R
repeatability
The closeness of agreement among a number of consecutive output values measuring the same input value under the same operating conditions, approaching from the same direction. resolution The least significant digit to which a physical quantity can be read. High resolution does not imply high accuracy.
S
skew Misalignment of the part with respect to the X and Y axes. Skewing creates measurement errors unless the part is repositioned or the deskew feature of the metrology software redefines the measurement axes. squareness The alignment of the camera relative to the motion of the metrology stage. If the camera is misaligned (out of square), the image will drift diagonally as the stage position is moved along one axis. substage lighting Illumination from below the stage glass. Used for profile or silhouette video edge measurements.
Small form factor (system) PC
A space saving personal computer where all electronics, disk drives and I/O connections are in the same enclosure.
T
telecentric A lens property where the light from the object stays parallel to the optical axis across the entire field of view, thereby eliminating optical distortion. This can only happen if the entrance aperture of the lens is larger than the field of view, requiring a large and expensive lens.
telecentric illumination
Optics are used to direct light from a fiber optic light guide or LED onto an object under inspection, producing a high contrast silhouette. A telecentric illumination increases edge contrast and measurement accuracy by decreasing diffuse reflections from the object. See the following figure.
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