This paper presents a low-cost hyperspectral measurement setup in a new application based on fluorescence detection in the visible (Vis) wavelength range. The aim of the setup is to take hyperspectral fluorescence images of viscous materials. Based on these images, fluorescent and non-fluorescent impurities in the viscous materials can be detected. For the illumination of the measurement object, a narrow-band high-power light-emitting diode (LED) with a center wavelength of 370 nm was used. The low-cost acquisition unit for the imaging consists of a linear variable filter (LVF) and a complementary metal oxide semiconductor (CMOS) 2D sensor array. The translucent wavelength range of the LVF is from 400 nm to 700 nm. For the confirmation of the concept, static measurements of fluorescent viscous materials with a non-fluorescent impurity have been performed and analyzed. With the presented setup, measurement surfaces in the micrometer range can be provided. The measureable minimum particle size of the impurities is in the nanometer range. The recording rate for the measurements depends on the exposure time of the used CMOS 2D sensor array and has been found to be in the microsecond range.
References
[1]
Kim, M.S.; Chen, Y.R.; Mehl, P.M. Hyperspectral reflectance and fluorescence imaging system for food quality and safety. Trans. ASAE 2001, 44, 721–729.
[2]
Gowen, A.; Odonnell, C.; Cullen, P.; Downey, G.; Frias, J. Hyperspectral imaging—An emerging process analytical tool for food quality and safety control. Trends Food Sci. Technol. 2007, 18, 590–598.
[3]
Kim, I.; Kim, M.S.; Chen, Y.R.; Kong, S.G. Detection of skin tumors on chicken carcasses using hyperspectral fluorescence imaging. Trans. ASAE 2004, 47, 1785–1792.
[4]
Kong, S.G.; Martin, M.; Vo-Dinh, T. Hyperspectral fluorescence imaging for mouse skin tumor detection. ETRI J. 2006, 28, 770–776.
[5]
Emadi, A.; Wu, H.; de Graaf, G.; Enoksson, P.; Correia, J.H.; Wolffenbuttel, R. Linear variable optical filter-based ultraviolet microspectrometer. Appl. Opt. 2012, 51, 4308–4315.
[6]
Schmidt, O.; Bassler, M.; Kiesel, P.; Knollenberg, C.; Johnson, N. Fluorescence spectrometer-on-a-fluidic-chip. Lab Chip 2007, 7, 626–629.
[7]
Chang, C.I. Hyperspectral Imaging: Techniques for Spectral Detection and Classification; Springer: New York, NY, USA, 2003.
Tauro, F.; Mocio, G.; Rapiti, E.; Grimaldi, S.; Porfiri, M. Assessment of fluorescent particles for surface flow analysis. Sensors 2012, 12, 15827–15840.
[11]
Miettinen, J.; Andersson, P. Acoustic emission of rolling bearings lubricated with contaminated grease. Tribol. Int. 2000, 33, 777–787.
[12]
Murr, P.J.; Wiesent, B.R.; Hirth, F.; Koch, A.W. Thin film measurement system for moving objects based on a laterally distributed linear variable filter spectrometer. Rev. Sci. Instrum. 2012, 83, 035110, doi:10.1063/1.3697750.
[13]
Wiesent, B.R.; Dorigo, D.D.; Koch, A.W. Limits of IR-spectrometers based on linear variable filters and detector arrays. Proc. SPIE 2010, 7767, 77670L, doi:10.1117/12.860532.
[14]
Lakowicz, J. Principles of Fluorescence Spectroscopy; Springer: New York, NY, USA, 2009.
[15]
Stern, O.; Volmer, M. über die abklingungszeit der fluoreszenz. Phys. Z. 1919, 20, 183–188.
