A G-Fresnel Optical Device and Image Processing Based Miniature Spectrometer for Mechanoluminescence Sensor Applications.

Min Min,Kim Kim,Song Song

doi:10.3390/s19163528

Min Min, Kim Kim + Show 1 more

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https://doi.org/10.3390/s19163528

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Abstract

This paper presents a miniature spectrometer fabricated based on a G-Fresnel optical device (i.e., diffraction grating and Fresnel lens) and operated by an image-processing algorithm, with an emphasis on the color space conversion in the range of visible light. The miniature spectrometer will be cost-effective and consists of a compact G-Fresnel optical device, which diffuses mixed visible light into the spectral image and a μ-processor platform embedded with an image-processing algorithm. The RGB color space commonly used in the image signal from a complementary metal–oxide–semiconductor (CMOS)-type image sensor is converted into the HSV color space, which is one of the most common methods to express color as a numeric value using hue (H), saturation (S), and value (V) via the color space conversion algorithm. Because the HSV color space has the advantages of expressing not only the three primary colors of light as the H but also its intensity as the V, it was possible to obtain both the wavelength and intensity information of the visible light from its spectral image. This miniature spectrometer yielded nonlinear sensitivity of hue in terms of wavelength. In this study, we introduce the potential of the G-Fresnel optical device, which is a miniature spectrometer, and demonstrated by measurement of the mechanoluminescence (ML) spectrum as a proof of concept.

Highlights

Spectrophotometers have been used to analyze the spectral information of fluorescence from particular substances in the area of biology, biomedicine, chemistry and astronomy.The optical properties of substances can be drawn from light transmitted or absorbed from the substances and the spectrum provides signature information about their physical and chemical properties [1,2]
We demonstrated a G-Fresnel optical device-based miniature spectrometer for wavelength and relative intensity measurements of visible light, such as an light emitting diode (LED) light source by the HSV color space, to yield a nonlinear sensitivity (H vs. the wavelength)
In comparison to Fraunhofer diffraction-based commercial benchtop spectrometers, the proposed miniature spectrometer offers a very compactly sized package owing to the G-Fresnel optical device and simple digital image processing algorithm

Summary

Introduction

Spectrophotometers have been used to analyze the spectral information (wavelength and intensity) of fluorescence from particular substances in the area of biology, biomedicine, chemistry and astronomy. The optical properties of substances can be drawn from light transmitted or absorbed from the substances and the spectrum provides signature information about their physical and chemical properties [1,2]. Spectrophotometers commonly use a miniature spectrometer suitable for measuring the narrowband or monochromatic light in the region of visible light or a luminescent sensor such as a photomultiplier tube (PMT) sensor as a detector. CaZnOS crystals can emit ML light with the wavelength ranging from violet to near infrared [11], typically, the ML microparticle emits the monochromatic visible light while exciting or loading, and the spectral information can be changed by the different level of Sensors 2019, 19, 3528; doi:10.3390/s19163528 www.mdpi.com/journal/sensors

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