Photonics Dictionary

A measurement technique used for the rapid quantitative evaluation of surface quality based on the detection and analysis of light scattered from the surface.

A flat plate having its surface formed into a random pattern by abrasives. Radiation wavelengths that are longer than the scale of the pattern are specularly reflected; shorter wavelengths are...

An optical system that records inhomogeneities within a medium by detecting the energy refracted by that portion of the medium in which the inhomogeneity occurs. The image appears in the form of a...

The formation of a picture or image in which the density gradients in a volume of flow are rendered visible. The image is formed by refraction and scattering from areas of varying refractive index.

The photomicrographic recording of Schlieren effects, irregular refractions of light from optic surfaces or areas of thin, transparent specimens, generally using a reticle with parallel transparent...

A camera that consists of a concave spherical mirror with an aspheric plate situated at the center of curvature of the mirror. The purpose of the plate is to correct the spherical aberration of the...

An aspheric plate placed at, or near, the center of curvature of a spherical reflector and used to correct for spherical aberration.

A prism that inverts and reverts an image while deviating the line of sight by a 45° angle.

Oscilloscope electronic circuit that produces an output pulse whose pulse width is determined by the time that the output voltage exceeds a specified level.

A form of infrared CCD that utilizes internal photoemission as a photodetection mechanism.

Schrödinger's cat is a thought experiment devised by the physicist Erwin Schrödinger in 1935 to illustrate the paradoxical nature of quantum mechanics, particularly the concept of...

A specific type of photographic plate designed with only a small amount of gelatin to function in the extreme ultraviolet and in positive-ray analysis.

A scientific CMOS (complementary metal-oxide-semiconductor) camera is a type of digital camera specifically designed for scientific imaging applications. It employs CMOS sensor technology, which...

Scientific complementary metal-oxide semiconductor (sCMOS) refers to a type of image sensor technology specifically designed for scientific and industrial imaging applications. Unlike traditional...

1. The variation in intensity of a light beam as it travels through the atmosphere. 2. In radiation physics, a light flash formed by an ionizing event in a phosphor; a flash formed when rapidly...

A pinhole camera used to record a radioactive tracer's distribution in a subject by means of a scintillation counter or a fluorescent screen; used when a recording emulsion is not practical.

An instrument designed to measure radiation indirectly through the use of several phosphors and a photomultiplier tube. The absorption of radiation by any phosphors results in light flashes that may...

A scintillation crystal, also known simply as a scintillator, is a material that emits light when it interacts with ionizing radiation such as gamma rays, x-rays, or charged particles. The emitted...

A scintillation detector is a radiation detection device that utilizes scintillation crystals to detect and measure ionizing radiation, such as gamma rays, x-rays, or charged particles. It consists...

A phosphor that has the ability to convert into light emission a portion of energy lost by ionization when a charged particle passes through the material.

The method of determining the energy distribution of high-speed charged particles by the luminous effect formed when the particles strike a material.

An instrument used to test the hardness of various materials. It measures the pressure on a standard point that is necessary to scratch the material.

A device used to take turbidimetric or nephelometric measurements by considering the contrast between a constant brightness field and an illuminated line positioned behind the solution being tested.

The cutting of pitch tooling surfaces by an optical technician to permit polishing compounds to flow across the surface of the tool.

Vision by means of retinal rods; vision of the dark-adapted eye. In scotopic vision, the level of luminance is so low that the retinal cones are not stimulated, and there is no color vision.

An instrument that uses an image intensifier to aid in the viewing of subjects in low-light-level environments.

A defect on a polished optical surface whose length is many times its width. Block reek is a chainlike scratch formed in polishing. A runner cut is a curved scratch caused by grinding. A sleek is a...

Thin layers intended to prevent damage to plastic optics.

The large, usually flat surface onto which an image is projected for viewing. May be reflecting or transmitting (rear projection).

The process of perforating a silicon or ceramic substrate with a series of tiny holes along which it will break. Nd:YAG or CO2 lasers are now routinely used.

Describing a laser in which the gas is permanently sealed within the tube.