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Towards Optoelectronic Technology: From Basic Research to Applications

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A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Optical Sensors".

Deadline for manuscript submissions: closed (20 July 2024) | Viewed by 26569

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Dr. Jacek Wojtas

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Institute of Optoelectronics, Military University of Technology, gen. Sylwestra Kaliskiego 2 Str., 00-908 Warsaw, Poland
Interests: optoelectronic engineering; optical metrology
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Dear Colleagues,

Optoelectronic technologies play a key role in a wide range of sophisticated systems and everyday devices, such as smartwatches and sensors that monitor the Martian atmosphere. A rapid development of these technologies is currently observed. On the one hand, it is driven by the needs of various and increasingly demanding applications, and on the other hand, it is inextricably linked to basic research.

This Special Issue provides a unique opportunity to combine the achievements of these two research areas: basic and application. Its main purpose is to review cutting-edge infrared technologies and state-of-the-art photonic devices and sensors that can be used in a wide variety of applications. One of the crucial areas of application is sensing technology, currently used in virtually all aspects of life. Sensors are applied in safety systems (perimeter protection, detection of hazardous substances, etc.), in industry for process control, and in medicine for diagnosis and monitoring.

A measurable effect of the SI will be the presentation of scientific discoveries and solutions to difficult engineering problems, but also the identification of directions for further development of the topics listed on the list of keywords.

Dr. Jacek Wojtas
Guest Editor

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Keywords

photonic technologies
laser and detector technologies, nanotechnology
fiber-optics, optical metrology, and instrumentation
spectroscopy
microscopy
interferometry
thermography, optical tomography, reflectometry
photometry
optical sensing
optical testing
environmental, security, space, medical, and industrial applications

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Published Papers (11 papers)

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Research

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19 pages, 1502 KiB

Open AccessArticle

Multi-Spectral Radiation Temperature Measurement: A High-Precision Method Based on Inversion Using an Enhanced Particle Swarm Optimization Algorithm with Multiple Strategies

by Xiaodong Wang and Shuaifeng Han

Sensors 2024, 24(18), 6003; https://doi.org/10.3390/s24186003 - 17 Sep 2024

Viewed by 766

Abstract

Multi-spectral temperature measurement technology has been found to have extensive applications in engineering practice. Addressing the challenges posed by unknown emissivity in multi-spectral temperature measurement data processing, this paper adds emissivity constraints to the objective function. It proposes a multi-spectral radiation temperature measurement data processing model realized through a particle swarm optimization algorithm improved based on multiple strategies. This paper simulates six material models with distinct emissivity trends. The simulation results indicate that the algorithm calculates an average relative temperature error of less than 0.3%, with an average computation time of merely 0.24 s. When applied to the temperature testing of silicon carbide and tungsten, experimental data further confirmed its accuracy: the absolute temperature error for silicon carbide (tungsten) is less than 4 K (7 K), and the average relative error is below 0.4% (0.3%), while two materials maintain an average computation time of 0.33 s. In summary, the improved particle swarm optimization algorithm demonstrates strong performance and high accuracy in multi-spectral radiation thermometry, making it a feasible solution for addressing multi-spectral temperature measurement challenges in practical engineering applications. Additionally, it can be extended to other multi-spectral systems. Full article

(This article belongs to the Special Issue Towards Optoelectronic Technology: From Basic Research to Applications)

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20 pages, 5766 KiB

Open AccessArticle

High-Accuracy Calibration Method of a Thermal Camera Using Two Reference Blackbodies

by Tomasz Sosnowski, Mariusz Kastek, Krzysztof Sawicki, Andrzej Ligienza, Sławomir Gogler and Bogusław Więcek

Sensors 2024, 24(17), 5831; https://doi.org/10.3390/s24175831 - 8 Sep 2024

Viewed by 3176

Abstract

Body temperature is one of the most important physiological parameters of a human being used to assess his basic vital functions. In medical practice, various types of measuring instruments are used to measure temperature, such as liquid thermometers, electronic thermometers, non-contact ear thermometers, and non-contact forehead thermometers. Such body temperature measurement techniques require the connection of appropriate sensors to a person, and non-contact thermometers operate over short distances and force a specific position of the person during the measurement. As a result, using the above methods, it is practically impossible to perform body temperature measurements of a moving human being. A thermal imaging camera can be used effectively for the purpose of the temperature measurement of moving objects, but the remote measurement of a human body temperature using a thermal imaging camera is affected by many factors that are difficult to control. Accurate remote measurement of human body temperature requires a measurement system that implements a specialized temperature determination algorithm. This article presents a model of a measurement system that facilitates the development of a highly accurate temperature measurement method. For the model, its parameters were determined on the calibration stand. The correct operation of the developed method and the effectiveness of temperature measurement have been confirmed by tests on a test stand using reference radiation sources. Full article

(This article belongs to the Special Issue Towards Optoelectronic Technology: From Basic Research to Applications)

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14 pages, 2424 KiB

Open AccessArticle

Efficiency–Accuracy Trade-Off in Light Field Estimation with Cost Volume Construction and Aggregation

by Bo Xiao, Stuart Perry, Xiujing Gao and Hongwu Huang

Sensors 2024, 24(11), 3583; https://doi.org/10.3390/s24113583 - 1 Jun 2024

Viewed by 736

Abstract

The Rich spatial and angular information in light field images enables accurate depth estimation, which is a crucial aspect of environmental perception. However, the abundance of light field information also leads to high computational costs and memory pressure. Typically, selectively pruning some light field information can significantly improve computational efficiency but at the expense of reduced depth estimation accuracy in the pruned model, especially in low-texture regions and occluded areas where angular diversity is reduced. In this study, we propose a lightweight disparity estimation model that balances speed and accuracy and enhances depth estimation accuracy in textureless regions. We combined cost matching methods based on absolute difference and correlation to construct cost volumes, improving both accuracy and robustness. Additionally, we developed a multi-scale disparity cost fusion architecture, employing 3D convolutions and a UNet-like structure to handle matching costs at different depth scales. This method effectively integrates information across scales, utilizing the UNet structure for efficient fusion and completion of cost volumes, thus yielding more precise depth maps. Extensive testing shows that our method achieves computational efficiency on par with the most efficient existing methods, yet with double the accuracy. Moreover, our approach achieves comparable accuracy to the current highest-accuracy methods but with an order of magnitude improvement in computational performance. Full article

(This article belongs to the Special Issue Towards Optoelectronic Technology: From Basic Research to Applications)

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12 pages, 1752 KiB

Open AccessArticle

Time-Efficient SNR Optimization of WMS-Based Gas Sensor Using a Genetic Algorithm

by Filip Musiałek, Dariusz Szabra and Jacek Wojtas

Sensors 2024, 24(6), 1842; https://doi.org/10.3390/s24061842 - 13 Mar 2024

Cited by 4 | Viewed by 1352

Abstract

This paper presents the description of the wavelength modulation spectroscopy (WMS) experiment, the parameters of which were established by use of the Artificial Intelligence (AI) algorithm. As a result, a significant improvement in the signal power to noise power ratio (SNR) was achieved, ranging from 1.6 to 6.5 times, depending on the harmonic. Typically, optimizing the operation conditions of WMS-based gas sensors is based on long-term simulations, complex mathematical model analysis, and iterative experimental trials. An innovative approach based on a biological-inspired genetic algorithm (GA) and custom-made electronics for laser control is proposed. The experimental setup was equipped with a 31.23 m Heriott multipass cell, software lock-in, and algorithms to control the modulation process of the quantum cascade laser (QCL) operating in the long-wavelength-infrared (LWIR) spectral range. The research results show that the applied evolutionary approach can efficiently and precisely explore a wide range of WMS parameter combinations, enabling researchers to dramatically reduce the time needed to identify optimal settings. It took only 300 s to test approximately 1.39 × 10³² combinations of parameters for key system components. Moreover, because the system is able to check all possible component settings, it is possible to unquestionably determine the operating conditions of WMS-based gas sensors for which the limit of detection (LOD) is the most favorable. Full article

(This article belongs to the Special Issue Towards Optoelectronic Technology: From Basic Research to Applications)

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14 pages, 5787 KiB

Open AccessArticle

Theoretical Analysis of GeSn Quantum Dots for Photodetection Applications

by Pin-Hao Lin, Soumava Ghosh and Guo-En Chang

Sensors 2024, 24(4), 1263; https://doi.org/10.3390/s24041263 - 16 Feb 2024

Cited by 1 | Viewed by 1206

Abstract

GeSn alloys have recently emerged as complementary metal–oxide–semiconductor (CMOS)-compatible materials for optoelectronic applications. Although various photonic devices based on GeSn thin films have been developed, low-dimensional GeSn quantum structures with improved efficiencies hold great promise for optoelectronic applications. This study theoretically analyses Ge-capped GeSn pyramid quantum dots (QDs) on Ge substrates to explore their potential for such applications. Theoretical models are presented to calculate the effects of the Sn content and the sizes of the GeSn QDs on the strain distributions caused by lattice mismatch, the band structures, transition energies, wavefunctions of confined electrons and holes, and transition probabilities. The bandgap energies of the GeSn QDs decrease with the increasing Sn content, leading to higher band offsets and improved carrier confinement, in addition to electron–hole wavefunction overlap. The GeSn QDs on the Ge substrate provide crucial type–I alignment, but with a limited band offset, thereby decreasing carrier confinement. However, the GeSn QDs on the Ge substrate show a direct bandgap at higher Sn compositions and exhibit a ground-state transition energy of ~0.8 eV, rendering this system suitable for applications in the telecommunication window (1550 nm). These results provide important insights into the practical feasibility of GeSn QD systems for optoelectronic applications. Full article

(This article belongs to the Special Issue Towards Optoelectronic Technology: From Basic Research to Applications)

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12 pages, 5338 KiB

Open AccessArticle

Two-Channel Detecting Sensor with Signal Cross-Correlation for FTIR Instruments

by Krzysztof Achtenberg, Janusz Mikołajczyk and Zbigniew Bielecki

Sensors 2022, 22(22), 8919; https://doi.org/10.3390/s22228919 - 18 Nov 2022

Cited by 2 | Viewed by 1869

Abstract

This paper’s purpose was to demonstrate a performance of a novel approach in a low-noise optical sensor for an FTIR spectrometer. Methods: Compared to the standard FTIR detection setup, our sensor ensures a higher signal-to-noise ratio (SNR) and lower signal standard deviation by reducing the uncorrelated noise components (e.g., thermal and 1/f noises of the detection module). Its construction is based on two-channel detection modules and a processing unit with implemented cross-correlation signal analyses. Each module was built of LWIR HgCdTe photodiodes and low-noise transimpedance amplifiers. Results: the experiments demonstrated a decrease in a signal standard deviation of about 1.7 times with a 10 dB-improvement in the SNR. Conclusion: this result indicates our sensor’s main benefit, especially in registered “weak” and noisy interferograms. Full article

(This article belongs to the Special Issue Towards Optoelectronic Technology: From Basic Research to Applications)

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16 pages, 4996 KiB

Open AccessArticle

Multi-Irradiance: A Method for Simultaneous Measurement of the Temperature and Spectral Emissivity of High-Temperature Targets in SWIR

by Yehan Sun, Jun Pan, Lijun Jiang, Libo Hao, Yu Cao and Helin Wang

Sensors 2022, 22(21), 8469; https://doi.org/10.3390/s22218469 - 3 Nov 2022

Viewed by 1815

Abstract

The currently used energy methods in spectral emissivity measurement are susceptible to the difference in temperature between the target and the reference blackbody. It is also limited by the state of the observation target and observation. This paper introduces the irradiance condition, while using the correlation between the information of emission energy and reflected energy of the high-temperature target. Based on the principle of radiative transmission and energy conservation, the relationship between the emissivity and bidirectional reflectance factor (BRF) was used to perform the retrieval of emissivity and temperature. An experimental device was designed, and graphite and rock were considered to verify the feasibility of the experimental scheme. The error of emissivity and temperature of both targets were, respectively, less than 5% and 0.5%, due to the Lambertian assumption, and the systematic errors had negligible impact on the retrieval. This verifies that the experimental observation method and scheme is reasonable. Full article

(This article belongs to the Special Issue Towards Optoelectronic Technology: From Basic Research to Applications)

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19 pages, 8613 KiB

Open AccessArticle

A Diagnostic Method Based on Active Thermography for the Degradation Assessment of Power Plant Boiler Tubes

by Sławomir Zator, Michał Tomaszewski and Mirosław Lasar

Sensors 2022, 22(21), 8401; https://doi.org/10.3390/s22218401 - 1 Nov 2022

Cited by 1 | Viewed by 1888

Abstract

Proper maintenance management of power infrastructure requires inspections, in order to gather knowledge about the facility’s current condition. For this purpose, periodic diagnostic tests are carried out, not only to determine the current state, but to also predict future conditions, and subsequently plan for the scope of necessary repair work. Currently, in the case of heat screens of power boilers, the diagnostic process takes many days, is very expensive, and usually does not cover the entire screen area. Therefore, it is necessary to develop new, noninvasive diagnostic methods. This study presents the concept and research for an alternative method of locating places with excessive energy boiler screen degradation that require replacement. It was assumed that the new method should be fast, require no scaffolding assembly, and permit checking of the entire screen surface; this is unlike the methods used currently, which require manual checking of selected screen tubes. The proposed method is based on active thermography, in which heat flux is forced by the liquid flowing inside the screen. Tests were carried out based on a model of an axial-symmetric system in the form of a tube, with controlled reductions in the wall thickness. An experiment was carried out many times by recording the pipe surface temperature in many characteristic places (different thicknesses of the tube walls) with a thermal imaging camera. A temperature change was forced by a controlled flow of hot or cold water. The methods of analysis were proposed and verified, allowing firstly, detection of places with a reduced wall thickness, and secondly, estimations of the wall thickness (i.e., excessive degradation). For the best-proposed model (one of the four analyzed), all of the thickness changes were detected, and the limit error of thickness obtained was 0.3 mm. Full article

(This article belongs to the Special Issue Towards Optoelectronic Technology: From Basic Research to Applications)

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16 pages, 3618 KiB

Open AccessArticle

Polarization Calibration of a Microwave Polarimeter with Near-Infrared Up-Conversion for Optical Correlation and Detection

by Francisco J. Casas, Patricio Vielva, R. Belen Barreiro, Enrique Martínez-González and G. Pascual-Cisneros

Sensors 2022, 22(20), 8080; https://doi.org/10.3390/s22208080 - 21 Oct 2022

Cited by 4 | Viewed by 1726

Abstract

This paper presents a polarization calibration method applied to a microwave polarimeter demonstrator based on a near-infrared (NIR) frequency up-conversion stage that allows both optical correlation and signal detection at a wavelength of 1550 nm. The instrument was designed to measure the polarization of cosmic microwave background (CMB) radiation from the sky, obtaining the Stokes parameters of the incoming signal simultaneously, in a frequency range from 10 to 20 GHz. A linearly polarized input signal with a variable polarization angle is used as excitation in the polarimeter calibration setup mounted in the laboratory. The polarimeter systematic errors can be corrected with the proposed calibration procedure, achieving high levels of polarization efficiency (low polarization percentage errors) and low polarization angle errors. The calibration method is based on the fitting of polarization errors by means of sinusoidal functions composed of additive or multiplicative terms. The accuracy of the fitting increases with the number of terms in such a way that the typical error levels required in low-frequency CMB experiments can be achieved with only a few terms in the fitting functions. On the other hand, assuming that the calibration signal is known with the required accuracy, additional terms can be calculated to reach the error levels needed in ultrasensitive B-mode polarization CMB experiments. Full article

(This article belongs to the Special Issue Towards Optoelectronic Technology: From Basic Research to Applications)

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14 pages, 5907 KiB

Open AccessArticle

A Reliable Method of Measuring the Conversion Degrees of Methacrylate Dental Resins

by Mirosław Kwaśny, Aneta Bombalska and Karolina Obroniecka

Sensors 2022, 22(6), 2170; https://doi.org/10.3390/s22062170 - 10 Mar 2022

Cited by 6 | Viewed by 2610

Abstract

The main aim of the study was to implement the most reliable method of measuring the degrees of conversion during photopolymerization of dental fillings. Contrary to the methods used so far, the method is based only on comparison with the monomer absorbance spectrum without reference bands. Another aim of the study was to prepare a comparative analysis of the polymerization kinetics of dental resins under various light sources and different environmental conditions (irradiance, light dose, temperature), with estimation of the degrees of conversion (DC) of the resins being the main metric. HRi Universal Enamel (UE2) and HRi Universal Dentine (UD2) were examined under two different types of light sources used in dentistry, LED and halogen. DC was measured by Fourier transform infrared spectroscopy (FTIR) in transmission mode from 5 s up to 7 days. Spectra were recorded from the parallel optical layers of samples that were placed between the KBr crystals. The results are expressed by the changes in the absorbance spectrum during the polymerization and the calculated conversion rates. The results of each experiment were averaged from three separate measurements of three samples, during which the samples were illuminated under identical conditions. The data were analyzed by performing ANOVA test comparisons between sample groups at the significance level α = 0.05. The degree of conversion of the UD2 resin was higher than that of UE2 for each experimental condition, but there was no statistically significant difference between the DC of those materials (p > 0.05). There was statistically significant difference (p < 0.01) in the DC caused by LED and halogen light sources producing the same light doses (38 J/cm²). This was the result of different features of light transmission to the filler in the resin composite. The efficacy of the LED source is twice as high as that of the halogen light source. Maximal DC without any other differences in conditions, such as resin type or light source, reached around 70% for temperatures of 22–37 °C. For 37 °C, this took 24 h, which is a contrast to the 7 days it took for 23 °C. The influences of different conditions and factors on reaction kinetics are only strong in the early and the rapid stage of conversion. The optimal time of irradiance using either light source is 20 s for a monolayer, and its thickness should not exceed 2 mm. Full article

(This article belongs to the Special Issue Towards Optoelectronic Technology: From Basic Research to Applications)

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66 pages, 52190 KiB

Open AccessEditor’s ChoiceReview

Ultraviolet Photodetectors: From Photocathodes to Low-Dimensional Solids

by Antoni Rogalski, Zbigniew Bielecki, Janusz Mikołajczyk and Jacek Wojtas

Sensors 2023, 23(9), 4452; https://doi.org/10.3390/s23094452 - 2 May 2023

Cited by 21 | Viewed by 7913

Abstract

The paper presents the long-term evolution and recent development of ultraviolet photodetectors. First, the general theory of ultraviolet (UV) photodetectors is briefly described. Then the different types of detectors are presented, starting with the older photoemission detectors through photomultipliers and image intensifiers. More attention is paid to silicon and different types of wide band gap semiconductor photodetectors such as AlGaN, SiC-based, and diamond detectors. Additionally, Ga₂O₃ is considered a promising material for solar-blind photodetectors due to its excellent electrical properties and a large bandgap energy. The last part of the paper deals with new UV photodetector concepts inspired by new device architectures based on low-dimensional solid materials. It is shown that the evolution of the architecture has shifted device performance toward higher sensitivity, higher frequency response, lower noise, and higher gain-bandwidth products. Full article

(This article belongs to the Special Issue Towards Optoelectronic Technology: From Basic Research to Applications)

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