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Proceedings Paper

Modulated white-LED interferometer
Author(s): Tatsuo Shiina; Noboru Izuhara; Masafumi Ito; Yasuyuki Okamura
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Paper Abstract

ZnSe and InGaN based white-LEDs have been utilized for an interferometer. These white-LED consist of blue-LED light and yellowish green one. When these white-LED were modulated by rectangular wave, there were differences in response speed between blue-LED light and yellowish light. The response speed of blue-LED light of ZnSe type white-LED was 50ns, while that of yellowish light was 5us. The spectral bandwidths of the blue-LED light and the yellowish light were 10nm and 100nm, respectively. Coherence lengths of these lights were 10um and 2um, respectively. Combining the blue-LED light with the yellowish light, we observe an unique interference when scanning the optical path of the low coherence interferometer. We also propose a method for a color separation of an interference in a low coherence interferometer with the ZnSe white-LED modulation. The ZnSe white-LED was modulated with much higher frequency (100kHz) than the Doppler frequency of the above interference. The interference fringe of white light appeared at the upper side on the rectangular modulated light emission, while that of the residual yellowish light was presented at the bottom. The interference fringe of the blue light was derived by subtracting the yellowish light interference from the white light one.

Paper Details

Date Published: 9 September 2002
PDF: 8 pages
Proc. SPIE 4920, Advanced Sensor Systems and Applications, (9 September 2002); doi: 10.1117/12.481970
Show Author Affiliations
Tatsuo Shiina, Wakayama Univ. (Japan)
Noboru Izuhara, Wakayama Univ. (Japan)
Masafumi Ito, Wakayama Univ. (Japan)
Yasuyuki Okamura, Wakayama Univ. (Japan)


Published in SPIE Proceedings Vol. 4920:
Advanced Sensor Systems and Applications
Yun-Jiang Rao; Julian D. C. Jones; Hiroshi Naruse; Robert I. Chen, Editor(s)

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