Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Resonance Raman measurements of carotenoids using light emitting diodes   We report on the development of a compact commercial instrument for measuring
carotenoids in skin tissue. The instrument uses two light emitting diodes
(LEDs) for dual-wavelength excitation and four photomultiplier tubes for
multichannel detection. Bandpass filters are used to select the excitation and
detection wavelengths. The f/1.3 optical system has high optical throughput and
single photon sensitivity, both of which are crucial in LED-based Raman
measurements. We employ a signal processing technique that compensates for
detector drift and error. The sensitivity and reproducibility of the LED Raman
instrument compares favorably to laser-based Raman spectrometers. This compact,
portable instrument is used for non-invasive measurement of carotenoid
molecules in human skin with a repeatability better than 10%.

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The categories of this paper are: quant-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: hep-lat
32
The categories of this paper are: atom-ph
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The categories of this paper are: q-fin
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The categories of this paper are: supr-con
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The categories of this paper are: q-bio
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The categories of this paper are: math-ph
35
The categories of this paper are: mtrl-th
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The categories of this paper are: patt-sol
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The categories of this paper are: econ
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The categories of this paper are: bayes-an
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The categories of this paper are: nucl-ex
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The categories of this paper are: funct-an
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The categories of this paper are: nlin
34
The categories of this paper are: chem-ph