Abbe Error
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Additional linear off-axis error introduced through amplification of tilt and wobble with a long moment arm. This type of error occurs when the point under measurement is a relatively long distance from the axis of motion. For example, XYZ stages incorporating an angle bracket between the moving elements will exhibit measurable Abbe error since the Z stage is significantly displaced above the X and Y axes. It appears as runout, but unlike true runout, Abbe error can be minimized by reducing the lever arm.
Source: FRT of America
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Abbe Number
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The ratio of refractivity to dispersion in an optical medium. Specifically: (nd-1)/(nF-nC), where n is the index of refraction for the Fraunhofer d, F and C lines, respectively.
Source: JML Optical Industries, Inc.
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Abbe's Principle
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To ensure the correctness of a linear measurement, the length measured and the reference scale must lie parallel to each other.
Source: Carl Zeiss
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Abbreviated Test Language for All Systems
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(ATLAS) -
A standard test programming language developed by the IEEE and maintained under various standards, such as IEE Std. 416 and 716. ATLAS 2000 also exists.
Source: A.T.E. Solutions, Inc.
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Aberration
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An optical defect resulting from design or fabrication error, e.g., coma, distortion, curvature of field that prevents the lens from achieving precise focus.
Source: JML Optical
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Overshoot or undershoot in a waveform.
Source: Tektronix
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Abnormality Management
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Being able to see and quickly take action to correct abnormalities (any straying from Standard Work). This is the goal of standardization and visual management. Continuous waste elimination and problem solving through kaizen are only possible when the abnormalities are visible.
Source: Kaizen and Lean Manufacturing Consulting
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Absolute Accuracy
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A measure of the uncertainty of an instrument reading compared to that of a primary standard traceable to NJST. [National Institute of Standards and Technology]
Source: Vibration and Test
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Absolute leakage
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The total current that flows in the circuit (wires) during an AC HiPot test. It is the absolute value of the vector sum of the ohmic and reactive (resistive and capacitive) current that flows in the circuit. An ideal cable has absolute current equal to the reacitive current during a hipot test. This current is a function of the voltage, frequency and capacitance of the circuit and can not be easily determined for leakage limit setting.
Source: CableTest
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Absolute Zero
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Under the absolute, or Kelvin, scale of temperature (which was invented by the British mathematician and physicist William Thomas, first Baron of Kelvin), 0 K (corresponding to -273 degrees C) is the coldest possible temperature and is known as absolute zero.
Source: Maxfield & Montrose Interactive Inc.
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Absorber
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Material, often ferrite, which is capable of absorbing HF radiation, used with Electromagnetic Compatibility
Source: Schaffner EMC
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Absorption
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Loss or dissipation of energy as it travels through a medium, Example: radio waves lose some of their energy as they travel through the atmosphere.
Source: Twisted Pair
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AC Coupling
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Circuit that passes an AC signal while blocking a DC voltage.
Source: Twisted Pair
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AC Coupling Low-Frequency Cut-Off (–3 dB)
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The –3 dB corner frequency of the high-pass filter that rejects the DC component of the input signal when the inputs are configured for AC coupling. This specification is important because it indicates which AC signals will be attenuated when AC coupling is used.
Source: National Instruments
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AC Fault Models
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Mathematical descriptions of faulty behavior designed to assess timing compliance of a circuit -- the most common examples are the gate-level transition and the path delay fault models.
Source: Inovys
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AC Scan
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Form of scan test application, where only the sample interval is required at the specified operating frequency in order to verify timing performance, as well as structural content. The scan data may be shifted at a different frequency (typically slower). AC scan allows slower testers to be utilized and does not place unnecessary constraints on the design to be able to shift at-speed.
Source: NP Test
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AC Testing
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The application of vectors to a circuit with the intent to verify the timing compliance -- for example, testing using the transition or path delay fault models to determine the delay or cycle-time involved in conducting register-to-register, input-to-register, and register-to-output transfers.
Source: Inovys
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Accelerated Life Testing
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An activity during development of a new product. Prototypes are subjected to stress levels (including vibration, usually random) that are much higher than those anticipated in the field. The purpose is to identify failure-prone, marginally-strong elements by causing them to fail. Those elements are strengthened and tests are continued at higher levels. Sometimes called Test, Analyze & Fix (TAAF) testing.
Source: Vibration and Test
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Accelerated Stress Testing
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A post-production activity on a sampling (100% at first) of units. The intent is to precipitate hidden or latent failures caused by poor workmanship and to prevent flawed units from reaching the next higher level of assembly or the customer. Intensity is typically half that achieved in accelerated life testing.
Source: Vibration and Shock
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Accelerated Test Condition
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Accelerated test conditions are defined as test conditions using one or more applied stress levels which exceed the maximum rated operating or storage stress levels but are less than or equal to the "Testing Rating" values.
Source: MIL-Std-883F at Defense Supply Center Columbus
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Accelerator
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A specialized piece of hardware that speeds up a software-based task. Usually used for speeding up simulation.
Source: EE Design
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A specialized piece of hardware that speeds up a software-based task. Usually used for speeding up simulation.
Source: EE Design
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