Photonics Dictionary

1. A solid figure whose base is a circle and whose sides taper upward evenly to a point or apex. Light rays diverging from or converging upon a point are sometimes referred to as a cone of light. 2....

The form taken by scattered light, as a result of the Tyndall effect.

Specified curved optic intended for maximum collection of light, including off-axis rays, before leaving the exit aperture.

The range of angle or solid angle values by which light may enter an optical system.

The second adjustable iris diaphragm in an optical system. In the common microscope condenser system, it usually is located beneath the substage condenser on a transmitted light microscope. When the...

The angular width of a radiation beam. With respect to a conical beam of light, it is the vertex angle of the cone. The beamwidth is a measure of the rate of divergence or convergence of a light...

A type of fiber optic connector consisting of two cone-shaped ferrules aligned by a mating sleeve.

1. A group of optical fibers that are fused and then treated to produce a vacuum-tight optical fiber cone or plate. 2. An artificial crystal in its raw state, after generation but prior to cutting or...

Scanning characterized by the generation of a plane or right circular cone with a vertex angle of about 180° by the direction of maximum radiation.

A parabolic, elliptical, hyperbolic or circular section created when a solid cone is intersected by a plane.

A lens with a surface that is a cone instead of the usual sphere.

A condenser that forms a hollow cone-shaped beam of light with its focal point in the plane of the specimen. If it is used with an objective having a numerical aperture lower than the minimum...

A technique whereby the sample is illuminated by a hollow cone of light larger than the acceptance angle of the objective, so that only scattered light is seen, revealing any irregularities of the...

The restricting aperture located at the front of the lens. It is usually defined as the maximum diameter of the entrance cone at the front vertex, for the specified field of view at infinity focus.

A narrow cone of light rays that diverge from a point source or converge to an image point.

The small central portion of the human retina that is responsible for providing the clearest, and most distinct aspects of human vision. Light from an object directly forms an image on the macula...

Vision at intermediate levels of luminance between photopic and scotopic vision, where both retinal cones and retinal rods are stimulated for visual use in dim, low light situations. See also...

An instrument consisting essentially of a tube 160 mm long, with an objective lens at the distant end and an eyepiece at the near end. The objective forms a real aerial image of the object in the...

A strip or annulus of glass coated with a semitransparent material such as inconel. The coating thickness, and as a result its transmission, varies linearly as a function of distance. The neutral...

The sine of the vertex angle of the largest cone of meridional rays that can enter or leave an optical system or element, multiplied by the refractive index of the medium in which the vertex of the...

Oleophobic is a term used to describe substances or materials that repel or resist oils. The word oleophobic comes from the Greek words "oleo," meaning oil, and "phobos," meaning fear. Oleophobic...

Opsins are a group of light-sensitive proteins found primarily in the retinas of vertebrate and invertebrate eyes, as well as in other light-sensitive tissues. These proteins play a crucial role in...

An otoscope is a medical device used by healthcare professionals, particularly ear, nose, and throat (ENT) specialists, primary care physicians, and pediatricians, to examine the ear canal and...

Vision by means of retinal cones; color vision. Relatively high levels of luminance are required for photopic vision.

The compression and intensification of a laser pulse of a specific width into a smaller pulse width. A spherical cavity, in conjunction with a beam compressor, is efficient for pulse amplification....

Half the vertex angle of the cone of light emitted by a fiber.

The restricting opening at the rear of a lens or prism that is commonly defined as the maximum diameter of the emergent cone for the specified field of view, at infinity focus.

The technique for measuring the index profile of an optical fiber by scanning the entrance face with the vertex of a high numerical aperture cone and measuring the change in power of refracted...

Rockwell hardness (Rc) refers to a method for measuring the hardness of a material, primarily metals, using an indentation test. It is named after the Rockwell scale, which was developed by Stanley...

Vision by means of retinal rods; vision of the dark-adapted eye. In scotopic vision, the level of luminance is so low that the retinal cones are not stimulated, and there is no color vision.

The unit solid angle subtended at the center of a sphere by an area on its surface equivalent to the square of the radius; the unit of solid angular measurement, often used in problems of...

Thermal interface materials (TIMs) are substances or compounds used to enhance the thermal conductivity between two surfaces in contact. These materials are primarily employed in electronic devices,...

The basis of color vision in the human eye. Three types of cones have been identified, each having a unique spectral response (red, green and blue).

A dark-field microscope used to view extremely small objects. These objects are suspended in a gas or liquid in an enclosure having a black background. A convergent pencil of bright light enters from...