AOI Automated Optical Inspection Back lighting Placement of a light source behind an object to highlight its shape, useful to hide surface details and emphasize the outline of an object. BGA Ball-Grid Array - a type of surface-mount packaging used for integrated circuits. CTF Contrast Transfer Function. Flange distance Distance from the mounting flange (the "metal ring" in rear part of the lens) to the camera detector plane. F-Number, F# The ratio of the lens focal length to the diameter of the entrance pupil. FOV or Field of view The area that is visible by a machine vision system. Depends on the type of the lens and on the working distance between object and camera. LED Light Emitting Diode. Line scan camera A camera based on a single row of photodectors. Machine vision Also called Artificial Vision, it is a wide-ranging term referring to the applications of computer vision to industry and manufacturing. Metrology The science of measurement: a key application of many machine vision technologies. OCR Optical Character Recognition: dedicated software to process images of written text into a computer-understandable format. PCB Printed Circuit Board. Scheimpflug Refers to the Scheimpflug principle: a geometric rule that describes the orientation of the plane of focus of an optical system (such as a camera) when the lens plane is not parallel to the image plane. SMD Surface-Mounted Device. Telecentricity Refers to the property of a telecentric lens to keep chief optical rays (rays passing through the center of the aperture stop) parallel to the optical axis. Working distance Distance (usually in mm) from the optimal focus plane where the object is placed to the front end of the lens mechanics.