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Proceedings Paper

Wide-Area, High Dynamic Range 3-D Imager
Author(s): Yoshikazu Kakinoki; Tetsuo Koezuka; Shinji Hashinami; Masato Nakashima
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Paper Abstract

This paper describes a 3-D laser scanning imager for visual inspection of mounted devices on printed circuit boards (PCB). A 3-D imager for this application must satisfy the following requirements: (1) It must be fast enough to sense a 250 by 330 mm area in 14 seconds; (2) It must have a measurement resolution of at least 125 gm; (3) It must be capable of measuring height and light intensity simultaneously; and (4) It must have an optical dynamic range of at least 10 4. We developed a wide-area telecentric scanning optical system which meets these requirements. It uses retroreflective triangulation optics and digital signal processing hardware. Our system scans a laser beam over a 256 mm length with a resolution of 125 μm, without scanning distortion. The retroreflection triangulation optics collect light reflected from objects on a printed circuit board and focus the image on a position-sensitive detector (PSD). This system measures the profile of objects with a vertical resolution of 30 μm, within a range of 7.6 mm. The digital signal processing hardware has a dynamic range of 10 4 and obtains range data from the output signals of the PSD. Its processing speed is 1M pixels/s. This hardware enables profile measurement of objects having a wide range of light reflectance (about 3000 times), from black devices to glossy metal, with an accuracy of 0.1 mm. This 3-D imager was used in an automated inspection system for PC board-mounted devices. This system detects missing, misplaced, and incorrectly installed devices with an inspection speed of 0.1 s/device.

Paper Details

Date Published: 1 April 1990
PDF: 12 pages
Proc. SPIE 1194, Optics, Illumination, and Image Sensing for Machine Vision IV, (1 April 1990); doi: 10.1117/12.969859
Show Author Affiliations
Yoshikazu Kakinoki, Fujitsu Laboratories Ltd., Atsugi (Japan)
Tetsuo Koezuka, Fujitsu Laboratories Ltd., Atsugi (Japan)
Shinji Hashinami, Fujitsu Laboratories Ltd., Atsugi (Japan)
Masato Nakashima, Fujitsu Laboratories Ltd., Atsugi (Japan)

Published in SPIE Proceedings Vol. 1194:
Optics, Illumination, and Image Sensing for Machine Vision IV
Donald J. Svetkoff, Editor(s)

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