Hairline crack detection in telecommunication cables using a CCD image sensor
✍ Scribed by Hirotaka Yoshida; Eiichi Sakita; Jun-ichi Masuda
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 281 KB
- Volume
- 82
- Category
- Article
- ISSN
- 1042-0967
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✦ Synopsis
Foamed polyethylene (PE) used as an insulating coat for cable cores may undergo state changes (deterioration due to oxidation) when deterioration factors resulting from long UV irradiation, humidity and temperature increases, and the like become serious. As a result, cracks occurring on the surface of the coat become a cause of deterioration of propagation quality or insulation strength of a cable. This paper discusses a technique for detecting hairline cracks occurring on the surface of this insulating coat simply and nondestructively by measuring the core of the communications cable installed outside a building, a signal processing technique for detecting the existence of a crack and its width from the detected signals, and an optical system for detecting the crack as a dark image based on a photoslicing method. An image sensor using a common light source as a photoemitting element and a one-dimensional CCD line sensor as a photoreceptive element was constructed, waveforms were analyzed with respect to the measured signals, and it was confirmed that cracks up to a width of about 10 2m on the currently used communications cable core can be detected by the proposed method.