Photonics Dictionary: L

Transparent matter that usually is drawn into a cylindrical, pyramidical or conical shape through which light is channeled from one end to the other by total internal reflections. Optical fibers are...

The generic term applied to all sources of visible radiation from burning matter to ionized vapors and lasers, regardless of the degree of excitation.

An LED, or light emitting diode, is a semiconductor device that emits light when an electric current passes through it. LEDs are widely used in various applications due to their energy efficiency,...

Technology that relies on a highly efficient photodetector that can detect incoming light signals at one frequency and transmit outgoing signals at another, thus permitting the sending and receiving...

The intensity distribution seen when scanning the image of a line, in the direction perpendicular to that line.

A linear positioning stage, also known as a linear stage or translation stage, is a precision mechanical device used to accurately move and position objects along a linear axis. These stages are...

Linear receive optics typically refers to the optical components and systems used in the reception (detection) of linearly polarized light signals in various applications, such as optical...

Linewidth, also known as spectral linewidth or line width, refers to a measure of the width of a frequency spectrum of a signal or a resonance. It indicates the range of frequencies over which the...

A defect in the cleaved end face of an optical fiber, in the form of a sharp protrusion at the edge of the fiber.

Multimode straight fiber capable of transporting linearly polarized light with any incident polarization angle, and in which no form of internal stress can develop that could lead to birefringence.

Liquid crystals are a state of matter that exhibits properties intermediate between those of conventional liquids and solid crystals. In a liquid crystal, the molecules are ordered like those in a...

A liquid crystal light valve (LCLV), also known as a spatial light modulator (SLM), is an optical device that modulates the intensity, phase, or polarization of light passing through it using liquid...

An optical fiber with a hollow core filled with a liquid material that has a higher refractive index than the solid surrounding it.

Liquid marble refers to a unique form of microscale liquid encapsulation, where small droplets of liquid are coated with a fine layer of hydrophobic powder, such as silica nanoparticles or Teflon....

A crystal often used for windows and refracting components in the ultraviolet, visible and infrared. Characteristically, this form has excellent transmission from 0.14 to 6.0 µm.

A device used to evaluate the quality of fiber optic splices made in the field by injecting light into the cladding of the fiber and measuring the output at the other end of the splice.

A fiber optic component or system designed in such a way that it can be operated by people without specialized knowledge of the field.

A long-pass filter is an optical filter that allows longer wavelengths of light to pass through while blocking or attenuating shorter wavelengths. These filters are designed to transmit light with a...

In fiber optic communications systems, generally one that operates between 1000 and 1700 nm.

A dye laser cell configuration in which the dye flows in the direction of the axis of the laser, yielding symmetrical energy distribution but small repetition rates.

In fiber optic cable, containment of the fiber or fibers within an outer protective tube in which they can move to some extent. The interstices usually are filled with an insulating material. See...

The Lorentz oscillator model is a theoretical model used in physics to describe the response of a charged particle (such as an electron) to an oscillating electric field. It is particularly employed...

A subtractive colorimeter that expresses a liquid's or object's color as a combination of three colors. These colors are developed through viewing the specimen object through three series of slides,...

Term used to describe an optical surface that contacts the test glass only at its edges.

Optical fiber that transmits a greater percentage of input light than does high-loss step-index fiber. Low-loss fiber requires higher purity materials and a more sophisticated drawing process and...

A lumen is a unit of measurement used to quantify the amount of luminous flux, which is the perceived power of light. In other words, the lumen measures the total amount of visible light emitted by a...

A type of photometer calibrated in luminance units (candles per square unit, or lamberts). In photography an exposure meter contains a luminance meter to record the average luminance of a scene.

Luminescence is the emission of light that occurs without the involved substance undergoing a significant increase in temperature. In other words, it is the production and emission of light by a...

Fiber that emits luminescent radiation excited by ultraviolet, x-ray or high-energy particles.

Pertaining to electromagnetic radiation as perceived by the eye; that is, with the contributions as wavelengths in the visible region weighted according to V(λ), which symbolizes the spectral...

A measure of the time-integrated amount of flux. It has units of lumen-seconds and might be used to describe such things as the radiant energy that the eye would receive from a photographic flash.

Descriptive of the radiant power of visible light modified by the eye response. It is the measure of the flow of visible light energy past any given point in space in a given time period, and is...

A spectrum that is continuous in the UV region with borders ranging from the visible to 300 A and lower.