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Proceedings Paper

A fiber-grating-based distributed light source
Author(s): G. E. Carver; T. R. Koch; D. Salvemini; K. S. Feder; P. S. Westbrook
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Paper Abstract

Line scan cameras are used for rapidly monitoring a moving web or sheet of material. Lighting for line scan inspection should illuminate a long narrow rectangle, which is imaged onto the linear array of pixels in a line scan camera. This distributed light source should provide a uniform power density at the desired wavelengths. Tungsten halogen lamps and LED arrays can meet many of these objectives, but not in a highly directional beam with minimal thermal issues. We have developed a new distributed light source that is based on diffracting light from a highly blazed grating written in the core of a single mode fiber. The grating is blazed such that out-coupling is 90 degrees to the fiber axis. The fiber is bonded to a cylindrical optic that collimates the azimuthal power distribution. Connecting a single laser diode to the fiber can generate 1 milliwatt per square centimeter over a 10 cm by 0.5 cm rectangular region. Longer gratings and/or multiple segments can be connected to illuminate longer regions. The distributed power density, spatial uniformity, degree of collimation, and spectral bandwidth of these illuminated rectangles are reported. This highly directional distributed source will enhance the utility of line scan cameras in multiple applications.

Paper Details

Date Published: 20 October 2006
PDF: 7 pages
Proc. SPIE 6371, Photonic Sensing Technologies, 63710H (20 October 2006); doi: 10.1117/12.685273
Show Author Affiliations
G. E. Carver, Princeton Lightwave (United States)
T. R. Koch, Princeton Lightwave (United States)
D. Salvemini, Princeton Lightwave (United States)
K. S. Feder, OFS Labs. (United States)
P. S. Westbrook, OFS Labs. (United States)

Published in SPIE Proceedings Vol. 6371:
Photonic Sensing Technologies
Michael A. Marcus; Brian Culshaw; John P. Dakin, Editor(s)

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