Advancements in Microlenses and their Diverse Applications in Optical Sensors

Dye-based, polymer-based, metal oxide-based and sol-gel composites acceptable for application in optical gas sensors are discussed in present chapter. Requirements to the components of composites for achievement requirement properties, as well advantages and disadvantages of these composites for application in optical sensors are analyzed. Chapter includes 5 figures, 8 Tables and 67 references.

Smart Grid is a promising power delivery infrastructure integrated with communication and information technologies. By incorporating monitoring, analysis, control and communications facilities, it is possible to optimize the performance of the power system, allowing electricity to be delivered more efficiently. In the transmission and distribution sector, online monitoring of transmission lines and primary equipments is of vital importance, which can improve the reliability of power systems effectively. Optical fiber sensors can provide an alternative to conventional electrical sensors for such applications, with high accuracy, long term stability, streamlined installation, and premium performance under harsh environmental conditions. These optical fiber sensors offer immunity to EMI and extraordinary resistance to mechanical fatigue and therefore they will have great potential in on-line monitoring applications in Smart Grid. In this paper, we present a summary of the on-line monitoring needs of Smart Grid and explore the use of optical fiber sensors in Smart Grid. First, the on-line monitoring needs of Smart Grid is summarized. Second, a review on optical fiber sensor technology is given. Third, the application of optical fiber sensors in Smart Grid is discussed, including transmission line monitoring, primary equipment monitoring and substation perimeter intrusion detection. Finally, future research directions of optical fiber sensors for power systems are discussed. Compared to other traditional electrical sensors, the application of optical fiber sensors in Smart Grid has unique advantages.

Chapter 13 - New Materials Based on Imprinted Polymers and their Application in Optical Sensors

In this study, an innovative method is presented for preparing optical fibers for application in fiber optic sensors operating in harsh environments. It is shown, how to attach a metal-coated fiber electrolytically to a metal sensing element, as well as an electroless method for depositing a nickel protective layer on optical fibers. Additionally, the results of the reliability tests of these methods are presented. It is also shown, that by depositing an additional nickel protective layer, it is possible to slow down the oxidation process of the copper coating. Analysis of the conducted experiments allows us to predict, that the connection method investigated and the method of protecting the fiber are robust and may find application in industrial optical sensors.

Optical fiber sensors have been used in military and biomedical applications for twenty years. Industrial and civil engineering applications of optical fiber sensors particularly for mechanical measurements require sometimes quite different configurations and parameters of sensors. In addition, a problem of cost effectiveness of the sensor is not so important for military and medical applications as in industrial ones. Hence each design of optical fiber sensor for mechanical parameter measurements is specific and should be tested not only in laboratory. The paper presents a short overview of methods and systems of optical fiber sensors which are used in mechanical measurements. Selected applications of optical fiber sensors are described in detail. Unique and quite new application of polarimetric fiber optic sensor for dynamic strain measurements is given as well. In conclusion, some advantages and disadvantages of optical fiber sensors applications in mechanical measurements are discussed.

Optical voltage and current sensors offer several benefits for use in high-voltage substations. Interface to relays and other secondary devices is one of the key issues when using optical sensors. Low energy analog interfaces provide an effective way for connecting optical sensors to relays. In this paper, several examples and applications of optical sensors connected to relays and recorders using low and high energy analog interfaces are discussed. In all cases, the performance of the entire system has been satisfactory. Lessons learned in these applications are also discussed

Microfibers have attracted growing interest recently especially in their fabrication methods and applications. This is due to a number of interesting optical properties of these devices, which can be used to develop low-cost, miniaturized and all-fiber based optical devices for various applications (Bilodeau et al., 1988; Birks and Li, 1992 ). For instance, many research efforts have focused on the development of microfiber based optical resonators that can serve as optical filters, which have many potential applications in optical communication and sensors. Of late, many microfiber structures have been reported such as microfiber loop resonator (MLR), microfiber coil resonator (MCR), microfiber knot resonator (MKR), reef knot microfiber resonator as an add/drop filter and etc. These devices are very sensitive to a change in the surrounding refractive index due to the large evanescent field that propagates outside the microfiber and thus they can find many applications in various optical sensors. The nonlinear properties of the micro/nanostructure inside the fiber can also be applied in fiber laser applications. This chapter thoroughly describes on the fabrication of microfibers and its structures such as MLR, MCR and MKR. A variety of applications of these structures will also be presented in this chapter.

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Ferrofluid is a novel kind of functional materials, which possesses both the magnetism of solid magnetic material and fluidity of liquid material. Due to its unique optical properties, especially the refractive index tunability under magnetic field, ferrofluid has been widely utilized for magnetic field and current sensing combined with various optical fiber structures. Hence, in this paper, the refractive index tunability of ferrofluid, which is mainly applied into the optical fiber sensors, is first reviewed and illustrated in detail. Then we mainly introduce our work on the applications of ferrofluid in optical fiber sensors based on the refractive index tunability of ferrofluid, including the whole physical configurations, the operating principles, and the performances of these optical fiber sensors. At last, the deficiencies of ferrofluid in the applications of optical fiber sensors as well as valuable potential prospects in further research are analyzed and presented. From all the above reviews and discussions, it can be foreseen that the characteristics of ferrofluid will be improved and the applications of ferrofluid-based optical fiber sensors will be developed rapidly and maturely.

Recent development and applications of optical and fiber-optic pH sensors

The information and the necessity of engineering monitoring of Dongying Yellow River Bridge are briefly introduced firstly. And then the application of optical fiber sensors in construction supervision, loading test and health monitoring of this bridge is illuminated. The distribution of the internal force monitoring sections, strain and temperature monitoring points and the measuring contents are concisely analyzed. The Encapsulation techniques, installation means and protective measures of optical fiber sensors used in this bridge are also clarified. The author emphasizes the comparison between the theoretical results and actual measuring data derived from optical fiber sensors under some load cases of all the three monitoring phases, which shows that the measuring data is accurate and reliable. Considering its other merits, the author proves that the optical fiber sensors fit the monitoring of large bridge. At last, the outline of health monitoring system integration, especially the accessing of sensors to Interrogator, is showed and the mode of date acquisition, display and analysis, through the long range wireless transmission, is specified.

Review on the graphene based optical fiber chemical and biological sensors

The integration of optical sensors and machine learning (ML) technologies has transformed agricultural monitoring, delivering precise, real-time insights into crop health, growth patterns, and environmental interactions. These sensorsspanning multispectral, hyperspectral, and RGB camerascapture intricate spectral signatures that detect subtle physiological shifts in crops. When paired with ML algorithms, the resulting data streams yield actionable intelligence, informing key decisions in precision agriculture, yield forecasting, and disease control.This Reprint of the second edition of the Special Issue entitled "Novel Applications of Optical Sensors and Machine Learning in Agricultural Monitoring" builds upon the foundational research established by prior studies in the field. Featuring 17 original research articles, this collection tackles key methodological challenges, including data imbalance, improved model transferability, and the fusion of multisensor data for resilient monitoring. Together, these works highlight the advancing capabilities of optical sensors in acquiring high-resolution, multidimensional datasets, which ML models exploit for advanced pattern recognition and predictive modeling. Beyond refining current approaches, the studies within this Reprint pave the way for emerging innovations, such as edge computing and AI-powered automation in agricultural ecosystems.

Recent research progress of optical fiber sensors based on D-shaped structure

Joint USGS‐CUAHSI Workshop: In Situ Optical Water Quality Sensor Networks; Shepherdstown, West Virginia, 8–10 June 2011; Advanced in situ optical water quality sensors and new techniques for data analysis hold enormous promise for advancing scientific understanding of aquatic systems through measurements of important biogeochemical parameters at the time scales over which they vary. High‐frequency and real‐time water quality data also provide the opportunity for early warning of water quality deterioration, trend detection, and science‐based decision support. However, developing networks of optical sensors in freshwater systems that report reliable and comparable data across and between sites remains a challenge to the research and monitoring community. To address this, the U.S. Geological Survey (USGS) and the Consortium of Universities for the Advancement of Hydrologic Science, Inc. (CUAHSI), convened a 3‐day workshop to explore ways to coordinate development of standards and applications for optical sensors, as well as handling, storage, and analysis of the continuous data they produce.