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Cylindrical lenses. A cylindrical lens is a lens which focuses light into a line instead of a point as a spherical lens would. The curved face or faces of a cylindrical lens are sections of a cylinder, and focus the image passing through it into a line parallel to intersection of the surface of the lens and a plane tangent to it along the cylinder's axis.
In 3D PALM/STORM, a type of optical super-resolution microscopy, a cylindrical lens can be introduced into the imaging system to create astigmatism, which allows measurement of the Z position of a diffraction-limited light source. [24] Laser line levels use a cylindrical lens to spread a laser beam from a point into a line.
The principal ray or chief ray (sometimes known as the b ray) in an optical system is the meridional ray that starts at an edge of an object and passes through the center of the aperture stop. [5] [8] [7] The distance between the chief ray (or an extension of it for a virtual image) and the optical axis at an image location defines the size of ...
The basic principles behind optical waveguides can be described using the concepts of geometrical or ray optics, as illustrated in the diagram. Light passing into a medium with higher refractive index bends toward the normal by the process of refraction (Figure a.). Take, for example, light passing from air into glass.
A diagram showing how to find the optical center O of a spherical lens. N and N' are the lens's nodal points. The optical center of a spherical lens is a point such that if a ray passes through it, the ray's path after leaving the lens will be parallel to its path before it entered.
A ray tracing diagram for a simple converging lens. A device which produces converging or diverging light rays due to refraction is known as a lens. Thin lenses produce focal points on either side that can be modeled using the lensmaker's equation. [5]
Each optical element (surface, interface, mirror, or beam travel) is described by a 2 × 2 ray transfer matrix which operates on a vector describing an incoming light ray to calculate the outgoing ray. Multiplication of the successive matrices thus yields a concise ray transfer matrix describing the entire optical system.
For a thin lens in air, the distance from the lens to the spot is the focal length of the lens, which is commonly represented by f in diagrams and equations. An extended hemispherical lens is a special type of plano-convex lens, in which the lens's curved surface is a full hemisphere and the lens is much thicker than the radius of curvature.