Definitions: L

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...

The law stating that the angle of reflection is equal to the angle of incidence, the incident ray, reflected ray and normal to the surface, all being located in the same plane.

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...

Defines the minimum operational standards for a self-sustaining fusion reactor as equivalence between energy released per volume unit and kinetic energy per unit volume.

In a fiber optic cable, the longitudinal length required for the transmission media, wrapped around a central member, to complete one helical wrap. Also called pitch.

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

The process of removing some of the constituents of a glass surface by chemical action.

A thin-film photoconductive cell that is sensitive to the infrared region. The photosensitive material of the cell is composed of lead selenide, and the cell is used in the detection of infrared...

A photoconductive cell having greatest sensitivity in the infrared region. The photosensitive material of the cell is lead sulfide, which is deposited on a glass plate.

A ferroelectric polycrystalline ceramic material used in optical memories for computers and as a piezoelectric transducer.

In a sequence of laser pulse emissions, the intitial pulse that often helps initiate a reaction at the target surface, whereas the trailing edge maintains the reaction.

In an optical waveguide, a mode whose field decays monotonically for a finite distance in the transverse direction but which becomes oscillatory everywhere beyond that finite distance.

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 erecting prism that inverts and reverses the image. It displaces the optical axis but does not deviate it.

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

The mechanical structure that holds a number of individual lens elements.

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.

One optical element of a multielement lens. See optical element.

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

A line passing through the center of a lens surface, from edge to edge.

The production of rough glass lens blanks that are pressed while red-hot to the approximate size and shape of the finished lens, ready for fine grinding and polishing. Large companies often do their...

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...

Also known as f number, lens speed is commonly represented as the ratio of the focal length to the diameter of the lens. Lower f numbers produce brighter images.

Two or more lenses arranged to act in conjunction with one another.

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...

The ratio of the intensities of a light bundle before and after passing through the lens.

A dial depth gauge graduated in diopters; a lens measure.

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,...

A hologram formed without lenses and with the object and reference points sharing the same plane. In the initial recording, each object point produces fringes having one spatial frequency across the...

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...

A matrix of miniature lenses, molded or formed onto a common base.

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...

An array or mosaic of optical surfaces. May be a number of lenses closely packed to form multiple images or many parallel cylinders used as a projection screen.

A type of additive color photography using a lenticular structure impressed on a film base and a camera lens with a filter having three sectors of red, blue and green. Exposure of the film through...

A method of image dissection whereby a lens transfers images onto a lenticular plate that in turn illustrates the images as structures of narrow parallel lines.

A rear or front projection screen composed of minute optical surfaces that introduce a spread to the light beam that conforms approximately to the light distribution requirements of the application.

A type of stereoscopic photography in which a pair of lenses focuses a pair of images, relative to the positions of the two eyes, onto film through a lenticular screen, which records the images as an...

The stereo image that is recorded by the lenticular, stereo photographic process.

The generic term describing the class of light particles having no strong interactions.

Leukocytes, commonly known as white blood cells, are a crucial component of the immune system in vertebrates, including humans. These cells are responsible for defending the body against infections...

Characterizes a substance whose plane of polarization is rotated counterclockwise as the observer looks through the material toward the light source. The rotation is negative.

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...