Photonics Dictionary

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.

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 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 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...

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.

Electromagnetic radiation detectable by the eye, ranging in wavelength from about 400 to 750 nm. In photonic applications light can be considered to cover the nonvisible portion of the spectrum which...

The ability of the human eye to adjust itself to an alteration in the intensity of light.

A device that serves to emit light of the same wavelength as the input light, only with an increase in intensity. It may be a solid-state device comprising photoconductive and luminescent layers...

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...

The process whereby white light is separated into its component wavelengths. Light beams of different wavelengths are separated from each other by undergoing a different angular deviation. Prisms and...

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.

The term for an image captured by a detector and from which a dark frame, bias frame and/or flat-field frame can be subtracted during image processing.

Any device that is used to sense and measure light. See exposure meter; photoelectric exposure meter; photoelectric photometer; reflected light meter.

A device that is designed to modulate a beam of light, usually from a laser source, by acting upon the beam directly. The three general types of devices operate in an acousto-optic, electro-optic or...

That property of a substance that determines that there will be a decrease in conductivity when exposed to light radiation.