aberration
The convergence to different foci, by a lens or mirror, of rays of light emanating from one and the same point, or the deviation of such rays from a single focus; a defect in a focusing mechanism that prevents the intended focal point.
Optics and imaging
189 entries in this trade.
aberrator
A device that simulates aberration in an image.
absorptance
Absorbed radiation and incident radiation in a ratio format; a measurement that shows how well a surface absorbs radiation.
accidental colour
A colour depending on the hypersensibility of the retina of the eye for complementary colours. They are purely subjective sensations of colour which often result from the contemplation of actually coloured bodies.
achromat
A lens that imparts little color; a lens that is achromatic.
achromatic
adjectiveOptics and imaging
Free from color; transmitting light without color-related distortion.
achromatic lens
A lens generally composed of two separate lenses, one convex and one concave and generally of different materials, in such a way that the chromatic aberration produced by one is corrected by the other.
achromaticity
The state or quality of being achromatic.
achromatism
The state or quality of being achromatic; achromaticity.
acoustooptics
The science that studies the diffraction of light by ultrasonic sound.
adaptive optics
An optical system in telescopes that reduces atmospheric distortion by dynamically measuring and correcting wavefront aberrations in real time, often by using a deformable mirror.
adaptometry
The measurement of threshold of brightness by means of an adaptometer
afocal
adjectiveOptics and imaging
Neither concave or convex (focal point at infinity)
Airy disk
The bright central region of the diffraction pattern resulting from a uniformly illuminated circular aperture.
Airy pattern
The Airy disk together with the series of concentric rings that surround it.
albedo
The fraction of incident light or radiation reflected by a surface or body, commonly expressed as a percentage.
amacratic
adjectiveOptics and imaging
Uniting the rays of light into one focus.
angle of incidence
The angle that a straight line, ray of light, etc., meeting a surface, makes with a normal to the surface at the point of meeting.
angle of reflection
The angle between the perpendicular and a ray reflected from a surface
angle of refraction
The angle between the perpendicular and a ray refracted at a surface
angular aperture
The apparent diameter of a lens' aperture as seen from the focal point.
anisoplanatism
The absence of spatial invariance over an extended field of view
anticorona
The glory optical phenomenon.
antireflective
adjectiveOptics and imaging
Preventing visible reflection.
apertometer
An instrument designed to measure the numerical aperture of a lens or objective of a microscope.
aperture
A hole which restricts the diameter of the lightpath through one plane in an optical system.
aplanat
A lens that has been corrected for spherical aberration and coma in order to produce a rectilinear image.
aplanatic
adjectiveOptics and imaging
Free from, or corrected for, spherical aberration and chromatic aberration
aplanatism
Lack of spherical aberration.
apochromat
A kind of lens corrected for chromatic and spherical aberration.
apochromatic
adjectiveOptics and imaging
Corrected for both chromatic aberration and spherical aberration
apochromatism
Freedom from both chromatic aberration and spherical aberration.
Arago spot
A bright point that appears at the centre of a circular object's shadow due to Fresnel diffraction.
aspecular
adjectiveOptics and imaging
Subtended at the origin by the specular axis and the axis of the receiver.
astigmatism
A defect of a lens such that light rays coming from a point do not meet at a focal point so that the image is blurred.
auxetometer
An instrument for measuring the magnifying power of a lens or system of lenses.
Barlow lens
A diverging lens which, used in series with other optics in an optical system, increases the effective focal length of an optical system as perceived by all components that are after it in the system.
beamsplitting
adjectiveOptics and imaging
Describes the optics of a beam splitter
best form lens
A lens that is designed to minimize spherical aberration.
biconcave
adjectiveOptics and imaging
Having both sides that are concave.
bispheric
adjectiveOptics and imaging
Having a different radius of curvature at the centre and the edges
brewster
A unit of stress optical coefficient which is equal to 10⁻¹² m²/N or 10⁻¹² Pa⁻¹. Symbol: B.
catadioptric
adjectiveOptics and imaging
Of or pertaining to optical systems that employ both reflective (catoptric) and refractive (dioptric) elements.
catadioptrics
The construction and use of catadioptric lenses and systems
caustic
The envelope of reflected or refracted rays of light for a given surface or object.
caustic curve
A curve to which the ray of light, reflected or refracted by another curve, are tangents, the reflecting or refracting curve and the luminous point being in one plane.
caustic surface
A surface to which rays reflected or refracted by another surface are tangents.
Christiansen effect
The reduced scattering of multi-phase microstructures at wavelengths where their refractive indices match.
Christiansen filter
A narrow bandpass or monochromatic optical filter which consists of an optical cell which is filled with a crushed substance (e.g. glass) and a (mostly organic) liquid.
chromatic
adjectiveOptics and imaging
Having the capacity to separate spectral colours by refraction.
chromatic aberration
An optical aberration in which an image has coloured fringes, caused by differential refraction of light of different wavelengths.
chromatics
The science of colours; the branch of optics that deals with the properties of colours.
chronostasis
A visual illusion in which a regular movement seems to pause the first time it is observed.
circle of confusion
An optical spot caused by a cone of light rays from a lens not coming to a perfect focus when imaging a point source.
coma
A defect characterized by diffuse, pear-shaped images that in an ideal image would appear as points.
comatic
adjectiveOptics and imaging
Of or pertaining to coma (the distortion of a lens).
complement
The color which, when mixed with the given color, gives black (for mixing pigments) or white (for mixing light).
concavo-convex
adjectiveOptics and imaging
Having one side concave and the other convex.
condenser
A lens (or combination of lenses) designed to gather light and focus it onto a specimen or part of a mechanism.
conformal optics
A method of designing optical systems in which the conformation of the lenses is chosen to optimize its interaction with the local environment