Photonics Dictionary

An accelerometer is a sensor or transducer that measures the rate of change of velocity of an object, or in simpler terms, it measures acceleration. Accelerometers are widely used in various...

An achromat, in the context of optics, refers to a type of lens or lens system designed to reduce chromatic aberration. Chromatic aberration is an optical phenomenon where different colors of light...

Color correcting; chromatic aberration corrected.

A lens consisting of two or more elements, usually of crown and flint glass, that has been corrected for chromatic aberration with respect to two selected wavelengths. Also known as achromat.

Location on the CIE chromaticity diagram which produces the color white for a given light source at a specified temperature.

Cemented prisms of differing refractive indices which refract incident light and, due to differing refractive indices, will not spatially separate individual wavelengths.

Use of achromatic design; the correction of chromatic aberration; without color or hue (grey, black and white)

Any fluorescence in which the wavelength of the emitted light differs from that of the absorbed light.

The coefficient Å in Angstrom's formula for the dispersing coefficient for dust present in the atmosphere. The formula is expressed as S × Ål-B where l represents wavelength and B...

A system used for measuring direct solar radiation.

An operational mode for radiometers that analogs the method of operation of an angstrom pyrheliometer. In this mode, the rearward-facing cavity is electrically heated, while the forward cavity is...

An angstrom, symbolized by the Ångström or Å, is a unit of length used to express atomic and molecular dimensions. It is equal to 0.1 nanometers or 1 × 10-10 meters. The...

Color vision whereby abnormal proportions of three colors are needed for color matching.

The elimination of magnetic moments and decrease in magnetic susceptibility with a decrease in temperature due to the equal power of atomic magnets.

An apochromat, often referred to as an apochromatic lens or apochromatic objective, is a type of optical system designed to minimize chromatic aberration. Chromatic aberration occurs when different...

An optical system that is corrected chromatically for three colors simultaneously.

The analysis and measurement of celestial bodies, their motions and positions.

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...

Spectrometric analysis of the distinct and characteristic spectra of atoms of elements. The atoms are energized to emit radiant energy, which, when dispersed by a prism or diffraction grating,...

An instrument for the detection of the energy distribution of b-particles and secondary electrons.

An adaptation by Philips and Sony of their audio compact disc technology for optical disc data storage and retrieval. Current capacity of a disc is 0.5 to 0.6 gigabytes of information.

1. Attribute of a visual sensation that permits a judgment to be made of the amount of pure chromatic color present. 2. The portion of a composite video signal that carries the chrominance values,...

An instrument designed to analyze the optical effects of color.

Having the property of color.

Chromatic aberration is an optical phenomenon that occurs when different wavelengths (colors) of light are refracted by a lens or optical system, leading to a failure to focus all colors to the same...

Change of sensitivity of the eye leading to changed color perception.

The ability of the instrument to separate wavelengths that are close together, numerically equal to the ratio of the shorter wavelength to the difference between two wavelengths that can just be...

The qualities of color associated with hue and saturation, but not brightness or lightness.

Proportions of standard primaries (tristimulus values) required for a color match; ratios of each tristimulus value of a color to their sum. In the CIE colorimetric system, designated X, Y and Z.

The plane diagram produced by plotting one of the three chromaticity coordinates (X,Y,Z) against another. The most common diagram is the CIE (X,Y) diagram, which is plotted in rectangular coordinates.

The sensations of hue and saturation, taken together, but not brightness or lightness.

The chemical method of separating compounds dissolved in one phase (usually mobile) through its equilibration with a second phase (usually stationary). The mechanism of separation may involve...

The difference between any color and a reference color having equal luminance and a specified chromaticity.

A technique of using dyes during endoscopy to improve tissue differentiation. Dyes such as methylene blue, Toluidine blue and Lugol's solution all have the ability to stain particular types of cells....

A naturally occurring pigment in tissue that may selectively absorb certain wavelengths and can be used to aid in targeting the beam in laser surgery.

A layer between the corona and the photosphere of the sun; its emission is overwhelmed by light emitted by the underlying, denser photosphere.

The chromatography method in which the stationary phase is supported in or on an inert packing in a column, through which the mobile phase passes.

An interferometer formed by two similar concave spherical mirrors arranged with the center of one sphere on the other mirror. In this instrument the field is more concentrated by the axis of the...

A device designed to measure crystal properties by analysis of crystal diffraction.

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

In an optical rangefinder, the system of wedges that rotate in opposite directions to aid in the detection of deviation in the image axis.

A device that produces an interferogram that can be directly related to the temperature gradient and thereby provides a direct measure of the convective heat transfer coefficients.