Wide-Area, High Dynamic Range 3-D Imager

Yoshikazu Kakinoki; Tetsuo Koezuka; Shinji Hashinami; Masato Nakashima

doi:10.1117/12.969859

1 April 1990 Wide-Area, High Dynamic Range 3-D Imager

Yoshikazu Kakinoki, Tetsuo Koezuka, Shinji Hashinami, Masato Nakashima

Proceedings Volume 1194, Optics, Illumination, and Image Sensing for Machine Vision IV; (1990) https://doi.org/10.1117/12.969859
Event: 1989 Symposium on Visual Communications, Image Processing, and Intelligent Robotics Systems, 1989, Philadelphia, PA, United States

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.

Citation Download Citation

Yoshikazu Kakinoki, Tetsuo Koezuka, Shinji Hashinami, and Masato Nakashima "Wide-Area, High Dynamic Range 3-D Imager", Proc. SPIE 1194, Optics, Illumination, and Image Sensing for Machine Vision IV, (1 April 1990); https://doi.org/10.1117/12.969859

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