| A |
| Aberration |
The failure of an "optical" lens to produce an exact point-to-point correspondence between the object and its resulting image. Various types are chromatic, spherical, coma, astigmatism and distortion.
|
| Absolute Zero |
The temperature at which all molecular motion ceases. This is the lowest theoretically possible temperature.
|
| Absorption |
The loss of light of certain wavelengths as it passes through a material and is converted to heat or other forms of energy.
|
| Accuracy |
The extent to which a camera can correctly measure or obtain a true value of an objects temperature.
|
| Active Illumination |
Lighting a scene with a light source coordinated with the acquisition of an image. Strobed flash tubes, pulsed lasers and scanned LIDAR beams are examples.
|
| Ambient light |
Light, which is present in the environment of the imaging front end and generated from outside sources.
|
| Analog |
A smooth, continuous voltage or current signal or function whose magnitude (value) is the information. From the word "analogous," meaning "similar to."
|
| Analog-to-Digital Converter (A/D) |
A device, which converts an analog voltage or current signal to a discrete series of digitally, encoded numbers (signal) for computer processing.
|
| Area |
Portion or area of the image to be analyzed. Area analysis measures the number of pixels, which fall in a specified range of gray levels for the feature of interest.
|
| Area Array Camera |
A solid state-imaging device with both rows and columns of pixels, forming an array, which produces a 2D image.
|
| Aspect ratio |
The ratio of the width to the height of a frame of a video image. The U.S. television standard is 4:3 or 1.333
|
| Auto focus |
The ability of an imaging system to control the focus of the lens to obtain the sharpest image on the detector.
|
| B | 
top |
| Baffle |
A type of shield that prohibits light from entering an optical system.
|
| Band pass Filter |
An absorbing filter that allows a known range of wavelengths to pass, blocking those of lower or higher frequency.
|
| Barrel Distortion |
An optical imperfection, which causes an image to bulge convexly on all sides similar to a barrel.
|
| Beam splitter |
An optical device which divides one beam into two or more separate beams. A simple coated piece of glass in the optical path might reflect 60% of the light down onto the object, while allowing the other 40% to pass.
|
| Blackbody |
An object, which emits the maximum amount of energy that is theoretically possible at the given temperature.
|
| BLIP |
A detector is referred to as BLIP (background limited) when its detectivity D* is limited by the noise associated with the photons from the background radiation and not by intrinsic detector noise.
|
| Bolometer (also, Microbolometer) |
An infrared detector, which absorbs the IR radiation and warms slightly; the electrical resistance across the bolometer changes as a function of temperature, which can be measured and calibrated.
|
| Brewster's Angle |
The angle at which incident light, by reflecting at a boundary between two mediums of different refractive indices (i.e. air/glass or air/water), becomes plane polarized. For air/glass it is about 67.4 degrees.
|
| Brightness |
The total amount of light or incident illumination on a scene or object per unit area. Also called intensity.
|
| BTU (British Thermal Unit) |
In the English measuring system, the BTU is the unit of heat. One BTU is the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit.
|
| Byte |
Eight bits of digital information. A byte has values from 0 to 255, and is the unit most commonly used to represent the gray scale value of one pixel.
|
| C |
top |
| Calibration |
1. A measurement or comparison against a standard. 2. The determination of any equipment deviation from a standard source so as to ascertain the proper correction factors.
|
| Calorie (also, gram-calorie) |
Not to be confused with the nutrionist’s definition of calories, the gram-calorie (also referred to as the calorie) is the amount of heat required to raise the temperature of one gram of water by one degree Celsius. This is equivalent to 4.186 Joules of energy in the SI measuring system.
|
| CCD |
(Interline Transfer) Data (charge) is transferred simultaneously out by odd and even lines or fields directly from the image sensors to their corresponding sensor registers. The output from the camera is always one field (frame) behind the image being captured.
|
| CCD |
Charge Coupled Device. A photosensitive image sensor implemented with large-scale integration technology.
|
| CCD |
(Frame Transfer) The entire image is transferred from the sensing area to a storage area on chip. Data (charge) is read out from the storage area in a full frame mode. This workhorse of the industry is also capable of non-RS-170 operation.
|
| Celsius |
The unit of temperature in the SI measuring system. Celsius is the temperature system referenced to the freezing & boiling points of water at sea level; 0 degrees C is freezing, and 100 degrees C is boiling (for water). One degree C is equal to one degree Kelvin (K), but the Kelvin units are referenced to absolute zero. 1 degree C I approximately equal to 0.556 degrees F.
|
| CID-Charge Injection Device |
A photosensitive image sensor implemented with large-scale integration technology. Based on charge injection technology, a CID can be randomly addressed, non-destructively read, can be subscanned in a small region and is less susceptible to charge overflow from bright pixels to neighbors. The pixel structure is contiguous with maximum surface to capture incident light, which is useful for sub-pixel measurement.
|
| C-mount |
A threaded means of mounting a lens to a camera.
|
| Collimate |
To produce light with parallel rays.
|
| Collimated Lighting |
Radiation from a given point with every light ray considered parallel. In actuality, even light from a very distant point source (i.e. a star) diverges somewhat. Note that all collimators have some aberrations.
|
| Color |
A visual object attribute, which may be described by a "coordinate system" such as hue, saturation and intensity (HSI), CIE or LAB. Wavelengths in the visible part of the electromagnetic spectrum to which retinal rods respond.
|
| Colorimetry |
Techniques used to measure color of an object or region and to define the results in a comparison or coordinate system.
|
| Composite Video |
A television signal, which is produced by combining both a video or picture signal with horizontal and vertical synch and blanking signals.
|
| Condenser Lens |
Used to collect and redirect light for the purpose of illumination. Often used to collect light from a small source and project even light onto an object.
|
| Contrast |
The difference of light intensity between two adjacent regions in the image of an object. Often expressed as the difference between the lightest and darkest portion of an image. Contrast between a flaw or feature and its background is the goal of illumination.
|
| Contrast Enhancement |
Stretching of the gray level values between dark and light portions of an image to improve both visibility and feature detection.
|
| Convection |
One of the three possible modes of heat transfer (the others are conduction and radiation), this refers to heat transfer when a moving fluid (can be liquid or gas) is present; the heat is transferred by the bulk motion of the fluid.
|
| Convolution |
Superimposing a m x n operator (usually a 3x3 or 5x5 mask) over an area of the image, multiplying the points together, summing the results to replace the original pixel with the new value. This operation is often performed on the entire image to enhance edges, features, remove noise and other filtering operations.
|
| Correlation |
A mathematical measure of the similarity between images or areas within an image. Pattern matching or correlation of an X by Y array size template to the same size image, produces a scaler number, the percentage of match. Typically, the template is walked through a larger array to find the highest match.
|
| Cross section |
A 3D profile of a slice of an object.
|
| D |
top |
| Dark current |
The current through a photodiode when a specific reverse bias voltage is applied, with no incident radiant power. Also referred to as Reverse Current.
|
| Dark field Illumination |
Lighting of objects, surfaces or particles at very shallow or low angles, so that light does not directly enter the optics. Objects are bright with a dark background. This grazing illumination causes specular reflections from abrupt surface irregularities.
|
| Depth Perception |
The perception of solidity of a visual object and its location in the spatial field, through the fusion in the brain of the two slightly dissimilar images from the two eyes.
|
| Depth-of-field |
The range of an imaging system in which objects are in focus.
|
| Detection Range |
The maximum range at which a specified target can be detected, though not identified. For military/security applications, the target is often specified as an upright, 6’ man, or a vehicle such as a pickup truck.
|
| Detectivity (D*) |
A parameter used to compare the performance of different detector types. D* is the signal-to-noise ratio at a particular electrical frequency and in a 1 Hz bandwidth when 1 Watt of radiant power is incident on a 1 cm2 active area detector. The higher D* the better the detector. D* is normally expressed either as a blackbody D* or as a peak wavelength D* within the practical operating frequency of the detector. The units of D* are centimeter-square root hertz per watt.
|
| Dichroic Filter |
A filter used to transmit light based on its wavelength, rather than on its plane of vibration. Transmits one color, while reflecting a second when illuminated with white light. Often used in heads-up displays.
|
| Diffraction Pattern Sampling |
Inspection by comparing portions of the interference pattern formed on a screen or special sensor from light waves diffracted by object edges.
|
| Diffuse Reflection |
Light that bounces off an object surface in many different directions. Light radiated from a matte surface is highly diffused.
|
| Diffuse Surface |
A surface that emits or reflects evenly in all directions, regardless of the direction of the incoming light (in the case of reflection).
|
| Diffused lighting |
Scattered soft lighting from a wide variety of angles used to eliminate shadows and specular glints from profiled, highly reflective surfaces.
|
| Digital Signal Processor (DSP) |
A VLSI chip designed for ultra high speed arithmetic processing. Often imbedded in a vision engine.
|
| Digital-to-Analog Converter |
A VLSI circuit used to convert digital computer processed images to analog for display on a monitor. DAC is the acronym.
|
| Digitization |
Sampling and conversion of an incoming video or other analog signal into a digital value for subsequent storage and processing.
|
| Dispersion |
Separation of a beam of light into its wavelength components, each of which travel at slightly different speeds. Also called chromatic dispersion.
|
| Dynamic Range |
The range in signal amplitude over which a communication receiver or audio amplifier is capable of operating while producing an acceptable output; usually expressed in decibels.
|
| E |
top |
| Electrical Noise |
1. An unwanted, often random disturbance to a signal that tends to obscure the signal's information content; caused primarily by the random thermal motions of particles in the system. 2. Any signal disturbance that interferes with the operation of a system. Any signal disturbance that interferes with the operation of a system. 3. Any random disturbance that obscures the clarity of a signal.
|
| Electro-magnetic Spectrum |
The total range of wavelengths, extending from the longest (audio) to the shortest (gamma rays) which can be physically generated. This entire spectrum is potentially useful for imaging, well beyond just the visible spectrum.
|
| Emissivity |
A value between 0 and 1 that represents a ratio between an object and a blackbody. The value represents the surface emitance of that object.
|
| Extension Tube |
A cylindrical threaded tube used to change the magnification, effective focal length and field of view of a lens when inserted between the lens and imaging sensor.
|
| F |
top |
| Fahrenheit |
The unit of temperature in the English measuring system. 32 degrees F is the freezing point of water at sea level, while 212 degrees F is the boiling point. One degree F is equal to 1.8 degrees C.
|
| Fast Fourier Transform |
Produces a new image, which represents the frequency domain content of the spatial or time domain image information. Data is represented as a series of sinusoidal waves.
|
| Fiducial |
A line, mark or shape used as a standard of reference for measurement or location.
|
| Field |
One of the two parts of a television frame in an interlaced scanning system. The odd plus the even field comprise one video frame. A field is scanned every 1/60th of a second.
|
| Field-of-view |
The 2D area which can be seen through the optical imaging system. (FOV)
|
| Fill Factor |
Term of measurement of FPA performance, which measures how much of the total FPA is sensitive to IR energy. Because the FPA is made of numerous individual detector cells, the pathways used to separate the cells and transmit signals measure the total amount of sensitivity. The higher the fill factor, the higher the ratio of sensitivity.
|
| Filtering |
The use of an optical filter for picture or color enhancement in front of the camera lens or light source. Also analog or digital image processing (IP) operations to enhance or modify an image. May be linear & non-linear.
|
| Fluorescence |
The emission of light or other electromagnetic radiation at longer wavelengths by matter as a result of absorption of a shorter wavelength. The emission lasts only as long as the stimulating irradiation is present.
|
| F-number |
The ratio of the focal length to the lens aperture. The smaller the f- number, the larger the lens diameter and brighter the image and narrower the depth-of-field.
|
| Focal Length |
The distance from a lens' principal point to the corresponding focal point on the object.
|
| Focal Plane |
Usually found at the image sensor, it is a plane perpendicular to the lens axis at the point of focus.
|
| Focus |
The point at which rays of light converge for any given point on the object in the image. Also called the focal point.
|
| Focus Following |
A ranging and tracking technique that uses image processing to measure object range based on best focus.
|
| Fourier Domain Inspection |
Evaluation of the Fourier transform (frequency information) of a 2D spatial image for features of interest.
|
| Frame |
The total area scanned in an image sensor while the video signal is not blanked. In interlaced scanning, two fields comprise one frame. Frame rate is typically 30 Hz.
|
| Frame Buffer |
Image memory in a frame grabber.
|
| Frame Grabber |
A device that interfaces with a camera and, on command, samples the video, converts the sample to a digital value and stores that in a computer's memory.
|
| Full Well Capacity |
The maximum number of carriers that can be accumulated in one detector pixel during one read-out cycle of the detector.
|
| G |
top |
| Gain |
Functionally similar to ‘contrast’ in a visual system, gain sets the span between the minimum and maximum thermal intensities that can be imaged simultaneously.
|
| Grating |
An optical element with an even arrangement of rods or stripes with spaces between them for light to pass. Its ability to separate wavelengths is expressed in line pairs per millimeter, for example. A moire grating of parallel dark and light stripes is an example. Also used for structured light projection.
|
| Gray level |
A quantized measurement of image irradiance (brightness), or other pixel property typically in the range between pure white and black.
|
| Graybody |
An “idealized” non-blackbody, in which the emissivity is assumed constant with respect to wavelength.
|
| Grayscale Image |
An image consisting of an array of pixels, which can have more than two values. Typically, up to 256 levels (8 bits) are used for each pixel.
|
| GUI |
An acronym for Graphical User Interface. Pronounced "gooie." A Windows based user interface screen or series of screens allowing the user to point-and-click to select icons rather than typing commands.
|
| H |
top |
| Hardware |
Electronic integrated circuits, boards and systems used by the system.
|
| Height/Range |
Object profile is usually measured by changes in range or distances from the sensor. 3D techniques are usually used.
|
| High Pass Filter |
Passes detailed high frequency image information, while attenuating low frequency, slow changing data.
|
| High Speed Imaging |
Imaging at frame rates greater than 60 Hz.
|
| Histogram |
A graphical representation of the frequency of occurrence of each intensity or range of intensities (gray levels) of pixels in an image. The height represents the number of observations occurring in each interval.
|
| Histogram Analysis |
Determination of the presence or absence of a feature or flaw based on the histogram values in a certain gray scale region.
|
| Histogram Equalization |
Modification of the histogram to evenly distribute a narrow range of image gray scale values across the entire available range.
|
| Hybrid FPA |
FPAs with a hybrid configuration have IR-sensitive detector cell material on one layer and the signal transmitting circuitry on another layer. A process known as Indium Bump Bonding bonds each layer. The hybrid configuration increases the fill factor and overall sensitivity of the FPA.
|
| Hyperspectral |
The use of many narrow sections of the electromagnetic spectrum in remote sensing.
|
| I |
top |
| Illumination |
Normally a wavelength or range of wavelengths of light or visible light used to enhance a scene so the detector, normally a camera, can produce an image.
|
| Image |
Projection of an object or scene onto a plane (i.e. screen or image sensor).
|
| Image Analysis |
Evaluation of an image based on its features for decision-making.
|
| Image Capture |
The process of acquiring an image of a part or scene, from sensor irradiation to acquisition of a digital image.
|
| Image Distortion |
A situation in which the image is not exactly true to scale with the object scale.
|
| Image Enhancement |
Image processing operations, which improve the visibility of image detail and features. Usually performed for humans.
|
| Image Intensifier |
Usually an electron tube equipped with a light sensitive electron emitter at one end and a phosphor screen at the other. Used to provide electron gain for imaging in low light conditions such as night vision.
|
| Image Memory |
An internal, high speed, large capacity storage area on a frame grabber card or in a computer dedicated to image retention.
|
| Image Plane |
The plane surface of the imaging sensor, perpendicular to the viewing direction, at which the optics are focused.
|
| Image Processing |
Digital manipulation of an image to aid feature visibility, make measurements or alter image contents.
|
| Incident Light |
Light which falls directly onto an object.
|
| Index of Refraction |
A property of a medium that measures the degree that light bends when passing between it and a vacuum.
|
| Infrared |
The region of the electromagnetic spectrum adjacent to the visible spectrum generally taken from about 800 nanometers (0.8 microns) to about 40 microns.
|
| Integration Time |
The time period over which the detector ‘views’ the target. Analogous to exposure time in visual cameras.
|
| Intensity |
The relative brightness of a portion of the image or illumination source.
|
| I/O |
An acronym for Input/Output data either entering or leaving a system.
|
| K |
top |
| Kelvin |
International temperature scale in which 0°Kelvin represents absolute zero (the point at which no heat energy exists within an object).
|
| L |
top |
| Lens |
A transparent piece of material with curved surfaces, which either converge or diverge light rays. Often used in groups for light control and focusing.
|
| Lens Types |
The lenses most commonly used in imaging are: refractive and catadioptric.
|
| LIDAR |
An acronym of Light Detection And Ranging. A system that uses light instead of microwaves for range and tracking measurements. LADAR uses a laser light source to measure velocity, altitude, height, range or profile
|
| Line Scan Camera |
A solid-state video camera consisting of a single row of pixels.
|
| Linearity |
Measures FPA detector performance over the range of temperatures to be measured. The ability of a detector to measure small temperature differences is often referred to as its linearity. Typical testing includes response of the detector from 40 to 50 degrees Celsius (°C) and 490 to 500°C.
|
| Look-Up Table (LUT) |
High speed digital memory used to transform image input values to outputs for thresholding, windowing and other mappings such as pseudo-color. (-)
|
| Low Pass Filter |
A digital or optical filter, which passes slow changing, low frequency information, while attenuating high frequency, detailed edge information.
|
| M |
top |
| Machine Vision |
The use of devices for optical non-contact sensing to automatically receive and interpret an image of a real scene, in order to obtain information and/or control machines or processes.
|
| Magnification |
The relationship between the length of a line or size of a feature in the object plane with the length or size of the same in the image plane.
|
| Median Filter |
A method of image smoothing, which replaces each pixel value with the median grayscale value of its immediate neighbors.
|
| Micron |
One millionth of a meter also called a micrometer.
|
| Minimum Resolvable Temperature Difference (MRTD) |
A measure of the minimum difference in energy (expressed in units of blackbody temperature) required to thermally discriminate a target from the background.
|
| MIPS |
Millions of Instructions per Second measure for computer processing speed.
|
| Mirror |
A smooth, highly polished surface, for reflecting light. It may be plane or curved.
|
| Modulation Transfer Function (MTF) |
The ability of a lens or optical system to reproduce (transfer) various levels of detail (modulation) of an object to the image as the frequency (usually sinusoidal) increases.
|
| Moiré Interferometry |
A method to determine 3D profile information of an object or scene, using interference of light stripes. Two identical gratings of known pitch are used. The first creates a shadow of parallel lines of light projected on the object. The second is placed in the imaging train, and superimposed on the shadow cast by the first grating, forming a moiré fringe pattern. Distance between the fringes or dark bands is directly related to range or profile. Varying the gap between the lines changes the sensitivity.
|
| Moiré Pattern |
A pattern resulting from the interference of light when gratings, screens or regularly spaced patterns are superimposed on one another. Two stacked window screens create this effect.
|
| Monochromatic |
Refers to light having only one color or a single wavelength of radiation.
|
| Monochrome |
Refers to a black and white image with shades of gray but no color.
|
| Monolithic FPA |
FPAs of the monolithic configuration have the IR-sensitive material (such as PtSi) and the signal transmission paths (which separate the material's detector cells) on the same surface layer. This technology has its benefits and drawbacks: Although it may be easier to manufacture, a lower fill factor results.
|
| N |
top |
| Narcissus Effect |
The effect where the detector images itself through reflection off a window in front of it.
|
| Noise |
Irrelevant or meaningless data resulting from various causes unrelated to the source. Random, undesired video signals.
|
| Noise Equivalent Temperature Difference (NETD) |
The noise rating of an IR FPA detector specifies the amount of radiation required to produce an output signal equal to the detectors own noise (due to inner component heat). Thus, it specifies the minimum detectable temperature difference. In general detector cooling is required to limit the detector's own noise and to improve the NETD.
|
| Non-Uniformity of Response |
The non-uniformity of the electrical characteristics of in-pixel read-out circuitry as well as of readout components like column amplifiers, endow the final IR image with a static, fixed offset pattern. This pattern has to be removed from each image to yield a useable result. This subtraction of a reference background image can be done off-line, either in the digital or in the analogue domain, both methods requiring an image-sized memory. Alternatively, there are readout techniques for integrating imagers that implicitly remove some non-uniformities. Two of them are double sampling and correlated double sampling (CDS).
|
| O |
top |
| Object Plane |
An imaginary plane at the object, which is focused by the optical system at the image plane on the sensor.
|
| Opaqueness |
Degree to which an object does not transmit light.
|
| Orientation |
The angle or degree of difference between the object coordinate system major axis relative to a reference axis as defined in a 3D measurement space.
|
| P |
top |
| Parallax |
The change in perspective of an object when viewed from two slightly different positions. The object appears to shift position relative to its background, and also appears to rotate slightly.
|
| Photoconductive Detector |
A detector with a constant bias voltage across it, which, when it absorbs a photon, the bulk resistance changes, causing a change in the current. The current change is monitored in an external circuit, and compared to calibration values to render radiometric temperature data.
|
| Photodiode |
A single photoelectric sensor element, either used stand-alone or a pixel site, part of a larger sensor array.
|
| Photometry |
Measurement of light, which is visible to the human eye (photopic response).
|
| Photon |
The elemental unit of light, having wave and particle behavior. It has motion, but no charge or mass.
|
| Photovoltaic Detector |
A detector in which absorbed photons cause a voltage potential that is measured in an external circuit, and compared to calibration values to render radiometric temperature data.
|
| Pinhole |
A small, sharp edged hole, acts as a lens aperture which produces a soft edged image, is distortion free, with a wide field of view and large depth of field.
|
| Pitch |
Is the distance between the centers of two adjacent pixels in an array.
|
| Pixel |
An acronym for "picture element." The smallest distinguishable and resolvable area in an image. The discrete location of an individual photo-sensor in a solid-state camera.
|
| Planks’ Law |
This relation describes the way in which all objects emit thermal radiation as a function of temperature and wavelength.
|
| Polarized Light |
Light, which has had the vibrations of the electric or magnetic field vector typically, restricted to a single direction in a plane perpendicular to its direction of travel. A type of filter, which absorbs one of the two perpendicular light rays, creates it. Crossing polarizers theoretically blocks all light transmission.
|
| Polarizer |
An optical device which converts natural or unpolarized light into polarized light by selective absorption of rays in one direction, and passing of rays perpendicular to the polarizing medium. Usually fabricated from stretched plastic sheets with oriented, parallel birefringent crystals. The first polarizers were constructed with parallel wires.
|
| Prism |
An optical device with two or more non-parallel, polished faces from which light is either reflected or refracted. Often used to redirect light as in binoculars. (2)
|
| Profile |
The 3D contour of an object.
|
| Q |
top |
| Quantum Efficiency (QE) |
A measurement of FPA sensitivity. Quantum efficiency refers to the relative efficiency in which IR energy is collected and converted into an electrical signal. The quantum efficiency is the photon-to-electron conversion efficiency of a photoelectric detector.
|
| R |
top |
| Radian |
An arc in a circle equal to the radius in length. [An angle of 57.3° at the center or a circle, formed by 2 radii cutting off such an arc—thus 1 radian = 57.3°].
|
| Radiometry |
Measurement of light within the entire optical spectrum.
|
| Range Measurement |
Determination of the distance from a sensor to the object.
|
| Reflection |
The process by which incident light leaves the surface from the same side as it is illuminated.
|
| Refraction |
The bending of light rays as they pass from one medium (i.e. air) to another (i.e. glass), each with a different index of refraction.
|
| Registration |
The closeness of the part to the actual position expected for image acquisition.
|
| Repeatability |
The ability of a system to reproduce or duplicate the same measurement.
|
| Resolution, Feature |
The smallest object or feature in an image, which may be sensed.
|
| Resolution, Image |
The number of rows and columns of pixels in an image.
|
| Resolution, Measurement |
The smallest movement measurable by a vision system.
|
| Resolution, Pixel Grayscale |
The number of resolvable shades of gray (i.e. 256).
|
| Resolution, Spatial |
A direct function of pixel spacing. Pixel size relative to the image field of view is key.
|
| Responsivity |
A measure of detector performance, measures the detector photocurrent (or voltage) output per unit incident radiant power at a particular wavelength. Expressed in units of Amps/Watt (or Volts/Watt)
|
| Reticle |
An optical element with a pattern located in the image plane to assist in calibration, measurement or alignment of a system or instrument. Examples are cross lines or grids.
|
| RGB |
An acronym for the Red-Green-Blue color space. This three primary color system is used for video color representation.
|
| RS-170 |
The Electronic Industries Association (EIA) standard governing monochrome television studio electrical signals. The broadcast standard of 30 complete images per second.
|
| RS-422; RS-423; RS-449 |
The Electronic Industries Association (EIA) standards for serial communication protocols intended to gradually replace the widely used RS-232-C standard.
|
| RS-232-C |
The Electronic Industries Association (EIA) standard governing serial communications over a twisted pair. Good to about 150 feet.
|
| S |
top |
| Saturation |
The degree to which a color is free of white. One of the three properties of color perception along with hue and intensity (HSI).
|
| Scattering |
Redirection of light reflecting off a surface or through an object. See diffuse.
|
| Sensitivity |
A measure of the minimum temperature difference that can be detected or viewed. A system with high sensitivity can detect very small temperature differences. This results in easy-to-interpret imagery and good performance through poor weather or in cold conditions. A camera's sensitivity is driven by the size of the optics, background conditions, operating temperature and integration time.
|
| Sharpening |
An image processing operation, which enhances edges. An unsharp mask adds a low pass filtered image to the original, resulting in edge enhancement.
|
| Shutter |
An electrical or mechanical device used to control the amount of time the imaging surface is exposed to light. Often used to stop blur from moving objects.
|
| Simple Lens |
A lens with only a single element.
|
| Sinusoidal Projection |
Use of a grating in which the dark stripes vary in their density sinusoidally across each one, rather than constant black. Improved profile or range discrimination is possible when used in a moiré type configuration.
|
| Solid-state Camera |
A camera, which uses a solid-state integrated circuit chip to convert incident light or other radiation into an analog electrical signal.
|
| Span |
The allowance of gray level acceptance for thresholding, adjustable from black to white from 0 to 100%.
|
| Spatial Light Modulator |
(Also SLM) A transparent screen used in optical computer systems to introduce an image into the optical processing path. Similar to liquid crystal computer display screens, their resolution approaches 512x512 and grayscale imaging 8 bits.
|
| Spectral Analysis |
Evaluation of the wavelength composition of object irradiance.
|
| Spectral Characteristics |
The unique combination of wavelengths of light radiated from a source or transmitter or reflected from an object.
|
| Spectral Response |
The characteristic of a sensor to respond to a distribution of light by wavelength in the electromagnetic spectrum.
|
| Specular Reflection |
Light rays that are highly redirected at or near the same angle of incidence to a surface. Observation at this angle allows the viewer to "see" the light source.
|
| Speed |
An object characteristic expressed in distance moved per unit time. Velocity. Image blur may be caused by high speeds unless strobes or shutters are used to "stop motion."
|
| Stefan-Boltzmann Law |
Describes the total rate of energy emission per unit surface area. The Stefan-Boltzmann Law is the spectrally integrated form of Planck’s Law (integrated over all wavelengths). This result takes the form E=sT4, where E is the rate of energy emitted per unit area, T is the absolute temperature in Kelvin, and s is a constant.
|
| Stereoscopic Approach |
The use of triangulation between two or more image views from differing positions. Used to determine range or depth.
|
| Sub pixel Resolution |
Mathematical techniques used on gray scale images to resolve an edge location to less than one pixel. A one tenth pixel resolution is reasonable in the factory.
|
| Synch Pulse |
Timing signals used to control the television scanning and display process. The horizontal synch triggers tracing of a new line from left to right, while the vertical synch initiates the start of a new field.
|
| Synchronous |
A camera characteristic denoting operation at a fixed frequency locked to the AC power line (typically 60 or 50Hz).
|
| T |
top |
| TDI Camera |
Time Delay Integration. Similar to a line scan, a TDI camera is comprised of a number of rows of pixels. As an object such as a web moves, the charge from one row is passed to the next row, synchronously continuing the integration. Requires far less illumination intensity than the standard line scan.
|
| Thermoelectric Cooling |
A solid-state device, which converts current into a temperature difference between two junctions. It is possible to put thermoelectric junctions in series or parallel to increase either the overall temperature drop or their power.
|
| Translucent |
An object characteristic in which part of the incident light is reflected and part is transmitted. The transmitted light emerges from the object diffused.
|
| Transmittance |
The ratio of the radiant power transmitted by an optical element or object to the incident radiant power.
|
| Tube Type Camera |
A camera in which the image is formed on a fluorescent screen, then read out sequentially in a raster scan type pattern by an electron beam for conversion to an analog voltage proportional to incoming light intensity.
|
| U |
top |
| Ultraviolet |
The region of the electromagnetic spectrum adjacent to the visible spectrum, but of higher frequency (shorter wavelength) than blue ranging from 1 to 400 nm.
|
| V |
top |
| Video |
Visual information encoded in a specific bandwidth and frequency spectrum location originally developed for television and radar imaging.
|
| Vidicon |
A generic name for a camera tube of normal light sensitivity. It outputs an analog voltage stream corresponding to the intensity of the incoming light.
|
| Visible Light |
The region of the electromagnetic spectrum in which the human retina is sensitive, ranging from about 400 to 750 nm in wavelength.
|
| W |
top |
| Wavelength |
The distance covered by one cycle of a sinusoidally varying wave as it travels at or near the speed of light. It is inversely proportional to frequency.
|
| Wien’s Law |
The wavelength at any given temperature (for a blackbody) that emits the greatest amount of energy is given by Wien’s Law.
|
| Windowing |
Performing imaging processing operations only within a predefined window or area in the image.
|
| X |
top |
| X-ray |
A portion of the electromagnetic spectrum beyond the ultraviolet with higher frequency and shorter wavelengths. Able to penetrate solid objects for internal, non-destructive evaluation.
|
| Z |
top |
| Zoom Lens |
A compound lens, which remains in focus as the image size is varied continuously. May be motorized or manually operated. (-)
|
