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Proceedings Paper

Broadband phosphor conversion LED source for stroboscopic white light interferometry
Author(s): B. Wälchli; V. Heikkinen; T. Paulin; I. Kassamakov; E. Hæggström
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Paper Abstract

We report on building a broadband LED light source for stroboscopic white light interferometry. We chose phosphor types, mass ratios, and encapsulant, to tailor the necessary emission spectrum. Based on known emission spectra, we mixed combinations of blue, cyan, yellow, and red down-conversion phosphors. The phosphor composite was excited with a modified UV LED (365 nm). UV provides primary excitation of blue phosphor BAM (BaMgAl10O17:Eu). The emission (≈ 450 nm) of the blue phosphor provides secondary excitation of longer wavelength phosphors (YAG (yttrium aluminum garnite), strontium-barium silicate, and sulfoselenide). The effective spectrum's FWHM was 244±1.5 nm; spectral drop was 14%. The pulse width was 2.2 μs when the LED was driven with 14 A. We used the source for static MEMS measurements in a SWLI system. The obtained SWLI interferogram features 883 nm FWHM and low side lobes.

Paper Details

Date Published: 5 May 2012
PDF: 6 pages
Proc. SPIE 8430, Optical Micro- and Nanometrology IV, 843019 (5 May 2012); doi: 10.1117/12.922114
Show Author Affiliations
B. Wälchli, Univ. of Helsinki (Finland)
V. Heikkinen, Univ. of Helsinki (Finland)
T. Paulin, Univ. of Helsinki (Finland)
I. Kassamakov, Univ. of Helsinki (Finland)
Helsinki Institute of Physics (Finland)
E. Hæggström, Univ. of Helsinki (Finland)


Published in SPIE Proceedings Vol. 8430:
Optical Micro- and Nanometrology IV
Christophe Gorecki; Anand K. Asundi; Wolfgang Osten, Editor(s)

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