Photonics Dictionary: L

A system that uses a continuous-wave laser to measure the velocity of an object by focusing the laser beam on the object, perpendicular to its direction of motion. An optical grating receives...

A laser, which stands for "light amplification by stimulated emission of radiation," is a device that produces coherent and focused beams of light through the process of optical amplification based...

Laser-induced fluorescence (LIF) is a spectroscopic technique that involves using a laser to excite molecules or atoms, leading to their emission of fluorescence light. This technique is widely used...

Laser-mediated gene transfer refers to a technique in molecular biology and genetic engineering that utilizes lasers to introduce genetic material into cells. This method is a type of gene delivery...

A contact tip made of artificial sapphire (AlO2) that allows surgeons to use laser power to cut and coagulate tissue simultaneously.

A machining process that uses a laser to cut three-dimensional molds or models.

In a diode laser, a mode in the plane of the active layer that is perpendicular to the direction of the emitted beam.

A lateral shearing interferometer is an optical device used in interferometry to measure phase differences between two beams of light. Interferometry is a technique that combines and analyzes...

A length that denotes the size of the unit cell in a crystal lattice. With respect to the cubic crystal, this is the length of the side of the unit cell. However, a simple definition of the term is...

A fiber used in conjunction with a source to excite the modes of another fiber in a particular fashion.

A Laurent polarimeter is an instrument used in optics for measuring the rotation of plane-polarized light caused by optically active substances. Optical rotation, also known as optical activity, is a...

The law stating that when light strikes a surface at such an angle that the reflected and refracted rays are perpendicular to each other, the maximum polarization of the light occurs in both...

In physics, the law of reversibility is often associated with the concept of reversibility in thermodynamics. The law asserts that any process that occurs in a closed system can, in theory, be...

In the optical shop, the process of positioning and marking a blank or lens before surfacing, cutting and edging.

In an optical waveguide, a ray for which geometric optics would predict total internal reflection at the core boundary, but which suffers loss by virtue of the curved core boundary.

The circle of confusion is a defocused or aberrated image of a point. Focus is generally set where the diameter of this circle is minimized or least.

Older fiber optic cable that may not be suitable for state-of-the-art applications and that is difficult for suppliers to sell.

An electron-beam tube designed so that the beam can be carried through a portion of the wall of an evacuated enclosure.

A lens blank is a piece of optical material in a raw, unfinished state, typically in the form of a disk or block, from which lenses are eventually fabricated. Lens blanks are made from various...

A rotating disc that holds several lenses of differing focal length about a diameter. Used to switch lenses in a system while maintaining focus.

A tool used to determine the curvature of a lens surface in terms of dioptric power. See lens watch; spherometer.

The metal tube that maintains the optical components of a lens in proper relationship. Some lenses are mounted in metal cells, which in turn are screwed to the front and rear of a shutter or lens...

Lens testing equipment refers to a range of specialized tools and instruments used to evaluate the optical performance, quality, and characteristics of lenses. These instruments are essential for...

A lens is a transparent optical device that focuses or diverges light, allowing it to pass through and form an image. Lenses are commonly used in optical systems, such as cameras, telescopes,...

Lensless microscopy, also known as computational or holographic microscopy, is an imaging technique that captures and reconstructs microscopic images without the use of traditional lenses. Instead of...

An ophthalmic instrument used to measure the magnitude and direction of the maximum and minimum powers of a spectacle lens, and mark the optical center of the lens by an ink dot. When the lens to be...

Lidar, short for light detection and ranging, is a remote sensing technology that uses laser light to measure distances and generate precise, three-dimensional information about the shape and...

The visual perception of contrasting forms is more difficult if the forms have the same luminance but different chromaticities, than if the forms have the same chromaticity but different luminances.

Light diffusion refers to the process by which light is scattered or spread out in various directions as it interacts with a medium or material. Unlike direct transmission through a transparent...

LiFi, short for light fidelity, is a wireless communication technology that utilizes visible light or infrared light to transmit data. Developed as an alternative or complementary technology to...

The term light field refers to the spatial distribution of light rays traveling in all directions through a given space. It includes information about the intensity and direction of light rays at...

Phenomenon caused by an ultrashort and ultra-intense light pulse propagating in a Kerr medium, such as air or water. When the pulse's power exceeds the critical power (approximately 3 GW in air),...

A homogeneous optical medium or coating that transmits only in particular regions of the spectrum. It is used to change or modify the total or relative energy distribution of a beam of light.

Technique for measuring the volume bulk of materials as they move along a conveyor with an accuracy of better than 1 percent. Based on the use of high-resolution arrays of solid-state detectors, the...

Also known as single plane illumination microscopy (SPIM), this process was designed for imaging of sensitive samples and fast biological processes in vivo. In this method, a light sheet illuminates...

A PN-PN device with incident light taking the place of gate current; three of the four semiconductor regions are available for circuit connections.

The spectroscopic analysis of optical line shapes and frequency shifts, using the technique of light beating; i.e., the mixing of two narrowband optical components to produce an AC component in the...

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,...

The maximum circular area over which radiance and radiant exposure can be averaged.

Line scan refers to a method of capturing images or data by scanning a single line at a time, as opposed to capturing the entire image simultaneously. This technique is commonly used in various...

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

A semiconductor laser in which the naturally occurring broad linewidth has been narrowed by incorporating the laser diode into a large resonant external cavity.

A line-scan camera, also known as a line-scan image sensor or linear array camera, is a type of digital camera designed to capture images one line or row of pixels at a time, rather than a full...