Large spot size diffuse reflectance FT-NIR spectral sensor for inhomogeneous samples

Mohamed Sadek; Shady Labib; Bassem Mortada; Mostafa Medhat; Tarek Zeinah; Ahmed Shebl; Ahmed Fadeel; Mina Gad; Hussien Abuelnaga; Botros George; Yasser Sabry; Bassam Saadany

doi:10.1117/12.2592468

20 June 2021 Large spot size diffuse reflectance FT-NIR spectral sensor for inhomogeneous samples

Mohamed Sadek, Shady Labib, Bassem Mortada, Mostafa Medhat, Tarek Zeinah, Ahmed Shebl, Ahmed Fadeel, Mina Gad, Hussien Abuelnaga, Botros George, Yasser Sabry, Bassam Saadany

Author Affiliations +

Proceedings Volume 11782, Optical Measurement Systems for Industrial Inspection XII; 117822B (2021) https://doi.org/10.1117/12.2592468
Event: SPIE Optical Metrology, 2021, Online Only

Conference Poster

Abstract

Diffuse reflectance infrared spectroscopy has gained traction in many industrial applications in the recent years due to the emergence of new generation of low cost handheld spectrometers that did not exist a decade ago. Real-time monitoring puts a limit on the sample preparation process especially with inhomogeneous samples in the food industry, like grains, hay, wheat and corn. The heterogeneity of the samples and the pseudo-random spatial arrangement of the grains in front of the optical interface, leads to prediction errors. The spatial variations depend also on the spot size of the diffuse-reflected scattered light from the sample that is collected by the spectrometer. A larger spot size leads to simultaneous averaging of a larger amount of spectrospatial information from different locations on the sample, leading to better repeatability and better prediction accuracy. Up to date, the Microelectromechanical (MEMS) based spectrometers reported in the literature have limited optical spot size, usually smaller than 3 mm in diameter. We report MEMS based FTIR spectral sensors with optical spot sizes of 6 mm, 10 mm and 20 mm working across the spectral range of 1350 nm to 2500 nm. The core spectral engine comprises monolithic MEMS chip, micro-optics for light coupling and a single photodetector in a tiny package. The optical head combines several miniaturized filament- based lamps and reflective optics for illumination. The sensors are compared and the 10-mm sensor gives an optimal performance with a Signal to Noise Ratio (SNR) of 4000:1 and spectrospatial photometric repeatability down to 0.02 absorbance units.

Conference Presentation

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Mohamed Sadek, Shady Labib, Bassem Mortada, Mostafa Medhat, Tarek Zeinah, Ahmed Shebl, Ahmed Fadeel, Mina Gad, Hussien Abuelnaga, Botros George, Yasser Sabry, and Bassam Saadany "Large spot size diffuse reflectance FT-NIR spectral sensor for inhomogeneous samples", Proc. SPIE 11782, Optical Measurement Systems for Industrial Inspection XII, 117822B (20 June 2021); https://doi.org/10.1117/12.2592468

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