Photonics Dictionary

A lens that is symmetrical and designed to work between 1:1 and about 4:1. It covers a field of about ±20° at f/8 or f/10, and may have a focal length up to about 30 in., although the usual...

A superposition of many zone plates, each reconstructing a real and virtual point image at the appropriate locations upon illumination by a reference beam.

In computerized industrial process control, the element that determines the choice and sequence of operations dependent on varying conditions.

A microscope that uses an extremely fine x-ray focal point to produce an enlarged photographic image of a sample. Also known as an x-ray shadow microscope.

The minimum amount of strength characteristic of an optical fiber, as determined by proof stressing; expressed in thousands of pounds of pressure per square inch.

Protein crystallography is a scientific technique used to determine the three-dimensional structure of proteins at atomic resolution. It involves growing crystals of a protein of interest and then...

Technique using a fiber optic assembly to illuminate an opaque object and transmit an image back from it without a lens system on the distal end.

The underexposure caused by the diffraction of light passing through small openings spaced closely together in masks used in photolithography.

A planar photocathode and a planar phosphor screen mounted in a close-spaced parallel configuration in an evacuated enclosure so that the ensemble of photoelectrons emitted from each photocathode...

A method of sensing by transmitting energy from the sensor and detecting the energy after it has been reflected by the object in its path.

A method used to approximate the values of the homogeneous second derivatives at each iteration in the course of lens design and that excels the rate of convergence of the damped least squares method...

Coded image obtained optically with a nonredundant pinhole array imaging aperture.

A noncontact, nondestructive method of measuring defects in thin composite materials, using a xenon flashtube to generate heat in a sample. A thermal imaging system detects differences in the rates...

A laser that emits energy in a series of short bursts or pulses and that remains inactive between each burst or pulse. The frequency of the pulses is termed the pulse-repetition frequency.

Separation of incident laser pulses by several seconds so holographic plates can be changed and sandwiched between the pulses. This technique combines the short exposure time of pulsed holography...

A type of laser welding that produces short-duration vapor pockets without buildup of heat in the part, useful for parts that are too thick for conduction welding and that move too slowly for keyhole...

A laser with a gain medium consisting of an organic dye, which is carbon-based. The dye is mixed with a solvent, allowing the molecules to diffuse evenly throughout the liquid. The dye medium is...

A pump laser is a type of laser used to provide the necessary energy to the gain medium of another laser or laser system, initiating the process of stimulated emission and producing laser light. The...

Pushbroom scanning is a technique used in remote sensing and imaging systems, particularly in satellite and aerial sensors, to capture images of the Earth's surface or other objects. In pushbroom...

Unlike the thermocouple or bolometer, the pyroelectric infrared detector is a current source with an output proportional to the rate of change of its temperature. Capable of extremely rapid response...

Q-switched operation, or q-switching, is a technique used in lasers to produce short and intense pulses of light. The term "Q" in q-switching stands for "quality factor," which is a measure of the...

A laser output that occurs when the cavity resonator Q is first kept very low, using rotating mirrors or saturable absorbers, so that the population inversion achieved is greater than usual. A high...

Q-switching, short for "quenching-switching," is a technique used in lasers to generate short, high-energy pulses of light. The term "Q" refers to the quality factor of the laser cavity, which...

The region of the cathode-ray tube phosphor screen restricted by the tube and instrument specification.

Quantitative oblique back illumination microscopy (qOBM) is an advanced imaging technique used in microscopy to achieve high-resolution imaging of biological samples, particularly cells and tissues....

Quantitative phase imaging (QPI) is an advanced imaging technique used in microscopy to measure and analyze the optical phase information of transparent specimens. Unlike traditional brightfield...

The term quantum refers to the fundamental unit or discrete amount of a physical quantity involved in interactions at the atomic and subatomic scales. It originates from quantum theory, a branch of...

A quantum cascade laser (QCL) is a type of semiconductor laser that operates based on the principles of quantum mechanics. It is a versatile and powerful device used for emitting coherent light in...

Quantum confinement refers to the phenomenon in quantum mechanics where the motion of charge carriers, such as electrons or holes, is restricted to a region of space that is smaller than their...

A photodetector in which an electrical charge is produced when incident photons change electrons within the detecting material from nonconducting to conducting states. See photoconductive detector;...

Quantum dot light-emitting diode (QLED) is a display technology that utilizes quantum dots, which are semiconductor nanocrystals, to produce vibrant and high-quality images. QLED displays are...

Quantum dot thin films refer to thin layers or coatings composed of quantum dots deposited onto a substrate surface. Quantum dots are nanoscale semiconductor particles typically ranging from a few to...

A quantum dot is a nanoscale semiconductor structure, typically composed of materials like cadmium selenide or indium arsenide, that exhibits unique quantum mechanical properties. These properties...

Quantum efficiency (QE) is a measure of the effectiveness with which a device or system, typically in the context of photonics or electronics, converts incoming photons (light) into a useful output...

Quantum entanglement is a phenomenon in quantum mechanics where two or more particles become correlated to such an extent that the state of one particle instantly influences the state of the...

Quantum key distribution (QKD) is a method of secure communication that utilizes principles from quantum mechanics to establish a shared secret key between two parties, typically referred to as Alice...

The area of optics in which quantum theory is used to describe light in discrete units or "quanta" of energy known as photons. First observed by Albert Einstein's photoelectric effect, this particle...

A quantum repeater is a crucial component in quantum communication networks, designed to extend the range over which quantum information can be transmitted. Quantum information, typically carried by...