Photonics Dictionary

Method of preserving the measured color value and color information as it is translated from differing devices. For example the output of a television display may be measured to have an identical...

The minimum value of luminance for vision. The value may vary with age as well as dark adaption period. (Measured range approximately log luminance -3 through 2.) About 10 -2 ml at the fovea, 10 -5...

The value of the distance of distinct vision, minimum focusing distance or near point, divided by the focal length of the lens. Magnification is produced when the optic is placed at its focal...

Least value of color value combinations which gives white light; minimum purity as determined to be white.

The ratio of the speed of light in a vacuum divided by the speed of light in the medium.

The measurement of heat energy as determined from absolute zero as the zero point on the scale. Increments are identical to the Celsius as well as Kelvin scales.

A perfect diffuser that exists only as a concept, or a white with known spectral characteristics used as a reference in measuring absolute reflectance.

The natural log of the ratio of absorbed intensity over the total intensity which gives a constant value assuming a stable volume as well as energy. In optical physics the absorbance may be defined...

A doped or absorbing transparent medium cut or molded into a wedge in order to measure the real and imaginary components of the refractive index. An internally reflected Gaussian beam is interfered...

The ratio of energy or intensity absorbed by the medium (numerator) to the total incident energy.

The transfer of energy from an incident electromagnetic energy field with wavelength or frequency to an atomic or molecular medium.

A group of frequencies or wavelengths on the electromagnetic spectrum which exhibits resonance or energy contributions near and in relation to a peak resonance wavelength.

The transition cross section constant coefficient which defines the transition probability of absorption from ground to a higher level within a given atomic or molecular species. The transition...

A hologram formed when the light of the illuminating beam is absorbed in correspondence with the recording exposure. In application, absorption holograms are intended for use in satellite...

The absorption index represents the imaginary component of the complex index of refraction, and not the real component. The imaginary component may characterize the attenuation per unit length...

An optical lens manufactured to control the transmission of light over a specified wavelength range. Low absorption lenses are produced which are anti-reflection coated for UV, VIS and IR wavelengths...

The wavelength or frequency corresponding to an absorption resonance with a given molecular or atomic species. The line spectrum will vary with the element as well as the molecular compound.

A measuring device that uses a light-sensitive cell or detector to determine the amount of light transmitted by a substance.

An absorption peak refers to a sharp increase or spike in the absorption of electromagnetic radiation at a particular wavelength or energy level. It is a distinctive feature in the absorption...

Measures the absorption or sample transmittance over a range of specified wavelengths. Sample may be placed within the device and the transmission measured to an accuracy of given percent. The...

Experimental method of measuring the transmission of a given sample as a function of the wavelength.

Fraction absorption over a specified range of wavelengths.

The measured change in absorption at a single wavelength while altering experimental parameters such as the incident intensity or pulse width.

Compilation of the Air Force Cambridge Research Laboratories that contains values of the line parameters of the 1-0 bands of 12C16O. Because of the high accuracy of this record, calculated spectra...

An atomic absorption spectrometer (AAS) is an analytical instrument used to determine the concentration of specific chemical elements in a sample by measuring the absorption of light at...

The analysis of the atomic structure of a sample by means of a source radiation that is absorbed and emitted by the sample with lines corresponding to the number and arrangement of atoms. Generally a...

The rule stating that positive uniaxial crystals have greater absorption with respect to the extraordinary component of light, whereas negative crystals have greater absorption for the ordinary...

That wavelength at which the absorption of a given element or system begins to demonstrate an inconstant value.

A lidar (light detection and ranging) technique used in pollution monitoring. Two light beams are emitted simultaneously, one at a wavelength that will be absorbed by the target particles, and the...

A spectrophotometer that measures the amount of ozone in the atmosphere through a comparison of solar energy at two wavelengths in the ozone's absorption band. This comparison is achieved by...

In laser pumping, parasitic absorption that occurs at certain wavelengths, decreasing pump efficiency and gain.

A cement used to reduce crosstalk in fiber optic bundles or plates.

The phenomenon whereby an electron within a band absorbs radiation by transferring from a low-energy level to an empty high-energy level.

A glass filter that transmits visible light while absorbing infrared energy (heat).

An optical fiber's absorption of electromagnetic waves due to hydroxyl ions remaining after contact with water.

Infrared radiation absorbed by crystals as a result of the excitation of lattice vibrations in which ions having opposite charges move relative to one another. These vibrations take place in a narrow...

Sharp and narrow absorption lines found in the spectra of stars. They result from the absorption of a part of a star's emittance by interstellar gases.

An absorbing coating medium between fibers, used in some fused fiber optic plates to absorb unwanted light. Such coatings are sometimes called EMA (extramural absorption).

Transmittance of a solution, or internal transmittance of a transparent solid, is an exponential function of the thickness of the layer.

An experimental research technique by which absorbed or unabsorbed radiation is analyzed in order to characterize and determine material properties, concentration as well as behavior under the...

The method that, by measuring the absorption along an atmospheric path at wavelengths ranging from two to a continuum, can determine pollution concentrations of gases.

Nanoparticle photonic resonator absorption microscopy is a microscopy technique that combines the principles of photonic resonators and nanoparticle imaging to visualize and study biological samples...

Amplification; the result of the excess of stimulated radiation over absorbed radiation.

The transformation of incident radiant energy into a photoelectric emission current.

The absorption of part of the photon energy by a molecule through which there is a slight energy change and the energy balance moves on.

Loss mechanisms that degrade the performance of all thin-film optical devices by removing radiant flux out of the specular beams.

The re-emission of absorbed energy, having the same wavelength as the incident energy, in an arbitrary direction from a particle because of an energy level transition within the material.

A laser dye whose absorption coefficient drops at high levels of incident radiation. The phenomenon is often called bleaching.

In optical emission spectroscopy, the reduction in radiant power in the central portion of spectral lines arising from the selective absorption by the cooler outer vapor of the source envelope of...