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5 May 2012 Broadband phosphor conversion LED source for stroboscopic white light interferometry
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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.
© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
B. Wälchli, V. Heikkinen, T. Paulin, I. Kassamakov, and E. Hæggström "Broadband phosphor conversion LED source for stroboscopic white light interferometry", Proc. SPIE 8430, Optical Micro- and Nanometrology IV, 843019 (5 May 2012);

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