Paper
20 September 2002 Near-infrared spectroscopic measurement system of the constituent concentration based on acousto-optic tunable filter
Qingbo Li, Chengzhi Jiang, Kexin Xu
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Abstract
The near-infrared spectroscopic measurement system of constituent concentration based on acousto-optic tunable filter (AOTF) is investigated in this paper. However, the diffracted beam is often mixed with zero order beam in AOTF optical system. In order to obtain high wavelength resolution and spectral signal-to noise ratio (SNR), the solutions to improve the purity and efficiency of the diffracted light are proposed. The orthogonal polarizing method and the combine modulation method of optics and electronics are discussed. The results show that both methods can effectively eliminate the inference of zero order light. Especially, the combined modulation method not only can increase wavelength resolution and spectral signal-to-noise ration but also simplify the optical system structure and reduce costs. The application concerning the determination of the milk principal constituents verifies the validity of this measuring instrument and analytical method. The results show that the speed is 30 seconds/sample. The milk principal constituents concentrations are determined with root mean square error of prediction (RMSEP): 0.1~0.2 g/dL. Correlation coefficients between prediction values and reference values are higher than 0.9. Moreover, the results are reliable with coefficient of variation (Cv) of repeatability below 0.02. Obviously, the individual component’s prediction accuracy and repeatability can meet practical measurement requirement.
© (2002) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Qingbo Li, Chengzhi Jiang, and Kexin Xu "Near-infrared spectroscopic measurement system of the constituent concentration based on acousto-optic tunable filter", Proc. SPIE 4927, Optical Design and Testing, (20 September 2002); https://doi.org/10.1117/12.471697
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KEYWORDS
Modulation

Signal to noise ratio

Near infrared spectroscopy

Acousto-optics

Near infrared

Spectral resolution

Tunable filters

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