Most existing multi-channel spectrometers are constructed by physically stacking single-channel spectrometers, resulting in their large size, high weight, and limited number of channels. Therefore, their miniaturization is urgently needed. In this paper, a microlens array grating is designed for miniature multi-channel spectrometers. A transmissive element integrating microlens arrays and gratings, the MLAG, enables simultaneous focusing and dispersion. Using soft lithography, the MLAG was fabricated with a deviation of less than 2.2%. The dimensions are 10 mm × 10 mm × 4 mm with over 2000 available units. The MLAG spectrometer operates in the 400-700 nm wavelength range with a resolution of 6 nm. Additionally, the designed MLAG multi-channel spectrometer is experimentally verified to have independently valid cells that can be used in multichannel spectrometers. The wavelength position repeatability deviation of each cell is about 0.5 nm, and the repeatability of displacement measurements by the chromatic confocal sensor with the designed MLAG multi-channel spectrometer is less than 0.5 μm.
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http://dx.doi.org/10.3390/s23208381 | DOI Listing |
The increasing demand for portable spectral analysis has driven the development of miniaturized spectrometers. Computational spectrometers, based on algorithmic reconstruction, are a potential solution to meet this demand. We report on the design and implementation of an integrated computational spectrometer on a silicon-on-insulator (SOI) substrate.
View Article and Find Full Text PDFFood Chem
February 2025
Federal University of Uberlândia, Institute of Chemistry, 2121 João Naves de Ávila Avenue, Santa Mônica, Uberlândia MG38400-902, Brazil. Electronic address:
This study introduces a novel optical method for formaldehyde determination in milk, based on the hypothesis that simultaneous reflectance and fluorescence measurements can enhance detection sensitivity compared to traditional methods. We aimed to address the challenge of accurately measuring low concentrations of formaldehyde in milk, a crucial issue for food safety. By employing a multi-channel spectrometer sensor and exploiting the reaction of formaldehyde with acetylacetone to form 3,5-diacetyl-1,4-dihydrolutidine (DDL), we measured reflectance of DDL at 415 nm and fluorescence at 515 nm.
View Article and Find Full Text PDFSensors (Basel)
September 2024
Department of Industrial Engineering, University of Rome Tor Vergata, 00133 Rome, Italy.
Optical-based sensing techniques and instruments, such as fluorometric systems, absorbance-based sensors, and photoacoustic spectrometers, are important tools for detecting food fraud, adulteration, and contamination for health and environmental purposes. All the aforementioned optical equipments generally require one or more low-frequency Lock-In Amplifiers (LIAs) to extract the signal of interest from background noise. In the cited applications, the required LIA frequency is quite low (up to 1 kHz), and this leads to a simplification of the hardware with consequent good results in portability, reduced size, weight, and low-cost characteristics.
View Article and Find Full Text PDFWe design and construct a broadband integrated multi-channel imaging spectrometer (MCIS) from visible light to near-infrared. This system can directly obtain spectral images that conform to the consistent visual habits of the human eyes through a single exposure of the detector. The genetic algorithm is used to calculate system parameters to minimize pixel waste between spectral channels, achieving nearly 100% utilization of detector pixels.
View Article and Find Full Text PDFSensors (Basel)
February 2024
Biomedical Engineering Institute, Chinese Academy of Medical Science and Peking Union Medical College, Tianjin 300192, China.
Multi-channel and multi-parameter near-infrared spectroscopy (NIRS) has gradually become a new research direction and hot spot due to its ability to provide real-time, continuous, comprehensive indicators of multiple parameters. However, multi-channel and multi-parameter detection may lead to crosstalk between signals. There is still a lack of benchmarks for the evaluation of the reliability, sensitivity, stability and response consistency of the NIRS instruments.
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