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Zurich Instruments AG - Lock-In Amplifiers 4/24 LB
SRC Dictionary Terms

Paschen series
An array of lines in the infrared region of the emission spectrum of atomic hydrogen. Their wave numbers are expressed by...
Luneburg lens
A dielectric sphere with an index of refraction that varies with distance from the sphere center. A parallel beam of rays is...
free-space optical interconnect
A type of internal photonic connection in an integrated circuit in which a holographic grating is used to focus light at...
Fresnel lens
A Fresnel lens is a type of optical lens that consists of a series of concentric grooves or steps carved into a flat, thin...
offset prism
A prism or prism assembly that serves to displace the instrument's optical axis.
reflection
Return of radiation by a surface, without change in wavelength. The reflection may be specular, from a smooth surface;...
penta prism
A five-sided prism containing two reflecting surfaces at 45° to each other, and two refracting faces perpendicular to...
Abbe prism
A form of roof prism used to invert an image. The prism has faces cut normal to the optical axis; therefore, the prism may...
chemical vapor deposition
Chemical vapor deposition is a process of applying dopants to a glass bait by flame reactions of gaseous compounds. See also...
achromatic prism
Cemented prisms of differing refractive indices which refract incident light and, due to differing refractive indices, will...
Raman spectroscopy
Raman spectroscopy is a technique used in analytical chemistry and physics to study vibrational, rotational, and other...
field emission display
An X-Y electrically addressable series of arrays with individual electron emitters bombarding a phosphor-coated transparent...
Rayleigh range
In the region of a Gaussian beam focus by a diffraction-limited lens, it is the axial distance from the point of minimum...
Barlow lens
A negative lens used to increase the effective focal length of a telescope objective.
inverse square law
The law stating that the illuminance (or irradiance) from a point source varies as the inverse square of the distance...
duplet lens system
An optical system having two sets of components separated by an air space, while successive lenses in each set are cemented...
integrating sphere
A hollow sphere coated internally with a white diffusing material and provided with openings for incident beam, specimen and...
relay condenser
A form of lens assembly used in a projection system to maximize efficiency and assure uniform illumination of the object...
polygonal mirror
A polygonal mirror, also known as a multifaceted mirror or facet mirror, is a type of optical component used in various...
equatorial mount
A telescope stand equipped with a polar axis that can be set parallel to the Earth's axis of rotation and a declination axis...
loose-tube buffering
In fiber optic cable, containment of the fiber or fibers within an outer protective tube in which they can move to some...
data bus
A system incorporated into fiber optic data communications characterized by several spatially distributed terminals that are...
disc colorimeter
A colorimeter using a spinning disc made of different colored sections for colorimetric analysis.
overhead projector
A projector used to project transparencies. A horizontal 8 x 10-in. stage for writing or laying down preformed...
coma
A lens aberration, resulting from different magnifications in the various lens zones, that occurs in that part of the image...
biocular
A term pertaining to devices (generally optical) designed for use with both eyes viewing through a single exit pupil. The...
thyratron
An arc discharge tube having a grid that is used to start the discharge through an atmosphere of inert gas or vapor at low...
sonde
A ruggedized scintillation counter used in oil well logging. The cylindrical housing contains a gamma ray source, a...
photovoltaic cell
A photovoltaic cell, commonly known as a solar cell, is a semiconductor device that directly converts light energy into...
surface-emitting laser diode
A semiconductor laser diode that emits light perpendicular to the active region. The output radiation is taken through the...
Mach-Zehnder interferometer
A Mach-Zehnder interferometer is an optical device used to measure the phase difference between two collimated beams of...
eye relief
Also termed eye distance. The distance between the vertex of the last optical surface of a visual optical system and the...
meniscus lens
A lens that has one convex surface and the other concave.
raster
The pattern of lines traced by rectilinear scanning in display systems.
atomic scattering factor
The efficiency of scattering by an atom in a particular direction, expressed as: where AA is the amplitude of the wave from...
slab laser
Solid-state laser geometry in which the standard rod is replaced by a slab of laser material. Often called...
beamsplitter
A beamsplitter is an optical device for dividing a beam into two or more separate beams. A simple beamsplitter may be a very...
cosine law of illumination
Law relating the illuminance (or irradiance) of a surface to the cosine of the angle, q, between the normal to the surface...
Snell's law of refraction
The incident ray, the normal to the refracting surface at the point of incidence of the ray at the surface, and the...
Maksutov corrector
A thick meniscus lens arranged concentric with the center of curvature of a spherical mirror to produce an image free of...
photoelectric exposure meter
A device consisting of a microammeter, a photovoltaic cell and a battery. It is used for the measurement of scene brightness...
Schmidt camera
A camera that consists of a concave spherical mirror with an aspheric plate situated at the center of curvature of the...
electric-discharge lamp
A lamp that uses the transmission of an electric current through a gas or vapor to produce illumination. Neon, mercury and...
superior mirage
An image of an object that appears above the object's true position as the result of abnormal refraction of the image rays...
radiation pyrometer
Also known as radiation thermometer. A pyrometer in which the radiant intensity from the source to be measured is used to...
Fresnel mirrors
Two plane mirrors that are not wholly located in the same plane. When light from a point source or slit reflects from the...
stereoscopic rangefinder
A rangefinder similar to a pair of binoculars with a long base, a dot or other wander mark provided in each eyepiece field,...
focal length
The focal length of a lens is the distance between the lens's optical center (or principal point) and the image sensor or...
spherical aberration
Spherical aberration is an optical aberration that occurs when light rays passing through a lens or curved optical surface...
Galilean telescope
A refracting telescope that yields an erect image by the use of a positive lens for its objective and a negative lens for...
panoramic camera
A camera designed to form a continuous record of an expansive section of the horizon. The typical panoramic camera is...
azimuthal polarization
Azimuthal polarization refers to a specific polarization state of light where the electric field vector of the...
Pechan prism
A prism made up of two air-spaced components. It has the ability to revert, and not invert, an image, and can be used in...
double refraction
The separation of unpolarized light into two plane-polarized elements by a doubly refracting crystal. When a crystal, such...
maser
An acronym for microwave amplification by stimulated emission of radiation. Predecessor to the laser, the maser or...
resolution target
A chart on paper or glass containing a series of sets of lines at progressively smaller spacing and used to ascertain the...
light diffusion
Light diffusion refers to the process by which light is scattered or spread out in various directions as it interacts with a...
telecentric lens
There are three types of telecentric lenses: -Image-space telecentric lenses are those in which the aperture stop is...
scanning electron microscope
A scanning electron microscope (SEM) is a powerful imaging instrument used in scientific research, materials...
detector-Dewar assembly
A detector-Dewar assembly typically refers to a combination of a detector and a Dewar flask used in scientific instruments,...
Sagnac interferometer
A type of interferometer in which two coils of optical fiber are arranged so that light from a single source travels...
Dove prism
A form of prism invented by H.W. Dove. It resembles half of a common right-angle prism in which a ray entering parallel to...
vertical-cavity laser diode
A type of surface-emitting laser diode that uses dielectric mirrors to produce surface emission. The laser cavity is...
Cooke triplet lens
The simplest lens in which all primary aberrations may be corrected. It consists of two positive crown elements on either...
degree of coherence
A quantitative measurement of the coherence of a light source; equal to the visibility (V) of the fringes of a two-beam...
Kerr cell
A cell filled with a transparent material that, when placed in a strong electrical field, exhibits double refraction. Since...
Airy disc
The central peak (including everything interior to the first zero or dark ring) of the focal diffraction pattern of a...
Kellner eyepiece
An eyepiece consisting of a planoconvex field lens and a cemented doublet as the eye lens.
Newtonian telescope
A telescope with a concave paraboloidal objective mirror and a small plane (diagonal) mirror that reflects rays from the...
blackbody simulator
A source that attempts to create the characteristics of an ideal blackbody. It consists of a cavity, generally spherical,...
hill cloud lens
A fish-eye lens designed to photograph cloud formations over the entire visible sky.
thermograph
The instrument used to collect thermal radiation information on an object by scanning. It consists basically of a detector,...
spectroheliograph
An instrument in which an image of the sun is scanned by the entrance slit of a monochromator, the exit slit simultaneously...
Haidinger fringes
Also known as constant angle or constant deviation fringes. The interference fringes observed with dense flat plates near...
ring-laser gyroscope
A ring laser gyroscope (RLG) is a type of gyroscope that uses laser light to detect and measure changes in orientation. It...
x-ray diffraction
The bending of x-rays by the regular layers of molecules in a crystal acting like a very small diffraction grating. The...
Michelson-Morley experiment
An optical experiment carried out conclusively in 1887 that demonstrated that the ether, a hypothetical medium postulated by...
Petzval surface
A paraboloidal surface on which the image is located when there is no astigmatism.
grating spectroscope
A spectroscope having a diffraction grating for the resolution of light of various wavelengths.
wide-angle lens
A wide-angle lens is a type of camera lens that has a shorter focal length than a standard or normal lens, allowing it to...
caustic
A surface that envelops a bundle of rays or bundle of normals to the wave surface. It may be observed as a hollow, luminous...
acceptance angle
The range of angle or solid angle values by which light may enter an optical system.
eye
The organ of vision or light sensitivity.
scanner
1. A device used to trace out an object and build up an image. One of the most common of these types is video scanning. The...
fullerenes
Molecules composed entirely of carbon, in the form of a hollow sphere, ellipsoid or tube. Also called buckyballs....
Snellen letter
The letter form used on visual performance test charts. The overall letter height is equal to five times the thickness of...
Malus's law
A law that uses the square of the cosine between the plane of polarization of a beam of plane-polarized light and the plane...
Dogmar/Aviar lens
A general-purpose lens, also known as the Celor lens, used widely in photography and commercial processing; it has the form...
colorimeter
A colorimeter is a device used to measure and quantify the color characteristics of an object or a light source. It provides...
halation
1. In a cathode-ray tube, the glow surrounding a bright spot that appears on the fluorescent screen as the result of the...
biplanar image tube
Also called proximity focus image intensifier. A compact image intensifier that utilizes a microchannel plate...
retrofocus lens
Also known as reversed telephoto lens. A lens consisting of an ordinary objective with a negative component near its front...
x-ray image spectrography
Irradiation of a cylindrical crystal with an x-ray beam resulting in Bragg diffraction that produces a slightly enlarged...
connector
Hardware installed on fiber cable ends to provide cable attachment to a transmitter, receiver or other cable. Usually a...
direct-vision prism
An assembly of multiple prisms that disperses incident light into its spectral components without deviating light at the...
diode laser
A diode laser is a type of laser that uses a semiconductor diode as the active medium to generate coherent light....
vertical external cavity surface-emitting laser
A laser that has a surface-emitting semiconductor gain element coupled to an external mirror designed to complete the laser...
Young's two-slit interference
The method by which Thomas Young in 1802 disproved Newton's corpuscular theory of light by the formation of interference...
aerocartography
The creation of topographical maps and charts from a stereographic record produced through the overlapping of consecutive...
holographic camera
A holographic camera, also known as a holographic imaging system or holographic recorder, is a specialized device used to...
Wollaston prism
A polarizing prism consisting of two calcite prisms cemented such that they deviate the two emerging beams (which are...
Billet's split lens
An experimental lens used to produce interference fringes. A positive lens is cut into halves along its center, and the...
Gauss lens
A telescope objective with excellent spherochromatic correction, consisting of a meniscus crown and a meniscus flint, both...
near-field scanning optical microscope
A scanning probe microscope that analyzes the surface of a specimen by recording the intensity of light as it is focused...
Bragg's law
The law expressing the condition under which a crystal will reflect a beam of x-rays with the greatest amount of distinction...
Amici prism
Also known as roof prism. A type of prism designed by G.B. Amici. It consists of a roof edge produced upon the long...
Winston cone
Specified curved optic intended for maximum collection of light, including off-axis rays, before leaving the exit aperture.
diffraction grating
A diffraction grating is an optical component consisting of a surface with a periodic structure of equally spaced, parallel...
reticle
A reticle, also known as a reticule or graticule, is a pattern or set of markings placed in the focal plane of an optical...
Verdet constant
A factor of an equation of the Faraday effect, which is the rotation of the plane of light polarization by transparent...
optical multimeter
An instrument that measures several optical parameters, such as optical power and wavelength, with a single measurement...
Petzval lens
A high-speed, narrow-field lens consisting of two achromats spaced about the aperture stop. Its uses include portrait...
critical illumination
Illumination in which the light source is imaged at the object.
multileg lightguide
A fiber optic bundle split along its length with the ends of the fibers extending separately to illuminate different points...
Littrow prism
A 30-60-90° spectrograph prism that is coated on the surface opposite the 60° angle with a reflecting film.
electron microscope
A device utilizing an electron beam for the observation and recording of submicroscopic samples with the aid of photographic...
collimator
An optical instrument consisting of a well- corrected objective lens or mirror with a light source and or object/image (i.e....
penumbra
A source of light will not cast a distinct shadow of an interfering, opaque object, but will cast a shadow having two parts:...
Callier coefficient
The coefficient termed by Callier as the ratio between the density of photographic negatives measured by parallel light and...
Wadsworth mounting
A system used for gratings that consists of a concave mirror, a grating and a plate holder mounted normal to the grating to...
Raman effect
When light is transmitted through matter, part of the light is scattered in random directions. A small part of the scattered...
camera tube
The electron beam tube of a television camera that converts an optical image into a pattern of electrostatic charges and...
degrees of freedom
The number of unique ways in which a part can move in an alignment system. In static alignment, there are six: one in the...
aerial survey
The creation of a planned sequence of data input that is obtained while airborne for use in aerial photogrammetry and other...
Cassegrain lens system
A two-mirror lens design used in astronomical telescopes, the primary being a parabola, the secondary a smaller hyperbola....
Fresnel rhomb
A type of quarter-wave retarder in the form of a glass rhomb; light entering the retarder undergoes two total internal...
hologram
An interference pattern that is recorded on a high-resolution plate, the two interfering beams formed by a coherent beam...
head-up display
An optical system that superimposes a synthetic display providing navigational or weapon-aiming information on a pilot's or...
steradian
The unit solid angle subtended at the center of a sphere by an area on its surface equivalent to the square of the radius;...
flying spot microscope
A microscope that uses a flying spot scanner, directed through the eyepiece, as a light source to determine the features of...
paraboloidal mirror
A concave mirror that has the form of a paraboloid of revolution. The paraboloidal mirror may have only a portion of a...
optical fiber
Optical fiber is a thin, flexible, transparent strand or filament made of glass or plastic used for transmitting light...
microscope eyepiece
An eyepiece located at the near end of the microscope tube. It often is a simple Huygens eyepiece, but compensating and...
Fourier transform spectrometer
An instrument using a Michelson interferometer, a beamsplitter, two plane mirrors and a detector to give Fourier analysis of...
Nicol prism
A prism invented by William Nicol in 1828 that is made of calcite, the end faces of which are ground to an angle of 68°...
radiometer
A device used to measure the intensity of radiant energy.
iris diaphragm
A mechanical device designed to smoothly vary the effective diameter of a lens, thereby controlling the amount of light...
angle of incidence
The angle formed between a ray of light striking a surface and the normal to that surface at the point of incidence.
elbow telescope
A refracting telescope that uses a prism to bend the line of sight 90°.
automatic optical inspection
A system for automatic industrial process control or measurement, consisting of an optical module for image acquisition, a...
optical density
A measure of the transmittance through an optical medium. Optical density equals the log to the base 10 of the reciprocal of...
Lissajous pattern
The pattern, formed by a character generation cathode-ray tube system, in which the characters are made up of wave shapes...
autocollimator
An autocollimator is an optical instrument used for measuring small angular deviations with high precision. It operates on...
standing wave
The combination of two waves having the same frequency and amplitude and traveling in opposite directions. Standing waves...
stereolithography
A method of creating real three-dimensional models by using lasers driven by CAD software. In contrast to the normal...
acoustical holography
The optical reconstruction of image information contained in a sound field. First the diffraction pattern, formed by an...
Gregorian telescope
A telescope with an ellipsoidal secondary concave mirror that reflects rays from a parabolic primary mirror through an...
ion laser
A laser in which the transition involved in stimulated emission of radiation takes place between two levels of an ionized...
optical axis
The imaginary line passing through both the centers of curvatures of the optical surfaces of a lens or mirror; the optical...
Fabry-Perot interferometer
A multiple-beam interferometer, usually consisting of two flat plates, with high reflective ability. The plates are set...
pyroelectric infrared detector
Unlike the thermocouple or bolometer, the pyroelectric infrared detector is a current source with an output proportional to...
Lloyd's mirror
A mirror employed with a very high incidence angle to form a pair of coherent light sources by reflection, and therefore...
dispersive power
A measure of the dispersive properties of a glass. The relative dispersion is defined as: where C, D, and F refer to the...
Rowland circle
The circle that contains the slit, grating and primary astigmatic focus of a concave diffraction grating.
slide projector
An optical projection device designed to project positive color transparencies onto a screen for viewing.
cold shield
That part of an infrared detector-Dewar assembly that limits the solid angle viewed by the sensor; it is maintained at a...
near-field holography
A lithography method that allows the transfer of fine-pitch gratings from a phase mask into photoresist. The exposure takes...
Ritchey-Common test
An interferometric method for describing the surface shape of large coated or uncoated optical flats. The procedure uses a...
optical profiler
Also known as a white-light interferometer. Measures surface texture and shape from nanometer-scale roughness to...
Cornu double prism
A compound prism formed by cementing together two 30° prisms, one of right-handed and one of left-handed quartz. It has...
light dispersion
The process whereby white light is separated into its component wavelengths. Light beams of different wavelengths are...
optical parametric oscillator
A laser-pumped crystal with nonlinear optical properties inside of an optical resonator in which the output generates...
fan
A set of rays through a lens originating at a common point and contained in one plane.
telephoto lens
A compound lens so constructed that its overall length is equal to or less than its effective focal length.
cathode-ray tube
A vacuum tube with an electron gun at one end and a fluorescent screen at the other. Electrons emitted from a heated...
secondary color
An aberration that remains after primary color is corrected. Primary color causes the back focus of a lens to vary with...
zoom lens
An optical system of variable focal length, the focal plane remaining in a fixed position. This result is achieved by moving...
Mangin mirror
A double-surfaced catadioptric spherical mirror whose spherical first surface consists of a negative meniscus (concave) lens...
fluorescence photography
The photographic recording of a subject that exhibits luminescence only for an extremely short time (10-8 s) after the...
prism power
The power, expressed in prism diopters, that is the linear displacement, in centimeters, produced by the prism one meter...
jig transit
An optical instrument containing a gimballed sighting telescope, used to measure angular relationships in horizontal and...
binocular microscope
A microscope designed with two eyepieces (oculars), permitting the use of both eyes when viewing through the instrument.
curvilinear distortion
A lens aberration in which the focal length varies radially outward from the center of the field. It has the effect of...
nodal points
Of all the rays passing through a lens from an off-axis object point to its corresponding image point, there is always one...
minimum angle of deviation
The smallest angle through which light is bent by an optical element or system. In a prism, the angle of deviation is a...
resonator
A resonator is a device or system that exhibits resonance, which is a phenomenon that occurs when an external force or...
diverging lens
A diverging lens is a type of lens that causes parallel rays of light to spread out or diverge. It is thinner in the center...
Pockels cell
A Pockels cell, also known as an electro-optic modulator, is an optical device used to control the polarization of light by...
Bohr's frequency relation
The law given by the formula: that is, the frequency of radiation emitted or absorbed by a system when E2 and E1...
high-speed movie camera
A camera designed to record at rates exceeding 50 fps. For frame rates up to about 500 fps, an ordinary pull-down mechanism...
phase-contrast microscope
A microscope that has an annular stop in the lower focal plane of the condenser, and a quarter-wave retarding and absorbing...
electrocapillarity modulator
A type of optical modulator with potential application in optical switching and displays, in which applied voltage causes a...
intrinsic detector
A photodetector composed of a photoconductive material that, when exposed to radiation, conducts without the aid of added...
short-arc lamp
A compact high-pressure light source in which an electrical discharge between electrodes spaced no more than 12 mm apart...
nematic phase
A form of liquid crystal with an appearance of moving, threadlike structures, particularly visible when observed in thick...
confocal resonator
A confocal resonator, also known as a confocal cavity or confocal laser resonator, is a type of optical resonator...
optical time-domain reflectometry
A method for characterizing a fiber wherein an optical pulse is transmitted through the fiber, and the resulting light...
keystone distortion
A type of geometrical distortion that brings about a trapezoidal display of a nominally rectangular picture. Usually...
polarization-preserving fiber
Single-mode fiber that preserves the plane of polarization of the light launched into it as the beam propagates through its...
Gaussian profile
An intensity distribution (intensity as a function of radial distance from the beam center) which is given by the Gaussian...
surface reflection
Also known as Fresnel reflection. That portion of the incident radiation that is reflected from the surface of a refractive...
powder camera
A camera system that uses a fine powder to diffract x-rays from the specimen. A beam of monochromatic x-rays passes through...
lens mount
The metal tube that maintains the optical components of a lens in proper relationship. Some lenses are mounted in metal...
evaporagraph
A sensor generally used for infrared imaging. It consists of two chambers separated by a thin, blackened membrane. An...
spectrograph
An optical instrument for forming the spectrum of a light source and recording it on a film. The dispersing medium may be a...
optical tooling target
Sets of paired lines carefully designed to give the most accurate pointing possible for various lengths of sight.
Rayleigh criterion of resolving power
When a lens system with a circular aperture is free of aberrations, the image of a point object will appear as a disc of...
modulation transfer function
Also called sine wave response and contrast transfer function. The modulation transfer function is the ratio of the...
Fizeau interferometer
A type of interferometer noted for producing narrow multiple-beam interference fringes. As a result, when compared with the...
t number
The equivalent f number of a fictitious lens that has a circular opening and 100 percent transmittance, which would give the...
trichromacy
The basis of color vision in the human eye. Three types of cones have been identified, each having a unique spectral...
rhomboid prism
A reflecting prism that is rhomboidal in shape. It has two parallel transmitting faces, and two parallel reflecting faces;...
endoscope
An endoscope is a medical device used for visualizing and examining the interior of hollow organs, body cavities, or...
optical camouflage
The use of retroreflective projection technology (RPT) to project a background image onto a masked object, such as a vehicle...
camera
A light-tight box that receives light from an object or scene and focuses it to form an image on a light-sensitive material...
cold mirror
A mirror whose coating serves to reflect visible radiation while transmitting the infrared.
contrast
The apparent difference in brightness between light and dark areas of an image. For a light target against a dark...
spectrometer
A kind of spectrograph in which some form of detector, other than a photographic film, is used to measure the distribution...
normalized frequency
Also referred to as the V number in fiber optics; the normalized frequency is a dimensionless quantity, denoted by the...
Brewster's angle
For light incident on a plane boundary between two regions having different refractive indices, the angle of incidence at...
additive color process
A process of color photography in which colors are added one to another in the form of light, rather than as colorants, to...
double-crucible method
A method of fabricating an optical waveguide by melting the core and clad glasses in two suitably joined concentric...
bimorph
A type of piezoelectric translator that uses two thin strips of piezoelectric material, one expanding while the other...
Foucault knife-edge test
The Foucault test is performed by moving a knife edge laterally into the image of a small point source. The eye, or a...
astigmatism
A lens aberration that results in the tangential and sagittal image planes being separated axially.
sag
1. In the geometric sense, an abbreviation for the term "sagitta,'' the height of a curve measured from the chord. ...
triplet
A lens assembly made up of three lens elements that may or may not be cemented.
double-Gauss lens
A fast, wide-angle lens used in television and photographic cameras, with excellent overall correction, but subject to...
infrared spectrophotometer
A spectrophotometer having a prism or, more frequently, a grating for the study and recording of infrared spectra. It...
Twyman-Green interferometer
A testing device that provides a contour map of the emergent wavefront for the observer in terms of the given wavelength of...
third-order theory
Calculations of lens aberrations whereby the first two terms of the series expansion are the only ones employed....
apochromat
An apochromat, often referred to as an apochromatic lens or apochromatic objective, is a type of optical system designed to...
barrel distortion
The negative distortion that causes a square grid pattern to be imaged as barrel-shaped.
depth of focus
The range of image distances that corresponds to the range of object distances covered by the depth of field.
periscope
An optical instrument designed to displace the line of sight in a vertical direction. For submarines and other military uses...
aperture stop
A physical constraint, often a lens retainer, that limits the diameter of the axial light bundle allowed to pass through a...
birefringence
Birefringence is an optical property of certain materials that causes them to exhibit different refractive indices for light...
charge-coupled device
A charge-coupled device (CCD) is a type of electronic image sensor used in various imaging devices, including digital...
variable-focus condenser
An Abbe condenser in which the upper lens element is fixed. The lower lens may focus the illumination between the elements...
flying spot scanner
A device used to scan, with a small, intensely bright spot, portions of a picture surface and to transform the original...
Senarmont prism
A polarizing beamsplitting prism similar in design to the Rochon prism. However, the Senarmont transmits the extraordinary...
chief ray
The ray that passes through the center of the aperture stop in an optical system. It often is called the principal ray of an...
achromatic lens
A lens consisting of two or more elements, usually of crown and flint glass, that has been corrected for chromatic...
vignetting
In an optical system, the gradual reduction of image illuminance as the off-axis angle increases, resulting from limitations...
vidicon
A small television tube originally developed for closed-circuit television. It is about 1 inch in diameter and 5 inches...
diffraction
As a wavefront of light passes by an opaque edge or through an opening, secondary weaker wavefronts are generated,...
landolt ring
A broken circle used as the test object in distinguishing visual acuity. The width of the gap in the circle is equal to the...
atomic absorption spectrometer
An atomic absorption spectrometer (AAS) is an analytical instrument used to determine the concentration of specific chemical...
Abbe refractometer
Device which measures the index of refraction of glass as well as the dispersion over visible range.
field stop
An aperture located at an image plane of an optical system that determines the size and shape of the image.
clear eye distance
In a visual optical system, the axial distance from the last mechanical surface of the eyepiece to the exit pupil.
Munsell notation
Alphanumerical description of color according to Munsell hue, value and chroma.
triclinic
With respect to a crystal, having three unequal axes intersecting at angles, only two of which can be equal and only one of...
prism binoculars
A pair of telescopes with prismatically erected images, mounted side by side with the eyepieces at the interocular distance...
refractive index contrast
A measure of the relative difference in refractive index between two optical materials. Most commonly used in fiber optics...
back focal length
The distance from the final optic within a system to the rear image point of the system. See focal length.
Planck's (radiation) law
The formula describing the spectral radiant emittance of a perfect blackbody as a function of its temperature and the...
critical angle
The least angle of incidence at which total internal reflection takes place. The angle of incidence in a denser medium, at...
curvature of field
A lens aberration that causes a flat object surface to be imaged onto a curved surface rather than a plane.
three-level laser
A laser having a material, such as ruby, that has an energy state structure of three levels: the ground state (1) wherein...
oscilloscope
A system in which a supplied signal causes the deflection of the electron beam in a cathode-ray tube, thus forming a visible...
motion picture camera
A camera equipped with a lens and a long length of perforated film, the latter being moved intermittently between exposures...
transverse mode
In the context of optics and lasers, a transverse mode refers to a specific spatial pattern of the electric field within the...
Huygenian eyepiece
An ocular having two planoconvex lenses that are formed from similar glass and that are separated by a space equal to half...
wedge
An optical element having plane-inclined surfaces. Usually the faces are inclined toward one another at very small angles....
smectic phase
A form of liquid crystal in which flow does not take place in the usual manner. When examined with polarized light, the...
monochromatic light
Light consisting of a single wavelength or a very narrow band of wavelengths.
serpentine bend mode filter
A device used in measuring attenuation in optical fiber. The loss caused by the bends in a short reference length of fiber...
stereoscope
A small instrument containing a picture support and a pair of magnifying lenses so arranged that the left eye sees only the...
principal plane
In a lens or lens system, that surface at which the projections of an entering and exiting ray intersect. Also known as the...
solar furnace
An optical system that is designed to produce a high temperature in a specified area by the optical direction and...
optical pyrometer
An instrument for determining the temperature of a hot object by examining the color spectrum of the visible light it gives...

(262 results found)

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