Photonics Dictionary

A sudden, brief increase in current or voltage in a circuit that can damage sensitive components and instruments. Preventive measures include slow-starter circuits, filtering and static control.

On a display monitor, a small, mobile rectangle, cross-hair or pointer that locates a feature in an image that is the object of attention, or indicates where the next character will appear in word...

The measure of departure from a flat surface, as applied to lenses; the reciprocal of radius. Applies to any surface, including lenses, mirrors and image surfaces.

A lens aberration that causes a flat object surface to be imaged onto a curved surface rather than a plane.

A lens aberration in which the focal length varies radially outward from the center of the field. It has the effect of making a straight tangential line in the object appear curved in the image,...

A custom optic refers to an optical component that is designed, manufactured, and tailored to meet specific requirements or applications. These optics can include lenses, mirrors, prisms, filters, or...

In computer graphics, intersection of a plane with a three-dimensional object to create a sectional view.

A technique for measuring fiber attenuation or distortion by performing two transmission measurements. One is at the output end of the full length of the fiber. The other is within 1 to 3 m of the...

1. In detector technology, the long wavelength at which detector response falls to a set percentage (usually 20 or 50 percent). 2. In fiber optics, the shortest wavelength at which a fiber transmits...

In filter terminology, that wavelength where the filter transmission increases beyond 5 percent.

The process of forming a lens to a given pattern, or of cutting a piece of glass along the line of scratch.

The point on a cutting line that will become the geometrical center of the cut lens.

Adhering material used to glue optical components that transmit in the infrared. It is easily dissolved by acetone.

An instrument designed to measure the proportion of light emitted by a source in the blue region of the spectrum.

The analysis of light in the blue region of the visible spectrum.

A small mass spectrometer, with a limited mass range, equipped with an analyzer to generate a cycloidal-path beam of the sample.

The tendency of charge carriers to spiral about an axis in a direction identical to that of an applied magnetic field that has an angular frequency formed by the value of the applied field and the...

In a cylindrical lens, the meridian parallel to the generating lines of the cylindrical surface. In a toric lens, the cylinder axis is the axis of the equivalent cylindrical surface that has been...

A cylindrical lens is an optical component that has different curvatures along its two orthogonal axes, resulting in a shape resembling a cylinder. Unlike spherical lenses, which have the same...

An endoscope used for the visual examination of the bladder.

A form of monochromator optical system consisting of two spherical concave mirrors used in conjunction with a movable diffraction grating.

Popular process for silicon and polycrystalline production that consists of an alteration of the original state of a substance; thus, single-crystal materials can be used to form a polycrystal.

A telescope similar to the customary Cassegrain telescope, but having a primary mirror that is ellipsoidal and a secondary that is spherical.

A Dammann grating is a type of diffractive optical element (DOE) used to create an array of equally spaced, uniform-intensity spots or beams. It is named after its inventor, Dr. Herbert Dammann. The...

An organizational method used in optical design computer programs. The technique produces one number (merit function) to measure the state of correction of an optical system. This number, which is...

Continuous conversion of oscillatory energy into heat, relative to time or distance.

The ability of the human eye to adjust itself to low levels of illumination.

A precision-engineered microminiature light source that is safe for darkroom use, yet emits a beam of light bright enough to read by.

A lightproof box used for storing photosensitive materials.

The current that flows in a photodetector when there is no optical radiation incident on the detector and operating voltages are applied.

The decay of an electrostatic charge image resulting from long exposure to the dark.

A frame taken to identify electronic noise in a CCD imaging device. A dark frame is recorded without exposing the CCD to any external light by, for example, leaving the shutter of a CCD camera...

A multilayer coating that manifests both a low radiant reflectance and radiant absorption.

The noise produced in a photodetector when the photocathode is shielded from all external optical radiation and operating voltages are applied.

An operate mode in which the sensor is programmed to perform a task such as generating output when the light level falls below a certain threshold.

The portion of a glow discharge tube that permits little or no light transmission.

A condenser that forms a hollow cone-shaped beam of light with its focal point in the plane of the specimen. If it is used with an objective having a numerical aperture lower than the minimum...

The transmission of light by a condenser to observe either very small particles or very fine lines with a microscope.

A technique whereby the sample is illuminated by a hollow cone of light larger than the acceptance angle of the objective, so that only scattered light is seen, revealing any irregularities of the...

A photomicrographic recording technique that utilizes dark-field illumination to render an image of an object having a refractive index much like that of the medium holding it. The object may be...

A spectrum having some lines that are darker than others or that contrast against a light, continuous-spectrum background.