7. GLOSSARY
The following terms may have additional meanings. The definitions that follow are in context of the Starrett Vision Metrology Systems.
Accuracy
The maximum error that the system will produce when measuring a true standard. An accessory lens that may be attached to zoom optics to increase magnification or increase the field of view.
Auxiliary Lens
AV
Automatic Video, an alternative designation for “CNC.”
Axis
A direction which allows movement and along which dimensions can be measured. In Manual and CNC metrology systems, three mutually- perpendicular axes are X (left to right), Y (front to back), and Z (bottom to top). Measurement along the X and Y axes is accomplished by moving the metrology stage horizontally. Measurement along the Z axis is accomplished by moving the camera and optics vertically, rather than moving the metrology stage. A condition where the parts of the video image are distorted by oversaturated bright regions so objects can be measured larger than they really are. To avoid blooming errors, observe the video image as you decrease illumination. Charge Coupled Device. The solid-state image sensing element of a video camera. Computer Numeric Control. In CNC metrology systems, motion of the stage and optics is both motorized and computer controlled, making these system suitable for repetitive measurements in a production environment. Non-CNC system may also be motorized; control will be manual by an operator. A light source that is on the same axis as the camera. Surfaces that face the camera are illuminated brightly, while surfaces angled even slightly away appear much darker. The result is a high-contrast lighting that can help sharpen edges for better detection by the Video Probe. By comparison, light that is not coaxial and shines from different directions (such as from the Ring Light) results in lower image contrast. Optical image distortion at the CCD sensor across the maximum field of view. Expressed in percent for the dimensional error along one axis divided by the true dimension. Emergency Stop. A switch with cuts power to the motors. An important safety feature. The condition which provides the sharpest image. Achieved by optimizing the distance between the object and imaging optics. Field of View. The region of the metrology stage that the camera sees and displays in the video image. “FOV measurement” refers to a measure- ment that can be done in a single field of view without moving the stage or camera. A video measurement performed in a single field of view without moving the stage or camera. Lighting applied to the object from the same side as the camera so that surface features can be viewed on the video monitor.
Blooming
CCD
CNC
Coaxial Light
Distortion
E-Stop
Focus
FOV
FOV Measurement
Illumination, Front
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