Photonics Dictionary: H

A helium-neon (HeNe) laser is a type of gas laser that emits visible red light at a wavelength of 632.8 nm. It operates based on the principle of stimulated emission of photons from excited helium...

Holmium lasers are a type of medical laser that utilizes holmium-doped crystals as the gain medium. The term holmium laser is often associated with a specific type of laser used in urology for...

Triggering a laser at a predetermined time by pumping it to a level just below its threshold and then using an auxiliary source that quickly pumps it above threshold. Means of achieving it in laser...

1. The value on either the leading or the trailing edge of a laser pulse at which the power is one-half of its maximum value. 2. The wavelength at which a filter is transmitting one-half of its peak...

The process of sealing laser components by means of frit seals, welding or bonding rather than using epoxy.

Harmonic generation refers to a nonlinear optical process in which incoming photons interact with a material and produce new photons at integer multiples of the frequency of the incoming photons....

The process of subjecting glass to temperature cycling to produce physico-chemical reactions that alter its properties. Similar processes can be accomplished with a laser -- most commonly a CO2,...

A material used in photodynamic therapy that is retained selectively by tumor tissue when injected into the body; it then fluoresces when exposed to blue light and necroses when exposed to red laser...

Laser cavity bounded by a plane mirror and a concave spherical mirror with the plane mirror located at the center of curvature of the concave mirror.

High harmonic generation (HHG) refers to a nonlinear optical process in which intense laser light interacts with a gaseous medium, typically an atom or a molecule, to produce harmonics of the...

Extensive data storage in the form of bits, with the use of high-resolution photographic materials and optics, and generally a laser.

The holographic recording of sequences of high-speed phenomena. With a multiple beam laser, multiple holograms that depict rapid events can be formed on a single medium.

The dip or gap in the profile of a laser beam's line width when it is both homogeneously and inhomogeneously broadened. When an inhomogeneously broadened spectral line is saturated by incident light,...

An infrared-transmitting optical fiber with a hollow core; it can be square, round or rectangular in cross section. Capable of carrying high laser power but subject to high bending losses.

A soft, malleable, stable rare-earth element. Holmium laser systems are used in surgical procedures involving the cutting and vaporizing of soft tissue, cartilage and calcific structures.

A camera system used to form a high-precision hologram of the subject on a photographic plate. It contains a high-power pulsed laser as the illuminating source.

An interference pattern that is recorded on a high-resolution plate, the two interfering beams formed by a coherent beam from a laser and light scattered by an object. If after processing, the plate...

A holographic camera, also known as a holographic imaging system or holographic recorder, is a specialized device used to capture 3D holographic images of objects or scenes. Unlike conventional...

A technique used to create a series of interrelated holographic images that give an appearance of motion when projected in sequence. A flashing laser is used in both the recording and projecting of...

A holographic grating is a type of diffraction grating that is produced using holographic recording techniques. It consists of a periodic structure of alternating transparent and opaque regions,...

The interferometric analysis of a complex object by utilizing the three-dimensional hologram. By causing a laser beam to diverge into two directions, one of which directly strikes a holographic...

The storage of data as bits in memory by holographic processes. The laser beam is divided into reference and object beams, and bit information is stored as a hologram.

A component used to modify light rays by diffraction; the HOE is produced by recording the interference pattern of two laser beams and can be used in place of lenses or prisms where diffraction...

A method of measuring flow velocity by seeding the flow with neutrally buoyant particles and using a pulsed laser to holographically record particle displacement during a short time period. An...

Holography is a technique used to capture and reconstruct three-dimensional images using the principles of interference and diffraction of light. Unlike conventional photography, which records only...

The broadening of a laser's line width in a way that affects every atom (or molecule), and thus the whole system, in the same manner. Examples are collision broadening, and natural or intrinsic...

Term applied to laser technology to denote an area of above-average intensity often attributable to atmospheric inconsistencies.

A gas laser having a mixture of gases that makes it useful in the lab. The mixture of gases flows through a pressure and gas-flow-rate-regulated, sealed vessel with such a gain that only the...

A photoreceptor material used in solar cells and in drums for laser printers and high-speed copiers because of its high quantum efficiency over a wide spectral band, high data-rate capability and...