straight line that is coincident with the axis of symmetry of the surfaces. Note: The optical axis of a system is often coincident with its mechanical axis, but it need not be, e.g., in the case of an off-axis parabolic reflector used to transmit signals to, or receive signals from, a geosynchronous satellite. Contrast with off-axis optical system. 2. In a lens element, the straight line which passes through the centers of curvature of the lens surfaces. [JP1] 3. In an optical system, the line formed by the coinciding principal axes of the series of optical elements. [JP1] 4. In an optical fiber, synonym fiber axis , which is the preferred term.

In a lens element, the straight line which passes through the centres of curvature of the lens surfaces. In an optical system, the line formed by the coinciding principal axes of the series of optical elements. 1/7/70

Pour une lentille ou un miroir courbe: ligne droite passant par le centre de courbure et normale à la surface. Pour un système optique: ligne formée par les axes optiques des principaux éléments consécutifs. 1/7/70

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