Photonics Dictionary

An advanced technique that allows the detection of one molecule within a crystal or a cell through optical excitation. Single-molecule spectroscopy (SMS) can image at subwavelength scales, down to a...

A single-photon avalanche diode (SPAD) is a specialized type of photodetector designed to detect extremely weak optical signals, down to the level of single photons. SPADs are widely used in...

A medical imaging method in which gamma camera heads rotate about the patient to detect radionuclides, enabling physicians to monitor functions within the body such as metabolism or blood flow.

A technique for observing the decay of light emissions from sources following their pulsed excitations, based on recording the arrival time of the first photoelectron after excitation. After many...

Referred to as SWCNTs, these cylindrical nanostructures composed of a folded sheet of graphene can be used as near-infrared markers for small animal multiplex imaging. Emitting at different...

A singlet lens is an optical lens made from a single piece of material, typically glass or plastic, with one or both surfaces being spherical or aspherical. It is the most basic type of lens used in...

A singulated die refers to an individual semiconductor chip that has been separated or singulated from a larger wafer. This term is commonly used in the semiconductor manufacturing industry. ...

Sisyphus cooling is a technique used in atomic physics to achieve ultracold temperatures of atoms or molecules by exploiting the periodic motion of particles in optical traps or lattices. The name...

The angle at which photoelectric sensors are aligned to prevent light from being reflected back to the sensor from the object during retroreflective sensing; also, the angle a measured part is...

Any ray through an optical system that is not a meridional ray. The plane created by a refracted skew ray does not contain the optical axis.

A system employing a dark trace tube in which the opacity of the screen is varied as a function of the power of the beam.

A filter designed to decrease the luminosity of the sky without decreasing that of the landscape in the foreground. A filter that has a depth of tint that decreases from top to bottom is used in...

Variations in signal detected on a bolometer that are caused by instabilities in the temperature of the sky.

Solid-state laser geometry in which the standard rod is replaced by a slab of laser material. Often called total-internal-reflection face-pumped laser (TIR-FPL).

A waveguide with a rectangular cross section that is composed entirely of dielectric materials.

The process of making an abrupt break in a spherical surface on a spectacle lens so that a new center of curvature is set for a portion of the lens. This has the effect of adding a prism to that...

A crystal, glass, or quartz slicing and cutting machine is a specialized piece of equipment used in the manufacturing process to precisely cut and slice materials such as crystals, glass, and quartz...

A lens designed for projection of color transparencies.

An optical projection device designed to project positive color transparencies onto a screen for viewing.

An aperture, usually rectangular in shape, with a large length-to-width ratio, and a fixed or adjustable shape through which radiation enters or leaves an instrument. The aperture is generally small...

The error inherent in spectral energy or spectrophotometric quantity due to the finite dimension of the entrance and exit slits.

In photonics, a slot modulator refers to a type of optical modulator that operates based on the principle of modifying the optical properties of a slot waveguide. A slot modulator is an optical...

A television system that uses a slow rate of horizontal scanning to increase its reproduction and transmittance accuracy of printed matter, photographs and illustrations.

The investigation of microstructures by an instrument that generates a narrow, highly collimated beam of x-rays.

Smart cities are urban environments that use information and communication technologies (ICT) and data-driven solutions to optimize city operations and services across various domains such as...

Smart microscopy refers to the integration of advanced technologies, such as artificial intelligence (AI), automation, and machine learning, into conventional microscopy techniques to enhance imaging...

A lack of resolution in a television image as a result of smear ghosts or an insufficiently high video-frequency response. The distortion appears to be extended horizontally and blurred.

A false image in television that follows the desired image so closely that it appears to be smeared.

A form of liquid crystal in which flow does not take place in the usual manner. When examined with polarized light, the substance often forms drops that display a series of fine lines. X-ray...

A transmission interference microscope that produces interference patterns of a sample by using birefringent plates that split a polarized beam of light into ordinary and extraordinary rays, then...

The incident ray, the normal to the refracting surface at the point of incidence of the ray at the surface, and the refracted ray all lie in a single plane. The ratio of the sine of the angle between...

The letter form used on visual performance test charts. The overall letter height is equal to five times the thickness of individual strokes. Normal 20/20 vision is represented by the ability to...

An instrument used for viewing in low levels of illumination by means of infrared radiation. A high-aperture lens forms an image of distant objects on the photocathode of an infrared-sensitive image...

A term describing an antireflection coating that may be applied to optics that cannot tolerate the high temperatures usually required for normal "hard'' coatings. Such coatings lack durability...

Term applied to radiation composed of particles or photons that will not easily penetrate a material because of their low energy levels.

A filter that creates spherical aberration resulting in an image with a soft outline.

A lens that exhibits spherical aberration when used at large aperture settings, and that forms an image with a slightly blurred outline.

A substance capable of converting solar radiation into thermal energy.

A group of solar cells that are electrically contacted and physically arranged so that they may be oriented in the direction of the sun simultaneously.

A series of solar cells arranged to collect solar radiation and to generate a given amount of electrical energy.

Solar radiation intensity existing in free space at the mean solar distance of the Earth. Commonly expressed in g cal cm-2min-1, the constant is equal to the amount of incident radiation -- in unit...